Geophysical investigation of the Cape Verde Archipelago
Geophysical investigation of the Cape Verde Archipelago
复制标题
佛得角群岛地球物理调查
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
P. Rona
中科院分区：
文献类型：
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作者：
B. Dash;M. Ball;G. King;L. W. Butler;P. Rona
佛得角群岛是中生代-新生代火山增生的一部分，呈向西开放的马蹄形，沿着断裂带从大西洋中脊向非洲汇聚。内部深海平原向西倾斜，深度从2.7公里增加到4.5公里。平原下为低起伏的声波基底，与300- γ负磁异常有关。Sal-Maio山脊两侧出现大位移正断层；表面的下垂很常见。磁异常趋势在岛屿北部呈南北向线性，在岛屿内部呈非线性，并可能与岛屿南部的东西向测深趋势同步变化。沿北部和东部山脊以及北西-东南方向横跨深海平原的200-250公里长的三角形反向折射线表明，2-3公里的半固化沉积物被3-6公里的玄武岩和6-8公里的深成岩所覆盖。莫霍河的深度在16到17公里之间。一条北西-东南走向的深断层在博阿维斯塔附近与萨尔-迈奥山脊相交。莫霍深度的一致和区域布格异常表明地壳底部缺乏局部起伏。整个群岛的地壳负荷是按地区调整的。
The Cape Verde Islands are emerged portions of a Mesozoic-Cenozoic volcanic accretion in the form of a westward-opening horseshoe along fracture zones converging from the mid-Atlantic ridge toward Africa. An interior abyssal plain slopes westward, increasing in depth from 2.7 to 4.5 km. The plain is underlain by low relief on acoustic basement that is associated with a 300-gamma negative magnetic anomaly. The flanks of the Sal-Maio ridge appear bounded by large-displacement normal faults; superficial slumping is common. The trends of magnetic anomalies are linear N-S north of the islands and less linear within the islands and may change coincident with E-W bathymetric trends south of the islands. A triangular pattern of reversed refraction lines 200–250 km long along the north and east ridges and NW-SE across the interior abyssal plain indicated 2–3 km of semiconsolidated sediments underlain by 3–6 km of basalt and 6–8 km of plutonic rocks. The depth of the Moho is between 16 and 17 km. A deep NW-SE trending fault intersects the Sal-Maio ridge near Boa Vista. The consistent depth to Moho and the regional Bouguer anomaly indicate lack of local relief at the base of the crust. The crustal load of the entire archipelago is regionally adjusted.