Synchronous late Pleistocene microfossil extinctions
rent across the central and southern parts of the Kerguelen Plateau. In the deep basins, highvelocity Antarctic Bottom Water flows eastward through the northern sector of the South Indian Basin, with important *iorthward flow crossing the midocean ridge at 1 1O°E. and 120°E. into the South Australian Basin. This northward branch traverses the western sector of the South Australian Basin and the Southeast Indian Ocean Manganese Pavement, and then flows between Broken Ridge and Naturaliste Plateau into the Wharton Basin. Major Cenozoic to Late Cretaceous hiatuses in the Wharton Basin revealed by deep-sea drilling suggest that northward-flowing bottom water through this conduit has been a very long-term feature. These results are presented in detail elsewhere (Kennett and Watkins, 1975; Kennett and Watkins, in press). This research was supported by National Science Foundation grants o pp 71-04027, o pp 74-18529, and Gv-25400. References Kennett, J . P., and N. D. Watkins. 1975. Deep-sea erosion and manganese nodule development in the southeast Indian Ocean. Science 188: 1011-1013. Kennett, J . P., and N. D. Watkins. In press. Regional deep sea dynamic processes recorded by Late Cenozoic sediments of the southeastern Indian Ocean. Geological Society ofAmerica Bulletin.
Synchronous late Pleistocene microfossil extinctions MELVIN H. MIYAJIMA
Antarctic Research Facility Department of Geology Florida State University Tallahassee, Florida 32306 Deep-sea biostratigraphic correlation of zonal boundaries between high- and low-latitude regions is complicated by time-transgressive first and last occurrences of some key species. In the late Pleistocene, however, extinction datums of the coccolith Pseudoemiliania lacunosa and the radiolarian Stylatractus universus are not coincident, but they do appear to follow the same sequence in both high and low latitudes. 274
Hays and Berggren (1971) show that the extinction of Stylatractus universus (flt'J! boundary) for the North Pacific and the southern ocean occurs at 400,000 years before present. Hays (personal corn. munication) suggests the same age for this extinction datum in the equatorial Pacific Ocean. The extinction datum age of Pseudoemiliana Iacunosa is not as precisely known. In the subantarcti southeast Indian Ocean the P. lacunosa datum occurs below the fl/'I' boundary at 400,000 year before present ±50,000 years (Miyajima, 1974, in press). Gartner (1973) indicates that in the equatorial Pacific the P. lacunosa datum occurs below the flI'I' boundary and suggests an age of 350,000 years before present. This age difference may be the result of assuming constant sedimentation rates. The discrepancy in age, however, can be resolved by relating the extinction datum of P. Lacunosa to the oxygen isotope curve of Emiliana and Shackleton (1974). Gartner (1972) recorded the last occurrence of P. lacunosa between stage 12/13 of the oxygen isotope curve. Emiliana and Shackleton (1974) date this interval (stage 12/13) between 400,000 and 450,000 years before present. An approximate age of 425,000 years before present is assigned to the extinction datum of P. lacunosa and suggests a concurrent datum in both the subantarctic and equatorial latitudes. Such a concurrent extinction for both fauna and flora would have been caused by a global change in the environment. One can only speculate on this problem due to a limited understanding of the ecology of these extinct microfossils as well as to the problems inherent to the dating techniques (i.e., the assumption of constant sedimentation rates). My observations of several high- and lowlatitude site samples, however, indicate that the cause may be due to dramatic climatic deterioration. Evidence of a climatic deterioration at 400,000 years before present in the equatorial latitudes is noted in the oxygen isotope curve at stage 12 and in the dissolution cycles (Event V) of Thompson and Saito (1974). Climatic changes in high latitudes during this time (400,000 years before present) are noted by the following paleoceanographic studies: Hays (1965, 1967) notes a break or gap in the ranges of the warm-water radiolarians at the f./'I! boundary in southern ocean samples; Kennett (1970, figure 3, page 128) indicates deposition of an interval of clay essentially barren of foramini fera in subantarctic Pacific Ocean sediments; Miyajima (in press) notes intervals of marl with a coccolith assemblage of dissolution resistant species containing siliceous microfossils and micromanganese nodules in subantarctic southeast Indian Ocean samples. The above evidence, although limited, suggests a change in the oceanic paleoenvironment to one ANTARCTIC JOURNAL
riot suitable for both Stylatractus universus and seudoemi1iania lacunosa. Although the cause of the extinction levels may be in doubt, the extinction clatums are nonetheless strati graphically important and useful. This research was supported by National Science Foundation grant oii 74-20109. References Emiliani, C., and N. J . Shackleton. 1974. The Brunhes Epoch: isotopic paleotemperatures and geochronology. Science, 183: 511-514. Gartner, S. 1972. Late Pleistocene calcareous nanofossils in the Caribbean and their interoceanic correlation. Palaeogeography, Palaeocliinatology, Palaeoecology, 12: 169-191. Gartner, S. 1973. Absolute chronology of the Late Neogene calcareous nanofossil succession in the equatorial Pacific. Bulletin of the Geological Society ojAmerica, 84: 2021-2034. Hays, J . D. 1965. Radiolaria and late Tertiary and Quaternary history of antarctic seas. Antarctic Research Series, 5: 125-134. Hays, J. D. 1967. Quaternary sediments of the antarctic ocean. In: Progress in Oceanography (Sears, M., editor), 4: 117-131. -1ays, J . D., and W. A. Berggren. 1971. Quaternary boundaries and correlations. In: Micropaleontology of Oceans (Funnell, B. M., and W. R. Riedel, editors). 669-691. Kennett, J. P. 1970. Pleistocene paleoclimates and foraminiferal biostratigraphy in subantarctic deep-sea cores. Deep-Sea Research, 17: 125-140. Miyajima, M. H. 1974. Absolute chronology of Upper Pleistocene calcareous nanofossil zones of the southeast Indian Ocean. Antarctic Journal of the U.S., TX(S): 261-262. iyajima, M. H. In press. Subantarctic region, southeast Indian Ocean: absolute chronology of upper Pleistocene calcareous nannofossil zones and paleoclimatic history determined from silicoflagellate, coccolith, and carbonate analyses. Tallahassee, Florida State University, Sedimentology Research Laboratory, Department of Geology. Contribution, 42. hompson, P. R., and T. Saito. 1974. Pacific Pleistocene sediments: planktonic foraminifera dissolution cycles and geochronology. Geology, 2(7): 333-335.
Chinstrap penguin at McMurdo Sound JAMES A. RAYMOND Scripps Institution of Oceanography University of Ca1fornia, San Diego La Jolla, Ca1fornia 92093
A single chinstrap penguin (Pygoscelis antarctica) was observed on 26 January 1974 at the edge of the September/October 1975
Chinstrap penguin, Pygoscelis antarctica, at the edge of the ice channel leading to McMurdo Station. This photograph was taken on 26 January 1975 from the bridge of USCGC
Glacier.
ice channel leading to McMurdo Station. The penguin was seen approximately 3 kilometers north of McMurdo Station from aboard USCGC Staten Island. George A. Llano, Office of Polar Programs, National Science Foundation, and George M. Jonkel, Office of Migratory Bird Movement, U.S. Fish and Wildlife Service, confirmed the sighting. The only other documented sighting of a chinstrap in the McMurdo Sound area was at Cape Royds in 1908 (Murray, 1909). Other chinstraps in the Ross Sea have been observed at Cape Crozier (Sladen et al., 1968) and at Cape Hallett (Crawford, 1974). The chinstrap penguin is found primarily in East Antarctica, but over the last 20 years evidence has accumulated that it is in progress of considerably extending its range (Conroy, 1975). References Conroy, J . W. H. 1975. Recent increases in penguin populations in Antarctica and the subantarctic. In: Biology of Penguins (Stonehouse, B., editor). Baltimore, University Park Press. 321-336. Crawford, R. D. 1974. Chinstrap penguin at Cape Hallett. Notornis, 21(3): 264-265. Murray, J . 1909. Appendix I, biology. In: The Heart of the Antarctic, Volume II (Shackletori, E. F-I., editor). London, Heineman. 258. Sladen, W. J . L., R. C. Wood, and E. P. Monaghan. 1968. The USARP bird banding program, 1958-1965. Antarctic Research Series, 12: 213-262.
275
Synchronous late Pleistocene microfossil extinctions MELVIN H. MIYAJIMA
Antarctic Research Facility Department of Geology Florida State University Tallahassee, Florida 32306 Deep-sea biostratigraphic correlation of zonal boundaries between high- and low-latitude regions is complicated by time-transgressive first and last occurrences of some key species. In the late Pleistocene, however, extinction datums of the coccolith Pseudoemiliania lacunosa and the radiolarian Stylatractus universus are not coincident, but they do appear to follow the same sequence in both high and low latitudes. 274
Hays and Berggren (1971) show that the extinction of Stylatractus universus (flt'J! boundary) for the North Pacific and the southern ocean occurs at 400,000 years before present. Hays (personal corn. munication) suggests the same age for this extinction datum in the equatorial Pacific Ocean. The extinction datum age of Pseudoemiliana Iacunosa is not as precisely known. In the subantarcti southeast Indian Ocean the P. lacunosa datum occurs below the fl/'I' boundary at 400,000 year before present ±50,000 years (Miyajima, 1974, in press). Gartner (1973) indicates that in the equatorial Pacific the P. lacunosa datum occurs below the flI'I' boundary and suggests an age of 350,000 years before present. This age difference may be the result of assuming constant sedimentation rates. The discrepancy in age, however, can be resolved by relating the extinction datum of P. Lacunosa to the oxygen isotope curve of Emiliana and Shackleton (1974). Gartner (1972) recorded the last occurrence of P. lacunosa between stage 12/13 of the oxygen isotope curve. Emiliana and Shackleton (1974) date this interval (stage 12/13) between 400,000 and 450,000 years before present. An approximate age of 425,000 years before present is assigned to the extinction datum of P. lacunosa and suggests a concurrent datum in both the subantarctic and equatorial latitudes. Such a concurrent extinction for both fauna and flora would have been caused by a global change in the environment. One can only speculate on this problem due to a limited understanding of the ecology of these extinct microfossils as well as to the problems inherent to the dating techniques (i.e., the assumption of constant sedimentation rates). My observations of several high- and lowlatitude site samples, however, indicate that the cause may be due to dramatic climatic deterioration. Evidence of a climatic deterioration at 400,000 years before present in the equatorial latitudes is noted in the oxygen isotope curve at stage 12 and in the dissolution cycles (Event V) of Thompson and Saito (1974). Climatic changes in high latitudes during this time (400,000 years before present) are noted by the following paleoceanographic studies: Hays (1965, 1967) notes a break or gap in the ranges of the warm-water radiolarians at the f./'I! boundary in southern ocean samples; Kennett (1970, figure 3, page 128) indicates deposition of an interval of clay essentially barren of foramini fera in subantarctic Pacific Ocean sediments; Miyajima (in press) notes intervals of marl with a coccolith assemblage of dissolution resistant species containing siliceous microfossils and micromanganese nodules in subantarctic southeast Indian Ocean samples. The above evidence, although limited, suggests a change in the oceanic paleoenvironment to one ANTARCTIC JOURNAL
riot suitable for both Stylatractus universus and seudoemi1iania lacunosa. Although the cause of the extinction levels may be in doubt, the extinction clatums are nonetheless strati graphically important and useful. This research was supported by National Science Foundation grant oii 74-20109. References Emiliani, C., and N. J . Shackleton. 1974. The Brunhes Epoch: isotopic paleotemperatures and geochronology. Science, 183: 511-514. Gartner, S. 1972. Late Pleistocene calcareous nanofossils in the Caribbean and their interoceanic correlation. Palaeogeography, Palaeocliinatology, Palaeoecology, 12: 169-191. Gartner, S. 1973. Absolute chronology of the Late Neogene calcareous nanofossil succession in the equatorial Pacific. Bulletin of the Geological Society ojAmerica, 84: 2021-2034. Hays, J . D. 1965. Radiolaria and late Tertiary and Quaternary history of antarctic seas. Antarctic Research Series, 5: 125-134. Hays, J. D. 1967. Quaternary sediments of the antarctic ocean. In: Progress in Oceanography (Sears, M., editor), 4: 117-131. -1ays, J . D., and W. A. Berggren. 1971. Quaternary boundaries and correlations. In: Micropaleontology of Oceans (Funnell, B. M., and W. R. Riedel, editors). 669-691. Kennett, J. P. 1970. Pleistocene paleoclimates and foraminiferal biostratigraphy in subantarctic deep-sea cores. Deep-Sea Research, 17: 125-140. Miyajima, M. H. 1974. Absolute chronology of Upper Pleistocene calcareous nanofossil zones of the southeast Indian Ocean. Antarctic Journal of the U.S., TX(S): 261-262. iyajima, M. H. In press. Subantarctic region, southeast Indian Ocean: absolute chronology of upper Pleistocene calcareous nannofossil zones and paleoclimatic history determined from silicoflagellate, coccolith, and carbonate analyses. Tallahassee, Florida State University, Sedimentology Research Laboratory, Department of Geology. Contribution, 42. hompson, P. R., and T. Saito. 1974. Pacific Pleistocene sediments: planktonic foraminifera dissolution cycles and geochronology. Geology, 2(7): 333-335.
Chinstrap penguin at McMurdo Sound JAMES A. RAYMOND Scripps Institution of Oceanography University of Ca1fornia, San Diego La Jolla, Ca1fornia 92093
A single chinstrap penguin (Pygoscelis antarctica) was observed on 26 January 1974 at the edge of the September/October 1975
Chinstrap penguin, Pygoscelis antarctica, at the edge of the ice channel leading to McMurdo Station. This photograph was taken on 26 January 1975 from the bridge of USCGC
Glacier.
ice channel leading to McMurdo Station. The penguin was seen approximately 3 kilometers north of McMurdo Station from aboard USCGC Staten Island. George A. Llano, Office of Polar Programs, National Science Foundation, and George M. Jonkel, Office of Migratory Bird Movement, U.S. Fish and Wildlife Service, confirmed the sighting. The only other documented sighting of a chinstrap in the McMurdo Sound area was at Cape Royds in 1908 (Murray, 1909). Other chinstraps in the Ross Sea have been observed at Cape Crozier (Sladen et al., 1968) and at Cape Hallett (Crawford, 1974). The chinstrap penguin is found primarily in East Antarctica, but over the last 20 years evidence has accumulated that it is in progress of considerably extending its range (Conroy, 1975). References Conroy, J . W. H. 1975. Recent increases in penguin populations in Antarctica and the subantarctic. In: Biology of Penguins (Stonehouse, B., editor). Baltimore, University Park Press. 321-336. Crawford, R. D. 1974. Chinstrap penguin at Cape Hallett. Notornis, 21(3): 264-265. Murray, J . 1909. Appendix I, biology. In: The Heart of the Antarctic, Volume II (Shackletori, E. F-I., editor). London, Heineman. 258. Sladen, W. J . L., R. C. Wood, and E. P. Monaghan. 1968. The USARP bird banding program, 1958-1965. Antarctic Research Series, 12: 213-262.
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