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Crustal structure of Gondwana- and Yangtze-typed blocks: An example by wide-angle seismic profile from Menglian to Malong in western Yunnan |
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| Authors: | |
| Institution: | 1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2. Institute of Geophysics, Chinese Seismological Bureau, Beijing 100081, China 3. Institute of Deposition Resource, Chinese Academy of Geological Sciences, Beijing 100037, China |
| Abstract: | The wide-angle seismic profile between Menglian and Malong crosses the Baoshan block (Gondwana-typed), and Simao and southwestern Yangtze blocks (Yangtze-typed). By in-terpreting the wide-angle seismic data, we obtained the seismic crust/upper mantle structure of P-wave velocities together with the seismic reflections of these three blocks, Changning- Menglian and Mojiang suture zones among the mentioned three blocks. Our interpreting results demonstrate that the P-wave crustal velocity of Simao block is slower than that of Baoshan and southwestern Yangtze block and the crustal thickness gradually thickens from the Baoshan block, Simao to southwestern Yangtze block. Crustal reflection patterns of these three blocks have dis-tinct differences too. For the Gondwana-typed blocks, seismic reflections in the upper crust are well developed while in middle-lower crust they are very weak. The crustal reflections in the Yangtze block are very well developed. The crustal reflection patterns in Simao and southwest-ern Yangtze blocks are distinguishable. The average thickness of the crust in the studied area is about 40 km. And we make some discussions on the crustal thickening model of the three blocks in western Yunnan and tectonic setting of seismic developing and interaction of Gondwana and Yangtze blocks. |
| Keywords: | Gondwana blocks Yangtze blocks wide-angle profile crustal structure tectonic setting |
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