Mineralogical and Petrochemical Characteristics and Genesis of Laoniugou Gneiss in Jiapigou Gold Mine, Jilin Province  

作　　者：孙晓明 徐克勤 任启江 REIDR.KEAYS 

机构地区：[1]Institute of East China Non-ferrous Metals, Geological Exploration Bureau, Nanjing, 210007 [2]Department of Earth Sciences, Nanjing University, Nanjing, 210008 [3]Department of Geology, Melbourne University, Melbourne, Parkville, Victoria 3052, Australia

出　　处：《Chinese Journal Of Geochemistry》1992年第3期224-236,共13页中国地球化学学报

基　　金：This project was financially supported by the National Natural Science Foundation of China

摘　　要：Detailed mineralogical and petrochemical studies show that the Laoniugou gneiss of the Jiapigou gold mine is composed mainly of plagioclase gneiss and irregular to lentiform plagioclase amphibolite melanic enclaves.The major element contents show an obvious bimodal and trondhjemitic series evolutional trend.This situation is significantly different from that encountered in bimodal calc-alkalic volcanic rocks in the rift-type Archaean greenstone belt.The contents of Rb,Sr and Ba are 7-21 ppm,153-363ppm and 201-1451 ppm respectively ,close to those of common Archaean grey gneisses.All the samples of plagioclase gneisses show positive Eu anomalies (even up to 4.6).The protoliths of the plagioclase gneiss are high-Al2O3 trondhjemitic series rocks,belonging to typical TTG of Archaean high-grade metamorphic terrain .The gneiss is quite similar to the B-type Amitsoq gneiss of W.Greenland .The authors believe that the plagioclase amphibolite enclaves are the relics of ancient oceanic crust while the plagioclase gneiss is the TTG ancient intrusive rock resulting from partial melting of the oceanic crust.Detailed mineralogical and petrochemical studies show that the Laoniugou gneiss of the Jiapigou gold mine is composed mainly of plagioclase gneiss and irregular to lentiform plagioclase amphibolite melanic enclaves. The major element contents show an obvious bimodal and trondhjemitic series evolutional trend. This situation is significantly different from that encountered in bimodal calc-alkalic volcanic rocks in the rift-type Archaean greenstone belt. The contents of Rb, Sr and Ba are 7-21 ppm, 153-363 ppm and 201-1451 ppm respectively, close to those of common Archaean grey gneisses. All the samples of plagioclase gneisses show positive Eu anomalies (even up to 4.6). The protoliths of the plagioclase gneiss are high-Al_2O_3 trondhjemitic series rocks, belonging to typical TTG of Archaean high-grade metamorphic terrain. The gneiss is quite similar to the B-type Amitsoq gneiss of W.Greenland. The authors believe that the plagioclase amphibolite enclaves are the relics of ancient oceanic crust while the plagioclase gneiss is the TTG ancient intrusive rock resulting from partial melting of the oceanic crust.

关 键 词：矿物学 岩石化学 金矿床 吉林 火山岩 地质构造 斜长岩 片麻岩 

分 类 号：P618.51[天文地球—矿床学]