远震P波层析成像研究羌塘中央隆起带深部结构  

Deep structure of the central uplift belt in the Qiangtang terrane Tibetan Plateaufrom teleseismic P-wave tomography

作　　者：邹长桥[1,2] 贺日政[1] 高锐[1] 张智[2] 郑洪伟[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]桂林理工大学地球科学学院,桂林541004

出　　处：《科学通报》2012年第28期2729-2739,共11页Chinese Science Bulletin

基　　金：国家自然科学基金(40974060;40774051;40804017);中国地质科学院地质研究所基本科研业务费专项资金(J0915);国土资源部公益行业基金(201011042;201011044;201011013)资助

摘　　要：利用在青藏高原羌塘中部(TITAN-I项目)部署的54套流动地震台站于2008年9月至2010年11月期间所记录的506个远震事件,共9532个高质量的P波初至走时数据运用FMTT方法进行层析成像反演,获得了羌塘中央隆起带下200km的深的地壳和上地幔三维P波速度结构.结果表明:羌塘中央隆起带的南北两侧块体的岩石圈速度结构明显不同.E-W向剖面(33°和33.5°N)显示,其两侧的岩石圈结构尺度整体上存在明显差异,南北羌塘地壳整体上呈E-W向高速异常,但北羌塘的高速异常已经延伸到岩石圈地幔,且本研究区内北羌塘盆地的东部有明显的低速异常块体.而沿N-S向的两条剖面(88.5°和89.5°E)显示,羌塘中央隆起带为一明显的边界构造断裂带.We have determined a detailed three-dimensional P-wave velocity structure of the crust and upper mantle down to a depth of 200 km beneath the central uplift belt of Qiangtang by applying Fast Marching Teleseismic Tomography （FMTT） to 9532 high-quality P-wave arrival times. The travel time data were determined by careful interpretations of original seismograms of 506 teleseismic events recorded by a network of 54 broadband stations deployed in the Qiangtang terrane on the Tibetan Plateau during September 2008 and November 2010. Our tomographic imaging beneath the central uplift belt of Qiangtang shows a deep boundary rupture structure for which the lithospheric velocity structure is significantly different on the northem and southern sides. Tomographic images along 33°N and 33.5°N show that lithospheric structures beneath the sides of the central uplift belt have different scales. The crust at the sides of the central uplift belt exhibits E-W trending high-velocity anomalies. However very low velocities are found within the crust beneath the northem Qiangtang basin overlying and high-velocity anomalies in the lithospheric mantle. Imaging along north-south profiles （88.5°E and 89.5°E） shows that the central uplift of Qiangtang is a significant tectonic boundary fault zone.

关 键 词：羌塘中央隆起带 远震层析成像 断裂构造 

分 类 号：P542[天文地球—构造地质学]