Sedimentary and crustal velocity structure of Trans-North China Orogen from joint inversion of Rayleigh wave phase velocity and ellipticity and some implication for Syn-rift volcanism
Sedimentary and crustal velocity structure of Trans-North China Orogen from joint inversion of Rayleigh wave phase velocity and ellipticity and some implication for Syn-rift volcanism
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DOI：
10.1016/j.tecto.2021.229104
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发表时间：
2021-11
期刊：
影响因子：
2.9
通讯作者：
Xiang Huang;Z. Ding;J. Ning;F. Niu;Guoliang Li;Xingchen Wang;Xiaoming Xu
中科院分区：
文献类型：
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作者：
Xiang Huang;Z. Ding;J. Ning;F. Niu;Guoliang Li;Xingchen Wang;Xiaoming Xu
本文提出了一个高分辨率的华北造山带及其邻区地壳和上地幔的三维剪切波速度模型，该模型是由环境噪声数据计算的瑞利波相速度和椭圆率联合反演得到的。三维速度模型揭示了整个研究区域沉积和地壳结构的巨大横向变化。除了位于造山带东西两侧的华北盆地和鄂尔多斯盆地之间存在较大的速度差外，我们还发现位于造山带中部的渭河-山西裂谷系内沉积物向北变薄，这表明在渐新世-上新世期间，裂谷作用可能从南部的渭河裂谷向北部的山西裂谷传播。虽然南北走向的裂谷是由低Vs在整个范围内的上地壳和中地壳，只有北段，其中大同火山杂岩，表现出大量的低速结构在下地壳和上地幔。低速异常的中心在火山杂岩以西约150 km处延伸到上地幔，推测下地壳中有一条近水平的通道，用于软流圈热物质的上涌。这些观测结果表明，山西裂谷北部是裂谷系中较活跃的一段，表现为同裂谷期大同火山杂岩。
We present a high-resolution 3-D shear wave velocity model of the crust and uppermost mantle beneath the Trans-North China Orogen and its adjacent regions derived from a joint inversion of Rayleigh wave phase velocity and ellipticity computed from ambient noise data. The 3-D velocity model reveals large lateral variations in sedimentary and crustal structure across the study area. In addition to the large velocity contrast between the North China Basin and the Ordos Basin located in the east and west sides of the orogen, we found a northward thinning of sediments within the Weihe-Shanxi Rift System that sits in the middle of the orogen, suggesting that the rifting has likely propagated from the Weihe Rift in the south to the Shanxi Rift in the north during the Oligocene-Pliocene. While the north-south trending rift is underlaid by a low Vs across the entire range in the upper and middle crust, only the north segment, which houses the Datong volcanic complex, exhibits a substantial low velocity structure in the lower crust and the uppermost mantle. The center of the low velocity anomaly extends into the uppermost mantle at a location approximately 150 km west to the volcanic complex, which is speculated for a nearly horizontal channel in the lower crust for the upwelling of the hot materials from the asthenosphere. These observations suggest that Shanxi Rift in the north is a more active segment within the rift system, which is manifested by the Quaternarysyn-rift Datong volcanic complex.