Late Eocene temperatures indicated by silicoflagellates ...
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N 2 N Z 0 2F6.4O 200 Figure 2. Percent fluctuations of Neogloboquadrina pachyderma (solid line) and percent fluctuations in reticulate ultrastructural forms (dashed) of N. pachyderma in the Late Miocene to Pleistocene sequence corded at DSDP site 284 (temperate South Pacific). High frequencies of Al. pachyderma represent cool intervals; low frequencies represent warm intervals. Characteristics of secondary calcification determined by examination of 50 specimens in each saàple (shown at right) using a scanning electron microscope. Note generally reciprocal relations between the two parameters. N.Z. Late Cenozoic stages are shown at right and Pleistocene disconformity is near the top of the sequence.
Jenkins, D. G. 1967. Recent distribution, origin, and coiling ratio changes in Globigerina. pachyderma (Ehrenberg). Micropaleontology, 13(2) : 195. Kennett, J . P. 1967. Paleo-oceanographic aspects of the foraminiferal zonation in the Upper Miocene-Lower Pliocene of New Zealand. Bologna, Committee on Neogene, 4th International Congress. Giornale di Geologia, 2(35) 143.
September-October 1974
Kennett, J . P., and M. S. Srinivasan. In press. Surface ultrastructural variation in Neogloboquadrina pachyderma (Ehrenberg): phenotypic variation and phylogeny in the Late Cenozoic. In: 0. L. Bandy Memorial Volume (Kolpack, R., and D. Gorsline, editors). Kennett, J . P., and P. Vella. In press. Late Cenozoic planktonic foraminifera and paleoceanography at DSDP site 284 in the cool subtropical South Pacific. In: Initial Reports of the Deep-Sea Drilling Project (Kennett, J . P., et al.), 29. Washington, D.C., U.S. Government Printing Office. Srinivasan, M. S., and J . P. Kennett. 1974. SEM ultrastructural variation in planktonic foraminifera: value in evolutionary and phenotypic studies. American Association of Petroleum Geologists Bulletin, 1: 86 (abstract). Srinivasan, M. S., and J . P. Kennett. In press. Evolution and phenotypic variation in the Late Cenozoic Neoglobo quadrina dutertrei plexus. In: Professor Asano Commemoration Volume (Takayanagi, Y., and T. Saito, editors). New York, Micropaleontology Press. Srinivasan, M. S., and J . P. Kennett. In press. Secondary calcification of the planktonic foraminifer Neoglobo quadrini pachyderma as a climatic index. Science.
Late Eocene temperatures indicated by silicoflagellates from the Oamaru diatomite, New Zealand YORK T. MANDRA*
California Academy of Sciences and San Francisco State University A. L. BRIGGER
California Academy of Sciences HIGH00HI MANDRA*
This paper reports the results of analyses of new data in our continuing studies of Late Eocene southern ocean water temperatures (Mandra et al., 1969, 1973c), silicoflagellates as indicators of paleotemperatures (Mandra, 1958; Mandra et al., 1972), and Late Eocene silicoflagellates from the Bain's and Totara localities of the Oamaru diatomite of New Zealand (Mandra et al., 1971a, 1973a). Hornibrook (1971) reviews the evidence for New Zealand Tertiary climates as published by the close of 1969. Fig. 1 summarizes the portion of his conclusions that relates to our present study. He reports that marine water temperatures, based on oxygen isotope studies, during the Runangan stage (Arnold Series, Late Eocene) at 41°S. in New Zealand were approximately 22°C. For the same time and place * Mailing address: 8 Bucareli Drive, San Francisco, California 94132. This is contribution 54, Biogeology Clean Laboratory, University of California, Santa Barbara.
265
Degrees C. 25 utr
N t
I ULII5OCENE I
CLIMATE ZONE
Subtropical
'
•
________ Worm 1.
15 --j"------___________ Cool temperate 10 ___________________________ Cold M/y before 38 25 present l A ki A r Lwh ILdI I N. Z. Stages RNOLD I LANDON I N. Z. Series David Crouch
Figure 1. N.Z. Eocene and Oligocene climates for Wellington (41 05W), expressed in terms of absolute time, relative time (stages and series), °C., and climate zone. Solid line represents temperatures based upon oxygen isotope data, dashed line represents temperatures based on paleontological analyses. (Adapted from Hornibrook, 1971.)
STRATIGRAPHIC SEQUENCE OF OAMARU DIATOMITE Epochs N. Z. Stages Symbols Lithologic Units Duntroonian Ld Oligocene
-
Whaingaroan Lwh McDonald Limestone -_ Runangan Ar Oamaru Diatomite Upper _____________ Eocene Lorne Volcanic Mem. Kaictan Ak David Crouch
Figure 2. Symbols and N.Z. stages and series used in fig. 1 here are expressed in terms of epochs. Note that a small part of the Oamaru diatomite in a few localities is lowermost Whaingaroan (lowermost Oligocene). The stages immediately above and below the two "Oamaru stages" are shown. The lithologic units immediately above and below the Oamaru diatomite are shown. This chart is part of a more comprehensive chart (unpublished) by the N.Z. Geological Survey.
his paleontological evidence indicates that the marine water temperature was approximately 24°C. Our studies based on silicoflagellates are in remarkable agreement with the paleontological and oxygen isotope data reported by Hornibrook (1971). Our analyses indicate that the surface and near-surface southern ocean waters in the area of the Oamaru 266
diatomite, New Zealand, during the Runangan stage had the following temperature ranges as recorded at five horizons: 21° to 28°C.; 22° to 27°C.; 21° to 27 0 C.; 20 0 to 27 0 C.; 19° to 25°C. The results are expressed in terms of temperature ranges because the degree of accuracy of our method has not yet been clearly established. What follows are the detailed data upon which these conclusions are based. Doig (1967) suggests that Bain's locality and the Totara locality of the Oamaru diatomite, South Island, New Zealand, should be called Bain's Farm section. The name Totara was to be suppressed . He indicated that his suggestion was supported by N. Z. Geological Survey (NzGs) geologists who have: extensively studied the Oamaru diatomite. Because the name Bain's Farm section now is used in a wider sense and covers a wider area, it now is necessary to nuriber its main diatomite localities. We collected our samples from beds 5, 6, and 7 of localities 3 and 4 of Bain's Farm section. Dr. A. R. Edwards, NZGS, assisted our extensive field study and collection of the Oamaru diatomite. We recollected NZGS samples S136/964, S136/966, and S136/67. These samples from Bain's Farm section locality 3 have the following map grid reference S136/475:657. Locality 4, formerly called Totara locality, was a recollection of NZGS sample S136/969. The map grid reference is S136/475:656. The Oamaru diatomite is a member of the Waiareka volcanic formation. According to the NZGs it is Runangan (Late Eocene). Fig. 2 shows the stratigraphic relationship of the Oamaru diatomitq to the overlying McDonald limestone and the underlying Lorne volcanic member. Our samples were treated by chemical extraction techniques (Mandra et al., 1973b). Depending on the abundance of silicoflagellates, four or six strekvn slides were made for each horizon. For example, B has very few silicoflagellates; therefore, six slides wre made. The remaining samples have many sil4oflagellates; hence only four slides for each of the otIier horizons were made. When possible, the proce4re was to work with a minimum of 200 specimens wth at least 50 specimens per slide. At least four slies per horizon were studied. Usually one author worked with no more than half the slides of one horizon. In this way each horizon was studied by at least two authors. The model by which silicoflagellates can be usd to estimate paleo temperatures is described in Mancra (19585 1969). It involves counts and ratios of the genera Dictyocha (fig. 3a and b) and Distephanus (fig. 4a and b). The data in the table indicate that each slide yields remarkably consistent results and that two researchers can duplicate each other's results. Therefore this study is one more increment in our attempt to demonstrate that the Dictyocha/Distepha ANTARCTIC JOURNAL
Figure 3a (left) and b (right). Scanning electron micrographs of the genus Dctyocha. The black line on the white background represents 10 I.L. Figure 3a is horizontal, b is tilted 8. The specimen is shown in stereo pair. The height of the specimen almost equals the diameter of the large, four-sided, basal ring. The ends of the four shorter abapical spines inside the basal ring are considerably below the plane of the basal ring.
3a
4a
3b
4b David Pierce
Figures 4a (left) and b (right). Scanning electron micrographs of the genus Distephanus. The black line on the white background represents 10 A. Figure 4a is horizontal, b is tilted 8. The specimen is shown in stereo pair. The plane of the larger basal ring is considerably below the plane of the smaller apical ring. The ends of the five shorter abapical spines inside the basal ring are well below the plane of the basal ring.
September-October 1974
267
Late Eocene paleotemperatures for five horizons in the Bain's Farm section, based upon the Dictyocha/Distephanus ratio method.
Field sample numbers
Number of Number of Dictyocha/ Approximate Currently Dictyocha Distephanus Distephanus temperatures suggeste i specimens specimens ratios (°C.) determined temperature from graph range (°C.)
BN 5 Slide 1 2 3 4 5 6
5 4 4 1 4 12
6 2 3 7 2 4
0.83 2.00 1.33 1.28 2.00 3.00
21 25 24 24 25 28
BN 6-3 Slide 1 2 3 4
101 89 105 100
53 68 75 71
1.90 1.30 1.40 1.40
25 24 24 24
BN 7-3 (5 feet below top of 7-3) Slide 1 2 3 4
76 85 117 67
50 47 105 59
1.52 1.80 1.11 1.13
24 25 23 23
BN 7-3 (10 feet below top of 7-3) Slide 1 2 3 4
72 20 73 69
45 29 64 64
1.60 2.75 1.14 1.07
25 26 23 22
BN 7-3 (22 feet below top of 7-3) Slide 1 2 3 4
66 101 73 60
53 101 61 62
1.23 1.00 1.19 0.96
23 22 22 21
nus ratio model will yield repeatable, consistent conclusions if correct laboratory techniques are used. Our conclusions concerning the Bain's Farm section of the Oamaru diatomite are supported by independent collateral evidence of other researchers. Support for this study was provided in part by National Science Foundation grant GV-25572. Facilities were provided incidental to National Science Foundation grant GB-23809 and National Aeronautics and Space Administration grant NGR-05-016--035, to Dr. Preston Cloud. References Doig, A. J . 1967. Further notes on the Oamaru diatomite. Microscopy: Journal of Quekett Microbiology Club, 30: 289-295. Hornibrook, N. de B. 1971. New Zealand Tertiary climate. New Zealand Geological Survey. Report, 47: 1-19. Mandra, Y. T. 1958. Fossil silicoflagellates from California. Ph.D. dissertation (unpublished), Stanford University. l47p.
268
21-28
22-27
21-27
20-27
19-25
Mandra, Y. T. 1969. Silicoflagellates: a new tool for the study of antarctic Tertiary climates. Antarctic Journa of the U.S., IV(5) : 172-174. Mandra, Y. T., and A. L. Brigger. 1972. Plate tectonics, paleomagnetism, tropical climate and Upper Eocene silicoflagellates. Antarctic Journal of the U.S., VII(5): 191193. Mandra, Y. T., and Highoohi Mandra. 1971. Upper Eocne silicoflagellates from New Zealand. Antarctic Journal of the U.S., VI(5): 177-178. Mandra, Y. T., A. L. Brigger, and Highoohi Mandra. 1974. Preliminary report on a study of fossil silicoflagellates from Oamaru, New Zealand. California Academy of Sciences. Occasional Paper, 107. lip. I Mandra, Y. T., A. L. Bigger, and Highoohi Mandra. 1973b. Chemical extraction techniques to free fossil silicoflagellates from marine sedimentary rocks. California Academy of Sciences. Proceedings, XXXIX(15) : 273-284. Mandra, Y. T., A. L. Brigger, and Highoohi Mandra. 1973c. Temperature fluctuations during the Late Eocene in southern ocean waters near South Island, New Zealand. Antarctic Journal of the U.S., VIII (5): 282-284.
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