安庆大龙山复式岩体锆石U-Pb年代学与地质意义  

U-Pb chronology and geological significance of zircons from Dalongshan complex pluton,Anqing

作　　者：徐庆安[1] Xu Qing′an(No.327 Geological Team,Bureau of Geology and Mineral Exploration of Anhui Province,Hefei 230011,Anhui,China)

机构地区：[1]安徽省地质矿产勘查局327地质队,安徽合肥230011

出　　处：《地质学刊》2023年第2期135-142,共8页Journal of Geology

基　　金：国家自然科学青年基金项目“中国中东部含矿与不含矿高镁埃达克质岩源区及氧逸度特征对比研究”(41203028)。

摘　　要：安徽安庆大龙山岩体位于扬子地台北东缘,发育大量中生代侵入岩浆岩。野外地质勘查发现,大龙山岩体可能为复式岩体,有多期岩浆作用,在其核部的正长岩附近发育一定量的闪长玢岩。对闪长玢岩和正长岩进行年代学研究,其锆石年龄分别为(137.7±1.9)Ma和(128.8±2.1)Ma。其中,在大龙山闪长玢岩中发育一定量的继承锆石,形成年代分别为古元古代(约2.0 Ga)和新元古代(约0.8 Ga),在正长岩中未发现捕获继承锆石。根据获取的继承锆石年龄,结合区域地质演化资料,推断大龙山岩体经历了复杂的演化过程:古元古代的褶皱“会聚”到伸展体制转换的“回返”,新元古代的拉张垮塌,中生代的多期次岩浆侵入和多来源、多阶段的结晶分异。The Dalongshan pluton is located in the northeastern margin of the Yangtze block,where a large number of Mesozoic intrusive magmatic rocks developed.The field geological survey shows that the Dalongshan pluton may be a complex pluton with multi-stage magmatism and there is a certain amount of diorite porphyrite near the syenite in its core.Dating of diorite porphyrites and syenites shows that their zircon ages are(137.7±1.9)Ma and(128.8±2.1)Ma,respectively.Among them,a certain amount of inherited zircons developed in the Dalongshan diorite porphyrite,and the U-Pb ages are respectively Paleoproterozoic(about 2.0 Ga)and Neoproterozoic(about 0.8 Ga),but no captured inherited zircons were found in syenites.Based on the obtained zircon ages and regional geological evolution material,it is concluded that the Dalongshan pluton has undergone a complex evolution process composed of the Paleoproterozoic fold convergence returning to the extensional system,the Neoproterozoic extensional collapse,and the Mesozoic multi-stage magmatic intrusion and multi-source and multi-stage crystal differentiation.

关 键 词：复式岩体 继承锆石 U-PB年龄 安徽大龙山 

分 类 号：P597.3[天文地球—地球化学]