埃达克岩及其成矿作用和相关问题的讨论

本文初步探讨了埃达克岩与相关大型矿床的关系，指出与埃达克岩浆有关的分异同化作用在一定条件下可以形成大型矿床；同时也强调了成矿后矿床保存的重要性。由于造山带的剥蚀速率快，导致和埃达克岩浆演化密切相关的形成于地壳浅部的大型斑岩矿床的保存有时限。因此在中国东部及“三北”地区中生代以前的造山带中，埃达克岩能否作为寻找相关大型矿床的标志值得商榷；但在新生代的西藏地区则是有可能的。近十年的研究认为中国东部侏罗纪—白垩纪的类似岩石并不属于埃达克岩系列，而是橄榄安粗岩及高钾钙碱性岩石系列。它们主要来源于富集地幔的部分熔融(不排除有下地壳物质混染的可能)及其后的结晶分异；一些中生代的斑岩型铜—金矿床和浅成低温热液矿床与此有关。

Discussion on Adakite, its Ore-Bearing Potential and Some Other Related Issues

This article primarily discusses the relationship between adakite and associated giant ore deposits. It supports the idea that magmatic processes associated with differentiation and assimilation of adakitic magmas may result in formation of giant ore deposits under favourable conditions. It also highlights the important issue of preservation of ore deposits after formation. Fast erosion rate of orogenic belts imposes time limits for survival of super-giant ores formed at shallow crustal depths associated with porphyries with affinity to adakitic magmas. Thus, it is debatable whether occurrence of adakite could be used as exploration guide for giant ore deposits associated with adakite in Pre-Mesozoic orogenic belts in China (eastern China and Northwest-North-Northeast of China); but it may have good potential for application in Cenozoic Tibetan region. In addition, extensive studies during last 10 years indicate that Jurassic-Cretaceous adakite-like rocks in eastern China belong to shoshonitic and K-high calc-alkalic rock series, instead of adakitic series. These rocks were generated by partial melting of enriched lithospheric mantle, not excluding the possibility of hybridization from lower crustal material, and subsequent fractional crystallization; and some Mesozoic porphyry Cu-Au deposits and epithermal deposits are genetically related to magmatic differentiation of these rocks.