与内蒙哈达特陶勒盖铅锌矿有关的花岗岩成因探讨

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-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Pb-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 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。

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

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 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 (δEu=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.