Late Pleistocene paleotemperatures

Table 1. Number of specimens of New Zealand Upper Eocene silicoflagellates in faunules from six Oamaru localities. Locality

Dictyocha Distephanus

William's Bluff Number of specimens 57 Approximate percentage 40 Jackson's Paddock Number of specimens 13 Approximate percentage 31 Allan's Farm Number of specimens 48 Approximate percentage 21 Troublesome Gully Number of specimens 80 Approximate percentage 23 Papakaio (Flume Gully) Number of specimens 99 Approximate percentage 32 Bain's Farm Number of specimens 139 Approximate percentage 18



5V2



16 11 1/2

0 0

142 100

9 22

14 33

6 14

0 0

42 100

66 29

42 19

36 16

35 15

227 100

114 33

121 35

32 9

0 0

347 100

76 25

102 33

32 10

0 0

309 100

100 13

302 40

5

756 100

Temperature (°C.) Currently Locality Dictyoch a/ determined suggested Disteph anus from graph temperature ratios (Mandra, 1969) range ('C.) William's Bluff 0.93 Jackson's Paddock 1.45 Allan's Farm 0.73 Troublesome Gully 0.70 Papakaio (Flume Gully) 1.30 Bain's Farm 1.40

Naviculopsis Mesocena Rocella

8

61 43

Table 2. Upper Eocene paleotemperatures for six Oamaru localities based on the Dictyocha/Distephanus ratio methodology (Mandra, 1969).

21

20-25

23

20-25

18

15-20

17

15-20

22

20-25

23

20-25

same as those based upon seven other groups of fossils and oxygen isotopes (Mandra and Mandra, 1970). Therefore, when other fossils are not present and oxygen isotope studies are not available, as is the case for our South Atlantic deep-sea core, then temperatures based on a study of silicofiagellates can be used with some confidence (Mandra, 1969). Comprehensive studies on the silicoflagellates of the Oamaru diatomites are being continued by the authors. Support for this study is being provided by the National Science Foundation under grant GV-25572. We are grateful to Dr. A. L. Brigger, research associate of the California Academy of Sciences, who supplied the excellent slides and other data that are so essential in our work, and to Mr. A. R. Edwards of the New Zea178

Total

Genera

210 28



land Geological Survey, who gave assistance both in the field and in the survey laboratory. References Edwards, A. R. 1968. Marine climates in the Oamaru District during Late Kaiatan to Early Whaingaroan time. Journal of the Biological Society (Victoria University, Wellington, New Zealand), 16(1): 75-79. Mandra, Y. T. 1969. Silicoflagellates: a new tool for the study of antarctic Tertiary climates. Antarctic Journal of the U.S., IV(5) : 172-174. and H. Mandra. 1970. Antarctic Tertiary marine climate based on silicoflagellates. Antarctic Journal of the U.S., V(5) : 178-180.

Late Pleistocene paleotemperatures: silicoflagellate and foram iniferal frequency changes in a deep-sea core JOHN P. JENDRZEJEWSKI and GARY A. ZARILLO

Department of Geology University of Rhode Island Climatic trends have been established previously for subantarctic cores using well documented paleoecologic indicators. The purpose of this study is to illustrate the potential use of silicofiagellates as paleoecological tools in marine Pleistocene sediments. We have examined changes in silicofiagellate and planktonic foraminiferal assemblages in a subantarctic core from the South Pacific (Eltanin core 33-22; depth 2,744 m; length 1,094 cm; 54°56'S. 120°W.). The core consists of carbonate ooze throughout and is rich in both calcareous and siliceous microfossils. Kennett (1970) established three planktonic foraminiferal zones in subantarctic cores and distinguished ANTARCTIC JOURNAL

0 80 20PERCENT 40 DIC6TYOCHA FORAMINIFERA

*1 LU LLJ

6 " LIZ

SILICOFLAGELLATES

PERCENTTONICWARMFORAMIWATNEIFRERA

PLANK

COILING IN G. PPCHYDERMA (PERCENT SINISTRAL)

Frequency curves for warm-water silicoflagellates (Dictyocha spp) and warm-water planktonic Foraminifera, Eltanin core 33-22. Remainder of the silicoflagellate assemblage consists of Distephanus speculum (seven varieties). Curves formed by percent Dictyocha and percent warm-water Foraminifera correlate closely. Successive peaks representing climatic warming events (Kennett, 1970) are numbered (in circles). Positions of the Late Pleistocene Globorotalia truncatulinoides and G. inflata zones (Kennett, 1970) are indicated, and also the percentage of left-coiling G. pachyderma. Long hash marks indicate silicoflagellate counts; short marks, foraminiferal counts.

eight climatic warming intervals for the middle and late Pleistocene (t = 0 to 1.2 million years before the present) based on oscillations of the polar species Gbbigerina pachyderma and several subpolar species. Climatically controlled foraminiferal frequency changes and foraminiferal zonations have likewise been determined for Eltanin core 33-22 (see fig.). The core contains the Gboborotalia truncatulinoides and Globorotalia inflata zone. Furthermore, five warm intervals are apparent (see fig.) that correlate well with the uppermost five warming peaks of Kennett (1970), the lowest of which (peak 5) is distinctly warmer than all others. Correlation with the chronolSeptember—October 1971

ogy established by Kennett (1970) suggests that Eltanin core 33-22 is 450,000 years old at its base. Although the systematics of the silicoflagellates are not well known (Mandra, 1968; Loeblich et al., 1968; Lipps, 1970) they are abundant enough in marine sediments to be used in environmental studies. Gemeinhardt (1934) demonstrated biogeographic provinciality among the silicofiagellates and thus established their potential for paleoecological work. In the South Atlantic, Diet yocha was found to occur in low and middle latitudes and Distephanus in higher latitudes. The only previous study utilizing silicofiagellates in paleoclimatic analyses was by Mandra (1969), who compared the ratio of Dictyocha to Distephanus within an Eocene South Atlantic core. In Eltanin core 33-22, silicoflagellate assemblages consist entirely of the two genera Distephanus and Dictyocha. Species present are Distephanus speculum (consisting of seven varieties), Dictyocha antarctica, D. fibula var. aculeata, and D. rhombus. From counts of 200 individuals in each sample, five peaks of high abundance of Dictyocha spp are demonstrated (see fig.) in the core. These intervals are separated by intervals consisting almost exclusively of Distephanus. Furthermore, a close correlation exists between the Dictyocha peaks and warm-water peaks defined by planktonic Foraminifera. Foraminiferal peak 3 shows no corresponding silicoflagellate warm peak. In other cores (Kennett, 1970; Hays, 1967) this apparent warming also is not defined clearly by the radiolarians. We thank James P. Kennett for his valuable guidance during this study and Eugene J . Tynan for his helpful discussion concerning the silicofiagellates. Lianne Armstrong drafted the figure. This work was partially supported by NSF grant GV-28305. References Gemeinhardt, K. 1934. Die Silicoflagellaten des südat lantischen Ozeans. Wissenschaftliche Ergebnisse der deutschen atlantischen Expedition auf dem Forschungs- und Vermessungsschifl "Meteor" 1925-1927, 12(1): 274-312.

Hays, J . D. 1967. Quaternary sediments of the antarctic ocean. Progress in Oceanography, 4: 117-131. Kennett, J . P. 1970. Pleistocene paleoclimates and foraminiferal biostratigraphy in subantarctic deep-sea cores. Deep-Sea Research, 17: 125-140. Lipps, J . H. 1970. Ecology and evolution of silicoflagellates. North American Paleontological Convention. Proceedings, 1969, p. 965-993.

Loeblich, A. R., III, L. A. Loeblich Helen Tappan, and A. R. Loeblich, Jr. 1968. Annotated ' index of fossil and Recent silicoflagellates and ebridians with description and illustrations of validly proposed taxa. Geological Society of America. Memoirs, 106: 319 p. Mandra, Y. T. 1968. Silicoflagellates from the Cretaceous, Eocene, and Miocene of California, U.S.A. California Academy of Sciences. Proceedings, fourth series, XXXVI (9): 231-277. 1969. Silicofiagellates: a new tool for the study of antarctic Tertiary climates. Antarctic Journal of the U.S., IV(5) : 172-174.

179