论个旧老矿区的新找矿方向

A New Round of Mineral Prospecting and Prospecting Targets in Gejiu,Yunnan Province

笔者通过对古地磁、氧同位素组成、稀土元素组成及成岩温度、SiO2含量的变化规律以及花岗岩的侵入时代等方面的综合研究,总结出个旧东区及西区的花岗岩体是同源的花岗岩岩浆侵入演化形成的,同样是成矿母岩,都有利于个旧东区与西区锡多金属矿床的形成。笔者总结了个旧矿区的矿床类型及成矿规律。个旧矿区的原生矿床类型有:1产于碎屑岩中的裂隙脉型矿化;2产于石灰岩和白云岩中的层状—脉状、网脉状的气成—热液矿床;3产于花岗岩凹部及花岗岩突起顶部接触带矽卡岩中的接触交代矿床。个旧矿区的热液活动及热液蚀变作用很突出,花岗岩中的热液蚀变有:碳酸盐化、绿泥石化、云英岩化、绢云母化、钠长石化。其中碳酸盐化、云英岩化与锡、铜、钨矿化密切相关。笔者指出:在个旧矿区不论东区老矿区的深部及老矿山之间和外围还是整个西区都有进行新一轮找矿的必要性及可能性,而且提出个旧矿区的东区及西区新一轮找矿的方向和靶区。本文还指出在个旧矿区长期以来所划定的五子山复式背斜及贾沙复式向斜没有证据,应予以否定,包括应重新认识原来认为的仅局限于复背斜控制成矿的观点,开阔视野开展新一轮找矿。

This paper analyses the geological features and metallogenic regularities of the old mining district in Gejie Contact metasomatic deposits are closely related to skarns in depressions and protrusions of granite bodie, Stratiform deposits are controlled by intraformational faulting. Primary deposits include： 1. crevice--vein infilling mineralization in clastic rocks; 2. pneumato--hydrothermal stratiform, vein and stockwork deposits limestones and dolomites, and 3. contact-metasomatic deposits in skarns. Hydrothermal activities aJ hydrothermal alterations are prominent in this mining district. Hydrothermal alterations in granitic roct include carbonatization, chloritization, greisenization, sericitization and albitization. Carbonatization ar greisenization are closely related to Sn--W mineralization. Presented in this paper are major element data for variant hydrothermal alteration granitic rocks in Gejiu. Different types of granite can be distinguished on tt basis of significant differences in major element associations. Prospecting targets for Sn--Cu--polymetallic mineralization in the east and west of the Gejiu mining district are also discussed in this paper.