南黄海卫星重力场及构造演化

SATELLITE GRAVITY FIELD AND TECTONIC EVOLUTION OF THE SOUTH YELLOW SEA

利用美国国家航空航天局1998年公布的EGM96全球重力模型,计算了南黄海区32°～37°N、120°～126°E范围内的2～360阶卫星重力场,分析了该区的卫星重力异常场特征,将南黄海区的卫星重力异常划分为8个异常区,长期的板块运动结果控制了该区的重力异常格局。晚二叠纪至早三叠纪,华北与华南古陆在秦岭—大别山—胶南—临津江带碰撞对接,南黄海区经历了一次造山运动,由此产生的挤压剪切形成南黄海盆地雏形,当时的沉积中心在南黄海中部隆起区。侏罗纪—白垩纪,Izanagi板块在亚洲大陆下向西北方向俯冲,南黄海区发生了剧烈的构造岩浆活动。晚白垩世,在拉张构造环境下发生张裂裂陷作用,南黄海区北部坳陷和南部坳陷分别裂陷,出现雏形,揭开了新生代盆地的序幕。新生代印度板块、欧亚板块及太平洋板块运动促使原坳陷区即中部隆起区上升,南、北两个断陷盆地发展成为两大坳陷。晚第三纪末期至第四纪,南黄海盆地进入区域沉降阶段。

The accuracy and resolution of satellite gravity data have been greatly improved along with the development of space technology. In this paper, satellite gravity anomaly is calculated to be 2～360 order for the region(32°～37°N,120°～126°E) in the South Yellow Sea using NASA EGM96 Geopotential Model. According to the features of satellite gravity anomaly, the satellite gravity anomalies of the South Yellow Sea can be divided into eight regions. The movement of plates mainly controls the gravity anomalies. During late Permian to early Triassic, the North China Block began to collide with the South China Block at QinlingDabieJiaonanImjingan Belt,and thus the South Yellow Sea suffered a contractional deformation. The South Yellow Sea basin formed in the thrust depression and the sedimentation center was located in the central upheaval region. From Jurassic to Cretaceous, the movement of Izanagi plate to Asian plate influenced the area. In late Cretaceous, the south fault basin and the north fault basin began to form under the extensional condition. The South Yellow Sea experienced complex deformation since the Eocene because the northward moving, anticlockwise rotating Indian plate collided with Asia. The two fault basins, the south and the north, turned into two downwarped basins in Cenozoic due to the movement of Indian, the Eurasian and the Pacific plates.