广西贵港市龙头山火山—次火山岩型金矿床地质特征

本文根据“七五”项目:《广西贵港市龙头山金矿床地质特征及找矿方向》的研究成果基础上撰写而成。文中侧重地论述了火山机构与矿床特征,并探讨了矿床成困。研究认为:矿床构造是一个晚中生代的残存火山颈机构。在其管道内的隐爆角砾岩、火山角砾岩、角砾熔岩、流纹斑岩和花岗斑岩等岩相带以及中酸性脉岩相,均属贫硅、富钾钙碱性系列的铝过饱和类岩石,是一套陆相中心式火山—次火山喷发—侵入岩系,属同源不同阶段的产物;该矿床金矿体受火山颈机构内的角砾状岩石及其内外接触带的断裂构造控制,多呈直立脉状,具有火山岩型与断裂充填型两类金矿化;成矿物质与流体主要源于火山岩浆喷气、热液,应属火山—次火山岩热液型金矿床。

GEOLOGICAL CHARACTERISTICS OF Mt. LONGTOUSHAN VOLCANIC-SUBVOLCANIC GOLD DEPOSIT, GUIGANG CITY, GUANGXI

The paper is written on the basis of the research results of "Geological Characteristics and Prospects of Mt. Longtoushan Gold Deposit, Guigang City, Guangxi" of the seventh five - year science and technolgy project of Bureau of Geology and Mineral Resources of Guangxi. The paper emphatically discribes the volcanic mechanism and the characteristics of the gold deposit, and also discusses the genesis of the gold deposit. The structure of deposit is a late Mesozoic residual volcanic neck. The cryptoexplosive breccia, volcanic breccia, breccia lava, rhyolite-porphyry, granite-porphyry and intermediate - acid dike rocks in the neck are all aluminium oversaturated rock of silicon-poor and potasium- rich alkali-calcic series, being continental central-type volcanic-subvolacanic effusive -intrusive rock series, and the products of the same sources and different stages. The gold orebodies are controlled by the brecciated rocks in the volcanic neck and the fractures in the contact zone. and appear as vertical veins. There are two types of gold mineralizations, i. e. , volcanic rock type and fracture-filled type. The ore-forming material and solution mainly come from volcanic exhalation and solution. So, the Mt. Longtoushan gold deposit is volcanic-subvolcanic hydrothermal gold deposit.