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首页> 外文期刊>Journal of geodynamics >Geodynamic insights of the Cameroon Volcanic Line (Western Africa) from isostatic gravity anomalies
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Geodynamic insights of the Cameroon Volcanic Line (Western Africa) from isostatic gravity anomalies

机译：等静重力异常对喀麦隆火山线（西非）的地球动力学见解

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The Cameroon Volcanic Line (CVL) is one of the major features of the African Plate which consists of volcanic islands of the Gulf of Guinea in the Atlantic Ocean, volcanoes and plutonic complexes in the continent trending NE-SW. Volcanic activities of the CVL are still current with eruptions of Mount Cameroon (the latest in 2000) and emission of deadly gases from lakes Monoun and Nyos in 1984 and 1986 respectively. Based on AiryHeiskanen local compensation model, this work computes isostatic gravity anomalies to study the geodynamics of the lithosphere beneath the CVL using the Earth Gravitational Model EGM2008 and the digital topographic data ETOPO1. Isostatic regional anomalies obtained outline two major crustal zones corresponding to two distinct quasi-ellipsoidal shape zones oriented NE-SW. The southern part of the CVL including Mount Cameroon, coastal and oceanic zones is characterized by the highest values, while the northern part comprising Kumbo zone, lakes Monoun and Nyos shows lower magnitudes. Successive and located positive anomalies observed on the isostatic residual anomaly map line up towards the CVL direction. These findings bring forward the fluctuations inside the crust and the lithosphere in conformity with the CVL direction. Upper mantle with higher density than asthenosphere and crust may influence the highly positive gravity anomalies observed in the study area. In conformity with the principle of isostasy, most of the mountains of the study area may be located in zones where the conditions of complete isostatic compensation are not satisfied. Asthenospheric uplift would therefore be the cause of upward flow of materials from depths through volcano vents or fractures in both Mount Cameroon and Kumbo regions, aiming at restoring the isostatic equilibrium.
机译：喀麦隆火山线（CVL）是非洲板块的主要特征之一，该板块由大西洋的几内亚湾的火山岛，大陆上的NE-SW趋势的火山和古生物构成。由于喀麦隆山的喷发（最近一次发生在2000年）以及1984年和1986年的莫诺恩湖和尼奥斯湖的致命气体排放，CVL的火山活动仍在继续。基于AiryHeiskanen局部补偿模型，这项工作使用地球引力模型EGM2008和数字地形数据ETOPO1计算了等静重力异常，以研究CVL下方岩石圈的地球动力学。所获得的等静压区域异常勾勒出两个主要的地壳区域，对应于两个方向为NE-SW的截然不同的准椭圆形区域。 CVL的南部（包括喀麦隆山，沿海和海洋区）的特征是最高值，而北部的Kumbo区，Monoun湖和Nyos湖则表现出较低的强度。在等静压残余异常图上观察到的相继且定位的正异常朝向CVL方向排列。这些发现提出了沿CVL方向的地壳和岩石圈内部的波动。密度高于软流圈和地壳的上地幔可能会影响在研究区域观测到的高度正重力异常。根据等静原理，研究区域的大多数山脉可能位于不满足完全等静压补偿条件的区域。因此，软流圈的隆升将是物质从深处向上流经喀麦隆山和坎博地区的火山喷口或裂缝的原因，目的是恢复等静压平衡。

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