台西南盆地新生代断裂特征与盆地演化

根据断裂发育特征和盆地结构分析,新生代台西南盆地的演化可划分为3个发展阶段:晚古新世—早渐新世陆缘裂陷期,此间断裂多为半地堑和地堑的边界断裂;晚渐新世—中中新世陆缘盆地坳陷期,受南海扩张运动的影响,南部坳陷发生快速拗陷,为盆地的沉降和沉积中心,而北部坳陷则处于隆起状态;晚中新世—全新世陆缘张裂期,由于南海洋壳沿马尼拉海沟向吕宋岛弧之下俯冲,致使南部坳陷沿现今的陆坡区发生一期新的张裂活动,并使南部坳陷快速沉降为深海盆,而菲律宾板块往北西方向俯冲,致使北部坳陷东部发生近东西向挤压构造运动,此时期盆地的沉积中心转移至北部坳陷。 

FRACTURE CHARACTERISTICS AND BASIN EVOLUTION OF THE TAIXINAN BASIN IN CENOZOIC

Based on fault development characteristics and basin structure analyses,there are 3 evolution stages of the Taixinan Basin in Cenozoic.From Late Paleocene to Early Oligocene,rift-depression basin on continental margin is formed during the first stage.Grabens are controlled by border fractures.From Late Oligocene to Middle Miocene,marginal sea basin is formed during the second stage.The southern depression of the Taixinan Basin subsides quickly influenced by the South China Sea movement and becomes the subsidence and sedimentary center of the basin.However,the northern depression of the Taixinan Basin is an up-lift at the same time.From Late Miocene to Holocene,extension fractures generate along continental margin.As the oceanic crust of South China Sea dives below the Luzon Island arc along the Manila trench,new extension movement takes place along slope of the southern depre-ssion.The southern depression subsides quickly again and becomes deep sea basin at last.At the same time,the Philippines plate dives northwest,resulting in compressive tectonic movement from east to west in the east of the northern depression.The northern depression has become the sedimentary center of the Taixinan Basin.