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Isotope evidence of paleo - El Nin??o - Southern Oscillation cycles in loess-paleosol record in the central United States

Geology

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Abstract

The ??13C of soil carbonate in rhizoconcretions collected from a loess-paleosol sequence in the central United States indicates that growing-season C3/C4 plant ratio oscillated by 35% on a 900 ?? 200 yr time scale during the late Wisconsinan glaciation. The pattern appears in phase with advance and retreat of the southern margin of the Laurentide ice sheet, suggesting influence by paleo-El Nin??o-Southern Oscillation cycles. The ??13C of soil organic matter indicates that the annual average C3/C4 plant ratio oscillated only by 18%, with a periodicity of 450 ?? 100 yr, and closely matched the cyclic pattern of loess-paleosol layers. It suggests a periodic enhancement of the penetration of the Gulf of Mexico air over the region during this time.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Isotope evidence of paleo - El Nin??o - Southern Oscillation cycles in loess-paleosol record in the central United States
Series title:
Geology
Volume
28
Issue:
9
Year Published:
2000
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geology
First page:
771
Last page:
774
Number of Pages:
4