北淮阳东段九王寨岩体地球化学特征、锆石U-Pb定年及地质意义  

Geochemical characteristics and zircon U-Pb dating of Jiuwangzhai intrusion in east part of North Huaiyang and their geological significance

作　　者：邱军强[1,2] 彭智[1] 陈芳[1,2] 董婷婷[1,2] 柳丙全[1] 

机构地区：[1]安徽省地质调查院,安徽合肥230001 [2]安徽省大陆成矿研究中心,安徽合肥230001

出　　处：《合肥工业大学学报（自然科学版）》2015年第11期1536-1546,共11页Journal of Hefei University of Technology：Natural Science

基　　金：中国地质调查局资助项目(1212011220547)

摘　　要：九王寨岩体位于北淮阳东段西部、金寨县南部,为过铝质高钾钙碱性系列岩石,岩性为石英闪长岩,具有较高的SiO2和Al2O3含量,富碱质、低钛等。稀土元素配分曲线右倾,Eu谷不明显,轻稀土分馏较明显,重稀土较平坦(分馏不明显),属轻稀土富集型。微量元素原始地幔蛛网图显示,大离子亲石元素Rb、Ba、Sr富集,而K亏损,高场强元素Y、Th、U、Zr、Hf富集,而Nb、Ta、P、Ti呈现低谷负异常,明显亏损。通过LA-ICPMS锆石U-Pb定年,获得九王寨岩体206Pb/238 U年龄为(151.7±1.8)^(135.3±1.4)Ma,相当于燕山中期,是中侏罗世末期—晚侏罗世末期岩浆活动的产物,代表九王寨岩体的成岩年龄,也说明九王寨岩体至少有2次岩浆侵位。岩浆来源于地壳,受到地幔物质的混染;九王寨岩体形成于燕山中期造山挤压的构造环境。Jiuwangzhai intrusion locates in the west of the east part of North Huaiyang and in the south of Jinzhai County. It belongs to peraluminous, high-K and calc-alkaline series rocks, with features of high contents of SiO2, Al2O3 and alkali and low content of Ti. The rare earth element（REE） distribution curves are characterized by right-dipping and no obvious Eu valley, and belong to light rare earth element（LREE） rich type for its REE distribution patterns indicate that the LREE is steep while the heavy rare earth element（HREE） is relatively flat. The primitive mantle-normalized patterns indicate that the intrusion enriches large ion lithophile elements such as Rb, Ba, Sr, but depletes K, and it enriches high field strength elements such as Y, Th, U, Zr, Hf, but obviously depletes Nb, Ta, P and Ti. Jiuwangzhai intrusion was dated to be from （151.7±1.8）Ma to （135.3±1.4）Ma by LA-ICP-MS zircon U-Pb method, which is equivalent to middle stage of Yanshanian and can represent the rock-forming age of Jiuwangzhai intrusion. It belongs to the magma activity products of middle to late Jurassic. It also shows that there are at least two emplacement of the magma. The magma came from continent crust and was contaminated by the mantle material. The research considers that Jiuwangzhai intrusion formed in the tectonic environment of middle Yanshan orogenic extrusion.

关 键 词：北淮阳地区 九王寨岩体 岩石地球化学 锆石U-PB定年 

分 类 号：P597.3[天文地球—地球化学] P588.122[天文地球—地质学]