| Late Permian Emeishan basalt formation is one of the five biggest pre-Tertiary flood basalt formations. Accompanying the vast eruption of the basalts, there are a lot of mafic-ultramafic intrusions and dikes, in which magmatic V-Ti-Fe, PGE and Ni-Cu deposits have been detected. Aiming at the elucidation of the PGE enrichment mechanism in the Emeishan Traps (a general term for temporally, spatially and genetically associated Emeishan basalts, mafic-ultramafic intrusions and dikes) and based upon the fundamental phenomena that locally PGE enrichments in intrusions are connected with the depletion of PGE in the voluminous volcanics, we systematically studied ore-controlling structures in the Panxi rift, and the impact of the distribution and geochemistry of igneous rocks on the distribution of ore deposits with an emphases on the analysis of ore-forming processes of the Yangliuping magmatic Ni-Cu-PGE sulfide deposit.Studies of regional geophysical signatures reveal that near surface high-speed terrain in the Panxi area is related to the upwelling of deeplying matter. Highly distributed ferromagnetic geologic bodies under the rift hints the injection of many mantle-originated mafic-ultramafic intrusions, and the presence of these intrusive bodies under many basalts-distributed areas suggests the universalism of magma penetrating activity during the Emeishan flood volcanism.Interpretation of remote sensing information manifests that main ore-controlling factors in the Panxi area are fault belts and igneous bodies. The combination of multi-structures is the key to ore-forming processes, while voluminous magma provided metallogenetic elements necessary to the formation of deposits.Dashibao formation basalt outcropped in the Danba area is part of the EmeishanZr/TiCVNb/Y rock type discrimination diagram. Plots of Th/Ta-Th, Ti/Zr-SiOi and Gd/Yb-La/Sm demonstrate that sampled basalts are derivatives of magma experienced crystallization differentiation with little crustal contamination, if there is any. Scattergrams of Pd-Cu, Pt-Mg# and Ir-Mg# indicate that this section of basalts was formed from S-undersaturated magma, which had a great potential to form magmatic PGE sulfide deposit provided it reached S-oversaturation en route to the surface. Compared with basalts from Kolbeinsey ridge and other places, Emeishan basalts have high PGE concentrations and Pd/Ir values, and this indicates that they were mantle melts of high melting degree.Yangliuping ore-bearing mafic-ultramafic intrusions consist of multi-lithofacies intruded along strata in one period, and the intrusions had suffered a high degree of self-alteration, which reflected that post-magmatic fluids were mainly composed of SiC>2 and CO2- Intrusions and basalts have geochemical features of continental flood basalts with negative Nb, Ta and Hf anomalies. Consistencies of the trace elements and PGE parameters among basalts, intrusions and ore-bodies indicate a genetic link among them.Based on ore-forming processes, ore-bodies of Yangliuping magmatic Ni-Cu-PGE sulfide deposit can be divided into three subtypes: 1) ore-bodies formed through magma differentiation by liquation, which is the main ore type and their emplacement is strictly controlled by lithofacies, 2) ore-bodies formed by contact metasomatism between intrusions and their wall rocks, and 3) ore-bodies formed by hydrothermal fluids. The ratios of sulfides to intrusives indicate that magma had experienced sulfide pre-concentration process before its final emplacement, and Donggu-Yuhaizi fault could be the pathway of the magma. Sulfur isotope composition of the deposit also shows that ore-forming elements came from the mantle. Based on the S isotope composition and trace elements characteristics of the intrusion, magma crystallization fractionation or magma mixing is the main factor triggering the happening of S-oversaturation and unmixing of sulfide melts.Studies reveal that under mantle plume operation, magma originated from mantle with high PGE concentrations provided ore-forming elements for the d...
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