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通过西非塞内加尔600公里剖面上所完成的23个大地电磁测深点的资料,确定了地壳和上地幔的导电率。资料是在一个构造变化区取得的,这些地区是:西非克拉通(稳定于1850±250亿年之后)、西非活动带(时代为350—650亿年之间)及塞内加尔盆地。从二维模拟中提出的地球模型表明,若干不均匀性伸延到岩石圈,甚至更深达软流圈,深度大约为460公里。盆地的西部向下延到10公里时,平均电阻率出现低值(20～30欧姆米)。盆地上地壳的异常被认为是初期裂谷的标志,它显示为本区地壳薄弱的模式。在其下方一直到300公里,电阻率为1000～3000欧姆米。盆地东部深度在20～30公里范围电阻率减小,其顶部主要的地幔导电导层位于300公里深处。西非克拉通边缘部分的点上,导电层出现的深度范围是30～40公里和80～100公里,电阻率在460公里深处陡降为40欧姆米。这个模型与收集到的地质和地球物理资料进行了对比,试图用板块构造来解释所观测到的某些非连续性。对比表明这个主要非连续带是将盆地和活动带从400公里深分隔开的一个带,解释为向东倾斜的前寒武纪减厚板。在西非克拉通于130～150公里范围内,确定了一个低电阻率带。130公里以上有一个1000～3000欧姆米的高阻层,克拉通之下大约460公里处出现导电率的突然上升。简要地说在Kedougou地区(克拉通内)一个引人注目的特性就是下部地壳是导电的。东塞内加尔Birrimian地向斜部分的实体包括优地槽海洋安山岩,多火山深海槽,特别是与蛇绿岩类同的火山岩以及一个冒地槽沉积的序列,表现了近代板块构造相的特征受分布广的海洋开口和大陆碰撞控制。下地壳导电物质解释为海洋地壳建造。
The conductivity of the crust and the upper mantle was determined from the data of 23 geomagnetic soundings on the 600-km section of Senegal in West Africa. The data were obtained in a tectonic change zone: the West African craton (stabilized at 1850 ± 25 billion years), the West African belt (between 35 and 65 billion years ago), and the Senegal basin. The earth model proposed from 2D simulations shows that a number of inhomogeneities extend into the lithosphere and even reach the asthenosphere to a depth of about 460 km. When the western part of the basin extends down 10 km, the average resistivity is low (20-30 ohm). The anomalies of the upper crust in the basin are considered to be signs of an early rift that shows a weak crustal pattern in this area. Beneath it is up to 300 kilometers with a resistivity of 1000 to 3000 ohm meters. The resistivity decreases in the depth of 20-30 km in the eastern part of the basin, with the topmost mantle conducting layer located 300 km deep. At the edge of the West African craton, the depth of the conductive layer appears in the range of 30-40 km and 80-100 km, and the resistivity drops sharply to 40 ohm at a depth of 460 km. This model is contrasted with the geologic and geophysical data collected in an attempt to explain the observed discontinuities in plate tectonics. A comparison shows that this major discontinuous zone is a zone that separates the basin and the activity zone 400 km deep, interpreted as an eastward Precambrian plate reduction. In the West African craton in the 130 to 150 km range, identified a low resistivity zone. Above 130 km there is a high resistivity layer of 1000 to 3000 ohm-meters with a sudden increase in conductivity around 460 km below cratonic. In short, one striking feature of the Kedougou region (cratonic) is that the lower crust is electrically conductive. The bodies of the syncline section of the Birrimian, East Senegal, include the Eudemonium marine andesite, the volcanic deep volcanic trough, especially the volcanic rocks of the same type as the ophiolite, and the sequence of a sag-trough sedimentary deposit, characterizing the tectonic facies of modern plate tectonics Wide ocean opening and continent collision control. Lower crust conductive material is interpreted as marine crust construction.