| Three—Phase Uplift of the Qinghai—Tibet Plateau Druing the Cenozoic Period：Igneous Petrology Constraints |
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| 摘 要： |
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| 关 键 词： | 火成岩 浩山带 抬升作用 青海－西藏平原 新生代 |
Three-phase uplift of the Qinghai-Tibet plateau during the Cenozoic period: Igneous petrology constraints |
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| Authors: | Shaocong Lai |
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| Institution: | 1. Department of Geology, Northwest University, 710069, Xi’an, China
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| Abstract: | In northern Qinghai-Tibet plateau there are developed Cenozoic volcanic rocks. They constitute a trachybasalt-shoshonite-latite-trachydacite
assemblage. According to the forming ages, three Cenozoic volcanic rock lithozones can be distinguished in the northern part
of the plateau. Cenozoic volcanic rocks and muscovite/two-mica granites forming the three belts in pairs represent the northern
and southern margins of the plateau in different periods. In fact, the tectonic setting of the northern part of the Qinghai-Tibet
plateau is significantly different from that of the southern part—Himalayas. The southern part has experienced subduction
and continent-continent collision. There are developed the Cenozoic S-type granites (muscovite/ two-mica granites) there.
But the northern part is characterized by Cenozoic basaltic magmatism which obviously comes from the upper mantle. Slight
doming of the upper mantle is recognized underneath the northern part of the plateau, which is the result of resistance of
the Tarim plate to the north direction-sense movement of the Tibetan plate. And at the same time, the uplift machanism shows
that the formation of the Qinghai-Tibet plateau involved three orogenic stages (35?23 Ma, 23?10 Ma and <2 Ma) of uplift in
the vertical direction and extension in the horizontal direction with the Gangdise-Qiangtang orogenic belt as its core. |
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