Spatial–temporal Frame, Evolution and Mineralization of the Northern Qilian Metallogenic Province

Four metallogenic epochs occurred in different tectonic environments during the evolution of the Northern Qilian metallogenic province through the geological time. The Middle Proterozoic metallogenic epoch witnessed the tectonic environment of crustal breakup caused by mantle diapirism, in which ultramafic–mafic rocks were intruded along deep fault belts and the superlarge Jinchuan magmatic Cu–Ni sulphide deposit was formed. In the Middle–Late Proterozoic metallogenic epoch the crust was further broken to form an intracontinental rift, in which the Chenjiamiao style massive Cu–Fe sulphide deposits hosted by basic volcanic tuff were formed in the lower volcano–sedimentary sequence, while the large sedex type Jingtieshan style Fe–Cu deposits were formed within the upper abyssal carbon–rich argillaceous sedimentary sequence. The Early Palaeozoic saw the aulacogen environment, within which the Baiyinchang style superlarge massive base and precious metal sulphide deposits hosted by quartz keratophyric tuff were formed in the Middle–Late Cambrian rifted island arc and the massive Cu–Zn sulphide deposits and magmatic chromite deposits associated with the ophiolite suite were formed in the Early–Middle Ordovician, and the Honggou style massive Cu–Fe sulphide deposits hosted by spilite were formed in the Late Ordovician back–arc basin environment. In the Late Palaeozoic–Meso–Cenozoic, the metallogenic province went into an intracontinental orogenic stage characterized by compressive tectonic environment, in which there occurred carbonate–quartz vein type and tectono–alteration gold deposits associated with ductile–shear structures.