与内蒙哈达特陶勒盖铅锌矿有关的花岗岩成因探讨  

Investigation of the Genesis of Granite in the Hardat Tolgoi Pb-Zn Ore Deposit,Inner Mongolia

作　　者：陈进全[1,2] 徐兆文[1] 雷菲 陈伟[1] 王浩[1] 王少华[1] 

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室(南京大学),南京大学地球科学与工程学院,南京210093 [2]福建地质调查研究院,福州350011

出　　处：《高校地质学报》2013年第3期415-424,共10页Geological Journal of China Universities

基　　金：国家自然科学基金(40973030)资助

摘　　要：哈达特陶勒盖铅锌矿床处于华北板块与西伯利亚板块交汇部位，是二连浩特一东乌珠穆沁旗多金属成矿带中新发现的一个中型铅锌矿床。矿区内与Ph—zn矿化有关的花岗岩为隐伏岩体，LA-ICP-MS锆石U—Pb定年显示，花岗岩侵入时间为（125±4,3）Ma，属于燕山期岩浆活动产物。岩石地球化学分析表明，花岗岩具有高硅、高碱（大部分Na〈K）、贫铁、弱过铝质的特征（A／CNK=0．99，1．08）；稀土配分模式图具有“M”型四分组效应，轻重稀土分馏不明显，Eu强烈亏损；大离子亲石元素（Rb，K）和Nd，Ta等元素富集，高场强元素（Nb，Ti）和Ba，Sr等元素亏损。研究结果揭示该花岗岩应属于碱性A型花岗岩。Nd—Pb同位素显示该碱性花岗岩主要来源于中元古代上地壳的部分熔融。构造环境判别图解则指示该碱性花岗岩形成于造山后的拉张构造环境。The Hardat Tolgoi Pb-Zn deposit is a medium-sized Pb-Zn deposit recently found in Erenhot-Dongwuqi polymetallic ore belt along the suture zone between the North China plate and the Siberia plate. The granite relevant to the Pb-Zn mineralization in the orefield is a concealed pluton. The LA-ICP-MS zircon U-Pb dating indicates that the granite was emplaced at 125 ± 4.3 Ma and thus was the products of ＂Yanshanian＂ magmatism. Detailed geochemical data show that the granite is composed of weakly peraluminous （A/CNK= 0.99-1.08） rocks with low iron, high silicon, and high alkali contents （mostly Na〈K）. The granite is enriched in large-ion lithophile elements （LILEs, such as Rb and K）, Nd and Ta, but is depleted in high-field strength elements （HFSEs, such as Nb and Ti）, Ba and Sr. The chondrite-normalized REE pattern shows M type with tetrad effect and strong Eu depletion （8Eu=0.003-0.013）. These results suggest that the alkaline feldspar granite belongs to alkalinity A type granite and was formed in a post-orogenic tectonic environment. Nd-Pb isotopic compositions show that the alkaline feldspar granite was derived from partial melting of the Mesoproterozoic upper crust.

关 键 词：碱性长石花岗岩 岩石化学 Nd—Pb同位素 哈达特陶勒盖铅锌矿床 内蒙阿巴嘎旗 

分 类 号：P588.121[天文地球—岩石学]