吉林红旗岭主要成矿岩体辉石地球化学特征及其意义

吉林红旗岭铜镍硫化物矿床是我国第二大岩浆型铜镍硫化物矿床。为查明其岩浆来源、结晶温压条件等, 通过薄片鉴定及电子探针分析方法对红旗岭成矿岩体辉石化学成分特征进行了研究。结果表明:红旗岭单斜辉石全部为普通辉石, 斜方辉石均为古铜辉石;辉石成分变化较大, 普遍富镁贫铁, 总体上表现出低w(TiO₂)、w(Al₂O₃)和w(Na₂O)的特征;单斜辉石Di端元比例变化较大, 具有由富镁向富钙方向演化的趋势, 与世界上一些典型镁铁超镁铁岩体单斜辉石的演化趋势明显不同。红旗岭主要成矿岩体母岩浆属于拉斑玄武质岩浆, 为幔源岩浆, 分异程度较高。辉石温压计算结果表明, 红旗岭主要成矿岩体辉石结晶温度为1 100~1 250℃, 岩体形成深度为12.3~20.7 km。

Geochemical Characteristics and Significance of Pyroxene from Major Metallogenetic Intrusions in Hongqiling,Jilin Province,China

The Hongqiling Cu Ni sulfide deposit is a magmatic deposit that ranks second in China. In order to investigate the source of magma and temperature & pressure conditions of crystallization,the chemical composition of the pyroxene in metallogenetic intrusions of Hongqiling was studied by rock slice identification and electron probe analysis.The results show that all clinopyroxene minerals are augite,and orthopyroxenes are all bronzite.The chemical compositions of the pyroxene change widely and the pyroxene is charactered by enrichment in Mg and depleting of Fe,with low content of TiO2 , Al2 O3 and Na2 O.The Di-endmember of the clinopyroxene changes widely with the evolution from Mg-enrichment to Ca-enrichment,which shows a different variation tendency with the clinopyroxene from other typical mafic-ultramafic intrusions in the world.The source of magma was mantle-derived basalt magma,with high degree of differentiation.According to pyroxene thermobarometer,the crystallization temperature of the pyroxene in major metallogenetic intrusions of Hongqiling is estimated to 1 100 1 250 ℃ and the rock-forming depth is around 12.3 20.7 km.