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| Titel |
Asian aridification linked to the first step of the Eocene-Oligocene climate Transition (EOT) in obliquity-dominated terrestrial records (Xining Basin, China) |
| VerfasserIn |
G. Q. Xiao, H. A. Abels, Z. Q. Yao, G. Dupont-Nivet, F. J. Hilgen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 6, no. 4 ; Nr. 6, no. 4 (2010-07-29), S.501-513 |
| Datensatznummer |
250003657
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| Publikation (Nr.) |
 copernicus.org/cp-6-501-2010.pdf |
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| Zusammenfassung |
| Asian terrestrial records of the Eocene-Oligocene Transition (EOT) are rare
and, when available, often poorly constrained in time, even though they are
crucial in understanding the atmospheric impact of this major step in
Cenozoic climate deterioration. Here, we present a detailed
cyclostratigraphic study of the continuous continental EOT succession
deposited between ~35 to 33 Ma in the Xining Basin at the northeastern
edge of Tibetan Plateau. Lithology supplemented with high-resolution
magnetic susceptibility (MS), median grain size (MGS) and color reflectance
(a*) records reveal a prominent ~3.4 m thick basic cyclicity of
alternating playa gypsum and dry mudflat red mudstones of latest Eocene age.
The magnetostratigraphic age model indicates that this cyclicity was most
likely forced by the 41-kyr obliquity cycle driving oscillations of drier
and wetter conditions in Asian interior climate from at least 1 million year
before the EOT. In addition, our results suggest a duration of ~0.9 Myr for magnetochron C13r that is in accordance with radiometric dates from
continental successions in Wyoming, USA, albeit somewhat shorter than in
current time scales. Detailed comparison of the EOT interval in the Tashan
section with marine records suggest that the most pronounced lithofacies
change in the Xining Basin corresponds to the first of two widely recognized
steps in oxygen isotopes across the EOT. This first step precedes the major
and second step (i.e. the base of Oi-1) and has recently been reported to be
mainly related to atmospheric cooling rather than ice volume growth.
Coincidence with lithofacies changes in our Chinese record would
suggest that the atmospheric impact of the first step was of global
significance, while the major ice volume increase of the second step did not
significantly affect Asian interior climate. |
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