北部湾大陆边缘地壳结构特征  

CRUSTAL STRUCTURE OF THE MARGIN OF THE BEIBU GULF

作　　者：阎全人[1] 王诚 李增悦[3] 王宗启 李继亮[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]兰州市供电局电安公司,甘肃兰州730050 [3]中国地质科学院562综合研究所,河北三河燕郊065201 [4]中国地质科学院地质研究所,北京100037

出　　处：《广西地质》2000年第3期13-17,共5页Guangxi Geology

基　　金：广西壮族自治区八五重点项目!(桂科 92 171K0 3 2 )经费资助

摘　　要：文章利用天然地震的PS转换波研究了北部湾陆缘地区的地壳结构特征。PS转换波测量表明 :本区地壳内部存在 4个明显的转换界面 :PSC、PSG、PSM、PSM1,分别代表上地壳、中地壳底界以及Moho面 (下地壳底界 )和上地幔顶部的第一转换面。计算结果表明 ,本区上地壳厚约 12km ,中地壳厚约 9km ,下地壳厚约 11km ,Moho面深约 32km。地壳厚度 (或Moho面深度 )由海向陆变厚 (或变深 ) ,由内陆的灵山到海陆交界处的北海、合浦 ,Moho面深度 (或地壳厚度 )由 34km变为 30km左右。PS转换波测深结果还表明 ,本区内NE向钦防—灵山断裂、合浦—博白断裂以及NW向小董—合浦断裂向深部延至中地壳 ,属壳断裂性质。北部湾陆缘地壳性质上仍为陆壳 ,由陆向洋明显减薄 ,北部湾盆地发育于这一减薄陆壳的前缘 ,是由地壳进一步伸展减薄所形成的。By the data of PS-waves of the earthquakes, The crustal structure of the margin of the Beibu Gulf is studied in this paper. The research shows that there are four remarkable transforming interfaces in the crust in this area, which are PSC、PSG、PSM and PSM 1. These interfaces stand for the bottoms of upper, middle, lower crusts and the first transforming interface in the upper mantle respectively. The thickness of upper crust is about 12 km, of middle crust is 9 km, of lower crust is 11 km. The depth of MOHO is about 32 km. The thickness of the crust becomes about 34 km from 30 km from the sea (near Beihai and Hepu) to the continent (near Lingshan). The results of PS-wave probe also indicate the faults in this area such as Qingfang-Lingshan fault, Hepu-Bobai fault and Xiaodong-Hepu fault all reach the bottoms of the middle crust. In conclusion, the crust of the margin of the Beibu gulf is the continental crust. It becomes remarkably thin from the inland toward the sea. The Beibu gulf basin locates in the front of this thinning continental crust, it originated from the extension of the crust.

关 键 词：北部湾 大陆边缘 PS转换波测量 地壳结构 

分 类 号：P183.2[天文地球—天文学] P736.15