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通过分析横跨班公湖-怒江缝合带中部的Hi-Climb剖面的53个宽频带台站记录的196个远震事件,总共获得了4764个接收函数.利用接收函数包含的Moho的Ps和PpPs的走时信息,获取了每个台站下方的地壳厚度和泊松比.接收函数CCP时深偏移的方法也被用来研究地壳和上地幔间断面的横向变化.研究结果显示:(1)拉萨地体和羌塘地体的Moho在班公湖-怒江缝合带附近叠置和存在约10km的错断,其构造的几何形态表现为拉萨地体的Moho向北抬升,而羌塘地体的Moho具有向南加深的趋势,推断和新生代以来班公湖-怒江缝合带构造活动的重新活跃有关;(2)泊松比沿整个剖面的变化为0.237～0.280,表明地壳物质主要为中酸性岩石.获得的所有台站的地壳厚度和泊松比呈现反相关关系,意味着羌塘地体南部地壳的增厚和拉萨地体的中酸性岩石逆冲插入羌塘地体有关;(3)地幔过渡带的厚度沿剖面维持在255km左右,说明印度板块和欧亚板块的碰撞所引起的构造活动局限在410km深度范围内.
A total of 4764 receiver functions were obtained by analyzing 196 teleseismic events recorded at 53 broadband stations across the Hi-Climb section of the central Bangong-Nujiang suture zone. Using the Ps and PpPs of Moho contained in the receiver function And the crustal thickness and Poisson’s ratio under each station were obtained.The method of CCP time migration was also used to study the lateral variation of the discontinuity between the crust and the upper mantle.The results show that: (1) Lhasa The Moho of the terrane and the Qiangtang terrane overlap with and have a fault of about 10 km near the Bangong-Nujiang suture zone. Its structural geometry shows that the Moho of the Lhasa terrane rises northward while that of the Qiangtang terrane Moho has the tendency of deepening to the south and inferring the reactivation of tectonic activities of the Banghu-Nujiang suture zone since the Cenozoic. (2) The Poisson’s ratio changes from 0.237 to 0.280 along the whole section, indicating that the crustal material is mainly acidic Rocks. The crustal thickness at all stations obtained is inversely related to the Poisson’s ratio, implying that the thickening of the southern crust in the Qiangtang terrane is associated with the thrusting of the moderate-acidic rocks in the Lhasa terrane into the Qiangtang terrane; and (3) the mantle The thickness of the transition zone is maintained along the section 255km or so, indicating that the tectonic activities caused by the collision between the Indian plate and the Eurasian plate are limited to a depth of 410km.