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Book Chapter

Temporal and Spatial Distribution of Ice-Rafted Mineral Grains in Pliocene Sediments of the North Atlantic: Implications for Late Cenozoic Climatic History

By
Richard Z. Poore
Richard Z. Poore
U.S. Geological Survey, 345 Middlefield Rd.
Menlo Park, California 94025, U.S.A.
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Published:
January 01, 1981

Abstract

An important result of Deep Sea Drilling Project (DSDP) Leg 12 was the discovery of ice-rafted mineral grains in Pliocene sediments of the Labrador Sea and the Hatton-Rockall Basin. The oldest (first) occurrence of ice-rafted mineral grains in these sediments is associated with the evolutionary first appearance of the planktic foraminifer Globorotalia inflata (d’Orbigny) and the extinction of the coccolith Reticulofenestra pseudoumbilica (Gartner), or the first occurrence of the coccolith Emiliania ovata Bukry, or both. This association yields a paleontologic age estimate of 3.0 m.y.BP for the start of low-elevation Northern Hemisphere glaciation extensive enough to produce icebergs in the North Atlantic. Results from subsequent drilling in the North Atlantic (DSDP Legs 37, 48, and 49) confirm that the first ice-rafting is at about 3.0 m.y.BP, and further show that during the Late Pliocene, icebergs penetrated as far south as 45° N. lat in the central North Atlantic (DSDP Hole 410) but not as far south as 37° N. lat (DSDP Holes 333 and 335).

The estimated age of 3.0 m.y.BP for the onset of Northern Hemisphere low-elevation glaciation derived from the North Atlantic is supported by a 3.2 m.y.BP estimate based on paleomagnetically controlled oxygen isotope data from the Equatorial Pacific. North Atlantic planktic foraminiferai assemblages show that warm sea-surface temperatures in the northwestern Atlantic preceded the initiation of Northern Hemisphere glaciation.

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Contents

SEPM Special Publication

The Deep Sea Drilling Project: A Decade of Progress

John E. Warme
John E. Warme
Colorado School of Mines, Golden Colorado.
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Robert G. Douglas
Robert G. Douglas
University of Southern California, Los Angeles California
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Edward L. Winterer
Edward L. Winterer
Scripps Institution of Oceanography, La Jolla California
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SEPM Society for Sedimentary Geology
Volume
32
ISBN electronic:
9781565761629
Publication date:
January 01, 1981

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