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• The host volcanic rocks of the Sinongduo Ag–Pb–Zn deposit erupted at approximately 61.9 Ma. • The sphalerite rich in Ag, In and Cd is a kind of Fe-poor sphalerite that is commonly found in IS epithermal deposits. • The Sinongduo Ag–Pb–Zn deposit is an IS epithermal deposit rather than a LS epithermal deposit. The Sinongduo Ag–Pb–Zn deposit was first defined as a typical low sulfidation (LS) epithermal deposit in the widespread Linzizong volcanic succession (LVS), Gangdese belt, Tibet. This paper we describe the lithology, mineralization, and hydrothermal alteration based on current advances in exploration, and use multiple chemical and geochronology methods, including whole-rock geochemistry (major and trace elements) of ores and the lithocap, the mineral chemistry of sphalerite, and the LA–MC–ICP-MS zircon U–Pb dating of host volcanic rocks to better constrain the genesis of the Sinongduo deposit and give some exploration advice. In the Sinongduo deposit, the host crystal tuff yields a zircon U–Pb age of 61.9 ± 0.4 Ma, indicating nearly simultaneous diagenesis and mineralization. The metallic minerals are mainly FeS-poor sphalerite, galena, pyrite, and minor chalcopyrite, along with silver and silver-based precious minerals. These minerals, particularly FeS–poor sphalerite, pyrite, and chalcopyrite, represent IS states. Mineral chemistry shows that the content of FeS in sphalerite is lower than 4.94 mol% and the Ag concentration is quite high, ranging from 16 to 1798 ppm with a mean concentration of 245 ppm. Low Ga/in ratios (<1) and enrichment of In and Sn in sphalerite imply that the ore-forming fluid is dominated by magmatic water with intermediate temperature. Gangue minerals include the silicic group (quartz and chalcedony), carbonates group (calcite, siderite, ankerite, etc.), and hematite. Alterations, including illite, montmorillonite, and sericite, are widely distributed. The results suggest that the Sinongduo deposit is not a LS epithermal deposit but a typical IS epithermal deposit and we believe that there is potential for Au and Ag exploration. [ABSTRACT FROM AUTHOR]

The geodynamic mechanism of the Early Cretaceous magmatic rocks in the southern Lhasa Terrane remains controversial. To constrain the Early Cretaceous petrogenesis and tectonic evolution of the Neo‐Tethyan oceanic slab, we have undertaken zircon U–Pb dating, whole‐rock major and trace element analyses, and Sr–Nd–Pb–Hf isotopic studies of the Cuocun gabbro from the southern Lhasa Terrane. The zircon U–Pb dating yielded an Early Cretaceous crystallization age of 146.9 ± 0.6 Ma (MSWD = 0.77, 2σ). The Cuocun gabbro is enriched in large‐ion lithophile elements (e.g., Rb, Sr, and Ba) and depleted in high‐field‐strength elements (e.g., Nb, Ta, and Ti). The initial 87Sr/86Sr value are low (0.70361–0.70460), εNd(t) and εHf(t) values are high and positive (from +5.1 to +6.6 and from +11.0 to 17.0, respectively), and Pb isotope specific value are homogeneous (initial 206Pb/204Pb = 18.163–18.457, 207Pb/204Pb = 15.541–15.632, and 208Pb/204Pb = 38.262–38.673). The gabbro originated from the partial melting of a depleted mantle wedge that had reacted with slab‐derived fluids, and the ascending magmas underwent fractional crystallization without significant crustal contamination. Combining our data with those from previous studies of Early Cretaceous magmatism in the southern Lhasa Terrane, we suggest that the Early Cretaceous magmatic rocks (147–130 Ma) in the southern Lhasa Terrane were generated within a continental marginal arc setting related to the rollback of the northwards subducting Neo‐Tethyan oceanic slab. [ABSTRACT FROM AUTHOR]

The article reports on the discovery of 341 Ma gabbro, that is located inXiongcun copper-gold district at southern margin of Lhasa terrane, Tibet. The methods employed and photographs of Xiongcun gabbro, marble and migmatization gneissare are presented. Zircon U-Pb ages of the gabbro in west of Xiongcun district are 341.55±0.89 Ma