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本文讨论南沙海域万安盆地和曾母盆地的地形地貌概况、沉积特征及区域断裂分布与剖面特性。万安盆地的新生代沉积分二个构造层,下构造层主要分布在基底半地堑中,为陆相沉积;上构造层为海相沉积。曾母盆地新生代沉积(未变质部分)按海退旋回划分出8个沉积旋回。万安盆地北东向断裂呈雁行排列,北西向断裂具走滑特征。作者指出上述沉积盆地的形成,与南海西南海盆的海底扩张紧密相关:万安盆地为拉张剪切盆地,曾母盆地为前陆盆地。
This article discusses the topography, sedimentary features and distribution of regional faults and profile features of Wan’an Basin and Zengmu Basin in Nansha Sea. The Cenozoic sediments of the Wan’an Basin are divided into two structural layers. The lower structural layers are mainly distributed in the basal half-graben and are continental sediments. The upper structural layers are marine sediments. The Cenozoic sediments (non-metamorphic parts) in the Zengmu Basin are divided into 8 sedimentary cycles according to the descending sea. The northeastern faults in Wan’an Basin are geese arranged in an exoskeleton, and the NW-trending faults are characterized by strike-slip. The author points out that the formation of the above sedimentary basins is closely related to the seafloor expansion in the southwest sea basin of the South China Sea: the Wan’an basin is a extensional shear basin and the Zengmu basin is the foreland basin.