Differences between the central Andean and Himalayan orogenic wedges: A matter of climate
Differences between the central Andean and Himalayan orogenic wedges: A matter of climate
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DOI：
10.1016/j.epsl.2023.118216
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发表时间：
2023-08
影响因子：
5.3
通讯作者：
P. DeCelles;B. Carrapa
中科院分区：
文献类型：
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作者：
P. DeCelles;B. Carrapa
安第斯山脉中部和喜马拉雅造山带提供了一个理想的自然实验来测试气候在控制造山运动中的潜在作用。两个造山楔的年龄和沿走向长度大致相等，都是在板块边缘汇聚构造环境中形成的：安第斯山脉处于弧后环境中，而喜马拉雅山则处于与青藏高原逆流区碰撞的环境中。尽管喜马拉雅山的构造缩短量是喜马拉雅造山楔的两到三倍，但安第斯山脉中部造山楔的体积和空中面积几乎是喜马拉雅造山楔的两倍。由于广泛的新生代变质岩和非常年轻（<10Ma）的低温热年代学年龄表明侵蚀率更高，喜马拉雅山输出的沉积物至少多出四倍。中部安第斯山脉在热年代学上是古老的（大多>20Ma），没有新生代变质岩的暴露，并且被火山岩和沉积岩覆盖，证明了浅层、缓慢的侵蚀。我们得出的结论是，自渐新世以来，印度季风相对于南美季风的强度更大，这解释了造山带大小和特征的差异。当把喜马拉雅山看作是在西藏造山拼贴画形成之后主要形成的造山楔时，喜马拉雅山既不是地球造山带中最大也不是最热的。
The Central Andean and Himalayan orogenic belts provide an ideal natural experiment to test the potential role of climate in controlling orogeny. Approximately equal in age and along-strike length, both orogenic wedges are forming in plate-marginal convergent tectonic settings: The Andes in a retroarc setting and the Himalaya in a collisional setting against the Tibetan backstop. The Central Andes orogenic wedge is volumetrically and aerially nearly two times larger than the Himalayan orogenic wedge, despite the Himalaya having accommodated two to three times more tectonic shortening. The Himalaya exports at least four times more sediment owing to much greater erosion rates as signified by widespread Cenozoic metamorphic rocks and very young (<10 Ma) low-temperature thermochronologic ages. The Central Andes are thermochronologically old (mostly >20 Ma), have no exposures of Cenozoic metamorphic rocks, and are mantled by volcanic and sedimentary rocks, attesting to shallow, slow erosion. We conclude that greater intensity of the Indian Monsoon relative to the South American Monsoon since Oligocene time accounts for the differences in orogen size and characteristics. When viewed as an orogenic wedge that has developed largely after formation of the Tibetan orogenic collage, the Himalaya is neither the largest nor hottest among Earth's orogens.