【摘要】 寻找青藏高原岩石圈热流物质向东流动的准确地震学证据及其动力学机制解释难点在于精确岩石圈厚度的求取.本文利用S波接收函数方法计算得到四川地区51个宽频台站的211个远震事件叠加接收函数,通过时深转换获得了该地区准确的地壳和岩石圈埋深分布.主要研究结果如下:四川地区地壳厚度变化范围为40～72 km,西藏的东部到四川盆地逐渐变薄,最厚的地方在雅江(YJI)地区,约为72 km,最薄的地方在盆地内部西充(XCO)地区,约为40 km,松潘-甘孜地块、川滇块体及滇中以北较厚,平均厚度为52～68 km,龙门山断裂西侧为55～60 km,四川盆地为40～50 km,存在10～15 km地壳厚度变化梯度;岩石圈埋深变化范围为100～180 km,整个四川地区表现出厚的四川盆地被薄的岩石圈环绕,外缘厚度为100～130 km,盆地内部为140～180 km,最厚的地方在"X"型断裂附近,呈现出"一凹两隆"的特征,最薄的地方是约100～120 km的龙门山断裂西侧及盆地西南部.建立的动力学模型为青藏高原东部热物质在向东流动的过程中被冷的、厚的、坚固的四川盆地阻挡,进而向东北和东南两个方向逃逸.更多还原

【Abstract】 Lithospheric thickness is one of most important parameters to evaluate the earthquake evidence and dynamic mechanism of Tibetan plateau hot flow moving eastward.This paper obtains the stacking S receiver functions of 51 permanent broad-band stations and 211 teleseismic events records with the method of S receiver functions in Sichuan region,we get the depth distribution of the Moho and LAB through transformation of the depth in this region.The main results of the research are as follows:the Moho depth ranges from 40 to 72 km in Sichuan region,it becomes thinner from eastern Tibet to Sichuan Basin,the thickest crust is about 72 km,located in Yajiang region,the thinnest crust is about 40 km,located in Xichong region,the average depth ranges from 52 to 68 km beneath the Songpan-Ganze fold and Sichuan-Yunnan terrane,the crustal thickness is estimated to be 55~60 km beneath western Longmenshan fault system and about 40km beneath Sichuan Basin,forming a step of 10~15km.the LAB depth ranges from 100 to 180 km,western Sichuan Basin is found to be surrounded by a thinner lithosphere,the depth ranges from 100 to 130 km beneath the basin boundary as thick as to from 140 to 180 km,the thickest lithosphere is about 180 km near "X" fault system,appearing as "one depression and two uplifts",the thinnest lithosphere ranges from 100 to 120 km beneath western Longmenshan fault system and northwestern Sichuan Basin,at the same time,the lithosphere thickness near Huamashi ranges from 100 to 120 km.The last dynamic model of this paper is as follows:it is proved that a eastward preferential hot asthenosphere flow from Tibetan plateau is resisted by the cold thick rigid Sichuan Basin with Seismic evidence,thus branching into a northeastward and a southeastward one.更多还原