青藏高原新生代三阶段造山隆升模式:火成岩岩石学约束

THREE-PHASE UPLIFTING MODEL OF QINGHAI-TIBET PLATEAU DURING CENOZOIC: IGNEOUS PETROLOGY CONSTRAINTS

从岩石大地构造学的角度 ,分析讨论了青藏高原新生代岩浆作用的特点、差异、成对性及其对高原隆升深部动力学过程的岩石学约束 ,在此基础上提出青藏高原是以冈底斯—羌塘造山带为核心 。

In northern Qinghai\|Tibet plateau are developed Cenozoic volcanic rocks, characterized by a rock assemblage of trachybasalt\|shoshonite\|latite\|trachydacite. According to their ages, there are three Cenozoic volcanic rock lithozones in the northern part of the plateau. Cenozoic volcanic rocks and muscovite/two\|mica granites constitute three belts in pairs and represent the north and south margins of the plateau in different periods. In fact, tectonic setting of the northern part of the Qinghai\|Tibet plateau is much different from that of the southern part Himalayas. The southern part is characterized by subduction and continent\|to\|continent collision. There also are developed Cenozoic S\|type granites (muscovite/two\|mica granite). But the northern part is characterized by Cenozoic basaltic magmatism obviously from the upper mantle. There occurred slight doming of the upper mantle underneath the northern part of the plateau, which is the result of resistance of the Tarim plate to the northward movement of the Tibetan plate. And at the same time, the uplift mechanism shows that the Qinghai\|Tibet plateau is formed by three orogenic stages (40-20, 23-10 and <2 Ma) of uplifting in vertical direction and extends in horizontal direction with the Gangdise\|Qiangtang orogenic belt as its center.