The Bangbule skarn lead‐zinc (Pb‐Zn) deposit (>1 Mt Zn + Pb) is located in the western Nyainqentanglha polymetallic metallogenetic belt, central Tibet. Lenticular orebodies are all hosted in skarn and developed in the contact zone between the quartz porphyry and carbonate strata of the mid Paleozoic Middle to Upper Chaguoluoma Formation as well as in carbonate and sandstone beds of the Upper Paleozoic Laga Formation. As a newly discovered skarn deposit, the geological background and metallogenesis of this deposit remain poorly understood. Detailed petrological, geochemical and geochronological data of the ore‐related quartz porphyry, helps constrain the mineralization age and contributes to discussion on the ore genesis of the Bangbule deposit. Both endoskarn and exoskarn are identified in the Bangbule deposit. From quartz porphyry to carbonate formation, the exoskarn is zoned from proximal garnet skarn to distal pyroxene skarn. Zircon U‐Pb dating results show that the quartz porphyry formed at 73.9 ± 0.8 Ma. Geochemical analysis results show that the quartz porphyry has high contents of SiO2 (71.40–74.94 wt%) and K2O + Na2O (3.76–8.46 wt%) with A/CNK values of 0.69 to 1.06. Besides, the quartz porphyry is enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and have low εNd(t) (from –8.25 to –8.19) and high initial (87Sr/86Sr)i values (0.713611–0.714478). Major, trace elements and whole‐rock F concentration analysis results from the endoskarn samples show higher TFe2O3, MgO, CaO, Pb + Zn, W, Sn, Mo and F etc., and lower alkalis (K2O, Na2O, Sr and Ba) than those of fresh quartz porphyry, indicating that the early ore‐forming fluids were an Ca‐Fe‐F‐enriched fluid. Massive ore in the proximal skarn might be related to the high F content in the magma, which lowered the solidus temperature of the quartz porphyry magma and caused a lower temperature of the ore‐forming fluids, as well as facilitating the precipitation of sphalerite and galena. Based on the geochemical characteristics presented in this study, we propose that the ore‐related quartz porphyry was formed by partial melting of crust materials with some juvenile crustal component input. The partial melting of the middle‐upper crust after the initial enrichment of lead and zinc elements are important for the formation of Pb‐Zn deposits. The case study of the Bangbule deposit has proven that there is still a crust‐derived magmatic source region in the western segment of the central Lhasa terrane. Therefore, there is still great potential for Pb‐Zn mineralization and Pb‐Zn exploration.

The Bayan Nuru ductile shear zone is located in the Yabulai–Bayan Nuru tectonic belt of the middle part of the southern Central Asian Orogenic Belt (CAOB) and east of the Langshan tectonic belt. This article is the first report on the Bayan Nuru ductile shear zone, and provides dynamic, kinematic, and geochronological data of the shear zone. Accurately determining the shear orientation and estimating the shearing age of the Bayan Nuruductile shear zone, has important reference value and significance for understanding the tectonic evolution in Alxa during “Yanshan movement” period. All shearing signatures, including asymmetrical folds, rotated porphyroclasts, “domino” structures, “mica fishes,” S–C fabrics, and asymmetric stress shadows, developed in the shear zone, indicate sinistral shear. The temperature environment at the time of formation of the shear zone was determined by the mineral deformation thermometer and EBSD quartz C‐axis fabric analysis. The temperature was 350–550°C. The differential stress (σ) was estimated to be 44.31–97.94 MPa and the strain rate(έ) to be 10−14 s−1(350°C) and 10−10s−1(550 °C). The average kinematic vorticity of the Bayan Nuru NNE‐trending ductile shear zone is 0.93, indicating that the shear zone was dominated by simple shear. The thickness of the ductile shear zone was reduced by 7%–22%. Combined with the age of granitic mylonite (289.53 ± 0.74 Ma) and the NNE‐trending spread feature, the Bayan Nuru ductile shear zone in the western part of the Langshan fault zone may have been formed in the context of continuous compressional intraplate deformation, caused by the subduction of the Paleo‐Pacific Plate at 170–150 Ma.

The Woka ductile shear zone is located at the southern margin of the middle section of the Gangdese magmatic belt and southeast of Lhasa. This article is a systematic study of the Woka ductile shear zone and provides kinematics, strain patterns, rheology, temperature environment, and geochronological data of the shear zone, which have great significance for understanding of the uplift and extension process of the southern section of the Gangdese. All shear indicators, such as asymmetrical folds, rotated porphyroclasts, and S-C fabrics, developed in the shear zone indicate the shear sense of top-to-the-northwest with the shear nature of detachment. Mineral deformation thermometer and EBSD quartz fabric analysis indicate that the shear zone has experienced early high-temperature (550-650 C) deformation and post-superimposed low temperature (380-420 C) deformation. The differential stress (σ) of the ductile shear zone was 28.08-46.73 MPa. Strain rates (έ) ranged from 10 −10 to 10 −14 s −1 under a hightemperature environment (600 C) and 10 −12 to 10 −16 s −1 under a low-temperature environment (420 C). Three-dimensional strain ellipsoid measurements of the Woka ductile shear zone indicate that all deformed samples appear as prolate ellipsoids (LStype tectonites), which represent an elongate strain. The average kinematic vorticity of the Woka ductile shear zone is 0.93, implying that the shear zone was dominated by simple shear. The thickness of the ductile shear zone was reduced by 12-28%. Combined with the U-Pb zircon age of the protolith of granitic protomylonite, the 40 Ar/ 39 Ar sericite age of granitic mylonite (22.38 ± 0.31 Ma) can represent the shear age. The Woka shear zone studied in this article may have been formed by the Great Counter Thrust (GCT) activity and uplift of the Gangdese batholith during the transforming period of the Lhasa Terrane from extrusion to a lateral extension.

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