农坪英云闪长斑岩体地质地球化学特征及成因类型

The geologic-geochemical characteristics and genetic type of Nongping quartz-mica dioritic porphyry mass

英云闪长斑岩是农坪斑岩型金 (铜 )矿床的赋矿岩体 ,呈大小不等的小岩株 ,形成于燕山中晚期。岩石矿物成分主要为中长石、石英、黑云母和少量角闪石、钾长石。岩石地球化学特征表明英云闪长斑岩富钠 ,属钙碱性系列 ,富成矿元素金、铜 ,富轻稀土 ,铕异常不明显。斑岩体相带发育 ,可划分为边缘相、过渡相、内部相。英云闪长斑岩岩石矿物特征、岩石地球化学特征表明其成因类型为Ⅰ型 ,形成于消减的活动板块边缘构造环境 ,与燕山中晚期太平洋板块向欧亚大陆板块俯冲有关。英云闪长斑岩为金、铜成矿提供物质来源 。

Appearing as different sized rock stems and formed in middle latter part of Yanshan Period,the quartz mica dioritic porphyry is the host rock of Nong ping porphyry typed gold copper deposit.The rock minerals of quartz mica dioritic porphyry are mainly feldspar,quartz,black mica,small amount of hornblende and potassium feldspar.The characteristics of its rock geochemistry show that the quartz mica dioritic porphyry which belongs to calcium alkali series is rich in sodium,mineralized elements of gold and copper,light rare earth.The porphyry mass phase zone is well developed which can be divided into marginal phase,intermediate phase and internal phase.The characteristics of its rock mineral and rock geochemistry show that it belongs to genetic type I formed in the structural environment of the fringe of the reducing active plate and had relation with nosing down from pacific plate to Eurasia plate in the middle latter part of Yanshan Period.The quartz mica dioritic porphry supplied materials for the mineralization of gold and copper,so it is the host rock of gold copper mineralization.