A constant Chinese Loess Plateau dust source since the late Miocene
A constant Chinese Loess Plateau dust source since the late Miocene
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DOI：
10.1016/j.quascirev.2019.106042
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发表时间：
2020-01-01
影响因子：
4
通讯作者：
Lu, Huayu
中科院分区：
文献类型：
--
作者：
Bird, Anna;Millar, Ian;Lu, Huayu
上新世-更新世边界标志着全球气候和东亚季风动力的重大变化。然而，这段时间全球大气尘埃循环的作用尚不清楚。特别是灰尘循环的变化对气候变化的影响程度、由气候变化驱动的程度，以及这些过程如何相互作用。中国黄土记录了过去40 Ma的沙尘循环历史以及干旱化和季风环流的影响。之前关于中国黄土高原的研究争论了沙尘源的变化是否发生在上新世-更新世边界，或者1.2 Ma，尽管这些间隔标志着季风动力学的重大变化。我们提供了来自多个地点的 Sr、Nd 和 Hf 同位素数据，并表明灰尘来源在这些边界上基本上保持不变。地球化学的变化是由于粒度和风化的变化造成的。虽然传输途径（河流、沙漠、直接风沙）尚不清楚，但这些示踪同位素表明灰尘主要来自青藏高原北部，还有一些来自当地基岩的输入。这表明，尽管气候条件发生了巨大变化，青藏高原上一个已确定的主要沙尘源自中新世晚期以来一直活跃且没有变化。黄土堆积的变化是青藏高原源区气候变化的函数，而不是上新世-更新世边界干旱加剧的影响。 (C) 2019 年由爱思唯尔有限公司出版。
The Pliocene-Pleistocene boundary marks a major change in global climate and East Asian monsoon dynamic. However, the role of the global atmospheric dust-cycle over this time is unclear; in particular the degree to which changes in the dust cycle influenced climate change, were driven by climate change, and how these processes interacted. Chinese loess records past dust-cycle history and the influences of aridification and monsoon circulation over the last 40 Ma. Previous work on the Chinese Loess Plateau argue over whether changes in dust source occur at the Pliocene-Pleistocene boundary, or at 1.2 Ma, despite these intervals marking major shifts in monsoon dynamics. We present Sr, Nd and Hf isotope data from multiple sites and show that dust source largely remains unchanged across these boundaries. Shifts in geochemistry are due to changes in grain-size and weathering. While the transport pathway (river, deserts, direct aeolian) is unclear, these tracer isotopes show that dust was dominantly sourced from the Northern Tibetan Plateau, with some input from the local bedrock. This shows that a major established and constant dust source on the Tibetan Plateau has been active and unchanged since late Miocene, despite dramatically changing climate conditions. Changes in loess accumulation are a function of climate change in Tibetan Plateau source regions rather than effects from increased aridification over the Pliocene-Pleistocene boundary. (C) 2019 Published by Elsevier Ltd.