| 内生金矿床成因与地幔地壳演化 |
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| 引用本文：.1984.The Metallogeny Of Endogenic Gold Deposits As Approached From The Evolution Of The Earth's Crust And The Mantle[J].Mineral Deposits,3(4):29~33 |
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| The Metallogeny Of Endogenic Gold Deposits As Approached From The Evolution Of The Earth's Crust And The Mantle |
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| Abstract:This paper discusses the source bed, the genetic types and the metallogenic regularity of gold deposits from the viewpoint of the evolution of the Earth's crust and the mantle. The initial source bed of endogenic gold deposits probably stems from the upper mantle. The distribution of gold in different zones of the concentric earth shows obviously the siderophile property, and the abundance of gold in the earth increases gradually from the crust through the mantle to the core. In the process of the evolution of the crust and the mantle, the partial melting and emplacement of pyrolite acts as motive factor making it possible for gold to be transferred from the mantle to the crust. The partial melting of the mantle decreases the siderophile trend and increases the sulphophile trend of gold; as a result, gold is comparatively concentrated in basic rocks but relatively deficient in ultrabasic rocks. Based on the distribution of the source bed of gold, the authors have classified the endogenic gold deposits into the mantle type and the crustal type. The associated gold in the copper-nickel sulfide deposits related to basic and ultrabasic rocks belongs to the mantle type, while the gold deposits produced as a result of the evolution of the gold-bearing greenstone belt and greenstone-like belt are of crustal type: The formation of the crustal type gold deposits is strictly controlled by such physical and chemical conditions as the introduction of enough water, temperatures lower than 300℃ and pressures less than 1500 atm. Therefore the gold deposits of the metamorphosed greenstone belts are chiefly products of low grade metamorphism of the greenschist facies. Generally speaking, granites of I type or S type fail to concentrate gold. Nevertheless, under local conditions, the formation of granite, the hot water activities and the increasing sulpbophile tendency and F, Cl and SiO2 affinity all contribute to promote the migration and enrichment of gold, thus producing the favorable conditions for the formation of crustal type gold deposits. Gold deposits may occur in various sorts of host rocks, though preferentially related to basic volcanic rocks. |
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