Characteristics and metallogenic regularities of ore deposits on the western slope of the southern section of the Da Hinggan Mountains metallogenic belt

Abstract：Located in Chagan Obo－Aououte－Chaobuleng area along the southern edge of the Siberian plate, the study area on the western slope of the southern section of the Da Hinggan Mountains metallogenic belt (northern Dong Ujimqin Banner of Inner Mongolia ) is controlled by multiple subduction, collision and connection of North China platform, and characterized by widely exposed Paleozoic volcanic-sedimentary rocks, complex structures, all kinds of intense magmatic activities, and widespread ore deposits and ore spots. The study area has special favorable geological structure and setting for mineralization. On the basis of geological survey, the authors studied geological features of ore deposits and genesis of typical deposits, and summarized metallogenic regularities of this area. The results show that there are many kinds of ore deposits such as iron, silver, copper, lead, zinc, gold, and molybdenum. The δ34S values of typical deposits vary from +1‰ to +8.6‰. The sulfur isotope compositions show different sources. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of different samples vary in ranges of 17.949～18.529, 15.370～15.691 and 37.653～38.460, respectively. The lead isotope compositions indicate that the sources of lead were wall rocks and granites. The main types of ore deposits were skarn deposits and medium-low temperature hydrothermal deposits, which were significantly affected by formation, structure and magma. In general, the wall rocks of metal deposits were Ordovician, Devonian and Carboniferous volcanic- sedimentary rocks. Skarn deposits were formed near the contact zone between the carbonate and granite, while medium-low temperature hydrothermal deposits were formed in argillite and sandstone without carbonate. NE- and NW-trending faults were important ore channels or places for ore storage. The regional ore deposits in the study area were formed in three periods, i.e. Hercynian, Indosinian and Yanshanian. They were closely related to granite intrusions in temporal and spatial distribution.