上黑龙江盆地二十一站岩体角闪石和黑云母成分特征及成岩成矿意义  

Compositional charactersistics,petrogenesis and metallogenic significance of amphibole and biotite from Ershiyizhan intrusion in Upper Heilongjiang basin

作　　者：程贤达 刘春花[1] 赵元艺[1] 水新芳 王远超 巩鑫 刘璇[3] 谭伟 许安民 CHENG Xianda;LIU Chunhua;ZHAO Yuanyi;SHUI Xinfang;WANG Yuanchao;GONG Xin;LIU Xuan;TAN Wei;XU Anmin(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing,100037; Xi’an Center of Mineral Resources Survey,CGS,Xi’an,710100;School of Earth Sciences and Resources,China University of Geosciences,Beijing,10083;th Gold Team of Chinese People’s Armed Police,Chengdu,610000)

机构地区：[1]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质调查局西安矿产资源调查中心,西安710100 [3]中国地质大学地球科学与资源学院,北京100083 [4]中国人民武装警察部队黄金第十二支队,成都610000

出　　处：《地质学报》2020年第3期782-798,共17页Acta Geologica Sinica

基　　金：国家重点研发专项“深地资源勘查开采”下属的课题“蒙古-鄂霍茨克洋构造体制成矿系统物质组成与过程(课题编号2017YFC0601303)”资助的成果。

摘　　要：二十一站岩体位于黑龙江省东北部大兴安岭地区塔河县境内,该岩体产出的岩石类型包括早白垩世二长岩和石英二长斑岩及早侏罗世花岗岩和二长岩等,在该岩体中已发现斑岩型铜金矿床,但是该岩体形成的物理化学条件和岩石成因尚不清楚,不同岩性岩浆岩的成矿潜力也不明确。鉴于此,本文以二十一站岩体中不同时代的花岗岩、二长岩、石英二长斑岩的黑云母和角闪石为研究对象,结合偏光显微镜、电子探针背散射图像和电子探针化学成分,对该岩体的岩石学、矿物学特征进行了研究,并对岩浆结晶的物理化学条件、岩石成因和成矿意义进行了探讨。结果显示:早白垩世二长岩中角闪石化学成分显示:角闪石富钙(CaO 11.21%~11.78%)、富镁(MgO 13.61%~14.85%)、贫钠(Na2O 0.80%~1.11%)和贫钾(K2O 0.40%~0.54%),属于镁角闪石,结晶温度为704.92~805.58℃,平均温度为761.82℃,压力为73.83~115.93MPa,对应岩浆侵位深度为2.8~4.4km,结晶时岩浆氧逸度为△NNO+1.63,含水量为H2O=4.92%,反映出岩浆结晶时高温、高氧逸度、富含水分、浅侵位的特征。黑云母的Fe2+/(Fe2++Mg)比值比较均一,反映黑云母未遭受后期流体改造,均为原生岩浆成因的黑云母。其中早侏罗世花岗岩和二长岩所代表的A类黑云母化学成分上富铁(TFeO 19.92%~22.42%)贫镁(MgO 7.99%~10.46%),属于铁质黑云母,早白垩世二长岩和石英二长斑岩所代表的B类黑云母相比于A类黑云母更富镁(MgO 12.38%~14.45%)和钛(TiO21.90%~2.75%),贫铁(TFeO 16.64%~17.97%)和铝(Al2O315.00%~16%.79),属于镁质黑云母。A类和B类黑云母对应岩浆结晶温度分别为720~740℃和750~780℃;压力为202.20~443.49MPa和158~231MPa,对应岩浆侵位深度为6.67~14.64km和5.24~7.24km;结晶时岩浆氧逸度分别为10-15~10-16和10-12~10-13;岩浆来源为壳源,且B类黑云母对应岩浆有地幔物质参与。因此,可以认为二十一站岩体中早白垩世二长�Ershiyizhan region localed in Tahe,Greater Khingan Mountains,northeastern Heilongjiang province,Early Jurassic granite,monzonite and Early Cretaceous monzonite,quartz-monzonite and so on are included.In which has discovered porphyry Cu-Au deposit,but the physical and chemical conditions of formation and the metallogenic potential of different lithologies are unclear.Based on the detailed petrographic observation of granite,monzonite,quartz-monzonite porphyry,this paper provides systematic chemical composition study on biotite and amphibole from samples of different lithologies to explore the formation conditions and the significance of petrogenesis and metallogenic.The results show that the amphibole from the Early Cretaceous monzonite,which are rich in magnesium(MgO 13.61%~14.85%),calcium(CaO 11.21%~11.78%),but poor in sodium(Na2 O 0.80%~1.11%)and potassium(K200.40%~0.54%),belong to Mg-amphibole.The crystallization temperatures of amphiboles are 704.92~805.58℃,average is 761.82℃,crystallization pressures are 73.83~115.93 MPa,emplacement depth are 2.8~4.4 km,the oxygen fugacity of magma is△NNO+1.63,and water content of magma are 4.45%~5.33%,average is 4.92%.All the parameters indicate that the magma crystallize at the conditions of high temperature,high oxygen fugacity,high water content and shallow emplacement.The Fe2+/(Fe2++Mg)of biotites is homogeneous,suggesting magnesia biotite.In which the type A-biotites from Early Jurassic granite and monzonite are Fe-biotite with rich in TFeO of 19.92%~22.42%and poor in MgO of 7.99%~10.46%.And the type B-biotite from Early Cretaceous monzonite and quartz-monzonite porphyry are Mg-biotite with rich in MgO of 12.38%~14.45%and TiO2 of 1.90%~2.75%,poor in TFeO of 16.64%~17.97%and Al2 O3 of 15.00%~16%.79.The crystallization temperatures of A-biotites and B-biotites are 720~740℃and 750~780℃,crystallization pressures are 202.20~443.49 MPa and 158~231 MPa,and emplacement depth are 6.67~14.64 km and 5.24~7.24 km,the oxygen fugacity are 10-15~10-16 and10-12~10-13,in addi

关 键 词：二十一站 角闪石 黑云母 成分特征 斑岩矿床 成矿潜力 

分 类 号：P581[天文地球—岩石学] P611[天文地球—地质学]