云南个旧卡房中三叠世安尼期变火山岩相序恢复及成矿分析

Facies sequence reestablishment and metallogenic analysis of Middle Triassic Anisian meta-volcanic rocks in the Kafang ore district,Gejiu,Yunnan

中三叠世安尼期个旧组卡房段变火山岩恢复为一套碱性基性-超基性岩组合,火山岩-沉积岩岩相组合包括爆发相、喷溢相、火山沉积相、潮坪相、后期盆地流体叠加相、矽卡岩相。垂向相序表现为爆发相→喷溢相→火山沉积相→潮坪相,属于弧后裂谷盆地背景下形成的岩相组合与相序结构。在研究区卡房段可划分为3个期次,进而组成一个旋回,垂直相序特征表明火山活动的多期次性、火山活动由强到弱的变化规律。后期盆地流体叠加相、矽卡岩相作为主要含矿岩相,可以作为今后的找矿指标。

The Middle Triassic Anisian meta-volcanic rocks in Kafang Member of Gejiu Formation could be restored into a set of alkaline basic-ultrabasic rock assemblages.The restored volcanic and sedimentary lithofacies includes explosive facies,effusive facies,volcanic sedimentary facies,tidal flat facies,late-basin-fluid superimposed facies and skarn facies.It is considered that the vertical facies sequence might be in order of explosive facies → effusive facies→volcanic sedimentary facies→tidal flat facies,belonging to the facies sequence structure and facies assemblage formed in a back-arc rift basin background.Kafang Member is divided into 3 volcanic stages in the study area,which composed a volcanic cycle.The characteristics of the vertical phase sequence indicate multi-stages of volcanic activities and variation of volcanic activities from strong to weak.Late-basin-fluid superimposed facies and skarn facies can be regarded as ore-bearing lithofacies and an ore-prospecting index in future.