琼东南盆地区的地壳密度与岩石结构

地壳岩石组成是理解地壳岩石圈演化的重要约束.我们以琼东南盆地区地壳速度结构模型为约束,正演拟合布格重力异常分布,获得了琼东南盆地区地壳密度结构模型.然后,对地壳密度模型进行温压校正,结合地壳速度模型以及全球常见地壳组成岩石的高温高压实验成果,推断了琼东南盆地区5个凹陷上地壳岩石组成.研究结果表明:琼东南盆地区地壳岩石密...

Crustal density and composition models beneath Qiongdongnan basin

Taking the crustal velocity structure model as constraints, we acquired the crustal density structure model of Qiongdongnan basin by forward fitting the Bouguer anomaly distribution. Then, after temperature-pressure correction of crustal density model, we combine the crustal velocity model and high temperature and pressure experiment results of the most common rock composition, to infer rock composition of the upper crust of five depressions in Qiongdongnan basin. The results show that crustal rock density exhibits strong vertical and horizontal heterogeneity in Qiongdongnan basin; the spatial variation of rock density is closely related to the structure pattern of alternate depressions and uplifts. The central part of the basin presents layered high density structures; there are three isolated high-density zones at the depth of 10 km, a uniform high density center at the depth of 16 km, and two separate high-density zones at 22 km. Our results support the simple shear model with simultaneous occurrence of lithosphere extension and mantle exhumation controlled by low-angle thrust fault(s).