Late Miocene–Pliocene climate evolution recorded by the red clay cover on the Xiaoshuizi planation surface, NE Tibetan Plateau
<p>The Pliocene climate and its driving mechanisms have attracted substantial scientific interest because of their potential as an analog for near-future climates. The late Miocene–Pliocene red clay sequence of the main Chinese Loess Plateau (CLP) has been widely used to reconstruct the histor...
Main Authors: | , , , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2019-03-01
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Series: | Climate of the Past |
Online Access: | https://www.clim-past.net/15/405/2019/cp-15-405-2019.pdf |
Summary: | <p>The Pliocene climate and its driving mechanisms have
attracted substantial scientific interest because of their potential as an
analog for near-future climates. The late Miocene–Pliocene red clay sequence
of the main Chinese Loess Plateau (CLP) has been widely used to reconstruct
the history of interior Asian aridification and the Asian monsoon. However,
red clay sequences deposited on the planation surface of the Tibetan Plateau
(TP) are rare. A continuous red clay sequence was recently discovered on the
uplifted Xiaoshuizi (XSZ) planation surface in the Maxian Mountains,
northeastern (NE) TP. In this study, we analyzed multiple climatic proxies
from the XSZ red clay sequence with the aim of reconstructing the late
Miocene–early Pliocene climate history of the NE TP and to assess regional
climatic differences between the central and western CLP. Our results
demonstrate the occurrence of minimal weathering and pedogenesis during the
late Miocene, which indicates that the climate was arid. We speculate that
precipitation delivered by the paleo East Asian summer monsoon (EASM) was
limited during this period and that the intensification of the circulation of the westerlies
resulted in arid conditions in the study region. Subsequently,
enhanced weathering and pedogenesis occurred intermittently during
4.7–3.9 Ma, which attests to an increase in effective moisture. We ascribe
the arid–humid climatic transition near <span class="inline-formula">∼4.7</span> Ma to the expansion of
the paleo-EASM. The warming of the high northern latitudes in response to
the closure of the Panama Seaway may have been responsible for the
thermodynamical enhancement of the paleo-EASM system, which permitted more
moisture to be transported to the NE TP.</p> |
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ISSN: | 1814-9324 1814-9332 |