A paleoclimatic and paleooceanographic study in a portion of the Southern ocean
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Date
1980-06
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Publisher
The Ohio State University
Abstract
Nine deep-sea piston cores recovered along a north-south track from 58 S to 52 30'S at about 10 E were dated using
Weaver's (1976) modification of McCollum's (1975) high
latitude diatom zonation and paleomagnetic data. Deduced
climatic fluctuations during the past five million years are
based on Weaver's (1973) model for climatically related marine
sedimentation and on the distribution of sediment types and
unconformities in the nine piston cores.
Conditions during part of the interval from the Pliocene/
Miocene transition (about 5.0 m.y. B.P.) were cool and are
represented by unconformities, which resulted from the increased
production of Antarctic Bottom Water. Climates that
began warming before the Gilbert "b" event (4.14 m.y. to 3.97
m.y. B.P.) is represented by siliceous sediment, which continued
accumulating until late Gilbert. Sometime after the beginning
of the Gauss magnetic epoch (3.32 - 2.43m.y. B.P.) climate
deteriorated and led to one or more episodes of regional
scouring or nondeposition, By the end of the Olduvai magnetic
event (1.86 – 1.71 m.y. B.P.) sediment began accumulating
again.
From the end of the Olduvai until the present, climate
and oceanographic conditions fluctuated but not as drastically
as earlier and sediment accumulated throughout most of the
area, The locus of erosion/nondeposition also shifted
geographically to areas in the north and south of the study
region in the Holcene and possibly the Pleistocene. The two positions of erosion /nondeposition suggest the action of two
bottom water masses, Antarctic Bottom Water and Circumpolar Deep Water.