班公湖-怒江成矿带金成矿规律及成矿作用初讨

金矿是班公湖-怒江成矿带的优势矿种之一。由于地质工作程度总体较低,金矿的成矿规律和成矿作用研究相对薄弱,严重制约了金矿的评价。本文在前人已有研究成果的基础上,通过大量的野外地质调查与综合研究成果,初步论述了班公湖-怒江成矿带金的成矿地质背景、金矿床的主要成因类型、时空分布特征和成矿作用。研究结果表明,班公湖-怒江成矿带金矿床(点)在空间分布上具有东西成带,相对集中的分布特征。金主要以共生、伴生的形式存在。矿床类型有矽卡岩型、斑岩型、造山型和浅成低温热液型等4类,其成矿时代集中于晚侏罗世—晚白垩世。依据矿床成因及成矿作用主控因素,可将班公湖-怒江成矿带金矿床归纳为与洋壳俯冲消减作用有关的岩浆热液金成矿系统和与大陆碰撞造山作用有关的金成矿系统。与洋壳俯冲消减作用有关的岩浆热液金成矿系统可进一步划分出浅成低温热液型金矿床、斑岩型铜金矿床、矽卡岩型金铜矿床等3种成因类型;而与大陆碰撞造山作用有关的金成矿系统包括浅成低温热液型铜金矿床、造山型金矿床、矽卡岩型金铜矿床等3种成因类型。

Gold mineralization in the Bangong Lake-Nujiang metallogenic zone, Xizang

The gold deposits have long been known as one of the dominant mineral resources in the Bangong Lake-Nujiang metallogenic zone in Xizang. In the present paper, the authors carry out a preliminary study of geological setting, genetic type, spatio-temporal distribution and mineralization of the gold deposits on the basis of previous results and field geological survey. The findings have disclosed that the gold deposits(spots)in the Bangong Lake-Nujiang metallogenic zone are E-W oriented, and occur mostly as paragenetic gold and associated gold, and scarcely as single gold. The above-mentioned gold deposits may be classified into four types:skarn-type, porphyry-type, orogeny-type and supergene low-temperature hydrothermal type. The mineralization ages may be traced back to the Late Jurassic to the Late Cretaceous. These gold deposits may be involved into two mineralization systems, including the magmatic-hydrothermal gold mineralization system associated with the oceanic crust subduction and the gold mineralization system associated with the continental collision and mountain-building. The former may be composed of three types of deposits:the supergene low-temperature hydrothermal type copper-gold deposit, porphyry-type copper-gold deposit and skarn-type gold-copper deposit, whereas the latter may be subdivided into three types as well:supergene low-temperature hydrothermal type copper-gold deposit, orogeny-type gold deposit and skarn-type gold-copper deposit.