Receiver function tomography of the central Tien Shan
Receiver function tomography of the central Tien Shan
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DOI：
10.1016/j.epsl.2004.05.039
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发表时间：
2004-08
影响因子：
5.3
通讯作者：
L. Vinnik;C. Reigber;I. Aleshin;G. Kosarev;M. Kaban;S. Oreshin;S. Roecker
中科院分区：
文献类型：
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作者：
L. Vinnik;C. Reigber;I. Aleshin;G. Kosarev;M. Kaban;S. Oreshin;S. Roecker
为了获得中亚天山深部结构的图像，我们对近40个地方宽带地震台站的P和S联合接收函数进行了反演。利用模拟退火法进行了反演。联合反演是对早期研究的改进，P和S接收函数分别进行了反演。利用这种方法，我们处理了通常用远震体波和面波层析成像技术研究的构造成像问题。我们证明了天山中部北部最上部的地幔是由一个几十公里厚的高速盖层组成的，它位于一个明显的低速带上方。该区的地壳结构为岩浆底侵作用提供了证据。这些特征可能与白垩纪-古近纪玄武岩喷发所显示的小羽流有关。在一条东南走向的走廊中也发现了低速层，可能与塔里木盆地的巴楚隆起相对应。造山带之下的地壳厚度从大约45公里到大约70公里不等。最小的值，很可能是从前造山时代继承下来的，在塔拉斯-费尔干纳断层附近被发现。北部的哈萨克盾和南部的塔里木盆地具有相似的价值特征。最大值位于边界范围下方。我们推断，天山中部的隆升不太可能仅由地壳缩短引起。
To obtain an image of the deep structure of the Tien Shan in central Asia, we invert P and S receiver functions jointly for almost 40 local broad-band seismograph stations. The inversion is performed using a simulated annealing technique. The combined inversion is an improvement on earlier studies, where P and S receiver functions were inverted separately. Using this approach, we deal with structural imaging problems that are usually investigated with teleseismic body wave and surface wave tomography techniques. We demonstrate that the uppermost mantle in the north of the central Tien Shan is composed of a high-velocity lid a few tens of kilometers thick above a pronounced low-velocity zone. The crustal structure in this region provides evidence of magmatic underplating. These features are likely related to a small plume that is manifested by basaltic eruptions of Cretaceous–Paleogene age. The low-velocity layer is also found in a southeast trending corridor, which may correspond to the Bachu uplift in the Tarim basin. Crustal thickness beneath the orogen varies from about 45 to about 70 km. The smallest values, most likely inherited from the pre-orogenic era, are found in a neighborhood of the Talas–Fergana fault. Similar values are characteristic of the Kazakh shield in the north and the Tarim basin in the south. The largest values are found beneath the bounding ranges. We infer that uplift of the central Tien Shan is unlikely to be caused by crustal shortening alone.