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42. PLEISTOCENE DIATOMS FROM SITE 262, LEG 27, DSDP
Anastasia P. Jouse and Galina H. Kazarina, Institute of Oceanology, Academy of Sciences of the USSR, Moscow
Site 262 is located near the axis of the Timor Trough,75 km south of the western tip of Timor and 230 kmnortheast of the Ashmore Reef. The water depth at thissite is 2315 meters.
The cored sediments are chiefly nanno oozes withsome terrigenous material. Forty-four samples wereselected for diatom analysis, generally one or twosamples per core. Other samples from each of the 47cores recovered were checked under the microscope.
Diatoms are present only in the upper 27 cores. Theyare not numerous in most samples which is probablydue to dilution by terrigenous and carbonate material.However, the recovered diatoms are well preserved andeasily determined, and they are sufficiently abundant tocharacterize the diatom flora wherever present.
METHODS
The material was treated in accordance with standardprocedures used in the Laboratory of Micropaleon-tology, Department of Ocean Geology, Institute ofOceanology, Academy of Sciences, USSR. The methodis as follows: 0.5 g of sediment is heated in a 10%Na5P3θio solution, then boiled for 60 minutes in a 30%H2O2 solution. During the next 5-6 days samples arewashed in distilled water to remove tripolyphosphateand particles of pelite. The sediments are then treatedwith 10% HC1 to remove carbonate material. Finally,the sample is washed and a portion of the material ismounted under a cover glass and examined under themicroscope. This procedure allows calculation of thenumber of diatom valves per g of sediment.
In determining the diatom content of the sedimentsuch species as Ethmodiscus rex, Thalassiotrix sp.,Thalassionema sp., and Chaetoceros sp. were ignoredbecause they generally occur only as fragments. Theabsolute abundance of diatoms is thus somewhat un-derstated. The relative abundance of each species isexpressed as a percentage of the total number ofdiatoms.
A list of the 97 recognized diatom species from Site262 and their relative abundances in each sample isgiven in Table 1. The abundance and distribution of themost typical and numerous species are shown on Figure1. Plates 1 through 7 are SEM photographs of somediatom species from this site and of typical species of theequatorial-tropical area of the Indian Ocean.
DISTRIBUTION OF DIATOMS
Figure 1 shows that the diatom content of thesediments varies significantly in the upper part of thesection (Cores 1-27). The maximum diatom con-centration observed—9,099,200 valves/g—is in Core 6,Section 6; the minimum concentration of 720,000valves/g is in Core 23, Section 3. The sediments have an
average concentration of about 2,500,000 valves/gwhich is relatively small compared to the number ofdiatoms in the surface sedimentary layer in adjacentparts of the Indian Ocean (Kozlova, 1969). The lowervalue at Site 262 is due to high dilution by carbonatematerial. On the whole, the diatom content of thesediments at Site 262 increases upward from Core 27.Cores 12 and 26, however, contain only sparse diatoms.
Remnants of siliceous organisms in the studiedsediments are diatoms, silicoflagellates, Radiolaria, andsponge spicules; neither the diatoms nor the othergroups are numerous.
SPECIES CHARACTERISTICS OF DIATOMS
Ninety-seven species of diatoms have been recognizedin the sediments of Site 262. The overwhelming majorityof them (38) are oceanic species. Neritic species areconsiderably less abundant (10) and some sublittoralspecies occur in the sediments as single specimens. Someof the observed diatoms could not be determinedspecifically.
Predominant among the oceanic species areAsteromphalus arachne, Coscinodiscus nodulifer,Hemidiscus cuneiformis, Hitzschia marina, Planktoniellasol, Pseudoeunotia doliolus, Rhizosolenia alata, Rh.bergonii, Rh. styliformis, Roperia tesselata,Thalassionema nitzschiodes, Thalassiosira oestrupii. Allof the diatom-bearing samples are characterized by thepresence of more or less numerous specimens of theoceanic species Thalassionema, Thalassiotrix, andChaetoceros, represented mainly by spores and bristles.
Among the neritic species one can distinguishActinoptychus bipunctatus, A. undulatus, Nitzschiabicapitata, N. interrupta, N. longicollum, andThalassiosira decipiens. The most significant sublittoralspecies are Actinocyelus ehrenbergii, Diploneis bombus,Cyclotella striata, Grammatophora marina, Melosirasulcata, and Pleirosigma angulatum.
Typical diatom species that make up a considerableportion of the total percentage are Actinocyelusehrenbergi, Coscinodiscus nodulifer, Cyclotella striata,Nitzschia marina, Planktoniella sol, Pseudoeunotiadoliolus, Rhizosolenia bergonii, Thalassionemanitzschioides, T. nitzschioides var. parva, Thalassiosiradecipiens, and T. oestrupii.
Figure 1 shows the distributions of the speciesexpressed in percentage of total number of diatoms. Thedistribution of the species Thalassiotrix is expressed asabundant, common, few, and rare.
On the basis of quantitative and qualitative variationsof the diatom flora the upper part of the section at Site262 can be divided into 5 zones:
Zone I — Cores 1-11Zone 11 — Core 12, Sections 3, 6
} Upp>er Pleistocene
925
A. P. JOUSE, G. H. KAZARINA
TABLE 1Percent of Total Number of Diatoms
Sample(Interval in cm)
1-2, 59-612-2, 42443-2,38-404-2, 16-185-5, 13-156-2, 170-1726-6, 50-527-3, 130-13284, 105-1078-7, 62-649-2, 15-179-6, 20-2210-3, 58-6010-6, 65-6711-3,16-1811-6,28-3013-3,404213-6, 87-8914-3, 95-9714-6, 70-7215-3, 64-6616-3, 104-10616-5, 16-1817-3, 16-1817-6, 57-5918-3,13-1518-6, 15-1719-6, 17-1920-6, 18-2021-6, 14-1622-3,10-1222-5, 35-3723-3, 16-1823-6,14-1624-3,15-1724-6, 394125-3, 69-7126-3, 90-92a
26-6, 53-55a
27-6, 3840
Diatoms/gSediment
1,887,0004,340,0003,540,0003,760,0002,199,0001,354,2009,099,2007,466,4004,500,0005,429,0002,818,0004,680,0002,832,0001,623,0002,224,8002,772,0003,420,0001,312,8001,843,2001,200,0004,440,0002,606,4001,475,000
879,6005,520,0004,099,2005,800,8002,364,0002,400,0002,628,0002,059,2001,018,200
720,000814,400
1,393,200800,000972,000
1,002,000
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926
PLEISTOCENE DIATOMS, SITE 262
TABLE 1 - Continued
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7
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na J
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8
| Th
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ira
sp.
A
+___++++++
+++
-+2+11_+___-_
_+
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-
| Th
alas
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sp.
B
___
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+_+
---++_++___+_
_+
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+
| Th
alas
sios
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sp. C
+-___-+++-+-++
1+1+++1+__+++
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-
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| T
rice
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v.
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++
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+
927
A. P. JOUSE, G. H. KAZARINA
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928
PLEISTOCENE DIATOMS, SITE 262
Zone III — Cores 13-25 } Middle Pleistocene
Zone IV - Core 26 Sections 3, 6 1 ? M i d d i e PleistoceneZone V — Core 27, Section 6 J
CHARACTERISTICS OF DIATOM COMPLEXESBY ZONES (FROM TOP DOWN)
Zone I is characterized by an abundance of diatoms,with the number of valves/g of sediment reaching amaximum value of 9,099,200 in Core 6, Section 6.Debris of Thalassionema, Thalassiotrix, etc., is alsoabundant but was not included in the total. Zone I issimilar to the lower zones in specific composition andrelative percentages of diatoms; however, some speciesattain their highest level in Zone I, such asThalassionema nitzschioides var. parva (32%),Thalassiosira oestrupii (18%), Planktoniella sol (13%),and Pseudoeunotia doliolus (5%).
Some peculiarities are noted in the distributions ofcertain species: Thalassiosira decipiens, a moderate- tocold-water type, occurs mainly in the upper part of ZoneI where it accounts for 6% of the total. It occurs onlysporadically in Zones III and V. Cyclotellα striαtα, acold-water species, typical for the sublittoral zone ofoceans, is represented by single specimens in Zone I butis more abundant in the other zones.
Judging from the diatom assemblage, the sediments ofZone I were formed in the pelagic zone of the ocean.This is indicated by the prevalence of typical oceanicspecies. The relatively high concentration of diatoms insediments of Cores 1-11 indicates a decrease in dilutioncompared with sediments of Cores 12-25. The diatomsin the upper cores from Site 262 correspond to theRecent tropical flora of the Indian Ocean (Kozlova,1968;1969; Kazarina and Demidenko, 1974).
Zone II, which includes Core 12, Sections 3-6, ischaracterized by a nearly complete absence of diatoms.
Zone III—Cores 13-25—contains rather numerous,but less abundant diatoms than Zone I. The maximumabundance is in Core 18, Section 6. The diatomsgradually decrease downward reaching a minimum of720,000 valves/g of sediment in Core 23, Section 3. Asimilar decrease occurs in the number of specimens forcertain oceanic species such as Ethmodiscus rex,Thalassiotrix sp., Thalassionema sp., and Chaetocerossp. Such species are abundant to common in Zone I butare sparse in the upper part of Zone III, and rare in thelower part of Zone III. Hence, these species form aninsignificant part of the diatom flora of Zone III.
With few exceptions, species typical for Zone I alsooccur in Zone III. The chief exceptions are Thalassiosiradecipiens, which is present only in Zone I, andCoscinodiscus sp. (Plate 2, Figures 10, 11; Plate 4,Figures 4, 5), which is present mainly in sediments ofZone III. This latter species is new and its ecological andbiostratigraphic characteristics are not well defined. Inthe tropical area of the Indian Ocean this species ispresent both in Pleistocene and Pliocene deposits(Kazarina and Demidenko, 1974) and has also beenreported in surface layers of Recent sediments (Kozlova,1969).
Some diatom species of Zone III show peculiarmorphological features which distinguish them from
typical modern forms and indicate their older age. Thus,for instance, dimensions of valves of Coscinodiscusnodulifer decrease with extension and duplication of the"nodule"; among Thalassiosira oestrupii, both small andnormal-size forms occur together. The small forms aresimilar to Thalassiosira oestrupii var. plana Jouse(1968a) described from Pacific Ocean sediments ofmiddle Pleistocene age. Rhizosolenia bergonii forms arelarger than normal and resemble forms transitional toRhizosolenia praebergonii Muchina. It is presentlyassumed that extinction of Rhizosolenia praebergoniimarks the Pliocene-Pleistocene boundary in sedimentsof the tropical Pacific Ocean (Jousé and Muchina, 1973;Burckle, 1972).
In addition, the number of sublittoral speciesincreases in sediments of Zone III. Similar variations inthe diatom flora of the Indian Ocean were pointed outearlier by Greville and Kolbe for the region of theSeychelle Islands where, in sediments recovered fromconsiderable depth and at great distance from land, alarge number of sublittoral and benthic species waspresent (Kolbe, 1957). We observe mainly the increaseof the species Cyclotella striata typical for deltaicenvironments in moderate latitudes. In Chilean-Peruvian offshore sediments Cyclotella striata is typicalfor the region of cold currents (Jouse, 1972).
In Zone III the number of sponge spicules increases asthe ocean diatom species, mainly Ethmodiscus rex,Thalassiotrix sp., Thalassionema sp., and Chaetocerossp. decrease. The increase in sponge spicules andsublittoral diatoms and the decrease in oceanic diatomsindicate that the sediments of Zone III (Cores 13-25)were deposited under shallower water conditions thanthe sediments of Zone I.
Diatom floras with species morphologically differentfrom modern forms correspond to a Pleistoceneevolutionary stage of diatom development.
In Zone IV, there are insufficient specimens tocharacterize a diatom flora.
In Zone V, small numbers of diatoms occur in Core27, Section 6; in Section 3 of Core 27 only singlespecimens are present. The diatom flora in Core 27 issimilar to that of Zone III.
No diatoms were observed in the interval betweenCore 28 and the bottom of the hole at Core 47.
BIOSTRATIGRAPHIC AND PALEOGEOGRAPHICCONCLUSIONS
Sediments of Cores 1-27 contain diatom floras typicalof the Pleistocene of the Indian Ocean. Associations ofdiatoms are similar to those known for the Pleistoceneof the equatorial-tropical area of the Indian Ocean(cores 4599, 5003, and 5174 of the Institute ofOceanology of the Academy of Sciences of the USSR)(Kozlova, 1970; Kazarina and Demidenko, 1974).
The Mesocena elliptica (Ehr.) Deji. Zonecorresponding in equatorial-tropical areas of the Pacificand Indian Oceans to deposits of lower, and probablythe lower part of middle, Pleistocene could not beestablished in the sediments of Site 262. Morphological-ly the diatoms of Zones III and IV compare closely withmiddle Pleistocene floras of subtropical and tropicalareas of the Pacific Ocean (Jousé, 1968b).
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A. P. JOUSE, G. H. KAZARINA
The sediments of Zone I, which contain moderndiatoms, correspond to the upper Pleistocene andHolocene. Consequently, the nearly 250 meters ofdiatom-bearing sediments were formed during the mid-dle and upper Pleistocene and Holocene, i.e., in the last0.7 to 1.0 m.y. Thus, sedimentation took place at a veryhigh rate during this time.
Ecological differences in the diatom floras of Zones Iand III indicate that paleogeographic conditions variedduring deposition of these sediments (Sections 1-27).Oceanic diatoms are dominant in Zone I indicating thatthe sediments were deposited in the pelagic zone of theocean. The relatively high concentration of diatoms herepoints to less dilution in this zone compared with ZoneIII. Cyclotella striata, a sublittoral, moderate- to cold-water species, indicates that the sediments of Zone IIIwere formed under shallower and colder water con-ditions than those of Zone I.
From Core 28 upwards there is an increase in thecontent of typical oceanic forms such as Ethmodiscusrex, Thalassiotrix, Thalassionema, and Chaetoceros.Thus, variations in diatom floras in this interval, whichrepresents a considerable part of the Pleistocene,proceeded in strict succession and with definiteconsistency.
REFERENCESBurckle, L. H., 1972. Late Cenozoic planktonic diatom zones
from the eastern equatorial Pacific. In First Symposium on
Recent and Fossil Marine Diatoms: Nova Hedwigia, v. 39,p. 217-246.
Jouse, A. P., 1968a. New species of diatoms in bottom sedi-ments of the Pacific and the Okhotsk Sea: Nov. Systemat.Plant. Vasculal. Moscow, (Nauka), 12-21, (in Russian).
, 1968b. Stratigraphy of Pleistocene sediments in thePacific Ocean: Comm. Study Quatern. Per. Bull. v. 35, p. 1-19, Moscow (Nauka), (in Russian).
, 1972. Diatoms in the surface sediment layer of theChilean-Peruvian Region of the Pacific Ocean:Oceanology, v. 12, p. 831-841, (in Russian).
Jouse, A. P. and Muchina, V. V., 1973. Zone Mezocenaelliptica (Ehr.) Deji, in the Pleistocene sediments of thePacific Ocean: Oceanology, v. 13, p. 467-475, (in Russian).
Kazarina, G. H. and Demidenko, E. L., 1974. Diatom andpaleomagnetic zones in the sediments of core 4599 (IndianOcean). In Micropaleontology of oceans and meeres:Moscow (Nauka), p. 83-93, (in Russian).
Kolbe, R. W., 1957. Diatoms from equatorial Indian Cores.Swedish Deep-Sea Exped. Rept., p. 1-50.
Kozlova, O. G., 1968. Diatoms and silicoflagellatae of theIndian Ocean. In Fossil diatoms of the USSR: Moscow,(Nauka), p. 119-127, (in Russian).
, 1969. Quantitative distribution and speciescomposition of diatoms and silicoflagellate in the surfacelayer of sediments of the Indian Ocean. InMicropaleontology and organogenous sedimentation in theoceans: Moscow (Nauka), p. 28-51, (in Russian).
, 1970. Biostratigraphy of sediments of the equatorialzone of the Indian Ocean: Oceanology, N 3, v. 10, p. 479-487, (in Russian).
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A. P. JOUSE, G. H. KAZARINA
PLATE 1
Figure 1 Actinocyclus ellipticus f. lanceolata GrunSample 10-6, 65-67 cm, 51µ in length.
Figure 2, 3 Actinocyclus erenbergii var. tenella Hust2. Sample 14-6, 70-72 cm, 35µ in diameter.3. Sample 10-6, 65-67 cm, 28µ in diameter.
Figure 4, 5 Actinoptychus bipunctatus Lohm4. Sample 10-3, 58-60 cm, 28µ in diameter.5. Sample 10-6, 65-67 cm, 22µ in diameter.
Figure 6 Actinoptychus undulatus RalfsSample 9-6, 20-22 cm, 40µ in diameter.
Figure 7 Asteromphalus arachne RalfsSample 11-3, 16-18 cm, 45µ in diameter.
Figure 8 Asteromphalus sp.Sample 10-6, 65-67 cm, 38µ in diameter.
Figure 9 Bacteriastrum hialinum LauderSample 9-6, 20-22 cm, 13µ in diameter.
Figure 10 Cyclotella striata (Ktz.) GrunSample 9-6, 20-22 cm, 38µ in diameter.
Figure 11 Cocconeis pseudomarginata GregorySample 10-6, 65-67 cm, 62µ in length.
Figure 12 Cocconeis sp.Sample 18-6, 15-17 cm, 38µ in length.
Figure 13 Planktoniella sol SchüttSample 9-6, 20-22 cm, 52µ in diameter.
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PLEISTOCENE DIATOMS, SITE 262
PLATE 1
13
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A. P. JOUSE, G. H. KAZARINA
PLATE 2
Figure 1 Coscinodiscus africanus YanischSample 9-6, 20-22 cm, 30µ in diameter.
Figure 2 Coscinodiscus crenulatus GrunSample 18-6, 15-17 cm, 34µ in diameter.
Figure 3 Coscinodiscus domifactus HendeySample 14-3, 95-96 cm, 38µ in diameter.
Figure 4 Coscinodiscus nodulifer A. SchmidtSample 10-6, 65-67 cm, 50µ in diameter.
Figure 5 Coscinodiscus nodulifer A. SchmidtSample 18-6, 15-17 cm, 38µ in diameter.
Figure 6 Coscinodiscus nitidus GregSample 20-6, 18-20 cm, 39µ in diameter.
Figure 7-9 Coscinodiscus sp. A.7. Sample 11-6, 28-30 cm, 23µ in diameter.8. Sample 20-6, 18-20 cm, 20µ in diameter.9. Sample 27-6, 14-16 cm, 25µ in diameter.
Figure 10 Diploneis bombus EhrSample 9-6, 20-22 cm, 35µ in length.
Figure 11 Diploneis suspecta A. SchmidtSample 14-6, 70-72 cm, 41µ in length.
Figure 12 Diploneis sp.Sample 14-3, 95-97 cm, 26µ in length.
Figure 13 Glyphodesmis nancoorense GrunSample 14-6, 70-72 cm, 65µ in length.
Figure 14, 15 Hemidiscus cuneiformisWaU14. Sample 9-6, 20-22 cm, 30µ in length.15. Sample 10-3, 58-60 cm, 50µ in length.
Figure 16 Nitzschiα interruptα HeidSample 8-4, 105-107 cm, 42µ in length.
Figure 17 Nitzschiα pαnduriformis GregSample 11-3, 16-18 cm, 48µ in length.
Figure 18 Nitzschiα mαrinα GrunSample 10-6, 65-67 cm, 130µ in length.
Figure 19 Pseudoeunotiα doliolus GrunSample 10-6, 65-67 cm, 65µ in length.
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PLEISTOCENE DIATOMS, SITE 262
PLATE 2
15
935
A. P. JOUSE, G. H. KAZARINA
PLATE 3
Figure 1 Rhizosolenia alata BrightSample 14-3, 95-97 cm, 45µ in length.
Figure 2, 3 Rhizosolenia bergonii Perag2. Sample 10-6, 65-67 cm, 48µ in length.3. Sample 11-3, 16-18 cm, 65µ in length.
Figure 4, 5 Rhizosolenia styliformis Bright4. Sample 11-3, 16-18 cm, 63µ in length.5. Sample 10-6, 65-67 cm, 48µ in length.
Figure 6, 7 Rhizosolenia sp.6. Sample 3-2, 38-40 cm, 35µ in length.7. Sample 7-3, 130-132 cm, 75µ in length.
Figure 8 Roperia tesselata GrunSample 4-2, 16-18 cm, 28µ in diameter.
Figure 9, 10 Thalassionema nitzschioides Grun9. Sample 18-6, 15-17 cm, 110µ in length.10. Sample 18-6, 15-17 cm, 32µ in length.
Figure 11-15 Thalassiosira oestrupii (Ostf.) Pr.-Lavr11. Sample 9-6, 20-22 cm, 25µ in diameter.12. Sample 10-6, 65-67 cm, 20µ in diameter.13. Sample 10-6, 65-67 cm, 18µ in diameter.14. Sample 18-3, 13-15 cm, 15µ in diameter.15. Sample 18-6, 15-17 cm, 12µ in diameter.
Figure 16 Thalassiosira sp. ASample 4-2, 16-18 cm, 28µ in diameter.
Figure 17 Thalassiosira sp. CSample 4-2, 16-18 cm, 48µ in diameter.
Figure 18, 19 Thalassiosira sp. B18. Sample 9-6, 20-22 cm, 22µ in diameter.19. Sample 9-6, 20-22 cm, 27µ in diameter.
936
PLEISTOCENE DIATOMS, SITE 262
PLATE 3
19
937
A. P. JOUSE, G. H. KAZARINA
PLATE 4
Figures 1,2, 5-12, Sample 8-4, 105-107 cm;Figures 3, 4, Sample 14-3, 95-97 cm.
Figure 1 Actinocyclus ellipticus f. lanceoiata Grun X2200.
Figure 2 Asteromphalus arachne Ralfs X385O.
Figure 3 Asteromphalus aff. robustus Castr × 1750.
Figure 4 Asterolampra marylandica Ehr ×2200.
Figure 5 Bacteriastrum hialinum Lauder X2700.
Figure 6 Coscinodiscus africanus (w.s.m.) Yanisch X2500.
Figure 7,8 Coscinodiscus crenulatus var. nodulifer Lohm7. X3000.
8. X3000.
Figure 9 Coscinodiscus lineatus Ehr X1050.
Figure 10-12 Coscinodiscus nodulifer A. Schmidt10. X1000.11. X3000.12. X3000.
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PLEISTOCENE DIATOMS, SITE 262
PLATE 4
"I •
939
A. P. JOUSE, G. H. KAZARINA
PLATE 5
Figures 1-5, Sample 14-3, 95-97 cm; Figures 6-12,Sample 8-4, 105-107 cm.
Figure 1, 2 Coscinodiscus aff. nodulifer A. Schmidt1. ×200.2. X1050.
Figure 3 Coscinodiscus radiatus Ehr × 1000.
Figure 4, 5 Coscinodiscus sp. A4. X4000.5. X3000.
Figure 6-8 Hemidiscus cuneiformis Wall6. X1550.7. X2200.8. X1700.
Figure 9 Navicula oblonga Ktz X1000.
Figure 10, 11 Nitzschia interrupta Heid10. X3500.11. X2700.
Figure 12 Nitzschia marina Grun X2400.
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PLEISTOCENE DIATOMS, SITE 262
PLATE 5
941
A. P. JOUSE, G. H. KAZARINA
PLATE 6
Figures 1-6, 9-12, Sample 8-4, 105-107 cm; Figure 7, 8, Sample 14-
3, 95-97 cm.
Figure 1 Nitzschia marina Grun X3100.
Figure 2-4 Planktonieüa sol Schütt2. X1100.3. X2000.4. X2000.
Figure 5 Rhizosolenia styliformis Bright × 1200.
Figure 6, 7 Roperia tesselata Grun6. X3700.7. X4500.
Figure 8 Roperia tesselata var. ovata Heid X1500.
Figure 9-11 Thalassionema nitzschioides Grun9. XI700.10. X3900.11. X6500.
Figure 12 Thalassiosira oestrupii (Ostf.) Pr.-Lavr X4000.
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PLEISTOCENE DIATOMS, SITE 262
PLATE 6
943
A. P. JOUSE, G. H. KAZARINA
PLATE 7
Figures 1-3, 6-10, 12, Sample 8-4, 105-107 cm;Figures 4, 5, 11, Sample 14-3, 95-97 cm.
Figure 1-3 Thalassiosira oestrupii (Ostf.) Pr.-Lavr1. X2500.2. X3900.3. X3800.
Figure 4, 5 Thalassiosira oestrupii aff. var. plana Jouse4. X4000.5. X7800.
Figure 6-9 Thalassiosira sp. A6. X2500.7. X4200.8. X3200.9. X3200.
Figure 10 Thalassiosira sp. C X2000.
Figure 11 Thalassiotrix sp. X4500.
Figure 12 Triceratium cinnamomeum Grev. X2000.
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PLEISTOCENE DIATOMS, SITE 262
PLATE 7
945
