Increasing Nd isotopic ratio of Asian dust indicates progressive uplift of the north Tibetan Plateau since the middle Miocene
Increasing Nd isotopic ratio of Asian dust indicates progressive uplift of the north Tibetan Plateau since the middle Miocene
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DOI：
10.1130/g31734.1
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发表时间：
2011-03-01
期刊：
影响因子：
5.8
通讯作者：
Chen, Jun
中科院分区：
文献类型：
--
作者：
Li, Gaojun;Pettke, Thomas;Chen, Jun
西藏隆升的时间和速率对于理解高原生长的地球动力学和造山运动对气候变化的影响至关重要。模式预测，青藏高原北部的隆升晚于青藏高原南部和中部的隆升，青藏高原的隆升是亚洲内陆干旱化的始作俑者，对亚洲季风的演变和全球气候的演变产生了重要影响。然而，NTP隆起的历史仍然不确定;场景范围从早中新世到过去的百万年。这一工作为亚洲尘埃的Nd同位素演化与NTP隆升的关系提供了新的证据。亚洲沙尘的源区位于NTP和中亚造山带之间的干旱地带。质量平衡计算表明，15 Ma以来太平洋尘埃的Nd值从-8.2下降到-10.4，反映了NTP物质对尘埃源的相对贡献增加（40%~ 70%）。由于中亚造山带的古海拔高度基本保持不变，因此，相对NTP碎屑贡献的增加被解释为反映了自15 Ma以来NTP以至少0.12 mm/年（-1）的速率进行的表面隆起。
The time and rate of Tibetan uplift is critical in understanding both the geodynamics of plateau growth and the influence of mountain building on climate change. Models predict that the uplift of the north Tibetan Plateau (NTP) occurred later than uplift of the south and central Tibetan Plateau; uplift of the NTP is believed to have initiated the aridity in the interior of Asia, and to have critically affected the evolution of Asian monsoon and, ultimately, global climate. The history of NTP uplift has remained uncertain, however; scenarios range from Early Miocene to the past million years. This work provides new evidence by relating the Nd isotopic evolution of Asian dust to NTP uplift. The sources of the Asian dust are located in the arid lands between the NTP and the Central Asia orogen. Mass balance calculations indicate that the decreasing epsilon(Nd) values, from -8.2 to -10.4 for Pacific dust since 15 Ma, reflects increasing relative contribution of NTP materials (40% to 70%) to the dust source. As paleoelevation in the Central Asia orogen has largely remained constant, the increasing relative NTP detritus contribution is interpreted to reflect the progressive surface uplift of the NTP at a rate of at least 0.12 mm yr(-1) since 15 Ma.