辽宁排山楼金矿床黑云母花岗岩成岩时代及地质意义

摘要：排山樓金矿床是华北克拉通北缘东段赤峰—朝阳—阜新金矿成矿带中的韧性剪切带型金矿，矿体主要赋存于EW向韧性剪切带的太古宙变质岩中。选择控矿韧性剪切带北部的黑云母花岗岩为研究对象，对其进行了全岩主量、微量元素地球化学特征分析及LAICPMS锆石UPb定年研究，探讨其成因类型、形成时代和构造背景。地球化学特征表明，岩石属于I型高钾钙碱性、准铝质—弱过铝质花岗岩，富集轻稀土元素及大离子亲石元素，呈弱的负Eu异常，亏损高场强元素，具有活动大陆边缘岩浆岩的地球化学亲缘性。锆石UPb定年结果显示，黑云母花岗岩侵入时代为早白垩世燕山期（（121.8±1.1）Ma）。通过野外观察黑云母花岗岩与控矿韧性剪切带之间的接触关系，对比岩矿间微量元素、同位素特征，结合华北克拉通区域构造演化，认为排山楼金矿床形成于岩石圈伸展的构造背景之下，成矿时代为早白垩世晚期，是韧性剪切作用导致矿源层成矿元素发生活化、迁移、富集的产物。

关键词：黑云母花岗岩；I型花岗岩；岩石地球化学；锆石UPb年龄；成矿时代；金矿；华北克拉通

中图分类号：P588.121；P618.51文献标志码：A

Formation Age and Geological Significance of Biotite Granite in Paishanlou Au Deposit of Liaoning， China

NIE Shijia， YANG Yanchen， HAN Shijiong， ZHANG Lin， WANG Fengbo

（College of Earth Sciences， Jilin University， Changchun 130061， Jilin， China）

Abstract： Paishanlou Au deposit，which is located in ChifengChaoyangFuxin gold metallogenic belt， the eastern segment of northern periphery of North China Craton， is ductile shear belthosted. The ore body is mainly hosted in Archean metamorphic rocks of EWtrending ductile shear belt. The biotite granite outcropped in the north of orecontrolling ductile shear belt was taken as the research object； the geochemical characteristics of wholerock major and trace elements were analyzed； LAICPMS zircon UPb age was measured； and the petrogenesis， formation age and tectonic setting were discussed. The biotite granite belongs to Itype granite with highK calcalkaline and quasialuminousweak peraluminous， showing the characteristics of minor negative Eu anomaly， eichment of light rare earth elements and large ion lithophile elements， and loss of high field strength elements； thus， the rocks have geochemical affinity of active continental margin magmatic rock. LAICPMS zircon UPb age is （121.8±1.1）Ma， so that the biotite granite is emplaced during Early Cretaceous Yanshanian. Based on the observation of contact relationship between biotite granite and orecontrolling ductile shear belt， the relationship of trace element and isotope characteristics between biotite granite and gold ore was contrasted. Combined with the tectonic evolution in North China Carton， it is indicated that Paishanlou Au deposit is formed in Early Cretaceous by the background of the regional extensional tectonism and lithosphere thinning process， and the mineralogenetic epoch is late Early Cretaceous. In general， Paishanlou Au deposit is the product of the activation， migration and eichment of source bed by ductile shearing.

Key words： biotite granite； Itype granite； petrogeochemistry； zircon UPb age； oreforming age； Au deposit； North China Craton

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