U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY

Palynological Data from Pliocene Sediments, DSDP Leg 5 Site 32,
Northeastern Pacific Ocean

by R. Farley Fleming

Open-File Report 92-712

This report is preliminary and has not been reviewed for conformity with
U.S. Geological Survey editorial standards (or with the North American
Stratigraphic Code).  Any use of trade, product, or firm names is for
descriptive purposes only and does not imply endorsement by the U.S.
Government.

TABLE OF CONTENTS

Introduction

Materials and Methods

Age Control

Data Matrices

Taxonomic Comments

Discussion

References

Appendix 1

Appendix 2

Appendix 3

Appendix 4

ILLUSTRATIONS

Figure 1

INTRODUCTION

Studies of Pliocene sea-surface temperatures of the North Atlantic Ocean
indicate that there were intervals during the Pliocene substantially
warmer than modern conditions (Dowsett and Poore, 1990; 1991).  One of
these intervals occurs at about 3 Ma (Dowsett and Poore, 1991).  One goal
of PRISM (Pliocene Research, Interpretation, and Synoptic Mapping) is to
produce a paleoclimatic map for the world at 3 Ma.  As part of this
effort, the Pliocene Continental Climates Project within PRISM is
attempting to reconstruct terrestrial vegetation patterns along the west
coast of North America during the Pliocene, especially at 3 Ma.

This report contains palynological data from DSDP Site 32, located in the
northeast Pacific Ocean approximately 380 km off the coast of California.
The data reported here consist of a matrix of absolute count data (numbers
of specimens) and a matrix of relative abundance data (percentages).
These data will be used in the future as a basis for making semi-
quantitative and quantitative estimates of climatic parameters during the
Pliocene for western North America.  Only preliminary interpretations are
presented in this report.

MATERIALS AND METHODS

Locality and Setting

Leg 5 of the Deep Sea Drilling Project (DSDP, now the Ocean Drilling
Program, ODP) drilled 12 sites in the northeast Pacific Ocean in 1969.
Site 32 of Leg 5 was drilled near the seaward margin of the Delgada Fan,
off the coast of California, at 37 degrees, 7.63 minutes north latitude
and 127 degrees, 33.38 minutes west longitude (Shipboard Scientific Party,
1970).  Figure 1 shows the position of Site 32 off the west coast of
California.

The Delgada Fan contains a mixture of terrigenous and clastic sediments
(McManus and others, 1970).  Most of the terrigenous sediments are derived
from areas now drained by the San Joaquin and Sacramento Rivers.  At
present, the San Joaquin River drains the southern part of the Great
Valley and the Sacramento River drains the northern part of the Great
Valley.  During the Pliocene, the Delgada Fan presumably received sediment
from the same general area, although a marine embayment filled much of the
Great Valley (Cole and Armentrout, 1979).

Approximately 215 m of sediment were cored at Site 32.  Cores 3 through 6
contain a total of 28.5 m of Pliocene sediments (Shipboard Scientific
Party, 1970).  Cores 3 through 6 were taken with little difficulty and
represent a continuously cored sequence, although some disturbance of
sediments was reported.  On the basis of diatom analyses by Barron (in
press), these cores preserve a nearly complete and relatively undisturbed
record from about 3.0 Ma to 5.0 Ma.  ODP stores the cores at the ODP Core
Repository at Scripps Oceanographic Institute in La Jolla, California.

Sample collection and sample positions

Appendix 1 lists the USGS sample number, DSDP core and section numbers,
and depth information for each of the 31 samples collected from Site 32
for this study.  Each core at Site 32 was 9 m in length and was divided
into 1.5 m sections, numbered 1-6 from the top down.  Top and bottom data
provided for each sample collected from Site 32 were measured from the top
of the section from which the sample was taken.  The depth of each sample
below seafloor (meters below seafloor, mbsf) was calculated using
published DSDP depth data for Site 32 (Shipboard Scientific Party, 1970)
and the depth information for each core and section.  The "DSDP depth"
provided by DSDP was calculated for the top of each sample.  The "midpoint
depth" calculated for this study is for the middle of each sample interval.

Discrepancies are apparent between some depths provided by DSDP and the
corresponding depths calculated in this report.  Sample D7706(86.44) has a
depth of 86.44 mbsf according to the sample listing provided by DSDP.
However, calculating the depth using the figures in Table 1 reveals that
86.56 mbsf is more accurate for this sample.  Similarly, sample D7706(105.9)
has a DSDP depth of 105.9 mbsf and its depth calculated with Table 1
measurements is 105.80 mbsf.  Appendices 2 and 3 use the depths calculated
in this study, which are listed in "midpoint depth" column of Appendix 1.

AGE CONTROL

The initial paleontological study of Site 32 was based primarily on
calcareous nannofossils (Shipboard Scientific Party, 1970).  In the
initial report, sediments from cores 3-6 were assigned to the Pliocene.
All sediment from Core 3 was assigned to the upper Pliocene; all sediment
from cores 4 and 5 and the upper 1.5 m of core 6 were assigned to the
lower Pliocene.

Barron (in press) integrated his diatom stratigraphy with the
biostratigraphic studies of Bukry and Bramlette (1970) and Gartner (1970)
and concluded that a nearly complete interval was recovered in cores 3-6
that ranges from 3.0 to 5.0 Ma.  Also, Barron (in press) refined the
Pliocene diatom stratigraphy for California based on calibration with
paleomagnetic and radiometric studies in the Centerville Beach outcrop
section (northern California), the Harris Grade outcrop section (southern
California), and DSDP Site 32.  His study provides critical absolute ages
for diatom horizons in the interval between 5.0 and 2.8 Ma (Barron, in
press).  This allows more accurate and precise dating of samples from Site 32.

Appendix 1 lists the age estimates for all samples from Site 32 used in
this study.  J. Barron provided the first set of samples from Site 32 with
his age assignments based on his calibration of diatom datums, and these
dates are italicized under "age" in Appendix 1.  I collected additional
samples from Site 32 cores and extrapolated and interpolated the ages for
these samples based on Barron's analyses.  This approach accepts Barron's
conclusion that the core records a complete and uniform record for the
interval 3-5 Ma and assumes a constant sedimentation rate of 18 m/m.y.

DATA MATRICES

The data matrix of Appendix 2 contains the absolute count data for the 31
samples from Site 32.  Some samples were too sparse for adequate
statistical counts.  For four of the sparse samples, only the presence of
a taxon or category is noted; two of these samples have preliminary count
data that are not considered reliable but is reported nonetheless.  Some
fossils were observed during preliminary scans (i.e., before statistical
counts were made) that were not encountered in the sample counts.  These
are listed in Appendix 2 as "trace."  Appendix 2 also presents fossils
that were unidentified because of their preservation.  These are listed
as "broken," "concealed," "corroded," or "crumpled."

The data matrix of Appendix 3 contains relative abundances for most of the
pollen categories listed in Appendix 2.  Appendix 3 omits two categories
of Appendix 2, Pinus bladders and Pinus bodies.  The percentage of Pinus
includes one-half of the Pinus bladders counts and excludes Pinus bodies.
The percentages are based on the sum of the terrestrial pollen and exclude
spores, algae (freshwater and marine), and pollen of aquatic plants (i.e.,
Potamogeton/Triglochin).  Occurrences listed as "trace" in Appendix 2 are
listed as "0" in Appendix 3.  The unidentified categories of Appendix 2
are combined as a single percentage in Appendix 3 and entered under "
indeterminates."  Appendix 3 contains count data for 27 of the 31 samples
collected from Site 32.  The four samples excluded from Appendix 3 are the
barren samples of Appendix 2.

TAXONOMIC COMMENTS

Some categories included in the raw data matrix (Appendix 2) and the
relative abundance data matrix (Appendix 3) need explanation.  All samples
from Site 32 contained common to abundant pollen referable to the
Taxodiaceae, Cupressaceae, or Taxaceae.  Pollen morphology in these three
gymnosperm families is basically the same, with subtle differences that
may permit identification at the individual family or genus level.  All
pollen of this group lacking diagnostic features for family or generic
level taxa were referred to "TCT undifferentiated."  If the pollen grain
exhibited a papilla without critical details of the wall structure
preserved, it was assigned to the Taxodiaceae.  If a papillate fossil
within this group preserved details of the wall structure associated with
the tenuitas, then it was assigned to Sequoia or Taxodium as appropriate.

There are six morphological categories that were not assigned to a
particular botanical group.  "Monosulcate type 1" is simple monosulcate
pollen that could be produced by gymnosperms (e.g., cycads) or
angiosperms (e.g., magnoliids).  "Monosulcate type 2" is reticulate
monosulcate pollen possibly produced by palms or the Agavaceae, but too
few specimens were observed to allow definitive assignment at this time.
"Tricolpate type 1" is simple tricolpate pollen that is prolate, psilate,
and relatively small.  This type is produced by a number of plant
families.  "Tricolpate type 2" pollen is prolate to spheroidal pollen with
long colpi and a eureticulate wall having a fine reticulum.  "Tricolporate
type 1" is tricolporate, prolate, psilate pollen similar to tricolpate
type 1 except that it is tricolporate; this type is also produced by a
number of plant families.  "Tricolporate type 2" is the most abundant of
the types assigned to morphological categories.  This pollen is
tricolporate and prolate and has a very fine reticulate or foveolate
pattern on the surface of the grain.

Besides "dinoflagellates undifferentiated," two additional dinoflagellate
types were counted.  "Dinoflagellate type 1" is a small chorate cyst.
"Dinoflagellate type 2" is a distinctive cyst that lacks processes, has
an intercalary archeopyle, and a surface ornamentation that appears finely
reticulate.

Question marks beside generic names (e.g., Acer?) indicate that the
identification is only tentative.  This usually indicates that only one
specimen was recovered and preservation or orientation allowed only
tentative assignment.  Familial categories are included for families that
have more or less distinctive pollen but for which generic distinctions
are lacking or difficult to determine.

DISCUSSION

Preliminary analysis of the data of Appendix 3 reveals patterns that
suggest departures from modern climatic conditions during the Pliocene.
In Appendix 4, relative abundances of selected taxa are plotted against
absolute time.  These data are compared with modern palynological data
from Heusser and Balsam (1977), who determined absolute and relative
abundance of palynomorphs in core top samples from 61 cores taken along
the continental margin of the northeast Pacific.  One of Heusser and
Balsam's cores, number 54, was taken approximately 200 km east of Site 32
(Figure 1); this core will be used for comparison with Pliocene sediments
from Site 32.  Heusser and Balsam (1977) also compared pollen relative
abundance with modern terrestrial vegetation distribution along the
Pacific northwest, which may allow inferences to be made about the
differences between modern and Pliocene vegetation.  Although Heusser and
Balsam provide a useful basis for comparison, they did not report the
presence of undifferentiated TCT pollen.  As discussed below, TCT is the
dominant fossil in most Site 32 samples.  At this time, data on TCT
abundance in modern marine sites near Site 32 is lacking.

All samples from Site 32 are dominated by pollen of TCT and Pinus.  Plot 1
(Appendix 4) shows the relative abundance of these two groups plotted
against age.  In general, TCT is dominant from 4.5 Ma to 2.8 Ma.  Pinus
becomes dominant at about 3.75 Ma and again at 3.0 Ma.  Plot 2 shows the
Pinus relative abundance profile with the level of Pinus in Heusser and
Balsam's modern site shown with a horizontal arrow.  This comparison
suggests that, except for the times around 3.75 Ma, Pinus is not as
abundant in Site 32 as it is in the modern site.  Adam and others (1990)
reported higher TCT values in the Pliocene than in younger sediments at
Tule Lake.  They developed a model in which increased TCT with respect to
Pinus indicates warmer conditions.   Using this model, they inferred
warmer conditions in the Pliocene from 2.8 Ma to 2.6 Ma (Adam and others,
1990).

Sequoia pollen was present in low amounts in Site 32.  Although fossils
referred to the Taxodiaceae could be Sequoia or Taxodium, they are more
likely to be Sequoia.  Even if the Taxodiaceae and Sequoia are added
together (thus representing the maximum possible Sequoia), the relative
abundance of this type is significantly lower than values for Sequoia in
Heusser and Balsam's modern sample (see Plot 3).  Heusser and Balsam's
data indicate that Sequoia stands today contribute significant amounts of
pollen to adjacent marine environments.  Data from Site 32 indicate that
Sequoia stands were significantly reduced during the Pliocene.

Other taxa in Site 32 have relative abundances similar to the modern
values.  For example, the relative abundance of Alnus in Site 32 (Plot 4)
was more or less similar to modern values except at 3.0 Ma, when Alnus
increased significantly.

Several exotic taxa are present in Pliocene sediments from Site 32 that
were apparently present in the Pliocene but have since been extirpated
from California.  These taxa are Carpinus, Carya, Ilex, Taxodium, Tilia,
Pterocarya, and Ulmus.  The presence of these taxa in the California
Neogene is already known.  For example, Axelrod (1950, 1980) reports
Pterocarya and Ilex from Pliocene Sonoma florules of California;
Daubenmire (1978) reports the presence of Tilia, Ulmus, and Carya in the
Neogene of west central North America.  Heusser (1981) recovered pollen of
Ilex, Ulmus, Tilia, and Pterocarya from lower Pliocene sediments of DSDP
Leg 63.

Apparently Taxodium has not previously been reported from the Pliocene of
California, although Leopold and Denton (1987) report Taxodium leaf
fossils from Miocene rocks in the Columbia basin west of the Rocky
Mountains and east of the Cascades.  Some Taxodium is present at 3.61 Ma
and 3.08 Ma in Site 32.  Taxodium is present in swamps in southeastern U.
S. today and thrives in habitats that have standing water throughout the
year.

Today Pterocarya occurs only in the Old World, in the Caucasus Mountains
and in China and Japan (Leopold and MacGinitie, 1972).  Leopold and
MacGinitie (1972) estimate that modern Pterocarya grows in areas with
effective temperatures equivalent to those found in central California
today.  In areas where it grows today, it appears to require summer
rainfall.  Also, Axelrod (1950) concludes that the presence of Ilex and
Pterocarya indicate summer precipitation during the Pliocene.  This is
consistent with the presence of Taxodium and its need for year-round
precipitation.

These data are preliminary but some of the patterns suggest that
paleoclimate in California during the Pliocene was different from the
present climate.  The presence of Ilex, Pterocarya  and Taxodium  suggests
that adequate moisture was present year-round.  The reduction in Sequoia
suggests that, even though there was enough moisture for Taxodium,
climatic conditions did not allow enough fog for Sequoia to exist in
amounts comparable to today.  Today Sequoia occupies foggy coastal areas
(Axelrod, 1986).

Additional sites along the west coast of North America (e.g., the
Centerville Beach section near Eureka, California) may provide
corroborative trends that will increase confidence in the patterns
observed at Site 32.  Results from Site 32 will be integrated with results
from other sites to reconstruct a paleovegetational and paleoclimatic
picture of western North America during the Pliocene.

REFERENCES

Adam, D. P., Bradbury, J. P., Rieck, H. J., and Sarna-Wojcicki, A. M.,
1990, Environmental changes in the Tule Lake Basin, Siskiyou and Modoc
Counties, California, from 3 to 2 million years before present.  U. S.
Geological Survey Bulletin 1933, 13 pages.

Axelrod, D. I., 1950, Studies in late Tertiary paleobotany II:  A Sonoma
florule from Napa, California.  Carnegie Institution of Washington
Publication 590, 71 pages.

Axelrod, D. I., 1980, Contributions to the Neogene Paleobotany of central
California.  University of California Press, 212 pages.

Axelrod, D. I., 1986, The Sierra Redwood (Sequoiadendron) Forest:  End of
a dynasty.  Geophytology 16(1):25-36.

Barron, J. A., 1992, Paleoceanographic and tectonic controls on the
Pliocene diatom record of California, in Tsuchi, Tyuichi, and Ingle, J.C.,
Jr., editors, Pacific Neogene:  Environment, Evolution and Events.
Proceedings of the 5th International Congress on Pacific Neogene
Stratigraphy, International Geological Correlation Program 246, p. 25-41.

Bukry, David, and Bramlette, M. N., 1970, Coccolith age determinations Leg
5, Deep Sea Drilling Project.  Initial Reports , Deep Sea Drilling
Project, volume 5, U.S. Government Printing Office, Washington, D.C., p.
487-494.

Cole, M. R., and Armentrout, J. M., 1979, Neogene paleogeography of the
western United States, in Armentrout, J. M., Cole, M. R., and TerBest,
Harry, Jr., (editors), Cenozoic Paleogeography of the Western United
States:  Pacific Coast Paleogeography Symposium 3, Society of Economic
Paleontologists and Mineralogists, p. 297-323.

Daubenmire, Rexford, 1978, Plant geography with special reference to North
America.  Academic Press, New York, NY, 338 pages.

Dowsett, H. J.,  and Poore, R. Z., 1990, A new planktic foraminifer
transfer function for estimating Pliocene through Holocene sea surface
temperatures.  Marine Micropaleontology 16(1/2):1-23.

Dowsett, H. J.,  and Poore, R. Z., 1991, Pliocene sea surface temperatures
of the North Atlantic Ocean at 3.0 Ma. Quaternary Science Reviews 10(2/3):
189-204.

Gartner, Stefan, 1970, Coccolith age determinations Leg 5, Deep Sea
Drilling Project.  Initial Reports , Deep Sea Drilling Project, volume 5,
U.S. Government Printing Office, Washington, D.C., p. 495-500.

Heusser, L. E., 1981, Pollen analysis of selected samples from Deep Sea
Drilling Project Leg 63.  Initial Reports , Deep Sea Drilling Project,
volume 63, U.S. Government Printing Office, Washington, D.C., p. 559-563.

Heusser, L. E., and Balsam, W. L., 1977, Pollen distribution in the
northeast Pacific Ocean.  Quaternary Research 7(1):45-62.

Leopold, E. B., and Denton, M. F., 1987, Comparative age of grassland and
steppe east and west of the northern Rocky Mountains.  Annals of the
Missouri Botanical Gardens 74:841-867.

Leopold, E. B., and MacGinitie, H. D., 1972, Development and affinities of
Tertiary floras in the Rocky Mountains, in Graham, Alan, (editor),
Floristics and paleofloristics of Asia and eastern North America:
Proceedings of Symposia for the Systematics Section, XI International
Botanical Congress, Elsevier, p. 147-200.

McManus, D. A., Weser, Oscar, Borch, C. C. van der, Vallier, Tracy, Burns,
R. E., 1970, Regional aspects of deep sea drilling in the northeast
Pacific.  Initial Reports, Deep Sea Drilling Project, volume 5, U.S.
Government Printing Office, Washington, D.C., p.  621-636.

Shipboard Scientific Party, 1970, Site 32.  Initial Reports , Deep Sea
Drilling Project, volume 5, U.S. Government Printing Office, Washington, D.
C., p. 15-56.

APPENDIX 1

Appendix 1 contains sample data for the 31 samples from DSDP Site 32.
Italicized numbers in age column are dates provided by John Barron and are
based on his analysis of DSDP Site 32 (Barron, in press).  Depths are
given in meters below seafloor (mbsf).

APPENDIX 2

Appendix 2 contains absolute count data for the 31 DSDP Site 32 samples in
this study.  Numbers in each cell are the numbers of specimens counted in
the samples for each palynomorph category.

APPENDIX 3

Appendix 3 contains relative abundances for selected pollen categories.
All values are percentages calculated using the data in Appendix 2.  See
text for discussion of the categories included in this appendix.  Four
samples of Appendix 3 are not included because of insufficient palynomorph
recovery -- these are labeled "barren" in Appendix 2.

APPENDIX 4

Appendix 4 contains plots of relative abundance profiles (percentage
versus age) for selected taxa from DSDP Site 32.  See text for discussion.

(end)