Indo-Chinese magmatic activity in the Badaguan ore district of Inner Mongolia and its metallogenic implications

Abstract: Systematical sampling of major granite rocks in the Badaguan ore district was conducted in this paper. Microscopic identification results reveal that the primary rocks include granite, biotite granite, granitic porphyry, moyite, and granodiorite porphyry, whereas LA-MC-ICP-MS zircon U-Pb ages of the six samples vary in the range of 243.87-231.63 Ma. Combined with emplacement ages of the metallogenic porphyry, it is inferred that all intrusive rocks were developed in the Indo-Chinese period, without existence of Hercynian or Yanshanian intrusions. According to the distribution of the ages, Indosinian magmatic activities were mainly concentrated in 243.87-237.11 Ma and 231.63-229.00 Ma, and surrounding rocks formed at the early stage of magmatic activity. Copper and molybdenum mineralization principally occurred at the late stage of magmatic activity. In addition, Indo-Chinese magmation on both sides of Okhotsk orogenic belt also have the similar two-stage characteristics, which was closely related to subduction of the Okhotsk Ocean. Based on summarizing the situation on both sides of the identified porphyry deposit, the authors consider that there exists possibility in the search for porphyry deposits of the early Indosinian period in the periphery of the Badaguan ore district or/and Ergun area.