时变重力测量确定青藏高原地壳隆升与增厚速率

Determination of Crust Uplifting and Thickening of Qinghai-Tibetan Plateau from Time-Variable Gravity Measurements

联合绝对重力和重力反演与气候实验卫星(gravity recovery and climate experiment,GRACE)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。研究结果表明,绝对重力呈明显的负变化,绝对重力和卫星重力的时变系统差也呈较一致的负值,鼎新(DXIN)、德令哈(DLHA)、西宁(XNIN)、拉萨(LHAS)和仲巴(XZZB)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,隆升速率分别约为2.01±0.15mm/a、1.88±0.19mm/a、1.91±0.10mm/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,平均隆升速率约为1.94±0.17mm/a,平均增厚速率约为2.35±3.30mm/a。

The crustal uplift and thickening of Qinghai-Tibetan plateau was determined by the com- bined use of long-term absolute gravity measurements and GRACE satellite gravity measurement data. The results show that the obvious negative gravity change rate was detected by absolute gravity meas- urements. The systematic difference of the gravity change rates between absolute gravity measure- ments and GRACE measurements was also negative as 5 base stations at Dingxin, Delingha, Xining, Lhas, and Zhongba which representing the Alxa, Qilian and Lhas blocks were all in a crustal uplift status. The rising rate can be estimated numerically, and the velocity of Lhasa, Qilian and Alxa block is about 2.01±0.15 mm/a,1. 88±0.19 mm/a and 1.91±0.10 mm/a, the crustal uplifting of the whole Qinghai-Tibetan plateau is about 1.94±0.17 mm/a, and the thickening is about 2.35 ± 3.30 mm/a caused by the collision between the Indian and the Asianplates in the double-direction.