23. BIOSTRATIGRAPHIC SUMMARY FOR LEG 1381 N.J. … · 2006-12-14 · stratigraphic and geochronological efforts that have been devoted to Leg 138 sediments with a view to further

Pisias, N.G., Mayer, L.A., Janecek, T.R., Palmer-Julson, A., and van Andel, T.H. (Eds.), 1995Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 138

23. BIOSTRATIGRAPHIC SUMMARY FOR LEG 1381

N.J. Shackleton,2 J.G. Baldauf,3 J.-A. Flores,4 M. Iwai,5 T.C. Moore, Jr.,6 I. Raffi,7 and E. Vincent8

ABSTRACT

The sediments recovered during Leg 138 have provided us with a remarkable opportunity to improve the stratigraphicframework for east-central Pacific Ocean Neogene age sediments. In this chapter, we review some of the data that have beengenerated and derive best estimates for the ages of potentially useful biostratigraphic datums, within the paleomagnetic temporalframework of Shackleton et al. determined for this volume and also, for comparison, according to the 1985 and 1992 paleomagnetictime scales of Berggren et al. and Cande and Kent, respectively.

INTRODUCTION

Despite advances in magnetostratigraphy, stable isotope stratig-raphy and various manifestations of cyclostratigraphy, it is still truethat biostratigraphy is the essential tool by which the geologicalevidence for environmental changes is put into a temporal frame-work. Advances in biostratigraphy and in other tools for stratigraphiccorrelation go hand in hand, and, in this chapter, we link the multiplestratigraphic and geochronological efforts that have been devoted toLeg 138 sediments with a view to further improvements in the basisof Neogene biostratigraphy and biochronology.

Remarkably high resolution was achieved in the shipboard bio-stratigraphies for all the major microfossil groups examined (Mayer,Pisias, Janecek, et al., 1992). Moreover, considerable further ad-vances have been made in the ensuing months. Detailed descriptionsof the biostratigraphy of the eleven sites cored during Leg 138 aregiven elsewhere: Baldauf and Iwai (this volume) for diatoms; Raffiand Flores (this volume) for nannofossils; Moore (this volume) forradiolarians; Vincent and Toumarkine (this volume) for Mioceneforaminifers; Shackleton, Hall, and Pate (this volume) for foramin-ifers in Site 846. Raffi et al. (this volume) have also reviewed andsynthesized the nannofossil biostratigraphy. In this chapter, we dis-cuss the data primarily in relation to the reliability of, and improvedage calibrations of, a large number of biostratigraphic datum levels.The locations of the Leg 138 sites and of others discussed in the textare given in Table 1.

Shipboard work was conducted using calibrations based on thesummaries by Berggren et al. (1985b). Much of the information forPacific sediments was summarized by Barron et al. (1985a) in areview that was largely based on the successes of Deep Sea DrillingProject (DSDP) Leg 85 (Pisias et al., 1985; Barron et al, 1985b).

1 Pisias, N.G., Mayer, L.A., Janecek, T.R., Palmer-Julson, A., and van Andel, T.H.(Eds.), 1995. Proc. ODP, Sci. Results, 138: College Station, TX (Ocean Drilling Program).

Subdepartment of Quaternary Research, Godwin Laboratory, University of Cam-bridge, Free School Lane, Cambridge, CB2 3RS, United Kingdom.

3 Ocean Drilling Program, Texas A&M University, 1000 Discovery Drive, CollegeStation, TX 77845, U.S.A.

4 Universidad de Salamanca, Departmento de Geologia, S-37008 Salamanca, Spain.5 Institute of Geology and Paleontology, Faculty of Science, Tohoku University,

Aobayama, Aoba-ku, Sendai 980, Japan.6 Center for Great Lakes and Aquatic Sciences, University of Michigan, 2200 Bon-

isteel Boulevard, Ann Arbor, MI 48109-2099, U.S.A.7 Universita degli Studi "G. D'Annunzio," Facoltà di Scienze Matematiche, Fisiche

e Naturli, Castelgandolfo, Italy 00040.8 Laboratoire de Géologie du Quaternaire, CNRS-Luminy, Case 907,13288 Marseille

Cedex 9, France.

TIME SCALE

The calibrations attempted here are possible in part because agemodels that were developed for the sites (Shackleton et al., this vol-ume) were independent of the biostratigraphy to a large extent. Theseage models originated from an astronomical calibration of GRAPEdensity cycles through the entire Pliocene. Because several sites havegood magnetic polarity records, this enabled the Pliocene magneticpolarity sequence to be dated astronomically, confirming the pioneer-ing work of Hilgen (1991a, 1991b). This calibration, together with anew radiometric date for the top of C5n obtained by Baksi (1992,1993), was used to put a new age calibration on the revised polaritysequence compiled by Cande and Kent (1992). Table 2 gives thecomplete polarity time scale of Shackleton et al. (this volume), hence-forth, SCHPS94. The age models developed for each site are verydetailed because they entailed correlating individual GRAPE densitymaxima and minima to insolation maxima and minima; they are listedas Tables 1 to 11 in Shackleton et al. (this volume).

Reliable magnetostratigraphy was obtained for major segments ofthe polarity scale in several sites, as follows: in Site 844, from theBrunhes to C5n; in Site 845, from the Gauss to C5ABn; in Site 848,from the Brunhes to the Gilbert and from C4 to C5n; in Site 850, fromthe basal Matuyama to the uppermost Gilbert; in Site 851, from theBrunhes to the Cochiti; in Site 852, from the Brunhes to C3Aand fromC4A to C5n; in Site 853, from the Brunhes to C4; and in Site 854,from the Brunhes to C5n. Details are given in the site chapters inMayer, Pisias, Janecek, et al. (1992), but it should be noted that partof the record of Site 844 has been reinterpreted by Schneider (thisvolume), who also provided additional data from Site 845. Despitethis broad coverage, we think that, for the section younger than about10 Ma, the reliability of the intersite correlations based on GRAPEdensity fluctuations is so good that datum age estimates should bebased on all sites rather than being based primarily on those sites thatpreserve a magnetostratigraphic record. From that point to the base ofthe magnetostratigraphic record of Site 845, we consider estimatesbased on Site 845 to be the most reliable.

The upper and lower depth limit of each datum (mcd) in each siteis given in Table 3 (complete table on CD-ROM, back pocket), whichsummarizes data in the individual chapters referred to above. We haveobtained the ages of the upper and lower limits defining each datumin each site, using the age models given in Tables 1 to 11 in Shackletonet al. (this volume); these are given in Table 4. In Table 5 (completetable on CD-ROM, back pocket), all the estimates for each datum aresorted by age. This provides an immediate indication of the appar-ent diachrony for each datum; the total (observed) diachrony is theamount by which the oldest age for the upper limit of the datumexceeds the youngest age estimate for the lower limit of the datum.

517

NJ. SHACKLETON ET AL.

Table 1. Location of sites discussed.

Site

ODP 844ODP 845ODP 846ODP 847ODP 848ODP 849ODP 850ODP 851ODP 852ODP 853ODP 854DSDP 608DSDP 573DSDP 574ODP 709ODP 710ODP 714

Longitude

7°55.279'N9°34.950'N3°05.696'S0°11.593'N2°59.634'S0°10.983'N1°17.837'N2°46.223'N5°17.566'N7°12.661'N11°13.433'N42°50.205'N0°29.91'N4°12.52'N3°54.9'S4°18.7'S5°03.6'N

Latitude

90°28.846'W94°35.448'W90°49.078'W95°19.227'W110°28.791'W1IO°31.183'W110°31.283'W110°34.308'W110°04.579'W109°45.084'W109°35.652'W23°O5.252'W133°18.57'W139°19.81'W60°33.1'W60°58.8'E73°47.2'E

Depth(m)

3414.53704.23307.33334.33853.43837.13786.13761.33861.03726.03567.9352643014561303838242038

The figures in Tables 4 and 5 have been used to make best estimatesof the age of each datum.

BEST ESTIMATESFOR BIOSTRATIGRAPHIC DATUMS

It is not obvious what is the most reliable means for obtaining a"best estimate" for each datum. For the majority of datums, we havemade the biostratigrapher's assumption, that the datum is "synchro-nous" and that the "scatter" is noise. In these cases, our aim was toestimate the age of least conflict, rounded to the nearest 0.01 Ma. Weworked with two different approaches. For the first approach, weobtained the median of the upper limits, and the median of the lowerlimits, for each datum. The datum age is the mean of these twofigures; obviously, the smaller the difference between the medianupper and lower limits, the better the estimate. We chose to use themedian, rather than the mean, because the mean is frequently heavilyweighted toward the distant values obtained in sites that were sampledat wider depth intervals. For the second approach, we simply took themidpoint between the oldest of all the upper limits, and the youngestof all the lower limits. If the diachrony is large, this method placesundue weight on discrepant estimates rather than on the best esti-mates. We have assumed that if the diachrony is less than the differ-ence between the medians, the second method proves the more reli-able estimate. A negative figure for diachrony means that there is nooverlap between lower and upper bounds on the estimates for thedatum, as one would expect if the datum is synchronous and there areno inconsistencies in the age models or the observations. Moore (thisvolume) used a graphic method that is related to our second approach,but which is even more conservative. Table 6 gives the estimates ofthe ages of every datum based on each of our two methods.

In the majority of cases, we assumed that the best estimate for theage of a datum was given by whichever of the two methods outlinedabove provided the better-constrained estimate. Only in the relativelyfew cases where diachrony is very clear, have we taken a differentapproach and looked for the youngest, well-constrained sample for anextinction, and the oldest, well-constrained sample for a first appear-ance. For ages younger than about 10 Ma, we have assumed that theage models are equally good for all sites, except that because it wasnot possible to develop high-resolution age models based on GRAPEdensity for Sites 844 and 845 (and parts of Sites 852, 853, and 854),we have used judgment to exclude discrepant estimates from thosesites. On the other hand, for the late Miocene, we paid special atten-tion to estimates that have been directly derived from the magneto-stratigraphy in the same site. For ages between 13.25 and 10 Ma, wehave assumed that estimates made in Site 845, which has a well-preserved magnetostratigraphy, are more reliable than those based on

other sites. This is appropriate since it has not so far proved possibleto develop detailed GRAPE density correlations between sites for theinterval older than 10 Ma. We have no age control other than biostra-tigraphy for those segments of the age models older than 13.25 Mafor any site. However, it is still useful to examine the degree of con-sistency among the age estimates.

Moore et al. (1993) took a different approach; they examined thespatial distribution of radiolarian datum ages among the Leg 138sites. We have not taken this approach for the other microfossil groupsfor two reasons. First, spatially variable preservation has a moreadverse effect on the other groups. Second, although Moore (thisvolume) attempted to cover all sites at comparable resolution, not allsites were examined at the same resolution for the other fossil groups.

In Table 7, we show four ages for each datum. First, we give the bestestimate as estimated above, based on the time scale of Shackleton etal. (this volume) and, hence, related to the magnetic polarity time scalein that chapter (SCHPS94). Second, we recalibrated these estimates tothe polarity time scale (CK92) of Cande and Kent (1992). We have notdiscussed these estimates, but present them for the benefit of those whomay choose to work with that scale. Third, we recalibrated the ageestimates back to the polarity scale (BKF85) presented by Berggren etal. (1985a). This scale was used for the Neogene time scale of Berggrenet al. (1985b), which formed the basis for shipboard work during thisand many other ODP cruises. Thus, the figures in this column (labeled"BKF85") may be compared with other estimates that were also basedon the BKF85 polarity time scale. Fourth, we give the ages (whereavailable) for those datums, as listed by the Shipboard Scientific Party(1992, tables 4-7). Because most of these ages are derived fromBKVC85, they are also based on the BKF85 polarity scale.

In Figure 1, we show the differences between our new estimatesfor the datum ages and those used by the Shipboard Scientific Party(1992, tables 4-7). Although Figure 1 correctly shows the differencesbetween our new calibrations and those previously in use, it is mis-leading because it combines the effect of using a new magnetostrati-graphic time scale with the effect of improving calibrations withrespect to the magnetostratigraphy. For example, the trend of devia-tions away from the zero line arises from the difference between ourmagnetostratigraphic time scale and the one that was the basis for theages used by the Shipboard Scientific Party (1992). Because theobjective of this chapter is to examine the biostratigraphic calibra-tions, we have removed this trend in Figure 2.

In Figure 2, we show differences between our new estimates for thedatum ages after recalculation with respect to the BKF85 magneto-stratigraphic time scale and the ages used by the Shipboard ScientificParty (1992). Several comments may be made about this figure, whichshows the extent to which our calibrations with respect to the magneticpolarity scale differ from those of the Shipboard Scientific Party (1992).First, most of the youngest datums have been studied widely and theirages are already well established with reference to the oxygen isotoperecord (e.g., Hays and Shackleton, 1976; Thierstein et al., 1976; Morleyand Shackleton, 1979; Backman and Shackleton, 1983). As might beexpected, in Figure 2, deviations for these datums fall close to the zeroline. The diatom datums had not previously been examined in the sameway, and we have almost certainly improved their age estimates. Sec-ond, in view of the fact that the magnetostratigraphy of Leg 138 ex-tended only to 13.25 Ma, ages older than that are dependent on earlierbiostratigraphic correlations. Third, the data in Figure 2 are not random;there is a clear tendency for nearby estimates to diverge in the same direc-tion, especially if they are for the same microfossil group. This sug-gests that there were indeed systematic errors in earlier age estimatesand that these were aggravated by the fact that it is only rarely possibleto examine all microfossil groups satisfactorily in the same sections.

NANNOFOSSIL CALIBRATIONS

In the interval from 9 to 13 Ma, there are surprising discrepanciesbetween our estimates and those used earlier that deserve comment.

518

BIOSTRATIGRAPHIC SUMMARY

Table 2. Magnetic polarity time scale used in this work (SCHPS94) and in previous studies (BKF85, CK92).

Name(BKF85 or

conventionalanomaly)

Brunhes/MatuyamaJaramillo (t)Jaramillo (o)Olduvai (t)Olduvai (o)Matuyama/GaussKaena (t)Kaena (o)Mammoth (t)mammoth (o)Gauss/GilbertCochiti (t)Cochiti (o)Nunivak (t)Nunivak (o)Sidufjall (t)Sidujfall (o)Thvera (t)Thvera (o)3A3A3A3A

4444444A4A4A4A

55

5 A5 A5A5 A

BKF85Age(Ma)

0.730.910.981.661.882.472.922.993.083.183.403.883.974.104.244.404.474.574.775.355.535.685.896.376.506.706.786.857.2S7.357.417.908.218.418.508.718.808.92

10.4210.5410.5911.0311.0911.5511.7311.8612.1212.4612.4912.5812.62

CK92Age(Ma)

0.7800.9841.0491.7571.9832.6003.0543.1273.2213.3253.5534.0334.1344.2654.4324.6114.6944.8125.0465.7055.9466.0786.3766.7446.9017.2457.3767.4647.8928.0478.0798.5298.8619.0699.1499.4289.4919.592

10.83410.94010.98911.37811.43411.85212.00012.10812.33312.61812.64912.71812.764

SCHPS94Age(Ma)

0.7800.9901.0701.7701.9502.6003.0543.1273.2213.3253.6104.1884.3204.4784.6044.7824.8804.9815.2285.8756.1226.2566.5556.9197.0727.4067.5337.6188.0278.1748.2058.6318.9459.1429.2189.4829.5439.639

10.83910.94310.99111.37311.42811.84111.98812.09612.32012.60512.63712.70512.752

Nameunified(CK92)

Cln(o)Clr.ln(t)Clr.ln(o)C2n (t)C2N (o)C2An.ln(t)C2An.ln(o)C2An.2n (t)C2An.2n (o)C2An.3n (t)C2An.3n (o)C3n.ln(t)C3n.ln(o)C3n.2n (t)C3n.2n (o)C3n.3n (t)C3n.3n (o)C3n.4n (t)C3n.4n (o)C3An.ln(t)C3An.ln(o)C3An.2n (t)C3An.2n (o)C3Bn (t)C3Bn (o)C4n.ln(t)C4n.ln(o)C4n.2n (t)C4n.2n (o)C4r.ln(t)C4r.ln(o)C4An (t)C4An (o)C4Ar.ln(t)C4Ar.ln(o)C4Ar.2n (t)C4Ar.2n (o)C5n.ln(t)C5n.2n (o)C5r.In(t)C5r.ln(o)C5r.2n (t)C5r.2n (o)C5An.ln(t)C5An.ln(o)C5An.2n (t)C5An.2n (o)C5Ar.ln(t)C5Ar.ln(o)C5Ar.2n (t)C5Ar.2n (o)

Name(BKF85 or

conventionalanomaly)

5AA5AA5AB5AB5AC5AC5AD5AD5B5B5B5B5C5C5C5C5C5C5D5D5E5E666A6A6A6A6AA6AA6AA6AA6B

6B6C6C6C6C6C6C

7

BKF85Age(Ma)

12.8313.0113.2013.4613.6914.0814.2014.6614.8714.9615.1315.2716.2216.5216.5616.7316.8016.9817.5717.9018.5619.0919.3520.4520.8821.1621.3821.7121.9022.0622.2522.3522.57NANA

22.9723.2723.4423.5523.7924.0424.21NANA

25.5

Notes: BKF85 = Berggren et al.SCHPS94 = Shackleton et al.

CK92Age(Ma)

12.94113.09413.26313.47613.67414.05914.16414.60814.80014.89015.03815.16216.03516.31816.35216.51516.58316.75517.31017.65018.31718.81719.08320.16220.54620.75221.02121.343NANA

21.78721.87722.16622.26322.47122.50522.59922.76023.35723.53723.67823.80023.99724.11524.722

SCHPS94Age(Ma)

12.92913.08313.25213.46613.66614.05314.15914.60714.80014.89015.03815.16216.03516.31816.35216.51516.58316.75517.31017.65018.31718.81719.08320.16220.54620.75221.02121.343

21.78721.87722.16622.26322.47122.50522.59922.76023.35723.53723.67823.80023.99724.11524.722

(1985a), CK92 = Cande and(this volume).

Nameunified(CK92)

C5AAn (t)C5AAn (o)C5ABn (t)C5ABn (o)C5ACn (t)C5ACn (o)C5ADn (t)C5ADn (o)C5Bn.ln(t)C5Bn.ln(o)C5Bn.2n (t)C5Bn.2nC5Cn.ln(t)C5Cn.ln(o)C5Cn.2n (t)C5Cn.2n (o)C5Cn.3n (t)C5Cn.3n (o)C5Dn (t)C5Dn (o)C5En (t)C5En (o)C6n (t)C6n (o)C6An.ln(t)C6An.ln(o)C6An.2n (t)C6An.2n (o)

C6AAn (t)C6AAn (o)C6AAr.ln(t)C6AAr.ln(o)C6AAr.2n (t)C6AAr.2n (o)C6Bn.ln(t)C6Bn.ln(o)C6Cn.ln(t)C6Cn.ln(o)C6Cn.2n (t)C6Cn.2n (o)C6Cn.3n (t)C6Cn.3n (o)C7n.ln(t)

Kent (1992), and(t) = termination and (o) = onset.

In BKF85 column, NA = not present in Berggren et al.column, NA = exact equivalent not present i

(1985a). In CK92n Cande and Kent (1992).

0 5 10 15

Age Ma (SCHPS94 time scale)

Figure 1. Differences between literature ages (Shipboard Scientific Party, 1992,

largely based on, or intended to be consistent with, Berggren et al., 1985b) and

ages estimated on the basis of Leg 138 results, based on the SCHPS94 time scale

(Shackleton et al., this volume). Open squares = diatoms, open diamonds =

foraminifers, open triangles = nannofossils, and crosses = radiolarians.

0 2 4 6 8 10 12 14 16


Figure 2. Differences between literature ages (Shipboard Scientific Party,

1992, largely based on, or intended to be consistent with, Berggren et al.,

1985b) and ages estimated on the basis of Leg 138 results, but recalculated in

terms of the magnetic polarity time scale used by Berggren et al. (1985a).

Symbols as in Figure 1.

519


Table 3. Depths (mcd) of datums in Leg 138 sites.

tttbtbtthbbtbtbtti

i

bbbtbi

tbtbbi

b1

bbb1

tbbi

bbt1tbbtb

N. reinholdiiN. fossil isR. matuyamaR. matuyamaR. praebergonii var. robustaP. doliusT. convexaN. jouseaeR. praebergoniiT. convexa f. convexaA. elegansN. cylindricaN. jouseaeT. miocenicaT. oestrupiiN. miocenicaN. miocenica var. elongataT. praeconvexaR. praepaleaceaT. miocenicaT. convexa var. aspinosaT. praeconvexaN. porteriN. miocenicaR. paleaceaT. btircklianaN. reinholdiiA. ellipticus var. javanicusN. marinaN. cylindricaT. yabeiA. nodulifer var. cyclopsC. loeblichiiN. fossilisT. burcklianaC. loeblichiiD. hustedtiiA. moronensisA. ellipticus f. lanceolataR. paleacea var. elongataC. gigas v. dioramaS. jouseanaC. coscinodiscusA. ingensC. pulchellusN. porteriT. bruniiC. gigas v. dioramaA. californicusC. lewisianusT. tappanaeT. cinnamoneumD. simonseniiC. peplumA. ellipticus

844

(t)

NA1.20NANANA

17.0024.3017.5519.92NANANA

24.9336.00NANA

33.0024.93NANA

37.8539.35

NA42.3342.33

NA43.85

NANA

47.8046.55

NA53.80NA

53.8056.6265.7069.86

NANANA

89.7589.75

123.12123.12

NA123.12

NA126.15147.71152.82157.70163.61172.67183.48

844(o)

NA2.40NANANA

19.9228.6024.9324.93NANANA

37.8537.85NANA

36.0037.85

NANA

39.3541.55

NA43.8543.85

NA45.35

NANA

49.3047.80

NA56.62

NA56.6268.7668.7671.35

NANANA

100.90100.90132.75132.25

NA132.95

NA132.75152.82163.61167.61172.67183.48193.03

845(t)

23.1521.2524.2525.75NA

38.6246.8150.6651.3061.16NA

72.6771.1786.3179.6089.31NANANA

92.0892.08

NANA

92.37NANANANANANA

121.79NANANANANA

134.74NANANA

166.35NANA

188.97176.76

NANANANA

205.15NANANA

251.00NA

845(o)

25.0224.2525.7527.25

NA39.9148.3151.3053.1662.66

NA74.1772.6787.6180.6590.61

NANANA

102.09102.09

NANA

107.06NANANANANANA

123.69NANANANANA

145.65NANANA

170.64NANA

190.96188.97

NANANANA

211.06NANANA

270.75NA

846

(t)

21.3723.7534.6349.9567.0073.3080.50

107.10125.50148.70

NA191.02202.45233.45233.45249.90250.26250.26

NA266.01266.01267.22283.00288.30293.60

NANANANA

309.60310.00

NANANANANA

328.44NA

337.48355.00355.00

NA355.00371.70

NA373.83373.83388.50

NA387.00

NANANANANA

846(o)

23.7526.2239.2150.7467.5074.0080.80

108.70125.70149.60

NA193.76203.50234.25234.25250.26261.18261.18

NA267.22267.22271.90284.05288.70293.80

NANANANA

310.20310.20

NANANANANA

328.60NA

347.78356.20356.20

NA356.20373.83

NA376.63374.00389.40

NA390.30

NANANANANA

847

(t)

12.3716.21NANA

52.2067.3579.7892.58

102.91121.23127.10145.83177.25184.54

NA193.87

NA215.60

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

847(o)

14.8320.05NANA

54.5668.8581.0194.83

104.10124.61135.05153.76180.25193.87

NA204.90

NA222.75

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

848

(t)

8.448.44

NANA24.3528.0629.7531.3534.3537.5535.5243.5548.60NANA59.1063.6063.6069.3570.8570.8572.35NA80.1680.16NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

848(o)

12.2712.27NANA

25.6828.2530.5132.7534.6439.0543.5546.1850.75NANA63.0665.0769.3570.8571.8571.8573.85NA80.7580.75NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

Notes: Full generic names appear in Table 6. In column headings, (t) = termination, and (o) = onset. In first column, t = top of range, b = bottom of range, tc = top of common occurrence,and be = bottom of common occurrence. NA = not present.

Only the first page of this table is reproduced here. The entire table appears on the CD-ROM (back pocket).

First, our age for the base of Discoaster hamatus, when convertedback to BKF85, is 9.87 Ma, whereas Backman et al. (1990) derivedan age of 10.50 Ma at tropical Indian Ocean DSDP Site 710 withprimary magnetostratigraphic control. However, Olafsson (1991) ob-tained an age of 9.9 Ma in Site 608 in the North Atlantic, also withprimary magnetostratigraphy. The base of C5N.2n is more securelydetermined both in that site and in Site 845 than in Site 710. Weconclude that our estimate is probably better than that of Backman etal. (1990).

The upper limit of Coccolithus miopelagicus in Site 608 is somedistance below the base of Discoaster hamatus (Olafsson, 1991),whereas the two datums are consistently close to each other in Leg138 sites (but in both regions, the upper limit of C. miopelagicus liesbetween the first occurrences of Catinaster coalitus and D. hamatus).Our estimate for the age of the base of D. hamatus is consistent withthat of Olafsson (1991). Thus, it seems likely that C. miopelagicus

disappeared earlier in the region of Site 608 than in the equatorialPacific and, hence, that ours is the more reliable estimate of the truelast appearance datum (LAD) of the species.

The base of Catinaster coalitus was estimated at 11.1 Ma byBackman et al. (1990), whereas our estimate is equivalent to 10.31Ma on the BKF85 scale. However, Backman et al. (1990) based theirestimate on an interpolation between the base of Discoaster hamatus(for which they used an age of 10.5 Ma) and the upper limit ofSphenolithus heteromorphus at 13.5 Ma; their estimate would becloser to ours using our age (discussed above) for the base of D.hamatus, and we conclude that our estimate is reliable.

Our age for the upper limit of Coronocyclus nitescens is equiva-lent to 11.86 Ma on the BKF85 scale, whereas Rio et al. (1990)obtained 12.66 ± 0.19 Ma at tropical Indian Ocean DSDP Site 714.Their age is based on an inteΦolation between the ages for the baseof Catinaster coalitus and the upper limit of Sphenolithus hetero-


morphus, using the ages obtained by Backman et al. (1990). Usingour ages for these two events, the discrepancy is significantly re-duced. The uncertainty quoted by Rio et al. (1990) is based on thelarge gap between the conventional depth (mbsf) for the core-catchersample and the remainder of the recovered core; probably a youngerage estimate would be more realistic, also, in view of the fact that thebase of Discoaster kugleri was observed higher in the same core(recovery in Site 714, Core 9H was less than 5 m; we assume that thesample given in Rio et al., 1990, table 26, as 714A-9H-5-30 was, infact, 714A-9H-4-30).

The age for the base of Discoaster kugleri in Site 714 (Backmanet al., 1990) was again based on a linear interpolation between thebase of D. hamatus (for which they used an age of 10.5 Ma) and theupper limit of S. heteromorphus at 13.5 Ma; our estimate is not inconflict with their data. The sedimentation rate in Site 714 was lowand, in light of our findings, it is significant that Rio et al. (1990)found the upper limit for Coronocyclus nitescens at the same positionas the lower limit of D. kugleri in Site 709, which has a much highersedimentation rate, confirming that these datums are close in age.

For the base of Triquetrorhabdalus rugosus, our estimate is essen-tially identical, when converted to the BKF85 scale, with that ob-tained by Olafsson in Site 608 with direct paleomagnetic control. Ourestimate for the upper limit of Cyclicargolithus floridanus agrees wellwith that given by Backman et al. (1990), based on an interpolationat central Pacific DSDP Site 574. Olafsson (1991) showed that thisspecies survived much longer at mid-latitude Site 608 (see also Raffiet al., this volume). However, our estimate for the base of Reticulo-fenestra pseudoumbilicus is equivalent to 13.88 Ma on the BKF85scale, much older than the 12.70 Ma estimate of Olafsson based onSite 608. In Site 608, the base of/?, pseudoumbilicus is well separatedfrom the upper limit of Sphenolithus heteromorphus, whereas at thethree Leg 138 sites that contain both datums, they were observed tocoincide. Because our estimate for the top of 5. heteromorphus is onlyslightly older than Olafsson's estimate based on Site 608, we assumethat this datum is essentially synchronous and that the first appearanceof R. pseudoumbilicus in the region of Site 608 is nearly 1 m.y. afterits first appearance in the Leg 138 region. Our estimate in Table 4 forthe upper limit of S. heteromorphus depends on a somewhat poorlyconstrained age model in Site 845, and an extension of the sedimen-tation rate observed in the interval with magnetostratigraphic controlyields a younger age estimate (about 13.47 Ma; Raffi and Flores, thisvolume) that is closer to that estimated by Olafsson (1991).

RADIOLARIAN AND DIATOM CALIBRATIONS

The ages for several of the radiolarian datums have been com-pared with estimates (Shipboard Scientific Party, 1992) that weremade by Johnson and Nigrini (1985) for the central Pacific DSDP Site573. Their estimates were based on an age model for the site that, inturn, depended on datum levels for the other microfossil groups, sothat precise comparison is inappropriate; we comment only on thosecases where a major disagreement is evident. Our age for the base ofDiartus pettersoni is equivalent to 11.56 Ma on the BKF85 scale,about 1 m.y. younger than that given by Johnson and Nigrini (1985)for Site 573. However, these authors observed much younger firstappearances in the western Pacific (11.0-11.3 Ma) and the IndianOcean (10.6-10.8 Ma), so that the first appearance of this species maybe significantly diachronous (conceivably explaining the seeminglyearlier appearance in Site 846). The upper limit of Dorcadospyrisalata displays an even greater discrepancy; again, however, Johnsonand Nigrini (1985) reported widely discrepant estimates in differentregions, with our estimate being closer to theirs for the westernPacific and for Site 573.

Regarding the diatom datums, it is significant that a number of theliterature estimates that we use (Shipboard Scientific Party, 1992) arebased on pioneering work by Burckle (1978) on piston cores fromthe equatorial Pacific Ocean that preserved magnetostratigraphic rec-

ords, but at a major sacrifice in sedimentation rate. In general, our ageestimates are close to the published figures, but with a pattern ofconsistent offsets for nearby datums that probably arise from artifactsof very low accumulation rate. We assume that our estimates, basedon higher sedimentation rates, are more reliable.

Our age estimates for the last appearance of Nitzschia cylindricaand the first appearance of Nitzschia jousseae are older than those ofBurckle (1978) and Barron et al. (1985a). It is possible that thisreflects a difference in species concepts, because forms intermediatebetween the two species were observed in Leg 138 sediments. Simi-larly, the age of the first appearance of Thalassiosira oestrupii maybe affected by differing species concepts.

FORAMINIFERAL DATUMS

For the upper limit of Globigerinoides fistulosus, we have in-cluded additional data from Sites 846 and 849 contributed by A.C.Mix (pers. comm., 1993). Samples typically contain only one or twospecimens, but one may assume that these are not reworked, as thereis no reservoir of material rich in this species to provide reworkedspecimens. The upper limit in Site 846 is at about the same age asobserved in Site 677 (Shackleton et al., 1990), but in Site 849 it issomewhat earlier. Several of the Pliocene datums were only deter-mined at close intervals in Site 846 (Shackleton et al., this volume);the estimates provided by that site are in excellent agreement withprevious data. In the middle Miocene sections, useful calibrationscome from Sites 844, 845, and 846.

INDIVIDUAL SITE AGE-DEPTH PLOTS

Figures 3 through 13 show the limits within which each datum isplaced in each site, plotted at the ages estimated in Table 7 (columnlabeled "SCHPS94"). For each site, the line represents the age modelfrom Shackleton et al. (this volume). These figures enable us to identifysite-specific problems (sedimentation rates are given by Shackleton etal, this volume). For example, Figure 5 suggests that there is a problemin the lower part of Site 846, where the base of Discoaster kugleriand the base of Diartus pettersoni both fall well off the calibrationline. These two datums fall in Core 138-846B-38X; the recovery inCore 138-846B-37X was low, and nothing was recovered in Core138-846B-39X. The distribution of D. kugleri above its reported firstappearance is erratic, and it is possible that this core contains mixedmaterial, although Raffi et al. (this volume) remind us that the firstappearance of D. kugleri is an unreliable marker.

In Figure 3 (Site 844), the apparent wide limits on the deepest twodiatom datums indicate that they fall between the lowest sample exam-ined and the bottom of the hole. In Figure 6 (Site 847), the departuresof three diatom datums from the age-depth line may indicate an errorin the age model, but this is not certain because in this site the diatomstratigraphy is based only on shipboard work. In Figures 12 and 13(Sites 853 and 854), a combination of poor preservation and low sedi-mentation rate limited the time resolution of many determinations.

WHICH DATUMS ARE SYNCHRONOUS?

Moore et al. (1993) have already examined the radiolarian datumlevels discussed here and separated out those that are broadly syn-chronous over the range covered by Leg 138 from those that are not.They were able to show, for those datums that are clearly nonsynchro-nous, that the spatial pattern of each extinction or first appearance isrelated to the presence of the species in some, but not all, of the watermasses overlying the Leg 138 coring sites, either shortly after thespecies first appears, or as its geographic range is reduced beforeextinction. Clearly, the reverse is axiomatically true: a datum cannotappear synchronous unless the species spread rapidly into all therelevant water masses when it first appeared, and its demise was notpreceded by a perceptible contraction in viable range.

521


Table 4. Ages (Ma) of datums in Leg 138 sites.

844

(I)

844

(o)845

(t)

845(o)

846

(t)

846

(o)

847

(t)

847

(o) (t) (o)

t N. reinholdiit N. fossilist R. matuyamab R. matuyamat R. praebergonii var. robustab P. doliust T. convexat N. jouseaeb R. praebergoniib T. convexa f. convexab A. eleganst N. cylindricab /v*. jouseaet 7*. miocenicab 7. oestrupiit M miocenicat /V. miocenα var. elongαtαt 7. prαeconvexαt /?. prαepαleαceαb 71 miocenicab 7". convexa var. aspinosab 7". praeconvexat /V. portedb M miocenicat /?. paleaceat 7". burcklianab /V. reinholdiit A ellipticus var. javanicusb M marinab /V. cylindricat T. vw/>eib A. nodulifer var. cyclopst C. loeblichiib TV. fossilisb 7*. burcklianab C loeblichiit Zλ hustedtiit A moronensisb A ellipticus f. lanceolatab ft. paleacea var. elongatat C g/gαs v. dioramat 5. jouseanat C. coscinodiscust A. ingenst C. pulchellust M porterib 7". bruniib C. g/gαs v. dioramat A. californicust C. lewisianust 7". tappanaeb 7. cinnamoneumb D. simonseniit C. pephtmb A. ellipticusb C blysmost A. californicusb A. ingenst C lewisianus var. similist 7". fragab C peplumt /?. marylandicusb C. coscinodiscus ss.b C nicobaricab E. huxleyit P. lacunosab Reentry medium Gephyrocapsa spp.t Large Gephyrocapsa spp.b Large Gephyrocapsa sppt C. macintyreib G. oceanic a si.t D. brouwerit Zλ pentaradiatust Zλ surculust Zλ tamalist 5. αfo/Mt /?. pseudoumbilicusbe D. asymmetricust A. primust C. acutusb C. rugosusb C. acutust 7. rugosust D. quinqueramust Circular reticulofene.stridst A. amplificus

NA0.115

NANANA

1.6293.2031.7002.114

NANANA

3.4616.002

NANA

5.5203.461

NANA

6.2566.657

NA7.2037.203

NA7.477

NANA

7.8517.749

NA8.025

NA8.0258.9049.906

10.266NANANA

11.24811.24812.21812.218

NA12.218

NA12.32712.92213.05313.18013.34013.5963.9014.1734.7585.2405.4666.3746.3746.3746.8596.859

NA0.3630.9071.0701.3601.4511.8132.1522.5102.916

NANA

NANANA

5.444NANANA

5.520NA

5.858

NA0.187

NANANA

2.1144.6593.4613.461

NANANA

6.2566.256

NANA

6.0026.256

NANA

6.6577.024

NA7.4777.477

NA7.651

NANA

7.9747.851

NA8.904

NA8.904

10.16810.16810.400

NANANA

11.56611.56612.56612.548

NA12.573

NA12.56613.05313.34013.45313.59613.90114.17314.49515.01815.46615.65916.59616.59616.59618.08118.081

NA0.5131.0701.2621.4511.6871.9162.2272.9163.418

NANANA

NANA

5.477NANANA

5.562NA

5.889

0.9570.8611.0131.088

NA1.7382.3412.7292.7933.742

NA4.9304.7435.8095.4356.040

NANANA

6.2126.212

NANA

6.226NANANANANANA

8.251NANANANANA

8.856NANANA

10.964NANA

12.05411.479

NANANANA

12.611NANANA

14.559NANANANANANA

16.276NANANANA

0.7010.9431.1711.2601.4121.6391.9612.573

NANANANANANANA

NA5.336

NA5.435

NANA

1.0511.0131.0881.164

NA1.8032.4922.7932.9813.895

NA5.0634.9305.8865.4936.141

NANANA

6.9766.976

NANA

7.339NANANANANANA

8.343NANANANANA

9.503NANANA

11.191NANA

12.12312.054

NANANA

NA12.796

NANANA

15.595NANANANANANA

16.450NANANANA

0.7161.0191.1941.3361.4871.7152.0972.622

NANANANANA

NANANA

5.351NA

5.458NANA

0.5560.6390.9181.3461.8581.9812.1322.7383.1353.774

NA4.8875.2225.8025.8026.1026.1116.111

NA6.5196.5196.5597.1257.2477.387

NANANANA

8.1868.235

NANANANANA

9.315NA

9.94011.08611.086

NA11.08612.031

NA12.15012.15012.966

NA12.883

NANANANANANANANANANANANANANANA

0.4381.0171.2281.5231.6161.6682.057

NA2.5092.9583.6083.7394.1344.4894.9255.0635.326

NA5.5865.9986.010

0.6390.7151.0791.3611.8701.9972.1422.7623.1403.806

NA4.9515.2425.8075.8076.1116.3656.365

NA6.5596.5596.7457.1477.2627.390

NANANANA

8.2598.259

NANANANANA

9.325NA

10.74611.16011.160

NA

11.16012.150

NA12.30612.15913.016

NA13.066

NANANANANANA

NANANANANANANANANA

0.4521.0471.2511.5421.6541.6802.069

NA2.5253.0133.6373.8484.1484.5064.9415.0925.348

NA5.5906.0106.020

0.3650.490

NANA

1.6602.0302.4242.8013.1593.7934.0264.5985.1915.368

NA5.605

NA6.074

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

0.0950.4091.0001.2221.4821.5801.7242.060

NA2.5962.7583.6833.7894.4664.5074.9765.0755.345

NA5.659

NANA

0.4540.650

NANA

1.7122.0602.4502.8763.2063.9184.3324.6775.2655.605

NA5.830

NA6.185

NA

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

0.1460.4491.0271.2401.4981.6021.7612.078

NA2.6122.7813.7013.8134.4864.5405.0185.0915.348

NA5.678

NANA

0.5530.553

NANA

1.5842.0492.3672.6383.1813.8373.4114.6985.093

NANA

5.6445.9825.9826.4606.5756.5756.697

NA7.3337.333

NANANANANA

NANANANANANA

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

0.3771.0211.187 •

1.4291.5621.6011.8452.4912.4912.7003.4113.7624.0274.3814.9195.2405.310

NA5.542

NA5.897

0.7750.775

NANA

1.7462.0692.4992.8373.2494.1924.6984.8795.240

NANA

5.9396.1016.4606.5756.6566.6566.819

NA7.3827.382

NANANA

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

NANANANANA

NA0.4601.0241.2271.4981.6011.6151.8912.5622.5622.8103.6493.8374.1924.4685.0145.2545.328

NA5.559

NA5.917


Table 4 (continued).

3 A. amplificus3 Circular reticulofenestridst Absence R. pseudoumbUkus3 A. primust M. convallisD D. berggrenii3 D. pentaradiatusb D. loeblichi3 Absence R. pseudoumbUkus: D. hamatus3 M. convallisb Zλ neohamatusb C. coalitusb Zλ hamatust C. miopelagicust C. floridanust C. nitescens:c D. kugleri3c Zλ kugleriJ D. kugleri3 C. macintyrei: C. premacintyrei3 7". rugosust Zλ signus3 /?. pseudoumbUkust 5. heteromorphust A/, ampliaperturab Zλ signust Acme D. deflandreit S. universusb C. tuberosat L. neoheteroporost A angularet 7! vetulum3 L. nigriniae3 7". trachelium3 P. minithorax3 A. angularet P. prismatiumt L. heteroporost A. jenghisi3 7*. davisianat S. peregrinat A. pliocenicab L. heteroporost Z.. audax

t P. fistula•3 L. neoheteroporost P. doliumb A. ypsilont D. penultimab S. tetrasb P. prismatiumt S. omnitubust 5. coronat S. johnsoni3 5. delmontensis to 5. peregrinat C caepab 5. omnitubust Zλ hughesib 5. berminghamit 5. wWj07

t ß. miralestensist Zλ pettersonib Zλ hughesib Zλ pettersoni to D. hughesit C japonicat C cristatat L. thornburgit L. renzaet C cornuta3 Zλ pettersonit Zλ α/αtob C japonicab C. cαe/jflb L. thornburgit S. armatat L parkeraet 0. octopylet C. bramletteit C costatab Zλ dentata to D. a/wto: L. stauropora3 L. parkerae: S. diaphenes3 C. bramlettei

844(t)

6.608NA

6.8947.2087.6938.0148.0088.0048.6959.3739.358

NA10.69210.21310.34713.55812.41211.31111.77112.391

NA12.76412.94613.04214.03914.03915.78616.204

NA0.3630.3630.9420.9421.0831.0831.4511.4511.4511.4511.4512.2062.5682.5682.9362.9363.8435.1802.2063.8433.4613.8433.4613.4615.5545.8075.7685.8075.8077.2037.467NA

8.0007.7498.0228.0008.0009.914

10.1688.904

11.82411.74411.82411.82412.32713.51012.98013.76114.41014.49514.88215.17315.46615.65915.65915.84417.019

844(o)

6.656NA

6.9467.3547.7338.0088.0048.3068.7589.4049.397NA

10.76110.34710.48113.58312.44511.36011.78712.412

NA12.79712.97013.10714.05514.05515.84016.219

NA0.7370.737

::

::

.083

.083

.451

.451

.933

.933

.933

.933

.9332.5682.9362.9363.4613.4615.1805.3002.5685.1803.8435.1805.1803.8435.8076.8796.8796.8796.8797.4677.749NA8.9048.0228.0088.9048.904

10.16810.5259.671

11.90111.82411.90111.90112.35113.59313.05313.90114.49514.59715.01815.24915.56615.77415.77415.91917.099

845(t)

6.552NA6.7447.175NA8.461NANANANANANA

10.71010.27210.41713.18312.10711.36411.70212.13012.13012.22812.636

NA13.84013.84015.89816.18716.2020.4020.575

.024

.053

.124

.194

.597

.487

.738

.668

.4872.0292.6222.8573.2893.1033.9673.2893.1673.9673.5934.7373.8054.3295.2987.0566.4356.7596.9777.1427.588NA

8.7968.2148.5878.8548.671

10.05510.37311.41211.74411.80711.80711.83812.42813.12113.60513.62614.17714.17714.17715.01015.84615.90315.91916.01116.052

845(o)

6.583NA

6.7837.381NA

8.485NANANANANANA

10.74310.29010.43113.20112.13011.38411.71912.14512.14512.26212.677NA

13.86113.86115.91216.20216.2290.4230.701

.053

.099

.194

.279

.740

.597

.798

.738

.5972.3312.8572.8803.5933.1674.0393.5933.2404.0393.6414.8493.8854.3585.3457.1426.5436.8077.0567.2667.627NA

8.8548.2478.6318.9038.724

10.10610.51811.44011.80711.83811.83811.86912.50113.19413.62613.67314.60714.60714.60715.05215.86115.91915.93216.02516.097

846(t)

6.1086.3997.0397.1117.7167.927NA

8.3948.6319.7609.337NA

10.69610.40310.55113.33013.33011.33511.77913.278

NANAXANA

13.33013.33015.64415.971

NA0.3810.4540.9881.1161.2221.2221.5591.4491.6871.6872.0692.3452.7142.7143.2683.3503.9894.3053.4214.0423.6504.1344.0424.7195.5025.5026.4196.5596.5597.2617.639NA

8.8418.3668.3669.1818.590

10.03210.77810.77811.76011.89812.974

NA12.348

NANANANANANANANANANANANA

846(o)

6.1536.4597.0707.1227.7897.953NA

8.5008.7139.7989.434NA

10.72310.49210.64014.05414.05411.36911.87513.317

NANANANA

14.05414.05415.93916.484

NA0.4170.603

.053

.145

.257

.257

.652

.479

.824

.8242.0902.3912.7972.7973.3033.3704.0424.3433.4384.1343.7484.1834.1344.7345.5335.5336.4916.6506.6507.3187.657NA

8.8728.5908.5909.3158.717

10.14810.84110.84111.81411.98113.225NA12.437


847(t)

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

0.404 (

847(o)

NANANANANANANANANANANANAXANTANANANANANANANANANANANANANANAXA).49O

0.583 0.6621.0671.0941.2231.1481.5041.5431.7121.7122.038 :2.450 :

.094

.148

.260

.223

.543

.703

.778

.778'.129!.609

2.713 2.7892.789 :3.201 :2.979 :3.562

1.8015.338(.048$.710

4.094 4.1062.979 :(.0484.094 4.1063.918 4.0944.106 4.2274.106 4.2274.829 4.8655.368 f5.662 i6.418 (

i.475i.756>.476

6.418 6.5916.476 (

NANANANANANANANANANANANANANANANANANANANANANANANANANANANA

5.520NANAXANANANANANANANANAXAXANANANANAXANANANAXAXANANANANANA

848(t)

6.490NA

6.9137.3168.2458.362NA

8.5358.5359.3799.1829.538NA

10.26110.288

NAXANAXAXAXAXAXANANANANANΛNA

0.4740.6321.0891.1221.1541.2201.4671.7461.7461.6901.4672.3542.6382.6383.5912.4713.6633.6632.4713.6633.8044.0524.0524.7514.9495.4246.3036.5676.1707.0577.506NA

8.8188.0178.4898.8188.718NANANANANANAXANANANANANANANANAXANANANANA

848(o)

6.509NA6.9297.3648.3628.473NA

8.5998.5999.4089.2069.660NA

10.28810.317

NANANANANANANANANAXAXAXANAXA

0.5610.6441.1201.1541.1861.2511.5201.7911.7911.7411.5202.4712.7092.7094.1562.5623.6753.6752.5623.6753.9264.1494.1494.7864.9925.4976.3456.5726.2257.4547.647NA

8.8938.1988.5658.8938.818NAXAXAXANANANANANANAXAXANAXANANAXANANANA



849(t)

844(o)

850(t)

850(o)

851(t)

851(o)

852(t)

852(o)

853(t)

853(o)

854(t)

854(o)

t N. reinholdüt N. fossilist R. matuyamab R. matuyamat R. praebergonii var. robustab P. doliust T. convexat N. jouseaeb R. praebergoniib T. convexa f. cowexab A. eleganst M cylindricab N. jouseaet T. miocenicab 7. oestrupiit /V. miocenicat /V. miocena var. elongatat 7". praeconvexat /?. praepaleaceab 7. miocenicab 7*. com•fctt/ var. aspinosab 7". praeconvexat /V. portedb iY. miocenicat /?. paleaceat 7". burcklianab /V. reinholdiit A ellipticus v&r.javanicusb /V. marinab /V. cylindricat 7". yαb<?/b A nodulifer var. cyclopst C. loeblichiib /V. fossilisb 7". burcklianab C. loeblichiit D. hustedtiit A moronensisb A ellipticus f. lanceolatab /?. paleacea var. co/n>eαit C. g/gfli v. dioramat 5. jouseanat C. coscinodiscust A ingenst C pulchellust /V. porterib 7. bruniib C. g/gα.ç v. dioramat A californicust C. lewisianust 7". tappanaeb 7". cinnamoneumb D. simonseniit C. peplumb A ellipticusb C blysmos

A. californicustb A ingenst C. lewisianus var. similist 7". fragab C. peplumt /?. marylandicusb C. coscinodiscus ss.b C nicobaricab £. huxleyit P. lacunosab Reentry medium Gephyrocapsa spp.t Large Gephyrocapsa spp.b Large Gephyrocapsa spp.t C. macintyreib G. oceanic a si.

D. brouweriD. pentaradiatusD. surculusD. tamalisS. abiesR. pseudoumbilicus

tttt

ttbe D. asymmetricust A primust C acutusb C. rugosusb C. acutust 7. rugosust D. quinqueramust Circular reticulofenestridst A amplificus

0.3610.9420.9421.110.700

1.9572.3802.7333.1413.764NA

4.9345.1595.812NA

6.0536.0536.053NA

6.4926.4926.713NA

7.235NA

8.2707.5737.507NA

8.0088.270NANANA

8.270NA

8.798NANANANANANANANANANANANΛNANANANANANANANANANΛNANANANANANA

0.401 (1.0031.1991.3681.5641.6982.052 '

NA2.4862.752 ;3.646 .3.788

NANANA

5.055 .5.3405.340 i5.595 i

NA

19361.1101.1101.2391.7412.0512.6222.8503.2173.875NA

1.9935.2265.864NΛ

5.0655.0655.065NΛ

3.5225.5225.835NA

7.314NA

3.3087.8677.783NA

3.0983.308NANANA

3.308NA

J.520NANΛNΛNΛNΛNΛNΛNΛNΛNΛNΛNΛNΛNΛNΛNΛNΛNANANΛNΛNA

NANANANΛNANA

1441.042.233.412.588.709

2.058NA

2.5362.7605.6925 792NANANA

5.0755.3545.3545.600NΛ

6.050 6.056

0.3630.714

NANANA

2.1262.3592.7653.2533.7993.5004.7044.9395.809

NA6.049

NA6.210

NA6.5786.5786.645

NA7.3147.3487.651

NA7.8537.8757.9748.034NANANA

8.744NA

9.1969.332

NANANANA

11.238NANANANANANANANANANANANANANANANANANΛ

NANANANA

0.4070.9571.2401.3941.5451.7002.140

NA2.6122.7503.6753 799NA

4.5544.9395.0315.333

NA5.6056.2246.008

0.6350.898

NANΛNA

2.1382.4032.8443 3524.2003.9944.9395.2685.835

NA6.074

NA6.227

NA6.6046.6046.665

NA7.3487.3837.956

NA7.8757.9568.0348.194NANΛNA

9.033NA

9.2589.401

NANANANA

11.308NANΛNANANΛNΛNANANANANANANANANΛNANΛNANANANΛNA

0.4581.0081.2931.4351.5991.8322.149

NA2.7022.7683.7203 807NA

4.6875.0315.0475.342

NA5.6206.2466.028

0.4870.784

NΛNA.660

1.7492.3382.7653.0423.7843.9464.6914.7975.589

NA6.0696.1956.323

NA6.404

NA6.597

NA7.1747.296

NANA

7.890NA

8.0708.070

NANANANANA

9.3729.558

NANANANA

11.180NANANANANANANANANANANANANANANA

NANANA

NANANANA

0.3441.0011.2501.4301.5551.6601.950NA

2.7582.7583.5513 7883.9084.5984.9724.9725.356

NA5.550

NA5.853

1699.050NANA.749.918

2.4412.8263.1473.8734.5054.7974.8765.677

NA6.1356.2156.454

NA6.484

NA6.802

NA7.296 <7.341

NANA

8.306NA

8.463 '8.463

NANANANANA

9.505 (

9.753NANANΛNA

11.363NANΛNANANANANAXANANANANANANANΛNΛNANΛNΛNANΛNA

0.364 (1.024 (1.2661.4501.6201.7231.976NA ;

2.765 ;2.765 :3.623 :3 8174.054 :

12751275NANA.868.868

2.3032.4935.1345.824NA

1.9911.991NANA

5.993NANANANANANANA

i.760NANANA

7.477NA

7.9517.951NANANANANA

>. 141 <NANANANANANANANANANANANANANANANANANANANANANANANΛ

NANANANA),415 (1979.209.513.669.669.807

2.490 :2.818 :2.928 ;5.593 :1.7815.875

4.648 4.4714.982 4.939 <4.982 4.905 <5 377 5.307NA NA

5.558 5.494 iNA NA

5.902 5.897 t

16773.677NANA

2.3032.3032.4932.8523 7781.290NA

5.0815.081NANA

5.222NANANΛNΛNANANA

3.843NANANA

7.588NA

3.0283.028NANAXANANA

J.470NAXANANANANΛNANANANANANANAXANANANANΛNANANΛNANΛNANANANA

NA1490.040.263.561.747.747.898

2.5482.8702.9915.6725.8415.9261.6801.9651.9395.332NA5.536NA

.993

NANANANANΛNANANANANANANANA

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA


NANA

0.7280.978

NA1.3141.4991.6441.7122.3702.7152.8043.8743.8744.1304.5454.9665.0635.321

NA5.321

NA5.860

NANΛNANANANANANΛNΛNANANANAXANANANΛNAXANANΛNANANAXANANΛNΛNANA

NANANANANΛXANANΛNANANANANΛNΛNAXANANANANANANANANANANAXANANANANANANΛNANA

0.7491.082

NA1.4991.6051.7121.7932.4692.7443.0713.9073.9074.3114.6155.0635.0905.370

NΛ5.370

NA5.904

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

NANANANA

0.4400.957

NANA

1.5861.586

NA2.3842.515

NANA

3.725NANANANANANA

3.725NA

NA

NANAXANANANANANANANANANANAXANΛNΛNANA

XANANΛNΛNAXANANANANANANA

NANANΛNΛNANANANANΛNΛXANANΛNANANANANANΛNANANANANANANANANANANANAXANANANA

0.6211.067

NANA

1.6951.695NA

2.4342.571

NANA

5.994NANANANANANΛ

5.994NANA



(t)849(o)

850(t)

850(o)

851(t)

851(o)

852(t)

852(o)

853(t)

853(o)

854(t)

854(o)

b A. amplificusb Circular reticulofenestridst Absence R. pseudoumbilicusb A. primust M. convaüisb D. berggreniib D. pentaradiatusb D. loeblichib Absence R. pseudoumbilicust D. hamatusb M. convallisb D. neohamatusb C. coalitusb D. hamatust C. miopelagicust C. floridanust C. nit esc enstc D. kugleribe D. kuglerib D. kuglerib C. macintyreit C. premacintyreib T. rugosust D. signusb /?. pseudoumbilicus

S. heteromorphusH. ampliapertura

b D. signusAcme D. deflandreiS. universus

b C tuberosaL. neoheteroporosA. angulareT. vetulum

b L. nigriniaeb T. tracheliumb P. minithoraxb A. angulare

P. prismatiumL. heteroporosA. jenghisi

b T. davisianaS. peregrinaA. pliocenica

b L. heteroporost L. audaxt P. fistulab L. neoheteroporost P. doliumb A. ypsilont D. penultimab S. tetrasb P. prismatiumt S. omnitubust S. coronat S. johnsonib 5. delmontensis to 5. peregrinat C. caepab 5. omnitubust D. hughesib 5. berminghamit 5. w o pt ß. miralestensist D. pettersonib D. hughesib D. pettersoni to D. hughesit C japonicat C. cristatat L. thornburgit L. renzaet C cornutab D. pettersonit D. α/α/αb C. japonicab C. cα<?/?αb L. thornburgit 5. armatat L. parkeraet O. octopylet C. bramletteit C. costatab D. dentata to D. α/αtot L. stauroporab L. parkeraet 5. diaphenesb C bramlettei

6.098NA

6.2566.878

NA7.521

NANA

9.0589.1909.0589.545

NA10.17310.376NANA11.315NANANANANANANANANANANA

0.3970.5830.9571.0421.0421.0421.4281.4281.7261.7261.5432.4822.6222.6223.2173.2073.7643.6943.2073.7643.9614.1744.1744.7375.3855.5866.2306.6526.2306.9707.617

NA8.9008.2088.2088.2088.5259.88110.7719.881

NANANANANANANANANANANANANANANANANA

6.120NA

6.2656.937

NA7.538

NANA

9.1199.2519.1199.593


0.5050.8131.0421.2491.2491.2491.5431.5431.7551.7551.6092.5062.8072.8073.3093.2173.9613.7643.2173.9614.0034.3234.3234.7465.4195.6226.3266.6826.3267.0727.841

NA9.0308.3468.3468.3468.62310.20710.87710.207NANANANANANANANANANANANANANANANANA

6.3026.7926.5186.828

NA7.383

NA8.3908.8479.4449.4929.444


0.4020.5821.0031.0031.1941.1941.4611.6281.7001.7001.4612.4492.6532.7293.1332.9793.6753.4842.9793.8113.8114.2004.2004.7625.3605.7546.3136.6456.3137.1167.710


6.3366.8286.5226.885

NA7.418

NA8.4218.8769.4929.5179.492


0.5820.6351.1281.1281.3151.3151.6281.7001.9311.9311.6282.5152.7292.8553.1853.1333.8113.6753.1333.9483.9484.3204.3204.8425.3935.7586.3756.6706.3757.1687.781

NA9.0338.3498.4049.0338.74410.18710.7029.678


6.462NA

7.0017.2127.2187.890

NA8.4048.5549.4609.4999.65610.80610.49010.501NANA

11.28911.692NANANANANANANANANANA

0.3200.4871.1121.1821.2501.1821.6601.6601.6601.6601.5622.2692.7262.7263.3672.9133.6743.4482.9133.7743.9464.1514.1514.5055.3735.7916.2456.6336.2826.8027.518

NA8.9428.1268.2718.8678.57210.05410.63810.120


6.501NA

7.0347.2267.2297.963

NA8.4318.7779.4729.5509.67410.82310.50110.510NANA11.30011.709NANANANANANANANANANA

0.3730.6511.1821.2501.3941.2501.7801.7801.7801.7801.6602.3712.7652.7653.4472.9563.7743.5142.9563.9464.1034.2684.2684.8775.4545.8306.2826.6786.3297.0127.721


6.551NA6.6877.179

NA8.0618.4058.4398.6309.2749.2749.414

NA10.67410.685NANANANANANANANANANANANANANA

0.3840.5321.1141.1141.1141.2051.7561.2431.756

2.3812.7412.7643.5183.1343.7553.4543.1343.8103.9984.1154.1154.4924.9835.8976.2446.8166.7717.2047.620

NA9.1138.0708.3788.981

9.946NANANANANANANANANANANANANANANANANANANA

6.687NA

6.7797.245

NA8.0798.4398.4708.7559.3869.3869.479

NA10.68510.727NANANANANANANANANANANANANANA

0.4440.7681.1501.1501.2431.2431.8031.2761.8031.7111.7112.4322.7642.8133.6333.1403.7763.5183.1403.9474.0574.1814.1814.9835.0766.0556.2756.8376.7957.2757.661

NA9.1638.1068.5319.1138.97310.054NANANANANANANANANANANANANANANANANANANA

6.539NA6.6717.118NA8.238NANANANANANANANANANANANANANANANANANANANANANANA0.0000.0001.0821.0821.0821.2951.2950.7081.8991.5861.586NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

6.570NA6.7737.176NA8.253NANANANANANANANANANANANANANANANANANANANANANANA0.2690.2691.2951.2951.2951.5861.5861.0372.1801.8991.899NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

NANANANANA5.994NANANANANANANANANANANANANANANANANANANANANANANA0.4970.4970.7831.1551.1551.4441.4441.4441.7691.7691.5492.1152.4902.490NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

NANANANANA8.199NANANANANANANANANANANANANANANANANANANANANANANA0.6500.6501.0331.2571.2571.5491.5491.5491.9131.9131.6522.3032.5902.590NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

525



849(t) (o)

S50(t)

850(o)

851(t)

85!(o)

852(t)

852(o)

853(t)

853(o)

854(t)

854(o)

b A. octopyleC. cingulataD. prismatica

ttb G. toxaria

C. tosaensisPulleniatina LG. fistulosus

tttb G. truncatulinoides

G. obliquusG. limbataG. altispiraS. seminulinaP. spectabilis

tttttb G. tumidat G. dehiscenst G. siakensist G. fohsi groupb G. fohsi lobatab G. fohsi fohsit G. archaeomenardiib G. praefohsib O. suturalisb P. sicana

NANANANANANA1.837NANA2.1513.4203.420

NANANANANANANANANANANA

NANANANANANA1.840NANA2.6223.7643.764NANANANANANANANANANANA

NANANANANANANANANA1.4472.4492.449NANANANAIM ANANANANANANA

NANANANANANANANANA2.0102.9792.979NANANANANANANANANANANA

NANANANANANA1.660NA2.7651.6602.7652.765

NA5.261

NA10.856NANANANANANANA

NANANANANANA2.269NA3.3672.2693.3673.367

NA5.549


NANANANANANANANANA1.608NA3.518

NA7.275

NA8.602

NANANANANANANA


NA8.028


NANANANANANANANANA1.082

NA1.082

NA5.090

NANANANANANANANANA


NA6.108

NANANANANANANANANA

NANANANANANANANANANANANANANANANANANANANANANANA

NANANANANANANANANANANANANANANANANANANANANANANA

depth (mcd)

Figure 3. Age-depth plot for Site 844. The line shows the age-depth relationshipgiven by Shackleton et al. (this volume). For each biostratigraphic datum, theupper and lower depth limits are shown at the ages estimated in the columnlabeled "Best" in Table 6. Symbols as in Figure 1, with the addition of solidtriangles = magnetics.

Here, we have examined the data from a biostratigrapher's stand-point. Table 5 (complete table on CD-ROM, back pocket) gives theupper and lower estimates of each datum in each site, with each upperand lower estimate sorted by age. If every age model were perfect, andif every datum were synchronous over the region covered, then everyupper bound would be younger than the true age of the event, and everylower bound would be older than the true age. If this were the case, theseparation would be an indication only of how closely the biostratigra-pher sampled for each datum in each site. In reality, there is someoverlap between the oldest upper limit, and the youngest older limit,for virtually every one of the datums. This overlap, which we call rawdiachrony, is estimated in Table 6 (column labeled "Best") for eachdatum considered. Several factors certainly contribute to this rawdiachrony. First, it is probable that not all datums should be regardedas synchronous; Moore et al. (1993), taking an ecologic rather than abiostratigraphic standpoint, demonstrated this for several of the da-tums discussed here. Second, the placement of several datums is seri-ously distorted by preservation problems in some sites. Third, some

Figure 4. As in Figure 3, for Site 845. Symbols as in Figure 3.

400


526



844(t)

844(o)

845(t)

845(o) (t)

846(o)

847(t)

847(o)

848(t) (o)

b A. octopylet C. cingulata

D. prismaticab G. toxaria

G. tosaensisPulleniatina LG. fistulosusG. truncatulinoidesG. obliquusG. limbataG. altispiraS. seminulinaP. spectabilisG. tumidaG. dehiscensG. siakensisG. fohsi group

b G. fohsi lobatab G. fohsi fohsit G. archaeomenardiib G. praefohsib O. summitsb P. sicana

16.62116.48116.85916.554


11.31813.17413.68614.12914.27114.86616.821

16.85916.55417.01916.621


11.36613.21313.72814.17314.31414.909

NA

16.43016.34816.415

NANANANANANANANANANANANANA

11.58412.84713.55013.70214.16515.101

NA

16.45016.36216.430

NANANANANANANANANANANANANA

11.59212.89113.57714.07914.64015.143

NA

NANANANA

0.454NA

1.744NANA

2.1753.0433.2024.335

NA5.489

NA11.59712.96013.211

NA14.24214.795

NA

NANANANA

0.794NA

1.747NANA

2.1783.0483.2074.337

NA5.491

NA11.68113.04413.336

NA14.39015.041

NA

NANANANANA

0.8581.5042.3302.4502.330NA

3.5623.9185.368NANANANANANANANANA

NANANANANA

1.2231.8482.4502.8012.450NA

3.9184.3325.605NANANANANANANANANA

NANANANANANANANANA

1.746NA

3.411NANANANANANANANANANANA

NANANANANANANANANA

3.411NA

4.879NANANANANANANANANANANA

Note: Full generic names appear in Table 6.

80 120 160

depth (mcd)

240

Figure 6. As in Figure 3, for Site 847. Symbols as in Figure 1. Figure 8. As in Figure 3, for Site 849. Symbols as in Figure 3.

40 60

depth (mcd)

Figure 7. As in Figure 3, for Site 848. Symbols as in Figure 3. Figure 9. As in Figure 3, for Site 850. Symbols as in Figure 3.

527


Figure 10. As in Figure 3, for Site 851. Symbols as in Figure 3. Figure 12. As in Figure 3, for Site 853. Symbols as in Figure 3, except for thedeletion of diatoms (open squares).

0 20 40 60 80 100 120

depth (mcd)


sites were examined at wide intervals for some microfossil groups; itseems clear that a datum is more readily mislocated if only scatteredsamples are examined. Fourth, because judgment is required to de-cide whether a species is "present" or "absent," it may be that thecriteria used were not optimal, or that they were not applied uni-formly. Finally, the age models that we have used may not be suffi-ciently accurate.

The column labeled "Uncertainty" in Table 7 indicates thosedatums that do appear to be diachronous, although it is difficult todevise an objective means for doing this. For the radiolarians, Mooreet al. (1993) showed that in the majority of cases, the diachrony ismappable and probably represents true ecological diachrony. Wherethis is not yet clear, we have indicated a query. In some cases, areexamination of the material may indicate that the datum is not, infact, diachronous, either because the age model is insufficiently pre-cise or because the datum was mislocated. Of course, a datum may befunctionally diachronous as a result of the species concerned beingsusceptible to dissolution or overgrowth, or simply being difficult toidentify, even if its spread or demise were not spatially diachronous.Thus, a large estimate of raw diachrony in the "Best" column shouldbe taken as a caution for that datum, regardless of its cause.

We have compared the diachrony of the datums for the variousmicrofossil groups, separating first appearance datums (FADs) fromlast appearance datums (LADs). The data suggest that no significantdifference exists between the reliability of FADs and LADs. How-ever, it is difficult to devise objective means for eliminating less

Figure 13. As in Figure 3, for Site 854. Symbols as in Figure 3, except for thedeletion of diatoms (open squares) and foraminifers (open diamonds).

reliable observations in a way that is valid for all fossil groups, so thatit is not easy to assess the relative quality of biostratigraphic datumsfrom different microfossil groups, except in a very general sense. Inaddition, one should devise a means of assessing diachrony that isapplicable to all groups. Finally, each biostratigrapher had differentobjectives in recording the information summarized here, and therewas not time to examine all datums in all sites with equal care. Forthese reasons, we have not tabulated these comparisons.

Another approach to the evaluation of datum levels is to examinethe distribution of estimates in individual sites for the age of eachdatum. Here, one has to take into account the fact that not all datumswere examined in equal depth resolution. In general, datums wereexamined at high resolution subject to the constraints of preservationon the one hand, and to the time available on the other; if poorpreservation is the reason a datum was not constrained closely, it isobvious that the observation is of less value. However, experienceshows that observations of the position of datums that are madehastily aboard ship in core-catcher samples frequently require revi-sion. For this reason, we have divided the 988 observations tabulatedinto those that are constrained within 0.21 m.y. or closer (786 obser-vations) and the rest (202 observations). In Table 8, the data for the"well-defined" datums and the remainder are summarized. We foundthat the well-defined nannofossil datums were examined on averageto within 0.05 Ma and that the radiolarians and diatoms were exam-


ined to within 0.08 and 0.09 Ma, respectively. We have estimated thedeviation of each of these individual datum age estimates from thebest value for that datum. The mean deviation of all nannofossildeterminations from the best value is about 0.09 Ma; the equivalentfigure for diatoms is 0.09 Ma, and for radiolarians, 0.15 Ma. For thewhole data set and for all microfossil groups, the mean deviation is0.39; taking the poorly constrained determinations only, the value is0.50. If the observation for less well-constrained datums were no lessreliable, one might expect the mean deviation to approximate half theconstraining range; the fact that the figure is far greater supports ourinitial assumption that the reliability of a biostratigraphic datum de-termination deteriorates more than proportionately if the observationshave been too widely spaced. In the context of ODP work, this findingstrongly supports the strategy of refining the placement of each datumin a single hole at a site, rather than covering each hole in less detail.The summary in Table 8 suggests that the resolution within which adatum is defined is absolutely critical; it may well be that many of thedatums that are indicated as possibly diachronous in Table 7 mayprove synchronous on closer examination.

It is not clear from Table 8 whether one can define the level ofrefinement beyond which the law of diminishing returns sets it. Atfirst sight, it appears that this point was passed in the case of thenannofossils. On the other hand, one may note that the reentry ofmedium-sized Gephyrocapsa spp., examined at all 11 sites, shows anoverall raw diachrony of only 0.01 Ma. This figure must be so lowpartly because of the chance that it is close to a magnetic reversal, sothat at the sites in which the GRAPE age model would be expected tobe less reliable, magnetostratigraphy fills the gap. However, the factremains that this datum is clearly applicable with a remarkably highdegree of precision. It may be that many other datums could bedefined with equal precision. It may also be the case that in parts ofour records, the age models could now be rendered more reliable byintroducing biostratigraphic constraints. One remarkable feature ofthe Leg 138 work is that it was possible to develop a set of age modelsthat did not contain biostratigraphical constraints, which provided anunusual opportunity to evaluate the reliability of the methods that aregenerally used. This does not mean that the age models are notamenable to further improvement.

To summarize the extent to which the Leg 138 calibrations mayaffect the biostratigraphic time scale, we show in Figure 14 the differ-ences between our calibrations and those in use aboard ship, excludingthose that we have characterized in Table 8 as being diachronous andexcluding the interval older than 14 Ma that is far from our primarymagnetostratigraphic control. Figure 14 shows that, for the Pliocene,the ages of all the reliable biostratigraphic datums were already knownwith respect to the polarity time scale to within 0.2 Ma; our newcalibrations are probably really significant only for the diatoms. How-ever, in the Miocene section, it seems clear that there were significantuncertainties in the ages of a number of important datums and that theLeg 138 calibrations have reduced those uncertainties.

CONCLUSIONS

The sediments recovered during Leg 138 have provided us anopportunity to obtain an internally consistent set of age estimates forbiostratigraphic datums from the main microfossil groups used inmarine biostratigraphy. For the time interval from 13.25 Ma to thepresent, these estimates are calibrated to the magnetic reversal scaleand are tabulated in terms of the polarity time scale developed byShackleton et al. (this volume) as well as for two other scales (BKF85;Cande and Kent, 1992). Although only a small number of datums aredemonstrably synchronous over the area studied to better than 0.1Ma, more intensive work on these sequences will probably increasethat number. The estimates given in Table 6 probably constitute themost homogeneous set of biostratigraphic datum ages that is at pres-ent available for the Neogene.

Table 5. Placement of biostratigraphic datums in Leg 138 sites.

ttttttItttttttttttttt1

tttttttttttttttttbbbbbbttttttttttttbbbbbbbbbbbbbbbbb

Biostratigraphicdatum

Nitzschia reinholdüNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia reinholdiiNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzsch ia foss HisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisNitzschia fossilisRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaRhizosolenia matuyamaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaR. praebergonii var. robustaPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolusPseudoeunotia doliolus

Limit ofplacement

ttttttt00ooooootttttttttoooooooootttoootttooottttttoooooo :tttt

Age(Ma)

0.280.36).380.55).57157) . %).45).63).63).67).70),77).941.05).09).28).49).55).63).71).79).861 9 4).18).64).67).72).77).9O.01.05.11

).92).94.01.08.09.11.09.11.39.16.24.40.58.66.66.70.86.87.71.74.75.75.87

>.3O.63.74.75.87.96.98

t 2.03t 2.05t 2.1300

.80

.92o 2.00o 2.05o 2.06o 2.07o 1 .11o 2.14

Type ofdatum

DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD

Site ofobservation

852849847848846851845847850846852851848849845844852847848846850851845849844847852846848850845851840846849845846845849845849846845849846848847851849846852847849848851846852844845851852849846847848850845851846849847848844850

Notes: In the column labeled "Biostratigraphic datum," t = top of range, b = base ofrange, tc = top of common occurrence, and be = bottom of common occurrence. Inthe column labeled "Age," t = the upper limit of the placement of the datum, and o= the lower limit. In the column labeled "Type of datum," D = diatom (from Baldaufand Iwai, this volume), F = foraminifer (from Vincent and Toumarkine, this volume;from the site chapters in Mayer, Pisias, Janecek et al., 1992; or from Shackleton etal., this volume), N = nannofossil (Raffi and Flores, this volume), and R = radiolarian(Moore, this volume).

Only the first page of this table is reproduced here. The entire table appears on theCD-ROM (back pocket).

529


Table 6. Estimates for ages of datums (see text for details).

bttbtttbt1

ttbtbtbbbttbtttbbt1

bttttbtttttbbbtttl

ttbbtbbebtttbti

bbbttttbbtttttttttbtbbbb

bt

Emiliania huxleyiStyiatractus universusPseudoemiliania lacunosaCollosphaera tuberosaNitzschia reinholdiiGloborotalia tosaensisNitzschia fossil isReentrance medium Gephyrocapsa spp.Pulleniatina left-coilingRhizosolenia matuyarnaLamprocyrtis neoheteroporosAnthocyrtidium angulareRhizosolenia matuyamaTheocorythium vetulumLamprocyrtis nigriniaeLarge Gephyrocapsa spp.Large Gephyrocapsa spp.Pterocorys minithoraxTheocorythium tracheliumCalcidiscus macintyreiLamprocyrtis heteroporosMedium Gephyrocapsa spp.R. praebergonii var. robustaPterocanium prismatiumGlobigerinoides fistulosusAnthocyrtidium angularePseudoeunotia doliolusDiscoaster brouweriGloborotalia limbataGloborotalia truncatulinoidesAnthocyrtidium jenghisiThalassiosira convexaDiscoaster pentaradiatusDiscoaster surculusTheocalyptra davisianaStichocorys peregrinaDiscoaster tamalisGlobigerinoides obliquusNitzschia jouseaeGloboquadrina altispiraLamprocyrtis neoheteroporosLamprocyrtis heteroporosRhizosolenia praebergoniiSphaeroidinellopsis seminulinaAnthocyrtidium pliocenicaSphenolithus spp.Phormostichoartus fistulaLychnodictyum audaxReticulofenestra pseudoumbilicusThalassiosira convexa f. convexaAmphirhopalum ypsilonPhormostichoartus doliumAsteromphalus elegansDiscoaster asymmetricusSpongaster tetrasDidymocyrtis penultimaPulleniatina spectabilisAmaurolithus primusPterocanium prismatiumNitzschia cylindricaCeratolithus acutusCeratolithus rugosusNitzschia jouseaeCeratolithus acutusTriquetrorhabdulus rugosusSolenosphaera omnitubusGloboquadrina dehiscensDiscoaster quinqueramusGloborotalia tumidaThalassiosira oestrupiiSiphostichartus coronaThalassiosira miocenicaAmaurolithus amplificusNitzschia miocenicaN. miocenica var. elongataCircular reticulofenestridsThalassiosira praeconvexaStichocorys johnsoniCalocycletta caepaAmaurolithus amplificusRossiella praepaleaceaThalassiosira miocenicaT. convexa var. aspinosaCircular reticulofenestridsStichocorys delmontensis to 5. peregrinaThalassiosira praeconvexaAbsence Reticulofenestra pseudoumbilicus

Med.

0.120.440.450.610.620.630.701.011.041.021.061.121.181.211.23.24.44.55.55.58.61.69.72.74.77.77

2.012.042.102.392.402.432.522.632.712.762.782.852.793.063.063.063.183.443.363.663.673.783.823.853.883.894.074.134.174.204.234.564.764.874.995.075.125.345.355.405.495.555.595.635.765.835.936.076.086.126.176.346.426.506.526.546.576.626.666.736.76

Dif.

0.040.100.060.080.140.350.140.060.360.150.070.060.130.110.080.050.060.110.160.040.100.040.070.090.140.070.100.060.800.120.100.130.060.050.130.090.040.480.110.310.150.160.080.260.180.050.020.060.050.130.140.150.700.090.120.140.210.100.070.150.060.020.250.020.010.050.000.020.540.040.010.030.050.040.050.020.190.070.210.020.120.080.130.050.050.160.04

Mid.

0.120.390.580.450.710.630.56

.02

.04

.05

.07

.13

.28

.22

.33

.22

.45

.40

.64

.58

.80

.71

.79

.74

.79

.831.971.972.172.392.392.672.502.732.672.732.862.782.783.202.992.963.123.223.393.754.353.843.833.833.823.894.014.204.054.454.334.544.344.845.195.095.055.355.355.275.495.526.425.656.285.805.975.976.106.126.206.356.616.376.526.536.556.636.706.696.65

Diac.

-0.040.230.300.360.51

-0.350.760.01

-0.36-0.07

0.080.100.230.060.220.060.220.710.240.180.550.200.160.060.090.150.330.360.32

-0.120.181.060.140.390.150.270.20

-0.040.040.440.860.790.270.680.410.251.670.310.080.030.360.410.040.540.310.590.000.130.990.310.500.300.340.03

-0.010.560.000.291.730.311.560.400.160.270.190.210.250.160.750.49

-0.120.100.060.330.250.050.78

Best

0.260.410.460.610.620.590.701.020.84

:

•

:

:

.05

.06

.12

.18

.22

.23

.24

.44

.55

.55

.58

.61

.69

.72

.74

.74

.772.011.962.182.392.402.432.522.632.712.762.782.782.783.053.063.063.183.203.363.663.673.783.823.833.883.894.014.134.174.204.334.564.764.874.995.075.125.345.355.405.495.555.595.635.765.835.936.076.086.126.176.346.426.506.526.546.556.626.666.696.76

Unc.

0.080.14

0.140.01

-0.070.070.060.130.060.080.050.060.110.160.040.100.040.070.060.010.070.10

0.00-0.12

0.100.130.060.050.130.090.04

-0.040.040.010.150.160.080.010.180.050.020.060.050.030.140.150.040.090.120.140.000.100.070.150.060.020.250.02

-0.010.050.000.020.540.040.010.030.050.040.050.020.190.070.210.02

-0.120.080.060.050.050.050.04

Choice

LitLitLitMedianMedianLitMedianMidLitMidMedianMedianMedianMidMedianMedianMedianMedianMedianMedianMedianMedianMedianMid846MedianMedianLit846

MedianMedianMedianMedianMedianMedianMedianMidMid846MedianMedianMedian846MedianMedianMpdianMedianMedianMidMedianMedianMidMedianMedianMedian846MedianMedianMedianMedianMedianMedianMedian

Median

MedianMedianMedianMedianMedianMedianMedianMedianMedianMedianMedianMedianMedianMidMedianMidMedianMedianMidMedian

Type

NRNRDFDNFDRRDRRNNRRNRNDRFRDNFFRDNNRRNFDFRRDFRNRRNDRRDNRRFNRDNNDNNRFNFDRDNDDNDRRNDDDNRDN

530



tbbbtbttttbbtttbbbbbtbbttbtbbtttttbttbbtbttctbbetttbttbtbbbb

abttbbtttbbbbttbtbtbbttttlbtbt

Nitzschia porteriAmaurolithus primusSolenosphaera omnitubusNitzschia miocenicaRossiella paleaceaNitzschia reinholdiiDiartus hughesiMinylitha convallisA. ellipticus var. javanicusThalassiosira burcklianaNitzschia marinaNitzschia cylindricaThalassiosira yabeiBotryostrobus miralestensisDiartus pettersoniDiscoaster berggreniiDiscoaster loeblichiiDiscoaster pentaradiatusDiartus pettersoni to D. hughesiAbsence R. pseudoumbilicusCoscinodiscus loeblichiiThalassiosira burcklianaDiartus hughesiStichocorys wolffiDenticulopsis simonseniiMinylitha convallisDiscoaster hamatusDiscoaster neohamatusCoscinodiscus loeblichiiDiscoaster neohamatusActinocyclus moronensisCyrtocapsella japonicaLithoperta thornburgiA. ellipticus f. lanceolataDiscoaster hamatusCoccolithus miopelagicusCarpocanopsis cristataCatinaster coalitusGloborotalia siakensisCoscinodiscus gigas var. dioramaR. paleacea var. elongataCraspedodiscus coscinodiscusDiscoaster kugleriSynedrajouseanaSphaeroidinella subdehiscensDiscoaster kugleriLithoperta renzaeCyrtocapsella cornutaDorcadospyris alataDiartus pettersoniActinocyclus ingensCoronocyclus nitescensCalcidiscus macintyreiCestodiscus pulchellusThalassiosira bruniiDiscoaster kugleriNitzschia porteriCyrtocapsella japonicaAnnellus californicusTriquetrorhabdulus rugosusCalcidiscus premacintyreiCoscinodiscus lewisianusGloborotalia fohsi lobataCoscinodiscus gigas var. dioramaDiscoaster signusCyclicargolithus floridanusThalassiosira tappanaeLithoperta thornburgiTriceratium cinnamoneumCalocycletta caepaDenticulopsis simonseniiSphenolithus heteromorphusStichocorys armataReticulofenestra pseudoumbilicusCestodiscus peplumActinocyclus ellipticusGloborotalia archaeomenardiiGloborotalia fohsi groupCoscinodiscus blysmosLiriospyrys parkaraeAcrocubus octopyleCarpocanopsis bramletteiAnellus californicusOrbulina suturalisCalocycletta costataActinocyclus ingensCoscinodiscus lewisianus var. similis

Med.

7.147 .17

7.207.277.367.647.657.737.757.817.928.038.178.218.438.078.458.468.708.718.798.848.898.899.359.379.409.529.559.609.66

10.0910.0910.3510.3810.4810.6810.7310.4711.1011.1311.3411.3611.4111.7411.8111.7911.8311.8611.8612.1012.4312.1412.0812.2812.4012.2312.4012.4512.8112.5112.9712.9413.0013.0813.4613.2013.3213.3213.3513.4713.9513.7413.9514.3214.0414.0414.0414.3414.4314.4714.6714.8914.8915.1215.3615.57

Dif.

0.020.120.150.110.050.230.090.050.150.310.090.070.190.100.130.150.060.070.170.150.290.290.100.130.300.060.030.041.240.120.190.120.170.810.080.040.070.041.410.150.070.200.030.320.330.060.050.030.050.080.100.030.010.450.180.020.160.090.240.030.040.170.230.050.070.250.290.050.270.080.260.210.090.210.870.270.270.270.330.260.270.280.260.260.060.230.19

Mid.

7.147.107.147.097.377.617.677.747.747.817.928.088.068.248.457.948.498.458.768.838.798.848.778.989.599.319.519.579.559.609.84

10.0910.5410.3510.5710.6010.6510.7910.9411.1311.1311.2811.4711.4111.7412.0611.8211.8611.8612.4212.1712.7312.1412.1412.1912.7112.2312.3912.4512.8212.5112.8612.9413.0013.0813.3813.2013.3313.3213.3513.4713.9513.7213.9514.0314.0414.0414.0414.3414.4614.5514.7514.8914.8915.1115.3615.57

Diac.

-0.020.440.250.490.05

-0.080.081.010.30

-0.31-0.09

0.220.420.260.281.040.130.010.270.46

-0.29-0.19

0.830.260.650.380.510.18

-1.24-0.12

0.870.071.74

-0.810.600.560.260.13

-0.03-0.07-0.07

0.230.27

-0.32-0.330.670.010.08

-0.031.160.101.20

-0.010.170.061.14

-0.160.08

-0.240.270.500.12

-0.23-0.05-0.07

0.36-0.29

0.55-0.27

0.32-0.26

0.180.090.180.26

-0.27-0.27-0.27-0.33-0.09-0.10

0.27-0.26-0.26

0.12-0.23-0.19

Best

7.147.177.207.277.377.617.677.737.757.817.928.038.178.218.438.458.458.558.708.718.798.848.898.899.359.379.409.529.559.609.66

10.0910.0910.3510.3810.4810.6810.7310.9411.1311.1311.3411.3411.4111.7411.7411.8211.8311.8611.8612.1012.1212.1412.1412.1912.2012.2312.3912.4512.6212.6512.8612.9413.0013.0813.1913.2013.3213.3213.3513.4713.5713.7213.9514.0314.0414.0414.0414.3414.4614.5514.7515.014.8915.1215.515.7

Unc.

-0.020.120.150.110.05

-0.080.080.050.15

-0.31-0.09

0.070.190.100.13

0.06

0.170.15

-0.29-0.19

0.100.130.300.060.030.04

-1.24-0.12

0.190.070.17

-0.810.080.040.070.04

-0.03-0.07-0.07

0.20-0.02-0.32-0.33-0.02

0.010.03

-0.030.080.10

-0.02-0.01

0.170.06

-0.02-0.16

0.08-0.24-0.03-0.03

0.12-0.23-0.05-0.07-0.02-0.29

0.05-0.27

0.08-0.26-0.02

0.090.180.26

-0.27-0.27-0.27-0.33-0.09-0.10

0.27

-0.260.06

Choice

MedianMedianMedianMedianMidMidMedianMedianMid

MedianMedianMedianMedianMagMedianMagMedianMedian

MidMedianMedianMedianMedianMedianMedian

MidMedianMidMedian

Median*Median*MedianMedianMidMidMidMedian845

Mid845MidMedianMidMedianMedian845

MidMid845

Mid

845845MidMid

845

Median

MedianMid845MedianMidMid

MidMid

MidMidMidLit

MedianLitLit

Type

DNRD

DRNDDDDDRRNNNRNDDRRDNNNDNDRRDNNRNFDDDNDFNRRRRDNNDDNDRDNNDFDNNDRDRDNRNDDFFDRRRDFRDD

531



btbttbbtbtItbbbt

Dorcadospyris dentata to D. alataLiriospyris stauroporaLiriospyris parkeraeHelicosphaera ampliapertaEucyrtidium diaphenesCarpocanopsis bramletteiDiscoaster signusAcme Discoaster deßandreiCestodiscus peplumCarpocanopsis cingulataRaphidodiscus marylandicusThalassiosira fragaPraeorbulina sicanaGiraffospyris toxariaAcrocubus octopyleDidymocyrtis prismatica

Med.

15.6915.8115.8215.8515.9516.0816.2116.2216.4316.4416.4916.4916.5016.5516.5916.68

Dif.

0.050.060.060.120.050.050.030.030.200.040.230.230.250.070.130.09

Mid.

15.7115.8415.8515.8715.9716.0816.2016.2216.4116.4216.4916.4916.5016.5916.5416.65

Diac.

0.280.130.150.060.09

-0.050.00

-0.03-0.08

0.12-0.23-0.23-0.25-0.07

0.170.43

Best

15.6915.8115.8215.8715.9516.0816.2016.2216.416.4416.4916.4916.5016.5916.5916.68

Unc.

0.050.060.060.060.05

-0.050.00

-0.03

0.04-0.23-0.23-0.25-0.07

0.130.09

Choice

MedianMedianMedianMidMedianMidMidpoint

LitMedian

MidMedianMedian

Type

RRRNRRNNDRDDFRRR

Notes: In Column 1, t = top; b = base; reent = reentry of the species; circ = circular. Med. = datum age based on the median of ageswhich define the upper and the low limits of the datum. Dif. = difference between these medians. Mid. = age at the midpointbetween the youngest estimate of the estimates of the lower limit and the oldest of the estimates of the upper limit of the datum.Diac. = diachrony (i.e., the amount by which the oldest of the estimates of the upper limit exceeds the youngest of the estimatesof the lower limit); if the figure in this column is negative, the data are fully consistent with a synchronous datum. Best = ourbest estimate of the datum age. Unc. = measure of the uncertainty in this estimate, generally from Diac. columns. Choice =whether the best estimate is based on the median (Median), on the midpoint (Mid), or if it is estimated on another basis (anasterisk indicates that a discrepant estimate was ignored; a blank implies that the two estimates are identical; a site numberindicates that the estimate is based on that site only; Mag implies that the estimate is based on the sites with magnetostratigraphy;Lit implies that the best estimate is from the published literature). Type = the microfossil type, with D = diatom, F = foraminifer,N = nannofossil, and R = radiolarian.

0 2 4 6 8


Figure 14. Differences between literature ages (Shipboard Scientific Party,1992; largely based on, or intended to be consistent with, Berggren et al.,1985b) and ages estimated here but recalculated in terms of the magneticpolarity time scale used by Berggren et al. (1985a). Differences for datumsshown in Table 7 as diachrons have not been plotted. Only the interval to 14Ma, in which we have primary magnetostratigraphic control, is shown. Sym-bols as in Figure 1.

In general, the reliability with which biostratigraphic datum planesare located improves disproportionately as they are examined in moredetail. At a site with several holes, effort should be devoted to coveringone hole carefully, rather than several holes in a cursory fashion. Whentime is a constraint, it is probably more valuable to determine a fewdatums carefully, instead of determining many with less attention.

ACKNOWLEDGMENTS

We thank the crew of the JOIDES Resolution for enabling Leg 138to return with such a magnificent legacy of material, and our col-leagues aboard ship for sharing nine weeks of exciting hard work forthe benefit of a generation of Pacific-loving paleoceanographers. Wethank Alan Mix and June Wilson for counting rare specimens of

Globigerinoidesfistulosus at our request. Simon Crowhurst and JenniTokens devoted a great deal of effort to the completion of the manu-script. This work was supported by NERC under Grant GST/554. Weare grateful to Jan Backman, John Barron, and Ken Miller for review-ing the manuscript and contributing a great deal to its improvement.

REFERENCES*

Backman, J., Schneider, D.A., Rio, D., and Okada, H., 1990. Neogene low-latitude magnetostratigraphy from Site 710 and revised age estimates ofMiocene nannofossil datum events. In Duncan, R.A., Backman, J., Peter-son, L.C., et al., Proc. ODP, Sci. Results, 115: College Station, TX (OceanDrilling Program), 271-276.

Backman, J., and Shackleton, NJ., 1983. Quantitative biochronology ofPliocene and early Pleistocene calcareous nannofossils from the Atlantic,Indian and Pacific oceans. Mar. Micropaleontol, 8:141-170.

Baksi, A.K., 1992. A 40Ar/39Ar age for the termination of Chron 5: a newcalibration point for the Miocene section of the GPTS. Eos, 27 October1992, 630. (Abstract)

Baksi, A.J., Hoffman, K.A., and Farrar, E., 1993. Anew calibration point forthe Late Miocene section of the geomagnetic polarity time scale: 4öAr/39Ardating of lava flows from Akaroa Volcano, New Zealand. Geophys. Res.Lett, 20:667-670.

Barron, J.A., Keller, G., and Dunn, D.A., 1985a. A multiple microfossilbiochronology for the Miocene. In Kennett, J.P. (Ed.), The MioceneOcean: Paleoceanography and Biogeography. Mem.—Geol. Soc. Am.,163:21-36.

Barron, J., Nigrini, CA., Pujos, A., Saito, T., Theyer, F., Thomas, E., andWeinrich, N., 1985b. Synthesis of biostratigraphy, central Equatorial Pa-cific, Deep Sea Drilling Project Leg 85: refinement of Oligocene toQuaternary biochronology. In Mayer, L., Theyer, F., Thomas, E., et al., Init.Repts. DSDP, 85: Washington (U.S. Govt. Printing Office), 905-934.

Berggren, W.A., Kent, D.V., and Flynn, J.J., 1985a. Jurassic to Paleogene: Part2. Paleogene geochronology and chronostratigraphy. In Snelling, NJ.(Ed.), The Chronology of the Geological Record. Geol. Soc. LondonMem., 10:141-195.

Berggren, W.A., Kent, D.V., and Van Couvering, J.A., 1985b. The Neogene:Part 2. Neogene geochronology and chronostratigraphy. In Snelling, NJ.(Ed.), The Chronology of the Geological Record. Geol. Soc. LondonMem., 10:211-260.

* Abbreviations for names of organizations and publication titles in ODP reference listsfollow the style given in Chemical Abstracts Service Source Index (published byAmerican Chemical Society).


Burckle, L.H., 1978. Early Miocene to Pliocene diatom datum level for theequatorial Pacific. Proc. Second Working Group Mtg. Biostratigraphic.Datum Planes Pacific Neogene, IGCP Proj. 114. Spec. Publ., Geol. Res.Dev. Ctr. 1:25-44.

Cande, S.C., and Kent, D.V., 1992. A new geomagnetic polarity time scale forthe Late Cretaceous and Cenozoic. J. Geophys. Res., 97:13917-13951.

Hays, J.D., and Shackleton, NJ., 1976. Globally synchronous extinction of theradiolarian Stylatractus universus. Geology, 4:649-652.

Hilgen, FJ., 1991a. Astronomical calibration of Gauss to Matuyama sapropelsin the Mediterranean and implication for the Geomagnetic Polarity TimeScale. Earth Planet. Sci. Lett., 104:226-244.

, 1991b. Extension of the astronomically calibrated (polarity) timescale to the Miocene/Pliocene boundary. Earth Planet. Sci. Lett., 107:349-368.

Johnson, D.A., and Nigrini, CA., 1985. Synchronous and time-transgressiveNeogene radiolarian datum levels in the equatorial Indian and PacificOceans. Mar. Micropaleontol, 9:489-523.

Mayer, L.A., Pisias, N.G., Janecek, T.R., et al., 1992. Proc. ODP, Init. Repts.,138 (Pts. 1 and 2): College Station, TX (Ocean Drilling Program).

Moore, T C , Jr., Shackleton, NJ., and Pisias, N.G., 1993. Paleoceanographyand the diachrony of radiolarian events in the eastern equatorial Pacific.Paleoceanography, 8:567-586.

Morley, J J., and Shackleton, NJ., 1979. Extension of the radiolarian Styla-tractus universus as a biostratigraphic datum to the Atlantic Ocean. Geol-ogy, 6:309-311.

Olafsson, G., 1991. Quantitative calcareous nannofossil biostratigraphy andbiochronology of early through late Miocene sediments from DSDP Hole608. Medd. Stockholms Univ. Inst. Geol. Geochem., 285.

Pisias, N.G., Barron, J.A., Nigrini, CA., and Dunn, D.A., 1985. Stratigraphicresolution of Leg 85 drill sites: an initial analysis. In Mayer, L., Theyer, F.,Thomas, E., et al., Init. Repts. DSDP, 85: Washington (U.S. Govt. PrintingOffice), 695-708.

Rio, D., Fornaciari, E., and Raffi, I., 1990. Late Oligocene through earlyPleistocene calcareous nannofossils from western equatorial Indian Ocean(Leg 115). In Duncan, R.A., Backman, J., Peterson, L.C., et al., Proc. ODP,Sci. Results, 115: College Station, TX (Ocean Drilling Program), 175-235.

Shipboard Scientific Party, 1992. Explanatory notes. In Mayer, L., Pisias, N.,Janecek, T., et al., Proc. ODP, Init. Repts., 138 (Pt. 1): College Station, TX(Ocean Drilling Program), 13-42.

Thierstein, H.R., Geitzenauer, K., Molfino, B., and Shackleton, NJ., 1977.Global synchroneity of late Quaternary coccolith datum levels: validationby oxygen isotopes. Geology, 5:400^104.

Date of initial receipt: 5 October 1993Date of acceptance: 11 March 1994Ms 138SR-127

533

N.J. SHACKLETON ET AL.

Table 7. Best estimates for ages of biostratigraphic datums determined in Leg 138 sites.

SCHPS94 CK92 BKF85 SSP92Rawdif.

Adjdif.

t Nitzschia reinholdiit Nitzschia fossilist Rhizosolenia matuyamab Rhizosolenia matuyamat R. praebergonii var. robustab Pseudoeunotia doliolust Thalassiosira convexat Nitzschia jouseaeb Rhizosolenia praebergoniib Thalassiosira convexa f. convexab Asteromphalus eleganst Nitzschia cylindricab Nitzschia jouseaeb Thalassiosira oestrupiit Thalassiosira miocenicat Nitzschia miocenicat /V. miocenica var. elongatat Thalassiosira praeconvexat Rossiella praepaleaceab Thalassiosira miocenicab 7. convexa var. aspinosab Thalassiosira praeconvexat Nitzschia portedb Nitzschia miocenicat Rossiella paleaceab Nitzschia reinholdiit A. ellipticus \ar.javanicust Thalassiosira burcklianab Nitzschia marinab Nitzschia cylindricat Thalassiosira vabeit Coscinodiscus loeblichiib Thalassiosira burcklianat Denticulopsis simonseniib Coscinodiscus loeblichiit Actinocyclus moronensisb A ellipticus f. lanceolatat Coscinodiscus gigas v. dioramab /?. paleacea var. elongatat Craspedodiscus coscinodiscust Synedrajouseanat Actinocyclus ingenst Cestodiscus pulchellusb Thalassiosira bruniit Nitzschia portedt2 Annellus californicust Coscinodiscus lewisianusb Coscinodiscus gigas v. dioramat Thalassiosira tappanaeb Triceratium cinnamoneumb Denticulopsis simonseniit Cestodiscus peplumb Actinocyclus ellipticusb Coscinodiscus blysmostl Anellus californicusb Actinocyclus ingenst Coscinodiscus lewisianus var. similisb Cestodiscus peplumt Thalassiosira fragat Raphidodiscus marylandicusb Crucidenticula nicobaricab Crasepedodiscus coscinodiscus ss.

Globorotalia tosaensisPulleniatina leftGlobigerinoides fistulosusGloborotalia limbata

b Globorotalia truncatulinoidesGlobigerinoides ohliquusGloboquadrina altispiraSphaeroidinellopsis seminulina

t Pulleniatina spectabilist Globoquadrina dehiscensb Globorotalia tumidat Globorotalia siakensisb Sphaeroidinella subdehiscensb Globorotalia fohsi lobatat Globorotalia archaeomenardiib Globorotalia fohsi groupb Orbulina suturalisb Praeorbulina sicanab Emiliania huxleyit Pseudoemiliania lacunosab Reentry medium Gephyrocapsa spp.t Large Gephyrocapsa spp.b Large Gephyrocapsa spp.t Calcidiscus macintyrei

0.620.701.051.181.722.012.432.783.183.834.014.875 . 1 25.635.836.076.086.176.526.546.556.697.147.277.377.617.757.817.928.038.178.798.849.359.559.66

10.3511.1311.1311.3411.4112.1012.1412.1912.2312.4512.8613.0013.2013.3213.4714.0314.0414.3415.0015.5015.7016.4016.4916.4918.1218.120.590.841.742.182.392.783.053.204.335.495.59

10.9411.7412.9414.0414.0414.8916.500.260.461.021.241.441.58

0.620.701.031.161.702.042.432.783.183.733.894.694.945.455.645.895.905.996.346.366.376.516.977.107.207.467.607.667.777.898.048.698.749.299.509.61

10.3211.1311.1311.3511.4212.1112.1512.2012.2412.4612.8713.0113.2113.3313.4814.0414.0414.3415.0015.5015.7016.4016.4916.4918.1218.120.590.841.732.202.402.783.053.204.145.315.40

10.9311.7412.9514.0414.0414.8916.500.260.461.001.221.421.56

0.620.660.961.081.611.932.312.653.043.583.734.464.685.135.305.495.495.585.875.885.896.066.546.626.686.846.997.057.167.287.358.058.108.618.818.949.80

10.7410.7410.9911.0711.8611.9111.9712.0212.2812.7512.9113.1413.2813.4614.0614.0614.3815.0815.6415.8516.6116.7016.7018.0518.050.590.781.632.092.282.652.923.063.985.005.08

10.5311.4312.8414.0614.0614.9616.710.260.460.931.141.341.48

0.650.850.941.101.551.802.102.603.003.603.904.304.505.105.105.555.655.806.006.10NA

6.306.706.756.807.307.357.007.407.557.557.908.208.808.408.909.90

10.7010.6010.8010.4011.5011.6011.8011.7012.4012.8012.6013.2013.4013.6514.2014.4014.6015.0015.5015.7016.4016.2016.7517.8017.30

NANA1.60NA1.901.802.903.003.905.305.20

10.4011.8013.50

NA14.0015.2016.300.260.460.921.121.321.45

-0.03-0.15

0.110.080.170.210.330.180.180.230.110.570.620.530.730.520.430.370.520.44NA

0.390.440.520.570.310.400.810.520.480.610.890.640.551.150.750.440.430.530.541.010.600.540.390.530.050.060.40

-0.00-0.09-0.18-0.17-0.37-0.26

0.000.000.000.000.29

-0.270.320.82NANA0 . 1 4NA0.490.980.150.200.430 . 1 9

0.390.53

-0.07-0.57

NA0.04

-0.310.200.000.000.090.120.120.13

-0.03-0.19

0.02-0.02

0.060.130.210.050.04

-0.02-0.17

0.160 . 1 8

0.030.20

-0.06-0.16-0.22-0.13-0.22

NA-0.24-0.16-0.13-0.12-0.46-0.36

0.05-0.24-0.27-0.20

0.15-0.10-0.20

0.410.04

-0.100.040.140.190.670.360.310.170.32

-0.12-0.05

0.31-0.06-0.12-0.19-0.14-0.34-0.22

0.080.140.150.210.50

-0.050.250.75NANA

0.03NA

0.38;

0.85:

0.020.060.08

-0.30-0.12

0.13-0.37-0.66

NA0.06

-0.240.410.000.000.010.020.020.03

534



SCHPS94 CK92 BKF85 SSP92Rawdif.

Adjdif.

b Medium Gephyrocapsa spp.t Discoaster brouwerit Discoaster pentaradiatust Discoaster surculust Discoaster tamalist Sphenoüthus spp.t Reticulofenestra pseudoumbilicusbe Discoaster asymmetricust Amaurolithus primust Ceratolithus acutusb Ceratolithus rugosusb Ceratolithus acutust Triquetrorhabdulus rugosust Discoaster quinqueramust Amaurolithus amplificust Circular reticulofenestridsb Amaurolithus amplificusb Circular reticulofenestridst Absence Reticulofenestra pseudoumbilicusb Amaurolithus primust Minylitha convallisb Discoaster berggreniib Discoaster loeblichiib Discoaster pentaradiatusb AbsenceReticulofenestra pseudoumbilicusb Minylitha convallist Discoaster hamatusb Discoaster neohamatust Discoaster neohamatusb Discoaster hamatust Coccolithus miopelagicusb Catinaster coalitustc Discoaster kugleribe Discoaster kuglerib Calcidiscus macintyreib Discoaster kuglerit Coronocyclus nitescensb Triquetrorhabdulus rugosust Calcidiscus premacintyreit Discoaster signust Cyclicargolithus floridanust Sphenolithus heteromorphusb Reticulofenestra pseudoumbilicust Helicosphaera ampliapertab Discoaster signust Acme Discoaster deflandreit Stylatractus universusb Collosphaera tuberosat Lamprocyrtis neoheteroporust Anthocyrtidium angularet Theocorythium vetulumb Lamprocyrtis nigriniaeb Pterocorys minithoraxb Theocorythium tracheliumt Lamprocyrtis heteroporust Pterocanium prismatiumb Anthocyrtidium angularet Anthocyrtidium jenghisib Theocalyptra davisianat Stichocorys peregrinab Lamprocyrtis neoheteroporusb Lamprocyrtis heteroporust Anthocyrtidium pliocenicat Phormostichoartus fistulat Lychnodictyum audaxb Amphirhopalum ypsilont Phormostichoartus doliumb Spongaster tetrast Didymocyrtis penultimab Pterocanium prismatiumt Solenosphaera omnitubust Siphostichartus coronat Stichocorys johnsonit Calocycletta caepab Stichocorys delmontensis to peregrinab Solenosphaera omnitubust Diartus hughesit Botryostrobus miralestensist Diartus pettersonib Diartus pettersoni to Diartus hughesib Diartus hughesit Stichocorys wolffit Cyrtocapsella japonicat Lithoperta thornburgit Carpocanopsis cristatat Lithoperta renzae

.691.962.522.632.783.663.824.134.564.995.075.345.355.555.936.126.506.626.767.177.738.458.458.558.719.379.409.529.60

10.3810.4810.7311.3611.7412.1412.2012.432.62

12.6513.0813.1913.5713.9515.8716.206.220.410.61

•

.06

.12

.22

.23

.55

.55

.61

.741.772.402.712.763.063.063.363.673.783.883.894.174.204.765.405.766.346.426.667.207.678.218.438.708.898.89

10.0910.0910.681 i

1.992.532.632.783.593.723.984.374.824.905.165.165.375.755.946.326.446.587.007.588.348.348.448.619.319.349.469.55

10.3610.4610.7211.3611.7412.1512.2112.4412.6312.6613.0913.2013.5813.9615.8716.2016.220.410.61

.04

.10

.20

.21

.53

.53

.60

.731.752.412.712.763.063.063.353.603.693.783.784.024.044.585.215.576.166.246.487.047.528.088.318.608.808.81

10.0510.0510.6611.83

1.581.892.402.502.653.443.573.834.194.574.644.874.875.055.385.535.855.986.166.566.977.697.697.817.978.628.648.768.879.849.97

10.2811.0211.4311.9111.9812.2512.4712.5113.0013.1313.5813.9816.0416.3916.410.410.610.971.031.131.141.441.451.501.63.66

2.292.582.632.922.933.213.453.543.623.633.873.894.384.925.235.745.796.026.586.907.427.667.968.158.169.489.48

10.2211.52

1.581.892.352.412.653.453.563.834.374.434.664.854.904.985.336.02NANANA6.70NA8.00NANANANA8.678.96NA

10.5010.4011.10NANANA

12.2012.8012.50

NANA

13.1013.5012.7016.0016.0516.050.410.600.951.051.091.271.461.36NA1.60NA2.102.572.502.90NA2.713.103.00NA3.503.70NANA4.704.905.806.206.10NA6.708.108.108.308.708.10NANANANA

0.110.070.170.220.130.210.260.300.190.560.410.490.440.570.600.10NANANA0.47NA0.45NANANANA0.730.56NA

-0.120.08

-0.37NANANA0.00

-0.380.12NANA0.090.071.25

-0.130.150.160.000.010.110.070.13

-0.040.090.19NA0.14NA0.300.140.260.16NA0.650.570.78NA0.390.47NANA0.690.860.540.220.56NA0.970.1 10.330.400.190.79NANAXANA

0.00-0.00

0.050.09

-0.00-0.01

0.01-0.00-0.18

0.14-0.02

0.02-0.03

0.070.05

-0.49NANANA

-0.14NA

-0.31NANANANA

-0.03-0.20

NA-0.66-0.43-0.82

NANANA

-0.22-0.55-0.03

NANA

0.030.081.280.040.340.360.000.010.02

-0.020.04

-0.13-0.02

0.09NA

0.03NA

0.190.010.130.02NA

0.500.350.54NA

0.130.17NANA

0.220.33

-0.06-0.41-0.08

NA0.20

-0.68-0.44-0.34-0.55

0.06NANANANA

535



t Cyrtocapsella cornutat Dorcad<>spyris alatab Diartus pettersonib Cyrtocapsella japonicab Lithoperta thornburgib Calocycletta caepat Stichocorys armatat Liriospyrys parkaraet Acrocubus octopylet Carpocanopsis bramletteit Calocycletta costatab Dorcadospyris dentata to D. alatat Liriσspyris stauroporab Liriospyris parkeraet Eucyrtidium diaphenesb Carpocanopsis bramletteit Carpocanopsis cingulatab Giraffospyris toxariab Acrocubus octopylet Didymocyrtis prismatica

SCHPS94

11.8311.8611.8612.3913.3213.3513.7214.4614.5514.7515.1215.6915.8115.8215.9516.0816.4416.5916.5916.68

CK92

11.8411.8711.8712.4013.3313.3613.7214.4614.5514.7515.1215.6915.8115.8215.9516.0816.4416.5916.5916.68

BKF85

11.5311.5711.5712.2013.2813.3213.7414.5014.6014.8115.2215.8415.9715.9816.1216.2616.6516.8116.8116.90

SSP92

11.6013.5012.50NANANANANANANA

15.0016.70NANANANANANANANA

Rawdif.

0.23-1.65-0.64

NANANANANANANA0.12

-1.01NANANANANANANANA

Adjdif.

-0.07-1.93-0.93 a

NANANANANANANA0.22

-0.86NANANANANANANANA

Note: SCHPS94 = our estimate, based on the time scale of Shackleton et al. (this volume); CK92 = ourestimate, calibrated back to the polarity time scale of Cande and Kent (1992); BKF85 = our estimate,calibrated back to the polarity time scale of Berggren et al. (1985a); SSP92 = age used by ShipboardScientific Party (1992), based on Berggren et al. (1985b). Raw difference = the difference betweenour estimate and that used by the Shipboard Scientific Party (1992). Adjusted difference = thedifference between our estimate recalibrated to BKF85, and that used by the Shipboard Scientific Party(1992). t = top of range, and b = bottom of range.

a This datum is probably significantly diachronous.

Table 8. Mean deviation of estimates from individual sites from calibra-

tion ages for those datums determined to 0.2 m.y. or better and for the

remainder.

Datum

RadiolariansNannofossilsDiatomsAll sroupsa

All groups11

Meandeviation

0.150.100.100.390.50

Meanconstraint

0.080.050.090.250.55

Notes: An insufficient number of foraminifer datums was determined for this compari-son. The radiolarian, nannofossil, and diatom datums were constrained within 0.2m.y. or better.

aAll groups, all data.bConstrained less well than 0.2 m.y.

536

Documents

23. BIOSTRATIGRAPHIC SUMMARY FOR LEG 1381 N.J. … · 2006-12-14 · stratigraphic and geochronological efforts that have been devoted to Leg 138 sediments with a view to further