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Pleistocene history of the subarctic pacific: periodic and step-wise changes in temperature and precipitation

Conference · · Geol. Soc. Am., Abstr. Programs; (United States)
OSTI ID:6320769
Piston core V20-110 records the last 1.8 Ma of North Pacific conditions. Samples at 11 Ka intervals were analyzed for calcite, foraminifera, diatoms, and IRD. Data implies that precipitation varied on a 41-Ka cycle from latest Pliocene to 700 Ka. During the late Pleistocene precipitation, like temperature, has been dominated by a 100 Ka period. There are six distinct intervals, bounded by rapid, unidirectional changes: a) 1.8-1.6 Ma-mostly ice-free, warm (approx.15/sup 0/C), high precipitation, moderately well-mixed waters; b) 1.6-1.3 Ma-slightly cooler (approx.12/sup 0/C), precipitation increasing to maximum, waters well mixed; c) 1.3-1.1 Ma-change to winter precipitation, slightly colder, increased seasonal contrast. d) 1.1 Ma-700 Ka-beginning of glacial mode; periods of high annual precipitation and strong stratification alternate with lower precipitation and more mixing, temperatures cool (approx.10/sup 0/C); e) 700-300 Ka-strong 100-ka cycles, high winter precipitation and low temperatures (5-10/sup 0/C) during glacials; interglacials drier and warmer, more mixing; summer precipitation low throughout; f) 300-0 Ka-glacial maxima cold (<5/sup 0/C), dry, well-mixed; interglacial maxima cool (approx.10/sup 0/C), summer precipitation, well-mixed; transitions high winter precipitation and strong vertical stratification. CCD fluctuating close to 2700 m, being above during glacials and transitions, below only during peak interglacials.
Research Organization:
LDGO, Palisades, NY (USA)
OSTI ID:
6320769
Report Number(s):
CONF-8510489-
Conference Information:
Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
Country of Publication:
United States
Language:
English