Modern Pacific Coccolith Assemblages: Derivation and Application to Late Pleistocene Paleotemperature Analysis
Kurt R. Geitzenauer, Michael B. Roche, Andrew McIntyre, 1976. "Modern Pacific Coccolith Assemblages: Derivation and Application to Late Pleistocene Paleotemperature Analysis", Investigation of Late Quaternary Paleoceanography and Paleoclimatology, R. M. Cune, J. D. Hays
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Factor analyses of relative abundance counts of coccoliths from selected Pacific Ocean core tops yield six assemblages that coincide with the following surface water masses and regions: (1) the Kuroshio system and Pacific Equatorial Water Mass; (2) the southern and northern central Pacific regions (both occupied by two assemblages), (3) the Western South Pacific Central Water Mass, and (4) the Subarctic Pacific and Intermediate Water Masses. The sixth assemblage represents a flora that is transitional between the subpolar and central Pacific regions in both hemispheres and that occurs as well within the Peru Current system.
Transfer functions relating the assemblages to sea-surface temperatures were applied to coccolith populations that existed over the past 200,000 yr and that were taken from cores in the western equatorial Pacific (cores V28-238 and V28-239) and the eastern Pacific (core V19-55). The values produced are floral indices calibrated on seabed samples to be unbiased estimates of summer sea-surface temperatures (T s), winter sea-surface temperatures (T w), and seasonality (T s – T w). T s in the western equatorial Pacific varies within relatively narrow limits, with a maximum range of 5.7° and 3.9°C. T w shows relatively greater fluctuation, with a maximum range of 8.9° and 6.3°C. T s and T w in the eastern Pacific show much less variation, with a maximum range of 1.9° and 3.3°C, respectively. There appears to be no correlation between T s and glacial events. A seasonality (T s − T w) maximum occurs in midcycle just before glaciation in “glacial cycles” (Kukla, 1961) B, D, and E. The seasonality change is greater in the western equatorial cores.
The foregoing adds evidence to support the theory that sea-surface temperature over the past 200,000 yr has not globally varied sinusoidally but is subject to complex regional dynamics.