青藏高原东缘地壳上地幔结构及其动力学意义  

Crust-upper mantle structure on the eastern margin of Tibet Plateau and its geodynamic implications

作　　者：张忠杰[1] 陈赟[1] 田小波[1] 

机构地区：[1]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029

出　　处：《地质科学》2009年第4期1136-1150,共15页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学创新研究群体科学基金项目(编号:40721003);中国科学院知识创新工程重要方向项目(编号:KZCX2-YW-132);中国科学院创新研究团队项目的资助

摘　　要：本文综述了我们在青藏高原东缘实施的垂直切过龙门山断裂带宽频带地震探测的研究成果,揭示了研究区复杂的地壳上地幔结构,结果表明松潘—甘孜地块与四川盆地西缘莫霍而深度为58 km与40 km±,在龙门山断裂带下方存在约15 km的莫霍面错断;松潘—甘孜与龙门山断裂带域地壳纵横波速度比V_p/V_s比值远大于1.73,预示着粘性下地壳流或基性/超基性物质的存在。探讨了研究区强烈的盆山之间以及深部不同层圈之间的相互作用,推断四川盆地对青藏高原东缘软流圈驱动的物质东向逃逸阻挡作用可能深达整个上地幔。We summarize results from broadband passive source tele-seismic observation across Longmenshan fault belt on the eastern margin of Tibetan Plateau, and reveal the complex arichtecture of the crust and upper mantle in the studied area. The results demonstrate crustal thickness thins from about 58 km under Songpan-Ganzi to about 40 km under Sichuan Basin, and about 15 km Moho offset beneath Longmenshan fault belt; much larger than 1.73 of the average crustal Vp/Vs beneath Songpan-Ganzi and Longmenshan fault belt suggests the existence of viscous lower crust or mafic/super-mafic materials in their crusts. We make further discussion on the interaction between Tibetan Plateau and its neighboring Sichuan Basin, and among crust,lithosphere and asthenosphere,and infer the Sichuan Basin barrier to the eastward Tibetan Plateau＇s flow may reach to the upper mantle.

关 键 词：青藏高原 龙门山 壳幔结构 盆山 层圈 相互作用 

分 类 号：P315[天文地球—地震学] P541[天文地球—固体地球物理学]