河南栾川矿集区燕山期两类岩体黑云母特征对比及其地质意义

河南栾川矿集区燕山期成矿小岩株与不成矿岩基在岩石学特征等方面表现出一定的相似性和差异性。以含矿的早白垩世早期南泥湖、上房沟岩株和不含矿的早白垩世晚期老君山岩基为例,通过研究其黑云母特征,综合探讨岩体成岩环境和成矿条件。研究表明,南泥湖和上房沟岩体结晶压力为38~115MPa,结晶深度为1.4~4.4km;3个岩体物源较深且相近,成岩背景与区域俯冲作用密切相关;南泥湖、上房沟岩体属于I型花岗岩,老君山岩体属于具有I型特征的S型花岗岩;南泥湖、上房沟岩体结晶温度为950~1 016℃,氧逸度为10-11.3~10-10 Pa,有利于成矿;老君山岩体结晶温度为870~940℃,氧逸度为10-12.4~10-11.5 Pa,不利于成矿。

Characteristics of biotites in two types of Yanshanian granitic pluton in Luanchuan ore concentration area of China and its significance

In the Luanchuan ore concentration area,the Yanshanian small stocks and batholiths show similar characteristics in several aspects.The Nannihu small stock and the Shangfanggou small stock contain ores and the Laojunshan batholith does not contain ores.This paper discusses the diagenetic environment and metallogenic conditions of these three Early Cretaceous granitic plutons based on the characteristics of biotite.The results show that the crystallization pressure of the Nannihu pluton and the Shangfanggou pluton is between 38 MPa and 115 MPa,and the crystallization depth is between 1.4 km and 4.4 km.These three granitic plutons share similar deep source and diagenetic environment that is likely related to the subduction process.The Nannihu pluton and the Shangfanggou pluton are I-type granites,whereas the Laojunshan pluton is S-type granite with the characteristics of I-type granite.The Nannihu and Shangfanggou plutons show the crystallization temperature of 9 50~10 16 ℃and the oxygen fugacity of 10 -11.3 ~ 10 -10 Pa. These constraints seem to be conducive tomineralization.The Laoj unshan pluton shows the crystallization temperature of 870 ~940℃ and theoxygen fugacity of 10 -12 .4 ~10 -11.5 Pa,which is not conducive to mineralization.