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The Hongge layered intrusion (259.3 ± 1.3 Ma) is one of several mafic–ultramafic intrusions that host giant Fe–Ti–V oxide ore deposits in the ~ 260 Ma Emeishan Large Igneous Province (ELIP), SW China. The Hongge intrusion consists of a lower olivine clinopyroxenite zone (LOZ), a middle clinopyroxenite zone (MCZ) and an upper gabbro zone (UGZ). Most of the 14 to 84 m-thick and 300 to 1700 m-long economic Fe–Ti–V oxide ore layers occur within the MCZ. This paper reports the concentrations of PGE in the oxide layers of the Hongge intrusion. Unlike in the economic PGE (platinum-group elements) mineralized (up to 1.2 ppm Pt and 1.8 ppm Pd) coeval Xinjie intrusion (259 ± 3 Ma), the oxide layers in the Hongge intrusion contain very low PGE (total PGE: 0.09–63.5 ppb). Chromite-bearing horizons in the Hongge intrusion are enriched in IPGE (Ir: 0.46–0.65 ppb; Ru: 2.25–3.29 ppb) relative to PPGE (Pt: 0.54–1.28 ppb; Pd: 0.30–0.90 ppb). In contrast, the massive magnetite layers in the Hongge intrusion show no IPGE enrichments relative to PPGE. All our samples from the Hongge intrusion collectively show no correlation between PGE and S contents, and weak positive correlations between IPGE and Cr contents, indicating removal of Ir, Ru from magma with crystallization of chromite. Positive correlations exist between IPGE and PPGE in the samples, indicating that all of the PGE was controlled by sulfide liquid. Most of the samples have mantle-normalized PGE patterns with a slope similar to that of the Emeishan picritic basalts, which are less fractionated than the coeval high-Ti basalts derived from the same Fe-, Ti-, V-rich magma series. The Hongge oxide-rich samples are characterized by Cu/Pd ratios (1.47–202 × 10 4 ) significantly higher than those for primitive mantle and the coeval picrites (0.99 × 10 4 ). The PGE tenors in bulk sulfides (i.e., in recalculated 100% sulfides) in the sulfide-bearing oxide ores of the Hongge intrusion (

The Hongge giant Fe-Ti-V oxide ore deposit is hosted by a layered intrusion located in the central part of the Emeishan large igneous province, SW China. The intrusion is relatively small in comparison with other typical oxide-bearing intrusions worldwide; it consists of a lower olivine clinopyroxenite zone, a middle clinopyroxenite zone, and an upper gabbro zone (herein referred to as the lower, middle, and upper zones). Most of the economic Fe-Ti-V oxide ore layers occur within the middle zone. The Hongge oxide ores are depleted in REE and enriched in Zr, Hf, Nb, and Ta as compared to the associated clinopyroxenites. This enrichment of elements that are compatible in titanomagnetite is consistent with the interpretation that the ores formed by accumulation of magnetite and ilmenite. As in the nearby coeval Panzhihua Fe-Ti-V oxide deposit described previously by others, mafic silicates in the Hongge deposit have much higher MgO contents than those in other oxide deposits associated with large layered intrusions in the world. This highlights the importance of relatively primitive parental magma becoming saturated in titanomagnetite at an early stage in the genesis of the giant Fe-Ti-V oxide deposits in the Emeishan large igneous province. Phase equilibrium constraints suggest that the parental magma of the Hongge deposit is similar to that of some of the most primitive high Ti basalts in the Emeishan large igneous province. The ferrobasaltic parental magma and the ferropicritic primary magma of the Hongge intrusion are similar in major and trace element composition to the ferropicritic-ferrobasaltic magma in the Pechenga belt, Kola peninsula, Russia. Depletion of incompatible trace elements in the oxide ores and associated rocks in the Hongge intrusion as compared to the coeval high-Ti basalts suggest that not all the magma involved in the development of the Hongge intrusion has been retained in the intrusion. The occurrence of multiple Fe-Ti oxide layers alternating with Fe-Ti oxide-bearing silicate layers within a single zone and the repetitive appearance of sulfides, olivine, and Cr-rich layers suggest that multiple pulses of magma were involved in the formation of the Hongge intrusion and related Fe-Ti-V oxide deposit. We propose that the middle zone of the Hongge intrusion was a magma stepwise flow-through system and that some of the liquid was lost to the peripheral lavas to form the basalt.

This paper presented the Pb-Zn deposits characteristics in southeast Chongqing. The Pb-Zn deposits occurred in Lower-Middle strata with develop the dolomites, limestones as ore-bearing host-rocks. They are veined, stratifed, stratoid, and lenticular in shape and locally pinch and swell with dominant ore minerals of sphalerite, galena, and pyrite . the Pb-Zn ore deposits grade changed from 0.32% to 7.06% for Pb and 4.21% to 14.29% for Zn. The Gaodongzi orebody has highest concentrations of Pb with 7.06% record and Zn with 14.29% record. The tectonic setting, ore-host rocks, wall-rock alternation, and mineral composition will control the Pb-Zn deposits distribution in Chongqing area.