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为了揭示南黄海北部白垩纪沉积物下的地震反射异常体的地质属性和形成过程,进行了地震反射和重、磁反演等研究,结合区域地表地质研究成果,推测该异常体可能为三叠纪下扬子地块深俯冲阶段经历高压变质作用后被拆离折返的岩体,并在南北两大地块汇聚、碰撞造山过程中被推覆至南黄海北部的古生代地层之上.研究结果显示:异常体内部地震反射特征表现为杂乱和空白反射,局部存在发散结构;与上、下地层之间存在2~3个同相轴的较强—强反射;另外,该异常体也具有高层速度(6 000~6 500m/s)、高密度(>2.7g/cm3)和中低磁化强度(-0.5A/m)等特征.通过海陆区域地质调查和类比,进一步揭示了该异常体和苏鲁三叠系高压变质地体具有时空上的一致性.这一发现为认识印支期东亚大陆碰撞和地质演化提供了参考.
In order to reveal the geological properties and formation process of the seismic reflection anomalies under Cretaceous sediments in the northern part of the southern Yellow Sea, seismic reflection, heavy and magnetic inversion and so on were carried out. According to the research results of regional surface geology, it is speculated that the anomaly may be Triassic During the deep subduction of the Jixi Yangtze block, the detachment and return of the rock subjected to high-pressure metamorphism took place and were converged on the two large blocks of the north and south. During the collision and orogeny, they were overthrown over the Paleozoic strata in the northern part of the southern Yellow Sea. : The seismic reflection characteristics of the anomalous body are characterized by clutter and blank reflection with locally divergent structure. There are 2 ~ 3 strong and strong reflection between the upper and lower strata. In addition, the anomalous body also has high velocity 6 000-6 500m / s), high density (> 2.7g / cm3) and low to medium magnetization (-0.5A / m), etc. The geological survey and analogy in the sea and land regions further reveal that the anomalous body and Sulu The Triassic high-pressure metamorphic terranes are spatiotemporal consistent, which provides a reference for understanding the collision and geological evolution of the Indosinian East Asian continent.