Types, typical deposits, tempo spatial distribution and tectonic settings of the copper deposits in Mongolia

Copper is one of the most important industrial mineral resources, and it had been the most important income of Mongolia till 2010 when it was replaced by coal. Generally, the levels of both research and exploitation for the mineral deposits in Mongolia are still low. The copper deposits in Mongolia can be divided into six types, including porphyry, volcanogenic massive sulfide ( VMS), granitoid-related, skarn, basalt and sandstone types, of which the most economically significant type is the porphyry type, as well as the VMS ones. The copper deposits in Mongolia were mainly formed during four periods, namely, the Latest Neoproterozoic ( Ediacaran), the Late Devonian, the Late Carboniferous and the Triassic -Early Jurassic. Spatially, the Mongolian copper deposits are generally distributed in two metallogenic belts, a southern one and a northern one, which were related to the evolution of the Paleo Asian Ocean and the Mongol -Okhotsk Ocean, respectively. The southern Cu belt are subdivided into three sub -belts, i. e., from north to south, the Devonian VMS -type Cu-Zn ( -polymetal) sub -belt, the Late Carboniferous porphyry Cu -Au sub -belt and the Late Devonian porphyry Cu-Au-Mo sub -belt; while the northern Cu belt can be subdivided into a northern sub -belt and a southern sub -belt, within which the Cu deposits show a general trend of eastward younger. The porphyry -type Cu deposits in Mongolia were all generated in subduction settings of oceanic plates, meaning that they belong to the "subduction type", in which the Paleo-Asian ocean -related southern Cu belt was formed in intra-ocean arc and back -arc settings above supra-subduction zones, whereas the northern Cu belt, which is related to the Mongol -Okhotsk Ocean, was formed in a continental margin arc environment. Due to effects of the Mongol Okhotsk orocline, the northern Cu belt is spatially confined within Mongolia in the west, but it stretches eastward out of Mongolia, with the northern and the southern sub -belts extending into the Transbaikal area of Russia and the northern Great Xing'an Range of China, respectively. For the southern Cu belt, except for the facticity that the northern sub -belt ( the Devonian VMS -type one) extends west northwestward into southern Chinese Altai, the eastern and western extensions of the other two sub -belts, as well as the eastern extension of the northern sub -belt itself, are all unclear yet. As a result, to make clarity regarding the reginal extension of these Cu sub -belts, especially the one containing the world -class superlarge Oyu Tolgoi Cu-Au-Mo deposit, prehensive comparison studies of regional structure-strata-magmatism-mineral deposit are required. Other types of Cu deposits, such as the skarn, granitoid-related, basalt and sandstone types, as well as the layered mafic complex type, are economically much less significance, with only small-scale deposits, occurrences, or prospects delineated, and their metallogenic and prospecting potentials need further work to uncover them.