Crustal structure of the central Qaidam basin imaged by seismic wide-angle reflection/refraction profiling
Crustal structure of the central Qaidam basin imaged by seismic wide-angle reflection/refraction profiling
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地震广角反射/折射剖面成像柴达木盆地中部地壳结构
DOI：
10.1016/j.tecto.2012.09.005
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发表时间：
2013-01
期刊：
影响因子：
2.9
通讯作者：
Liu, Hongbing
中科院分区：
文献类型：
--
作者：
Xu, Qiang;Jin, Zhijun;Mooney, Walter D.;Okaya, Nihal;Wang, Shangxu;Gao, Xing;Tang, Liangjie;Pei, Shunping;Liu, Hongbing
本文介绍了青藏高原最大的盆地柴达木盆地中部地震广角反射/折射剖面的研究结果。这条350 km长的剖面从东昆仑山北方边缘延伸到祁连山南缘。P波和S波速度结构和泊松比数据提供了对组合物的约束。这里的地壳由一个近地表沉积层和一个四层结晶地壳组成，具有几个重要特征。(1)柴达木盆地的沉积充填物最厚达8km，盆地形状反映了莫霍面的抬升。(2)在结晶地壳的四层中，P（S）波速度随深度增加而增加，速度范围为5.9 - 6.3km/s（3.45 - 3.65km/s），6.45 - 6.55km/s（3.7km/s），6.65km/s（3.8km/s）和6.7 - 6.9km/s（3.8 - 3.9km/s）;（3）低速带，3 - 5%在柴达木盆地及其向祁连山过渡的地壳下半部分，检测到地震速度降低。(4)结晶地壳厚度以盆地北方边缘祁连山以下最厚（58 - 62km），盆地中心以下最薄（52km）。地壳厚度的变化主要是由地壳最底层的厚度变化引起的。(5)泊松比和P波速度值表明，柴达木地壳基本上有一个长英质成分与中间层在其基础上。根据本文所报道的地壳结构，我们认为，晚新生代会聚是由厚皮构造变形所适应的，厚皮构造变形涉及整个昆仑-柴达木-祁连系的地壳。
We present the results of a seismic wide-angle reflection/refraction profile across the central Qaidam basin, the largest basin within the Qinghai-Tibetan plateau. The 350-km‐long profile extends from the northern margin of the East-Kunlun Shan to the southern margin of the Qilian Shan. The P- and S-wave velocity structure and Poisson's ratio data provide constraints on composition. The crust here consists of a near-surface sedimentary layer and a four-layered crystalline crust having several significant features. (1) The sedimentary fill of the Qaidam basin reaches a maximum thickness of 8km, and the basin shape mirrors the uplifted Moho. (2) Within the four layers of the crystalline crust, P- (S-) wave velocities increase with depth and fall within the following velocity ranges: 5.9–6.3km/s (3.45–3.65km/s), 6.45–6.55km/s (3.7km/s), 6.65km/s (3.8km/s), and 6.7–6.9km/s (3.8–3.9km/s), respectively; (3) low-velocity zones with a 3–5% reduction in seismic velocity are detected in the lower half of the crust beneath the Qaidam basin and its transition to the Qilian Shan. (4) The crystalline crust is thickest beneath the northern margin of the basin towards the Qilian Shan (58–62km) and thinnest beneath the center of the basin (52km). Variations in crustal thickness are caused most pronouncedly by thickness variations in the lowermost layer of the crust. (5) Poisson's ratio and P-wave velocity values suggest that the Qaidam crust has an essentially felsic composition with an intermediate layer at its base. Based on the crustal structure reported here, we suggest that late Cenozoic convergence is accommodated by thick-skinned tectonic deformation with thickening involving the entire crust across the Kunlun–Qaidam–Qilian system.
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影响因子：
2.9
作者：
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通讯作者：
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影响因子：
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影响因子：
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通讯作者：
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