1:1 000 000 REGIONAL GRAVITY SURVEY IN CENTRAL AND EASTERN QINGHAI-TIBET PLATEAU AND THE RESULTS OBTAINED
ZHANG Sheng-ju1, DONG Yi-guo2
1. Shaanxi Academy of Geological Survey, Xi'an 710014, China;
2. No. 2 Geophysical Research Party of Shaanxi Academy of Geological Survey, Xi'an 710016, China
The authors constructed a series of gravity base maps and interpretation maps on the basis of interpretation of the 1:1 000 000 regional gravity data from central-eastern Qinghai-Tibet plateau. Some new tectonic units were delineated, such as Jiali lower crust melt zone, Lhasa lower crust uplift, Wulawula-Zaduo Paleozoic uplift zone, Tanggula Yanshanian magamtic arcs, and South Gangdise Yanshanian-Himalayan magamtic arcs. The authors support the opinion that Bangongcuo-Nujiang juncture zone should serve as the northern boundary of the Gangdise Mountain. Over 100 faults and many zones of intermediate-acidic magamtic rocks were recognized, in which the Tanggula magamtic belt is unfavorable to petroleum accumulation in Qiangtang basin. It is also concluded that there are widespread igneous layers beneath the middle-lower crust in northern Gangdise-Kekexili and there also exist very strong tectonic stress opposite to the adjusting power of the gravity balance in the plateau crust. All of these conclusions provide evidence for further study of geological tectonics in Qinghai-Tibet plateau and contribute to the search for polymetallic deposits related to magmatic rocks.
