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一般认为,碱性玄武岩的源区深40—80公里,而金伯利岩的源区为80—250公里。因此,对这两类岩石的研究,可了解地球深达250公里的情况。上地幔中由40公里到250公里这一区段很重要,因它是板块活动和地震形成的关键地区、是大部分岩浆和许多与矿床有关的热液的发源地,同时又是形成地球的水圈和大气圈的气体散发地区。 从金伯利岩在全球的分布看(图1),它主要同前寒武纪稳定地块有关。非洲的金伯利岩(图2)没有例外地都出现在西非地块。刚果地块和卡拉哈里地块上。一些金伯利岩虽产于环绕稳定地块的褶皱带中,
It is generally accepted that alkaline basalts have a source depth of 40-80 km, while kimberlites have a source area of 80-250 km. Therefore, the study of these two types of rocks can understand the earth’s depth of 250 km. The section of the upper mantle, from 40 km to 250 km, is important because it is a key area for the formation of plates and earthquakes and is the source of most magma and many deposit-related hydrothermal fluids that simultaneously form the Earth’s Hydrosphere and atmosphere of the gas distribution area. From the distribution of kimberlite in the world (Figure 1), it is mainly related to the stable Precambrian block. The kimberlites in Africa (Figure 2) have all emerged in West Africa plots without exception. Congo plots and Kalahari plots. Although some kimberlite rocks are produced in the fold belt around a stable block,