摘要
利用2009—2013年的GPS水平速度场,使用三维线性球面弹性块体模型,综合前人研究成果建立了阿尔金断裂及其邻区的三维块体几何模型,反演得到阿尔金断裂不同断层段和其邻区主要活动断裂的现今滑动速率。结果表明：阿尔金断裂柴达木盆地以南段左旋走滑速率为（7.8±0.2）mm/a,该段向北至肃北左旋走滑速率为（7.5±0.1）mm/a,肃北—昌马段左旋走滑速率为5.3-5.5mm/a,昌马以北段的左旋走滑速率仅有（1.0±0.4）mm/a。阿尔金断裂左旋走滑速率总体表现出从南向北减小的趋势,衰减主要集中在祁连山地区,并转换为这一地区明显的地壳挤压作用。
The Tibetan plateau is bounded by Altyn Tagh Fault in its northern edge,this well known for the characteristic of left-lateral strike-slip from late Quaternary,but its magnitude of left-lateral slip rate measured by geological way,either on a high level（ 20 - 30 mm / a） or on a lower level（ - 9mm / a）,is hotly debated,and that is central to reviewing the existent deformation mechanism of Tibet plateau.The present-day fault slip rate along Altyn Tagh Fault has revealed by Global Positioning System（ GPS）,however the limited GPS stations and its poor distribution might increase the uncertainties of the predicted fault slip rates,especially to this so mega fault with 1500 km length approximately.A dense GPS velocity field（ from 2009 to 2013） has obtained along Altyn Tagh Fault and its vicinity,which provides us a good opportunity to study its slip rates along its different fault segments in detail. In this paper,we use the spherical linear elastic block theory constrained by new geodetic observations from GPS stations we have mentioned,to estimate fault slip rates along the Altyn Tagh Fault and other major faults in its vicinity. Our 3D geometric block model is based on the previous researches of active block. Then the optimal locking depths of Altyn Tough Fault are fixed by trail tactics,the result of optimal locking depths shows that it is from 10 km to 15 km in the southern part of Altyn Tagh Fault,in its middle and north segment the locking depths are deeper than its southern part,and in its north terminal the locking depth is 11 km. Then the fault slip rates along Altyn Tough Fault are obtained as well as other fault slip rates of major faults in its vicinity. The left-lateral fault slip rates of different segments along Altyn Tough Fault are（ 7. 8± 0. 2） mm / a（ south of Qaidam Basin）,（ 7. 5± 0. 1） mm / a（ south of Subei）,（ 5. 3 - 5. 5） mm / a（ from Subei to Changma） and（ 1. 0±0. 4） mm/a（ north of Changma）,which trend to decreasing from south to north along the fault strike,and the decreasing of the slip rate is mainly confined within the Qilian Range,and converted to the crustal contraction in this area.
出处
《地震地质》
EI
CSCD
北大核心
2015年第3期869-879,共11页
Seismology and Geology
基金
中国地震局地震行业科研专项(201208009)
国家自然科学基金(41174083)
国家留学基金(20135020)
地震科技星火计划项目(XH14070Y)共同资助
