伸展背景下的埃达克质岩:黑龙江呼玛地区早白垩世侵入岩的年代学和地球化学特征  

Adakitic-Like Rocks in Extensional Setting:Chronological and Geochemical Characteristics of Early Cretaceous Intrusive Rocks in Huma Area,Heilongjiang Province

作　　者：张坤 史冬岩 常翔鲲 朴星海 王伟东 Zhang Kun;Shi Dongyan;Chang Xiangkun;Piao Xinghai;Wang Weidong(Heilongjiang Mining Group Co.,Ltd.,Harbin 150000,China;Institute of Geosciences and Resources,China University of Geosciences,Beijing 100083,China;College of Earth Sciences,Jilin University,Changchun 130061,China;Institute of Geochemistry Chinese Academy of Sciences,Guiyang 550081,China;The Fifth Geolgical Survey Institute of Heilongjiang Province,Harbin 150036,China)

机构地区：[1]黑龙江省矿业集团有限责任公司,哈尔滨150000 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]吉林大学地球科学学院,长春130061 [4]中国科学院地球化学研究所,贵阳550081 [5]黑龙江省第五地质勘查院,哈尔滨150036

出　　处：《吉林大学学报（地球科学版）》2024年第4期1248-1263,共16页Journal of Jilin University：Earth Science Edition

基　　金：中国地质调查局项目(12120114028101);黑龙江省1∶5万区域地质矿产调查项目(HLJKD2015-06)。

摘　　要：为理清大兴安岭兴安地块中生代岩体的岩石成因及构造背景,本文通过岩石学、年代学、全岩地球化学等方法,对大兴安岭东北部的黑龙江省呼玛地区早白垩世侵入岩进行了研究。结果显示:研究区早白垩世中性侵入岩为钙碱性-高钾钙碱性系列准铝质-弱过铝质岩石,成岩时间在(121.3±1.2)~(118.7±0.9)Ma之间,稀土元素配分曲线显示为右倾模式,Eu微弱正异常(0.98~1.11),富集K、Sr、Ba等大离子亲石元素,亏损Nb、Ta、Ti、P等高场强元素。岩石同时具有高的Sr/Y(57.66~145.76)、LaN/YbN(11.66~29.52)和较高的Mg^(#)(50.93~57.63)、w(Cr)(77.00×10^(-6)~92.60×10^(-6))、w(Ni)(23.20×10^(-6)~32.60×10^(-6))值,显示出埃达克质岩特征。综合本次研究认为该期侵入岩主要形成于蒙古-鄂霍茨克洋闭合后的伸展环境,由加厚下地壳导致的岩石圈拆沉,软流圈幔源岩浆上涌形成埃达克质岩石。To elucidate the petrogenesis and tectonic settings of the Mesozoic rock formations in the Xing’an region of the Greater Khingan Range,this study employs petrology,chronology,and whole-rock geochemistry methods to investigate the Early Cretaceous intrusive rocks in the Huma area of Heilongjiang Province.The results reveal that the intrusive rocks are calc-alkaline to high-potassium calc-alkaline,quasi-aluminous to weakly peraluminous,crystallizing between(121.3±1.2)and(118.7±0.9)Ma.The rare earth element distribution patterns display a rightward trend with a weak positive Eu anomaly(0.98-1.11),enriched in large ion lithophile elements like K,Sr,Ba,and depleted in high field strength elements such as Nb,Ta,Ti,and P.The rocks show elevated ratios of Sr/Y(57.66-145.76),La N/Yb N(11.66-29.52),high Mg#(50.93-57.63),w(Cr)(77.00×10^(-6)-92.60×10^(-6)),and w(Ni)(23.20×10^(-6)-32.60×10^(-6)),indicating adakitic-like characteristics.Based on the comprehensive research,it is believed that the intrusive rocks primarily crystallized in an extensional environment following the closure of the Mongolian-Okhotsk Ocean,likely caused by lithospheric delamination thickening the lower crust and resulting in the upwelling of mantle-derived magma,forming adakitic-like rocks.

关 键 词：呼玛地区 花岗岩 锆石U-PB测年 地球化学 埃达克质岩 

分 类 号：P59[天文地球—地球化学]