辽东五龙-四道沟金矿集区花岗杂岩SHRIMP U-Pb年龄、地球化学特征及地质意义  

SHRIMP U-Pb Age and Geochemical Characteristics of Granites in Wulong-Sidaogou Gold Deposit, East Liaoning

作　　者：杨凤超[1,2] 宋运红[2] 杨佳林[2] 沈鑫[2] 顾玉超[2] YANG Fengchao;SONG Yunhong;YANG Jialin;SHEN Xin;GU Yuchao(College of Earth Science,Jilin University,Changchun 130061,Jilin,China;Shenyang Institute of Geology and Mineral Resources,China Geological Survey,Shenyang 110034,Liaoning,China)

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]中国地质调查局沈阳地质调查中心,辽宁沈阳110034

出　　处：《大地构造与成矿学》2018年第5期940-954,共15页Geotectonica et Metallogenia

基　　金：国家重点研发计划(2016YFC0600108);中国地质调查局地质调查项目(DD20160049)共同资助

摘　　要：辽东五龙?四道沟金矿集区位于华北地台东北部营口?宽甸古隆起南部,鸭绿江断裂带西侧,为中国北方重要的金矿集中区之一。金矿化主要发生在早白垩世三股流二长花岗岩?花岗闪长岩岩体外围的晚侏罗世五龙二长花岗岩岩体内部。五龙岩体主体为含二云母二长花岗岩,获得锆石SHRIMP U-Pb年龄为165.0±3.3 Ma和157.1±1.8 Ma;以高硅(SiO_2=72.61%~74.45%)、中铝(Al_2O_3=13.46%~14.74%)、高钾(K_2O=3.99%~6.03%)、高镁(MgO=0.22%~0.28%)、A/CNK值为1.04~1.14和高DI(89.54~92.43)为特征,呈现高分异高钾钙碱性I型花岗岩特征;稀土元素总量较低,轻重稀土元素之间的分馏强烈,Eu负到正异常,亏损Nb、Ta、P、Ti、Y等高场强元素,富集Rb、Ba、K、Sr等大离子亲石元素;ε_(Hf)(t)值为-35.66^-25.26,单阶段Hf模式年龄t_(DM)为1805~2238 Ma,两阶段Hf模式年龄t^C_(DM)为2804~3453 Ma。三股流岩体主要由角闪黑云母二长花岗岩和花岗闪长岩组成,锆石SHRIMP U-Pb年龄为122.7±1.6 Ma和123.3±1.4 Ma;二长花岗岩以高硅(SiO_2=72.00%~73.50%),花岗闪长岩以低硅(SiO_2=67.09%~69.26%)为特征。两种岩石都具有高铝(Al_2O_3=14.23%~15.26%)、高钾(K_2O=3.77%~4.86%)、高镁(MgO=0.51%~1.74%)和A/CNK值为0.95~1.11的特征,呈现高钾钙碱性I型花岗岩特征;稀土元素总量较高,轻重稀土元素之间的分馏强烈,Eu负异常明显,亏损Nb、Ta、P、Ti等高场强元素,富集Rb、K等大离子亲石元素;ε_(Hf)(t)值为-25.31^-20.86,单阶段Hf模式年龄t_(DM)为1590~1766 Ma,两阶段Hf模式年龄t^C_(DM)为2510~2781 Ma。岩石学、地球化学和年代学研究显示,矿集区存在两期岩浆活动,即早白垩世和中?晚侏罗世,其中五龙岩体为金矿体的形成提供了容矿场所,三股流岩体则直接影响区内一期金矿化作用。三股流和五龙岩体均形成于活动大陆边缘大地构造环境,其中三股流岩体可能形成于弧后伸展环境,而五龙岩体可能形成于陆壳加厚的背�The Wulong-Sidaogou is an important gold ore-concentrated area in North China,which is located in the south of the Yingkou-Kuandian uplift in the northeast of the North China Craton,on the west side of the Yalujiang fault zone.The gold deposits in the area occur mostly in the Wulong granite that intruded by the Sanguliu granite.SHRIMP U-Pb dating yield ages of 122.7±1.6 Ma and 123.3±1.4 Ma for the Sanguliu granites and 165.0±3.3 Ma and 157.1±1.8 Ma for the Wulong granites.The Early Cretaceous Sanguliu granites are high-K calc-alkaline I-type,containing hornblende,with low Nb and Y contents and A/CNK of^1.0,and exhibiting negative correlation between P2O5 and SiO2.The Sanguliu granites are characterized by relative low rare earth element concentrations but highly fractionated REE patterns,depleted in high field strength elements like Nb,Ta,P,and Ti,enriched in large ion lithophile elements such as Rb and K.The Middle-Late Jurassic Wulong granites are highly differentiated high-K alkaline I-type,containing muscovite and locally minor hornblende.The granites are characterized by A/CNK of 1.04 to 1.14,DI of 89.54 to 92.43,and a negatively correlation between P2O5 and SiO2.The rocks have trace element signatures similar to those of the Sanguliu granites,such as low and highly fractionated REE,depletion of high field strength elements,and enrichment of large ion lithophile elements.The Sanguliu and Wulong granites were likely formed in active continental margin,with the Sanguliu granites formed in extensional and the Wulong granites formed in compressive settings.We,therefore,suggest that formation of the granites and associated gold deposits in the study area was closely related to the Mesozoic magmatism possibly triggered by breakoff of the subducting slab of the Paleo-Pacific Ocean.

关 键 词：五龙金矿 三股流岩体 五龙岩体 侏罗纪 白垩纪 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]