Temporal-spatial distribution, tectonic evolution and metallogenic response of the magmatic rocks in the Boluokenu metallogenic belt, west Tianshan, Xinjiang

The Boluokenu metallogenic belt, suited in the north margin of the West Tianshan in Xingjiang, is highlighted by the well prospecting results in recent years. In this paper, based on a comprehensive collection of former research results in petrology, the temporal-spatial distribution pattern of the magmatic rocks in this belt was studied preliminary, particularly on the characteristic of the Late Paleozoic magmatism which has a close association with mineralization. The geological history of the Boluokenu belt is closely related to the evolution of the North Tianshan Ocean. In the Pre-Cambrian, a unified basement was formed and the North Tianshan Ocean was opening. A passive continental margin was evolved in Cambrian, while the spreading of the North Tianshan Ocean is still underway. The subduction of the North Tianshan Ocean to the Yili Block results a continental-arc environment developed in Ordovician. The subduction peaked at Devonian to the early stage of Late Carboniferous and caused a series of calc-alkali magmatism. The Boluokenu belt enters into a terrestrial environment in the Early Permian, however, the subduction of residual ocean basin of the North Tianshan Ocean ceased not until to the Middle Permian. An entirely intra-continental setting was developed in the Later Permian and the regional tectonic stress changed from compression to extension accordingly. During the tectonic evolution, two large ore concenreation area, namely Lailisigao'er and Axi, were developed, and two metallogenic systems were formed respectively, the skarn-porphry-vein Fe, Cu, Mo, Au, Sb, Pb, and Zn metallogenic system which was related to the magmatic intrusive activity, and the epithermal-porphyry Au, Pb, Zn, and Cu metallogenic system that was associated with the subvolcanic hydrothermal activity.