川滇地区重力场特征与地壳变形研究

对川滇地区重力场特征进行了研究，获得了研究区内地壳厚度分布及变形特征。总体上，研究区内地壳厚度从西北向东南逐渐减小。川滇菱形块体中内部出现了广泛的地壳增厚现象，并可能一直延伸至菱形块体的最南端。丽江-小金河断裂带在重力场特征上表现为龙门山断裂带向西南的延伸，其东侧主体构造走向等特征与扬子地块一致，推测丽江-小金河断裂带与龙门山断裂、红河断裂带一起构成了扬子地块的西边界。滇西地区布格重力一阶导数与现今地壳变形格局总体一致，主体构造方向为北北西-近南北向，代表了“新”构造主体构造线的方向；上延至45km后，主体构造上转变为以近东西向为主。

Study on Characteristics of Gravity Field and Crustal Deformation in Sichuan- Yunnan Region

Moho depth distribution and crustal deformation pattern between different sub-blocks in Sichuan-Yunnan region are presented here based on the studies of the gravity field characteristics. Generally, Moho depth within study area decreases gradually from northwest to southeast. There is an obvious extensive crustal thickening in whole Sichuan-Yunnan rhombic block. According to the gravity characteristics, the Lijiang-Xiaojinhe fault is shown to be the southwestward extension of the Longmenshan fault; to the east of these faults, the gravity field and main structural orientation of the Middle Yunnan sub-block are consistent with those of the Yangtze block, indicating these faults and the Red River fault zone are the west boundary of Yangtze block. The 1~(st) vertical derivative of Bouguer gravity data in Sichuan-Yunnan region is generally similar to the present-day crustal deformation pattern. The main structural orientation is NNW or nearly SN, representing the major structural orietation of a later tectonism; while it changes into nearly EW based on gravity horizontal direction derivative data after upward 45km.