泸定大河沟村辉长岩体岩石地球化学特征、锆石U-Pb定年及地质意义  

Petrogeochemical Characteristics and Zircon U-Pb Dating of the Gabbro Intrusive in Dahegou Village,Luding and Their Geological Significances

作　　者：刘祥 赵德军[2] 骆志红[1] 贾志泉[1] LIU Xiang;ZHAO De-jun;LUO Zhi-hong;JIA Zhi-quan(The 108th Geological Team,BGEEMRSP,Chengdu 611230;Chengdu University of Technology,Chengdu 610059)

机构地区：[1]四川省地质矿产勘查开发局一0八地质队,崇州611230 [2]成都理工大学,成都610059

出　　处：《四川地质学报》2021年第2期203-208,共6页Acta Geologica Sichuan

摘　　要：大河沟村辉长岩体位于康定杂岩带泸定县大河沟村一带,岩性为辉长岩。LA-ICP-MS锆石U-Pb法测得辉长岩体的结晶年龄为782±6Ma,表明该辉长岩体形成时代为下南华世早期。岩石主量元素FeOT/MgO比值为1.03~2.35且富集轻稀土(LaN/YbN=4.19~6.07)和无明显Eu异常(δEu=0.93~0.97)等地球化学特征表明大河沟村辉长岩的源岩是受板片流体交代的地幔楔橄榄岩。在岩浆演化过程中经历了镁铁质矿物(橄榄石、辉石)的分离结晶和微不足道的地壳混染作用。按照地球化学判别标准,大河沟村辉长岩具有岛弧玄武岩和洋中脊玄武岩的双重地球化学特征,具有初始弧后盆地玄武岩的印记。The Gabbro intrusive in Dahegou Village occurs in the Kangding Complex belt.The gabbro yields a zircon U-Pb age of 782±6 Ma which indicates that it was emplaced in the Early Nanhua Epoch.The gabbro is characterized by FeO/MgO rations of 1.03~2.35 and La/Yb ratios of 4.19~6.07 withδEu values of 0.93~0.97 which indicate that its protolith was mantle wedge peridotite replaced by plate-sheet fluid,undergone mafic mineral crystallization differentiation and minor crustal contamination.Geochemically,the gabbro is characteristic of both island-arc basalt and mid-ocean ridge basalt.

关 键 词：大河沟村辉长岩 康定杂岩带 锆石U-Pb年龄 地球化学 

分 类 号：P581[天文地球—岩石学]