现今塔里木克拉通岩石圈厚度分析及机制探讨  

Discussion on Thickness of the Tarim Craton Lithosphere and Its Mechanism

作　　者：范桃园[1,2] 安美建[1,2] 

机构地区：[1]国土资源部新构造运动与地质灾害重点实验室,北京100081 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地质论评》2009年第3期329-334,共6页Geological Review

基　　金：国家自然科学基金资助项目(批准号40674058);中国地质科学院地质力学研究所基本科研业务费资助项目(批准号DZLXKJ200801)的成果

摘　　要：塔里木盆地是青藏高原周边稳定的克拉通陆块,在印度板块与欧亚板块碰撞过程中一直保持稳定,盆地内部没有发生强烈的变形,其地壳热状态也同样保持稳定,地温梯度没有明显的变化,以热力学为基础的岩石圈热学厚度约为250km左右,该厚度是热稳态岩石圈的厚度。而最新的地震热学方法的研究成果表明塔里木盆地的岩石圈厚度仅为150km左右,这表明塔里木盆地岩石圈的热结构可能并不是处于稳态状态,其底部正在或已经发生了减薄。本文利用构造热演化方法对塔里木岩石圈减薄的热演化过程进行了定量分析,探讨了塔里木盆地岩石圈减薄可能的三种机制:印度板块与欧亚板块碰撞后青藏高原岩石圈底部的软流圈较塔里木盆地岩石圈底部的软流圈的温度要高,青藏高原的软流圈地幔向塔里木盆地岩石圈底部侵入形成的热扰动使得塔里木盆地岩石圈底部的温度升高;塔里木岩石圈与其下流动的软流圈的摩擦剪切生热导致其岩石圈地幔底部温度升高,使得岩石圈底部发生热侵蚀,从而使得与软流圈接触的岩石圈地幔不断地加入到软流圈地幔;在塔里木盆地岩石圈的下部,青藏高原的岩石圈在该处发生了拆沉,从而诱发的软流圈地幔对流,上升的软流圈地幔流使得岩石圈地幔的温度升高而熔融,成为软流圈地幔。Tarim basin is the craton block south to the Qinghai—Xizang（Qinghai—Tibet） plateau, which didn’t deformed intensively and kept stable and the geothermal state was also not changed abruptly during the collision between Indian Plate and Eurasian Plate. The geothermal lithosphere is about 250km thick, which is determined by the surface heat flow and the lithosphere thermal parameters when the thermal state is steady. Whereas the seismic thermal lithosphere is about 150km thick, which means the Tarim lithosphere is not steady and became thinner. In this paper, writers analyzed the Tarim lithosphere thinning mechanism based on the tectonic thermal evolution quantitative method, and discussed three possibilities：the hotter India asthenosphere intruded under the Tarim lithosphere and made the Tarim lithosphere became unsteady;the bottom of Tarim lithosphere is heated by friction of the atheonosphere flow and washed off by the hot asthenosphere; the Xizang （Tibet） lithosphere delamination induced the convection, and the upflowing mentle heated the bottom of the Tarim lithosphere and make it enthinning.

关 键 词：塔里木 岩石圈厚度 减薄机制 热演化 

分 类 号：P542[天文地球—构造地质学]