Palaeogeography, Palaeoclimatology, Palaeoecology Elsevier Publishing Company, Amsterdam-Printed in The Netherlands

P L A N K T O N B I O S T R A T I G R A P H Y A N D P A L E O E C O L O G Y O F T H E

E A S T E R N N O R T H P A C I F I C O C E A N : I N T R O D U C T I O N

JERE H. LIPPS

Department of Geology and Institute of Ecology, University of California, Davis, Calif'. (U. & A.)

(Received January I 1, 1972)

ABSTRACT

Lipps, J. H., 1972. Plankton biostratigraphy and paleoecology of the eastern North Pacific Ocean : Introduction. Palaeogeogr., PalaeoclimatoL, Palaeoecol., 12:3 14.

A symposium on "Eastern North Pacific Plankton Biostratigraphy and Paleoecology" was organized in order to assess the current status of plankton studies in this large region, to reconcile differing viewpoints, and to indicate areas in need of study. A review of the literature to date indicates that Upper Cretaceous strata can be zoned and correlated to the European stages by means of planktonic Foraminifera, and potentially by radiolarians and calcareous nannoplankton. The Cenozoic 'also could be zoned biostratigraphically using plankton, but zones have not been designated formally, although correlation between the eastern Pacific and the European Cenozoic stages is possible now.

Modern oceanography and plankton biogeography in the eastern Pacific is characterized by the Transitional water mass and province, dominated chiefly by subarctic water and plankton but with admixed warmer water types. The region is biotically variable because of variable oceanographic conditions. By comparison of the modern and fossil distributional patterns, the eastern Pacific is inferred to have been influenced at least since near the end of the Cretaceous by a southward flowing current with characteristics intermediate from those of more northerly and more southerly regions.

iNTRODUCTION

Fossil p lankton have been used wi th great success for correlat ion of Cretaceous and

Tert iary strata th roughout the world. Zones, established on the basis o f occurrences o f

these organisms, are recognized in many widely separated areas. The def ini t ion and

in terpre ta t ion o f these zones varies among workers, but even wi th this disagreement,

p lankton have provided evidence for correla t ions no t previously possible, especially in

Cretaceous and Early Ter t iary strata. Corre la t ion of high-lat i tude rocks, especially o f the

later Cenozoic , by means o f p lankton is more diff icul t because o f biogeographic differences

be tween low and high la t i tude biotas. Fossil p lanktonic biotas o f high la t i tudes are no t

yet well known, as most previous investigations have been pursued in low-lat i tude regions.

In many large areas of the earth, p lanktonic biotas have been only part ial ly studied. One

such area is the eastern Nor th Pacific region.

4 J.H. LIPPS

Originally, much work on plankton biostratigraphy was accomplished in this region, although it was not until the past decade that interest was renewed as a result of the general increased world-wide attention given fossil plankton. Now, many reports have been published on aspects of this work, but there are still large neglected areas of plankton studies. For all of these reasons, a symposium dealing with eastern North Pacific fossil plankton was organized for the Geological Society of America Cordilleran Section meetings in Riverside, California, March 25, 1971. The purpose of the symposium was to assess the current status of plankton studies in the region, to reconcile different views that have arisen in the past, and to indicate areas in need of study.

Fourteen papers were delivered at the symposium with extended discussions of the Tertiary and Cretaceous plankton. Of these original papers, seven are published in the present volume.

The papers by Bandy on Neogene planktonic foraminiferal zonation, by Casey on Neogene Radiolaria, by Sliter on Cretaceous planktonic foraminiferal zoogeography and by Wornardt on diatom biostratigraphy summarize and reconcile much work on these problems, while the papers by Cornell on Cretaceous chrysomonad cysts, by McKeel and Lipps on Oregon Tertiary calcareous plankton, and by Orr on Tertiary siliceous plankton from off the Oregon coast attack new problems in eastern Pacific plankton studies. Obviously, there are large parts of the stratigraphic column, many geographic areas and some important groups that have not been dealt with in this symposium. Although the task of dealing with this subject in its entirety is immense, if not impossible, the gaps in this symposium volume do reflect for the most part a lack of intensive research on these subjects.

HISTORICAL REVIEW OF STRATIGRAPHIC SCHEMES

The history of eastern North Pacific Cretaceous and Cenozoic biostratigraphy indicates a neglect until recently of planktonic organisms. Previous biostratigraphic schemes are based chiefly on benthonic organisms, especially mollusks and Foraminifera, and correla- tions to the type areas of the original stages and epochs in Europe have been tenuous and subject to much question. More recent work with plankton has eliminated some of these problems, although many difficulties remain. Previous work on Cretaceous and Cenozoic biostratigraphy is briefly summarized below.

Cretaceous

Cretaceous sedimentary rocks are widely exposed along the eastern Pacific margin. These strata represent melange, flysch and associated materials deposited adjacent to the continental margin along an active subduction zone (Moores, 1970). In some places the sediments contain abundant plankton, but bivalves and gastropods are probably more common in the coarse-grained rocks, at least locally.

INTRODUCTI ON 5

Since 1856 when Trask described cephalopods from northern California, which incidentally he thought came from rocks of Miocene age, these larger megafossils have been described in some detail. A fairly complete biostratigraphic sequence has been established based on both ammonites and benthic mollusks (see Popenoe et al., 1960, for detailed review). In 1945, Goudkoff zoned the Upper Cretaceous on the basis of Foraminifera, chiefly benthonic but including 4 planktonic species as well.

Since 1960 planktonic Foraminifera (Douglas and Sliter, 1966; Sliter, 1968; Douglas, 1969, 1970), calcareous nannoplankton (Wilson and Lipps, 1970) and Radiolaria (Foreman, 1968; Pessagno, 1969, 1970, 1971) have been utilized biostratigraphically in the Upper Cretaceous with great potential for close correlation to the type European stages. So far, zonation is possible only on the basis of planktonic Foraminifera (Fig. 1).

)PEA N IGES

RICHTIAN

~ANIAN

TON IAN

IACIAN

O N I A N

EASTERN PACIF/C REGION

BENTHIC FORAMINIFERA i

D-1 D-2

E F-1

F-2

G-1

G-2

P L A N K T O N I C FORAMINIFERA z

kaoane¢.~

a4.c6~

p ~

Fig.1. Correlation o f Cretaceous European Stages and eastern Pacific benthonic and planktonic foraminiferal zones. ~ After Goudkof f (1945); 2after Douglas (1969).

Cenozoic

Marine and non-marine Cenozoic rocks and their included faunas are widely distributed throughout much of the eastern North Pacific margin, undergoing numerous lateral and vertical facies changes. Most of these rocks and faunas were deposited in one of three general types of environments: terrestrial, shallow-marine and deep-marine, containing terrestrial plants and vertebrates, larger invertebrates, and abundant micro-organisms,

6 J.H. LIPPS

respectively. There are few areas where facies and faunas representing these general environments are intercalated and, as a result, several different bases for stratigraphic subdivision have been developed.

Five schemes of stratigraphic classification are currently used along the eastern Pacific margin (Fig.2). Commonly, terrestrial deposits are classified by mammalian provincial ages (Wood et al., 1941), marine deposits containing larger invertebrates by megafaunal "stages" (C. E. Weaver et al., 1944; Durham, 1954), and deeper-water deposits by benthonic foraminiferal microfaunal stages (Kleinpell, 1938; Mallory, 1959). In addition to these three well-established schemes, two others based on planktonic organisms and radiometric age dates have been developing recently.

NORTH AMERICAN WILLIONS BENTHONIC WILUONS OF MOLLUSKAN OF FORAMINIFERAL PROVINCIAL YEARS "STA~ES" YEARS

AGES ''~ A~o 3 STAGES ~ AGO ~

RANCHOLABREAN ).015 ~ "UPPER"

IRVINGIONIAN ~ ' LOIER" - - 2 - ~ _d_

RLANCA, SAN JOAQUI, "~ '~ /C # / ' '

HEMPILLIAN w ETGHEGOIN o ~ ~ - - 4 - -

CLARENDONIAN ~ ~ ~ ~ JACALITOS ~_ ~ ~" ' 8 . . , , ~

8ARSTOVIAN \ ~ / ~ x ~ " - - 6 - ,EROS, --- ?- %- -

HEMINUFORUIAN \ ~u~4r~ ~ I 0 -- " ClERBO ~ ~ ~' ~ .

ARINAREEAN ~" ~ ,- ~ ~ uJ / " - - 1 2 - -

IHITNEYAN ~"- ~1 BRIONES ~ LUISIA'N"

ORELLAN -30 \ TEMBLOR (~ RELIZIAN 0 \ } - - 1 6 - -

CHADRONIAN \ VAQUEROS l~ ~... SAUCES&AN 22

DUUHESNEAN ~ \ wz BLAKELEY L ~ ZEMORRIAN - - - - - 4 0 ~ ~

UINTAN . .. ~ --LINCOLN " , ~ REFUU,AN

URIDOERIAN ~ - " - NEASEY " ~ NARIZIAN

WASATGHIAN ~ TEJON

CLARKFORRIAN \ ~, ,~ ~ ~ ~ ULATISIAN \ ~ ~ 'TRANSITION" / / ~ / o /

TIFFANIAN ~ \ o, PENUTIAN DOWENG(NE / / \

L~ " 6 0 / / BULITIAN ~> TORREJON mAN \ CAPAY ~ w \ w~

DRAGONIAN ~ MEOANOS I ~ YNEZIAN J

PUERCAN ~ WARTINEZ DANIAN ~

EUROPEAN STAGES

CALABRIAN

ASTIAN

PJAUENZrAN

ZANOLIAN

TORTONIA N- MESSINIAN

I

~ LANOHIAN

BUROIGALIAN

AQUITANIAN

CRATTIAN -i

LATORFIAN - RUPELIAN

- I PRIABONiAN

LUTETIAN

YPRESIA N

LANUENIAN

DAN[AN

Fig.2. Relationship of Cenozoic stratigraphic classifications used in the eastern North Pacific. Correlations to European Stages are based on planktonic foraminiferal and calcareous nannoplankton occurrences (see text). Sources: 'Wood et al., 1941; 2Durham, Kleinpell and Savage, in Durham, 1954; 3based on potassium-argon dates (Evernden et al., 1964); 4Weaver et al., 1944; Smodified from Kleinpell, 1938; Mallory, 1959; Kleinpell and Weaver, 1963; 6Loeblich, 1958; Martin, 1964. Loeblich recommended that the term "Cheneyan Stage" of Goudkoff (l 945, p. 967) be replaced by "Danian Stage" because of its planktonic, foraminiferal assemblage; 7potassium argon dates from Turner (1970).

INTRODUCTION 7

The provincial ages, based on characteristic terrestrial mammalian assemblages (Wood et al., 1941), used by vertebrate paleontologists and paleobotanists, are tenuously correlated with the marine stages; Durham, Kleinpell and Savage (in Durham, 1954, fig. 3) indicated relationships which are generally accepted and are those used in Fig.2. Some- what different correlations have been suggested by Durham et al. ( 1954, fig. 2), Savage (1955, fig. 3), Repenning and Vedder (1961, table 235. 1), and Mitchell and Repenning (1963, table 1). These correlations were first made to the megafaunal "stages", with which direct correlation is sometimes possible, and thence indirectly to the microfaunal stages.

Correlation of the microfaunal stages with the megafaunal "stages" is commonly direct as the different organisms may occur together. Nevertheless, parts of the two classifications are not yet well related and different correlations have been suggested (Weaver et al., 1944: Durham, Kleinpell and Savage in Durham, 1954, fig. 3; Holman, 1958, chart 1; Mitchell and Repenning, 1963, table 1). The correlations proposed in Durham (1954) are used ill Fig.2.

Recently, radiometric ages have been determined for some California Cenozoic rocks. Although it would be desirable to use a radiometric scale for relating ages of various sedimentary rocks (Ingle, 1967, p.220), sufficient data of this type are not yet available to securely provide such a basis. Most radiometric dates have been obtained from non- marine rocks assigned to the mammalian provincial ages (Evernden et al., 1964; Evernden and James, 1964; Axelrod, 1966), although some age dates are now available from marine rocks (see Turner, 1970).

Planktonic organisms are also used for stratigraphic zonation, although study of fossil plankton has not progressed far, probably because satisfactory stratigraphic results have been obtained within the local areas by using benthonic organisms and because diagnostic plankton are difficult to find. Bramlette and Sullivan (1961) recognized six zones based on calcareous nannoplankton in the Lower Tertiary rocks of California and they correlated these with the European stages. This portion of the section can also be zoned by planktonic Foraminifera (Steineck and Gibson, 1971), but further detailed study is necessary. Such foraminiferal zones for other parts of the California Tertiary were recognized by Loeblich (1958), Lipps (1964, 1967a, b), Martin (1964), Parker (1964), Ingle (1967) and Bandy and Ingle (1970). Martini and Bramlette (1963), Lipps (1968) and Wilcoxon ( t 969) suggested correlations of calcareous nannoplankton zones of the Upper Tertiary m the Experimental Mohole near Guadalupe lsland off Baja California and at Newport Bay, California, with planktonic foraminiferal zones of tropical areas.

The stratigraphic subdivisions presented in Fig.2 have been correlated variously with those of Europe. For example, the Oligocene of one scheme does not necessarily correspond to the Oligocene of another. This lack of correspondence is due, in part, to the different bases for classification and, in part, to the historical development of the schemes. The older schemes are based on provincial organisms; hence intercontinental correlation by co- occurrences of species is impossible. Indeed, Kleinpell (1938, p. 173) stated, "1 t is doubtful whether any Middle Tertiary correlation between Europe and California more refined than that derived by the Lyellian method can be made on the basis of faunal evidence alone".

8 J.H. LIPPS

Mallory (1959, p.101) believed that this was also true of the Lower Tertiary. Two schools

of opinion developed early; the various viewpoints were stated by Schenck (1935), Kleinpell (1938), Schenck and Childs (1942), Weaver et al. (1944), Mallory (1959) and Kleinpell and Weaver (1963) for the megafaunal and microfaunal stages. These divergent opinions are indicated on Fig.2 by diagonal lines through the disputed stratigraphic interval. Mammalian provincial ages are generally correlated with the European section as indicated on Fig.2, but not without question (Savage, 1955).

Correlation of eastern Pacific stages with European stages as inferred from planktonic foraminiferal and nannoplankton occurrences documented by Bramlette and Silllivan (1961), Ingle (1967), Lipps (1964, 1967a, b, 1968) and Bandy and Ingle (1970) are indicated on the right side of Fig.2.

MODERN OCEANOGRAPHY AND PLANKTON DISTRIBUTIONS IN THE EASTERN NORTH PACIFIC

The planktonic biotas of the eastern North Pacific appear to have been distinct from those of more southerly areas at least as long ago as the Late Cretaceous, according to the papers in this symposium. There have been variations in distinctness during this period, but in general, the paleobiogeography of plankton indicates that differences similar to the modern situation have existed for a long period of time. The modern plankton distributions are briefly summarized here; more detailed discussion can be found in the literature cited. These modern conditions can be used as a basis for comparison and interpretations of the fossil plankton assemblages described in the papers of this symposium.

Today, planktonic species, like those of many other terrestrial and marine groups, are distributed in a gradient from few species in polar seas to many in tropical seas that

corresponds in a general way to the climatic gradient of the earth. The underlying causes of this species diversity gradient is largely unl~aown, although many hypotheses have been suggested (see Pianka, 1966, and Sanders, 1968, for summaries). Most recently environ- mental stability or predictability, particularly among resources, has been suggested as a primary factor controlling species diversity (Margalef, 1968; Sanders, 1968; Valentine, 1971).

In areas of environmental fluctuations adaptations must be of a more general kind in order to cope with differing conditions. Contrary to this, areas of environmental stability permit specialization to minor environmental and biotic variations, resulting in increased species diversity (Sanders, 1968). As with other organisms planktonic species diversity is high in stable tropical waters where species appear to avoid competition by vertical migrations (Lipps, 1970). Thus although modern species may seem to be responding to temperature, and would therefore provide a basis for inferring past temperatures, they may in fact be responding to a related factor such as environmental stability. Low species diversity might similarly indicate fluctuating physical conditions. Although the causes of these distributional patterns cannot now be determined specifically for planktonic organisms, assumptions relating them to a single simple ecological variable may well result in erroneous paleoecologic interpretations.

INTRODUCTION 9

Most living plankton are distributed in the seas in approximate latitudinal belts that

correspond to the distribution of water characteristics such as temperature, salinity,

oxygen, historical and biological factors, as well as others. These various properties

combine to produce water masses (Sverdrup et al., 1942) of similar characteristics. Boundaries between water masses are regions of changing characteristics commonly

marked by sharp changes in salinity and temperature (Fig.3) which may limit the ranges

of plankton (Johnson and Brinton, 1963; Raymont, 1963).

- , •

/0'

Y A I , ' N / T V L

i i

Fig.3. Oceanography in the North Pacific Ocean (after Bradshaw, 1959)•

In the North Pacific four modern zoogeographic provinces, corresponding to water

masses (Fig.3), are recognized on the basis of the presence of particular species (Bradshaw,

1959; Brinton, 1962; Venrick, 1971). These provinces include: the Subarctic province, restricted to cold water of low salinity in the Gulf of Alaska, Bering Sea, and North Pacific

above 45 ° N; the Transitional province, restricted to the zone of cold Arctic water and warm, more southerly water that mix as the Kuroshio extension and North Pacific Currents transport water across the Pacific above 40 ° N latitude, and to the California

10 J.H. LIPPS

Current that extends southward along the eastern Pacific to about 25 ° N; the Central

province that occupies the region of the central current gyres; and the Equatorial province

that lies below about 20 ° N in the eastern and central Pacific, but that extends northward

to nearly 36 ° in the west as a result of the warm Kuroshio Current. These various provinces contain quite distinct assemblages of plankton. Cooler-water

faunas are characterized by few species of simple morphology. Both the numbers of

species and the degree of morphologic complexity increase in warmer waters. Only four

or five species occur in Subarctic waters while more than 30 species occur in the

Equatorial waters. The Transitional and Central provinces are occupied by intermediate

numbers that vary from time to time.

MODERN DISTRIBUTIONS OFF CALIFORNIA

The planktonic biota off California today is a Transitional one. However, areas of

eastern boundary currents, such as off California, are oceanographically complex (Wooster

and Reid, 1963) and biotic distributions are not simple (Fig.4). In these areas, species that

are normally geographically and oceanographically separated overlap often in time and

space as well as at different times in the same place. Off California rare species from the

Fig.4. Complex distribution of modern eastern Pacific plankton, as indicated by euphausids (after Brinton, 1962).

INTRODUCTION 11

central and southern warm-water provinces are regular constituents of the cool-water

Transitional assemblage found there. During summers, these species may occur in the

more southerly parts of the California Current off Baja and southern California (Bradshaw,

1959; Brinton, 1962; Johnson and Brinton, 1963). Moreover, during certain extended periods when apparently anomalous atmospheric conditions result in winds from the

south (Namias, 1960), positive temperature, salinity and sea-level anomalies (Reid, 1960; Stewart, 1960), and north-flowing currents (Reid, 1960; Schwartzlose, 1963), tropical

and subtropical phytoplankton, zooplankton and fish occur far north of their normal southern ranges in waters off southern and central California (Balech, 1960; Berner, 1960;

Brinton, 1960; Radovich, 1960). This phenomenon occurred during 1957-1958 when a period of rather constant biotic and oceanographic conditions persisted.

Upwellmg along the coast of California produces areas of markedly different water conditions, particularly of lowered temperature and increased nutrients (Wooster and

Reid, 1963). In areas affected by upwelling both the benthonic and planktonic biota may be composed of species that normally live far to the north (Hubbs, 1948; Valentine, 1955;

Longhurst, 1967). These complications have possibly existed for millions of years, and could cause

anomalous past distributions, especially at times of varied current or atmospheric patterns. In addition conditions that seem anomalous today may provide bases for inference of the more general and widespread conditions at times in the past.

If planktonic organisms are to be used for paleoecologic analysis, there must be confidence that their distribution in fossil deposits represents their distributions when they are alive in the overlying waters. Biostratigraphers and paleoecologists have cast doubt on the validity of this supposition because there is evidence that suggests that plankton can be carried to foreign environments (Fagerstrom, 1964, p. 1205). Murray (1897, p.22), however, long ago stated that "The distribution of dead shells of the pelagic Foraminifera on the floor of the ocean corresponds exactly with the distribution of the living specimens

of the sea". This fact has been generally confirmed in many places of the earth, including regions of ocean-wide extent like the Indian Ocean (Belyaeva, 1964) to smaller geographica! areas like the Gulf of Mexico (Phleger, 1954, pp. 10- 14), and the Okhotsk Sea (Lipps and Warme, 1966) among others. It appears that in spite of possible post-death transportation or destruction, death assemblages of planktonic organisms are reliable estimates of former

assemblages living in the water column. Thus it appears that the assemblages described in the papers of this symposium are

representative of the biotas that lived in this region. Throughout the Late Cretaceous and Cenozoic, palterns of distribution and abundance can be observed that are easily accounted

for by oceanographic situations analogous to those observed during recent time.

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Oceanic Fish Mvest. Rep., 7:127 132.

12 J.H. LIPPS

Bandy, O. L. and Ingle, J. C., 1970, Neogene planktonic events and radiometric scale, California. GeoL Soc. A m , Spec. Pap., 124: 131-172.

Belyaeva, N. V., 1964. Raspredelenie planktonnykh foraminifer v vodakh i na dne lndiyskogo Okeana: Akad. Nauk SSSR, Tr. Inst. Okeanol., 68: 12-83. [Distribution of planktonic Foraminifera in the water and on the floor of the Indian Ocean].

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INTRODUCTION 13

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