基于绝对重力和GRACE数据研究青藏高原地壳隆升与增厚

The crust of Qinghai-Tibet plateau is still uplifting and thickening nowadays by the collision between the Indian plate and Eurasian plate which revealed by the results of geological and tectonic, it is also a complex and hot problem which has been studying by global geoscientists. However, almost no quantitative evidence shows whether the plateau is still uplifting or thickening for the bad natural environment and inconvenient traffic. So it is impossible to acquire entire geodetic monitoring observation data. With the implement of several great scientific projects since the late 1990s, long term accumulated geodetic data including GPS，leveling and gravity data are used to study the geodynamic of Qinghai-Tibet plateau. The main research are the processing of the long term FG5 absolute gravimeter measurement data which accuracy is about 1-2 microgal and GRACE gravity satellite data which was launched since 2002. The emphases of the project are the processing and method of acquiring crust vertical deformation, gravity change by omitting the geophysics model effects such as surface mass change, great earthquake and GIA, and so on. The products from this project can be used in quantitative analysis on the velocity of crust uplifting and thickening and establish of the mechanism model according to various density model, which has the important scientific and practical significance.

关于青藏高原地壳的隆升与增厚，是一个复杂的科学热点问题。印度板块和欧亚板块的碰撞挤压导致地壳的隆升与增厚，已被地质、构造学等方面资料证实，但利用大地测量资料定量确定高原地壳的隆升与增厚却很少，主要是由于高原自然条件相当恶劣，交通极不发达，要在一个短期内全面完整地获得大地测量监测资料是不现实的。随着九十年代末期实施的多个重大科学工程，为研究青藏高原地球动力学提供了长期累积的大地测量资料，包括GPS、水准和重力等。本课题基于精度高达1-2微伽的FG5绝对重力仪和于2002年发射的GRACE重力卫星的长期观测数据，深入研究提取构造运动引起的地壳垂直形变、重力变化的理论和方法，消除地表流体变化引起的荷载效应、以及大震和GIA等地球物理模型效应。基于变密度模型定量研究青藏高原及其周围地区地壳的隆升与增厚速率，建立其隆升与增厚机制的模型，具有重要的科学意义和研究价值。

关于青藏高原地壳的隆升与增厚，是一个复杂的科学热点问题。印度板块和欧亚板块的碰撞挤压导致地壳的隆升与增厚，已被地质、构造学等方面资料证实，但利用大地测量资料定量确定高原地壳的隆升与增厚却很少。本课题联合绝对重力和GRACE卫星重力多年观测数据，获得了青藏高原多个基准站区域的地壳垂直形变速率，结果表明，鼎新、德令哈、西宁、拉萨和仲巴5个基准站的区域地壳垂直形变呈明显的隆升状态，即拉萨块体、祁连块体和阿拉善块体处于地壳隆升状态，隆升速率分别为2.01±0.15 mm/a、1.88±0.19mm/a、1.91±0.10 mm/a。在印度板块和欧亚板块的双向挤压下，青藏高原的地壳在不断的隆升与增厚，平均隆升速率为1.94±0.17mm/a，平均增厚速率为2.35±3.30mm/a。本课题深入研究了提取构造运动引起的地壳垂直形变、重力变化的理论和方法，建立青藏高原隆升与增厚机制的模型，具有重要的科学意义和研究价值。