Cenozoic volcanism and tectonic evolution of the Tibetan plateau
Cenozoic volcanism and tectonic evolution of the Tibetan plateau
复制标题
DOI：
10.1016/j.gr.2010.09.005
复制
发表时间：
2011-06
影响因子：
6.1
通讯作者：
Linqi Xia;Xiangmin Li;Zhongping Ma;Xueyi Xu;Zuchun Xia
中科院分区：
文献类型：
--
作者：
Linqi Xia;Xiangmin Li;Zhongping Ma;Xueyi Xu;Zuchun Xia
青藏高原新生代火山活动是印度-亚洲大陆碰撞的火山响应，具有系统的时空变化。随着印度-亚洲碰撞由接触碰撞（即“软碰撞”或“同碰撞”）向全面碰撞（即“硬碰撞”）的转变，火山作用逐渐由富Na+富K向钾-超钾+埃达克质成分沿着转变。富钠、富钾火山岩主要分布在藏南拉萨地区，其次分布在藏中羌塘地区，年龄为65- 40 Ma。广泛分布的钾质-超钾质熔岩和次级埃达克岩形成于45 ~ 26 Ma。随后的后碰撞火山作用向南迁移，在拉萨盆地产生了约26 - 8 Ma的超钾质和埃达克质熔岩。此后，在羌塘西部和松潘-甘孜地区，钾质和少量埃达克质火山活动向北更新，并在~ 20 Ma以后成为广泛而连续的火山活动。这种时空变化对青藏高原深部演化的地球动力学过程提供了重要的制约。这些过程包括俯冲的新特提斯板块的回滚和断裂，随后是增厚的拉萨岩石圈根的移除，从而导致印度岩石圈向北的下冲。青藏高原自南向北呈历时性隆升。高原南部可能是在渐新世晚期形成并维持下来的，而北方高原直到中新世中期才达到今天的海拔高度和规模，当时西羌塘和松潘-甘孜岩石圈的下部由于俯冲的印度岩石圈持续不断地向北推挤而开始沉降和分离。
Cenozoic volcanism on the Tibetan plateau, which shows systematic variations in space and time, is the volcanic response to the India–Asia continental collision. The volcanism gradually changed from Na-rich+K-rich to potassic–ultrapotassic+adakitic compositions along with the India–Asia collision shifting from contact-collision (i.e. “soft collision” or “syn-collision”) to all-sided collision (i.e. “hard collision”). The sodium-rich and potasium-rich lavas with ages of 65–40Ma distribute mainly in the Lhasa terrane of southern Tibet and subordinately in the Qiangtang terrane of central Tibet. The widespread potassic–ultrapotassic lavas and subordinate adakites were generated from ~45 to 26Ma in the Qiangtang terrane of central Tibet. Subsequent post-collisional volcanism migrated southwards, producing ultrapotassic and adakitic lavas coevally between ~26 and 8Ma in the Lhasa terrane. Then potassic and minor adakitic volcanism was renewed to the north and has become extensive and semicontinuous since ~20Ma in the western Qiangtang and Songpan–Ganze terranes. Such spatial–temporal variations provide important constraints on the geodynamic processes that evolved at depth to form the Tibetan plateau. These processes involve roll-back and break-off of the subducted Neo-Tethyan slab followed by removal of the thickened Lhasa lithospheric root, and consequently northward underthrusting of the Indian lithosphere. The Tibetan plateau is suggested to have risen diachronously from south to north. Whereas the southern part of the plateau may have been created and maintained since the late-Oligocene, the northern plateau would have not attained its present-day elevation and size until the mid-Miocene when the lower part of the western Qiangtang and Songpan–Ganze lithospheres began to founder and detach owing to the persistently northward push of the underthrust Indian lithosphere.