关于侵入岩体中金矿床成因研究若干问题的讨论

SOME PROBLEMS ABOUT THE GENESIS OF GOLD DEPOSITS IN INTRUSIVES

各时代、不同类型侵入岩中的金矿床是金矿的主要类型。关于金矿床与岩体的成因关系目前尚存在不同的看法,但传统的岩浆热液成因观点仍居统治地位。其原因往往在于不少研究者把岩浆热液成因当成了固定模式应用于具体矿床的研究,而不是建立在综合研究的基础之上。本文结合近年来金矿的研究进展,强调侵入岩中金矿床的成因研究要综合考虑成岩成矿的时代与时差、成矿流体和成矿物质的来源等各方面因素。金矿床定年的进展研究表明,矿床与岩体常存在大的时差,从而排除了矿床与岩体的直接成因联系,也否定了岩浆热液成因的观点,其成矿流体为大气降水、建造水或其混合水,成矿物质可来自岩体、岩体围岩或深部。因此,本文认为侵入岩体中的金矿床多不是岩浆热液成因,而是后期改造成矿作用的产物。

Gold deposits in intrusives of varying ages and types are a main gold type. The genetic relation between gold deposits and intrusives remains controversial, but traditional magmatic hy-drothermal metallogeny is still predominant. This is because the view of magmatic hydrothermal origin is regarded by many researchers as a fixed model and applied in the study of concrete deposits rather than based on an integrated study. On the basis of recent studies of gold deposits, this paper emphasizes a comprehensive consideration of the formation ages and age gap of intrusives and gold deposits and the sources of ore-forming fluids and substances in the genetic study of gold deposits in intrusives. The advances in dating of gold deposits indicate a big time hiatus between deposits and intrusives, which precludes a direct genetic connection between gold and magmatism. Ore-forming fluids of gold deposits might be meteoric, formational or mixing waters , and ore-forming substances might be derived from intrusives, country rocks of intrusives or the deep levels of the crust. This paper holds that gold deposits in intrusives are not of magmatic hydrothermal origin, but a product of late-stage reworking mineralization.