呼包盆地周缘壳、幔结构研究

Structure of crust and mantle beneath the Hu-bao basin and its adiacent resion

对呼包盆地周边七个台站的远震接收函数研究表明:研究区地壳厚度为43-46 km,地壳速度比和S波速度结构均无异常;阴山造山带岩石圈埋深为65-85 km,且上地慢S波平均速度偏低,是典型的异常地慢区.根据S波速度结构和地壳厚度随地形高程反比的变化关系,以及地表广泛出露的慢源玄武岩分布,推测该区地慢深部热物质上涌是阴山造山带隆升的原因之一.上升的软流层物质与地慢发生交代、侵蚀作用导致岩石圈减薄,S波速度降低.呼包盆地的形成可能与深部物质上涌造成的拉张效应有关.

Teleseismic receiver functions of seven seismic stations around the Hu-bao Basin indicate that crustal thickness of the region is 43-46 km with a normal crustal Vp/Vs ratio and S wave velocity. Lithospheric depth is 65 -85 km in the Yinshan tectonic zone with a lower average S wave veolocity, which shows a typical abnormal mantle. Based on S wave velocity structure and the negative correlation between crustal thickness and elevation, as well as the widespread basalt from mantle, we presume that upwelling of asthenospheric materials is one of the main reasons for uplift of the Yinshan orogen. The thinning of lithosphere and lower S wave velocity are attributed to metasomatism and erosion by the upwelling asthenosphere, while the formation of the Hu bao Basin may be related to the extension caused by asthenosphere upwelling.