Molybdenite Re-Os and U-Pb zircon dating and genesis of the Dayana W-Mo deposit in eastern Ujumchin, Inner Mongolia

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• 作者：Anping Xiang^a ; ^b ; ; Yuchuan Chen^a ; Leon Bagas^a ; ^c ; Hongquan She^a ; Yongjian Kang^a ; Wensheng Yang^a ; Changjian Li^a
• 关键词：East Ujumchin ; Inner Mongolia ; Wolframite ; Molybdenite ; Geochronology ; Quartz vein ; Biotite monzogranite ; LA-ICP-MS ; Re&ndash ; Os
• 刊名：Ore Geology Reviews
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：78
• 期：Complete
• 页码：268-280
• 全文大小：2946 K

文摘

The Dayana W-Mo deposit in eastern Ujumchin of Inner Mongolia is a quartz-vein type deposit in the mid-western part of the Central Asian Orogenic Belt (CAOB). Biotite monzogranite, quartz porphyry and hornfels host W-Mo in quartz veins. Based on spatial relationships, molybdenite was deposited first followed by wolframite. This contribution presents precise laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) U–Pb zircon dating and geochemical analysis of the biotite monzogranite. The U–Pb dating shows that the monzogranite is 134 ± 1 Ma. Major and trace element geochemistry shows that the monzogranite is characterized by high SiO₂ and K₂O contents, a “Right-inclined” shape of the chondrite normalized REE patterns, enrichment of large ion lithophile elements (LILEs), and depletion of high field strength elements (HFSEs) such as Nb, P, Ba. The monzogranite is high-K calc-alkaline, has a strong negative Eu anomaly (Eu/Eu* = 0.04–0.45), low P₂O₅ content, high A/CNK of > 1.2, enriched in large-ion lithophile elements (LILEs; such as Rb, Th, U, Nd, and Hf), and notably depleted in Ba, Sr, P, Ti, and Nb. These characteristics define the Dayana monzogranite as a highly fractionated peraluminous granite. Re–Os isotopic analysis of seven molybdenite samples from the deposit yield an isochron age of 133 ± 3 Ma (MSWD = 2.2), which indicates that the monzogranite and ore have the same age within error, are probably genetically related, and related to a major Early Cretaceous mineralizing event in China known as the Yanshanian.