TEMPORAL-SPATIAL DISTRIBUTION AND GEODYMANIC SETTINGS OF MAGMATIC Ni-Cu-(PGE) SULFIDE DEPOSITS IN CHINA

Abstract

Magmatic Ni-Cu-(PGE) sulfide deposits in China mainly outcrop over vast areas in Central Asian orogenic belt (Tianshan-Altay region in northern Xinjiang), on the northern margin of the North China craton (Jilin-Liaoning-Beijing-Hebei-Inner Mongolia) and its southwestern margin (Gansu) and on the western and northern margins of the Yangtze craton (Shaanxi-Sichuan-Yunnan). They are controlled by mafic-ultramafic intrusions and occur in groups and zones. According to their rock types and geological characteristics, these deposits may be divided into three types: basal Ni-Cu-(PGE) sulfide deposits in mafic-ultramafic intrusions, Ni-Cu-(PGE) sulfide deposits in intrusions related to flood basalts and Ni-Cu-(PGE) sulfide deposits in komatiite. The metallogenic epochs of these deposits are mainly early Neoproterozoic (1000 - 800 Ma) and late Paleozoic (295 - 250 Ma), and their corresponding geodynamic settings are assembly and breakup of the supercontinent Rodinia, post-collision of active orogenic belts and substantial eruption of Permian blood basalt, which are all associated with activities of mantle superplumes. According to the tectonic settings, these deposits may be divided into four types, i. e.: paleocontinental-margin rift type, mantle plume type, back-arc extensional type and orogenic postcollisional type. According to the tectonic settings, rock- and ore-forming epochs and geological characteristics, they are divided into four metallogenic provinces (belts), i. e.: early Neoproterozoic Ni-Cu-(PGE) deposits associated with convergence and divergence of the supercontinent Rodinia, Ni-Cu-(PGE) deposits on the northern margin of the North China craton, Ni-Cu-(PGE) deposits associated with postcollision of the Central Asian orogenic belt and Ni-Cu-(PGE) deposits in the Emeishan mantle plume region.