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[Display omitted] • To computationally simulate the ore-forming process in the Luziyuan deposit. • To determine the boundary conditions of the deposit model in a scientific way. • To identify the controlling ore-forming mechanism in the Luziyuan deposit. • To use computational simulations for identifying the location of an ore deposit. The giant Luziyuan Pb-Zn deposit is a typical hydrothermal ore-forming deposit in the southern Baoshan block of SE Tibet. Although extensive studies were conducted to understand the ore-forming system associated with the Luziyuan Pb-Zn deposit through using the traditional geoscience methods, the ore-forming process involved in this deposit has not been justified in a strictly scientific manner to date. In this paper, the hydrothermal ore-forming process of the Luziyuan Pb-Zn deposit is computationally simulated through using the dual length-scale approach associated with the finite element method (FEM). In the dual length-scale approach, the FEM is first used to simulate the regional model of a large length-scale in the geological region where the Luziyuan Pb-Zn deposit is located. Afterward, the FEM is then used to simulate the deposit model of the Luziyuan Pb-Zn deposit. Particularly, the boundary conditions of the deposit model are consistently determined from using the computational simulation results of the regional model. The related numerical results demonstrated that: (1) the pore-fluid convection provides a continuous source of ore-forming fluid and ore-forming material for the Luziyuan Pb-Zn deposit; (2) the convective pore-fluid flow is the main dynamic mechanism, which controls the temperature, pore-fluid velocity and chemical species distribution in the Luziyuan Pb-Zn deposit; (3) the localized structure is the main controlling factor for the localized pore-fluid flow pattern, which further controls the formation and location of the orebody in the Luziyuan Pb-Zn deposit; (4) the dual length-scale approach associated with the FEM is very useful for simulating the hydrothermal ore-forming process of the Luziyuan Pb-Zn deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lilong ultramafic igneous rocks are Late Cretaceous sulfide-bearing cumulates. • Mantle sources of Lilong ultramafic igneous rocks had been metasomatized by terrigenous sediment- and altered oceanic crust-derived fluids. • Deeply subducted oceanic crust plays an important role in the formation of sulfide-bearing juvenile mafic lower crust of magmatic arc. Post-collisional porphyry copper deposit (PCD) is a new genetic type of PCDs discovered in the Himalayan–Tibetan orogenic belt. It is believed that the formation of ore-forming magmas results from the re-melting of a sulfide-bearing, thickened, juvenile mafic lower crust in a magmatic arc associated with the oceanic plate subduction. However, the material contribution of subduction processes to the formation of this particular arc magma remains unclear. In this paper, we attempted to present a study that includes petrology, mineral geochemistry, whole rock Sr–Nd–Li isotopes, of Late Cretaceous Lilong ultramafic igneous rocks, south Lhasa sub-terrane, Tibet. The target ultramafic igneous rocks are sulfide-bearing cumulates. They show relative depletion in whole rock Nd isotopic compositions, slightly elevated (87Sr/86Sr) i ratios (0.7043–0.7059), and variable δ7Li values (2.8–9.0‰). Simulation results showed that trace element of melts in equilibrium with cumulus hornblende grains exhibit typical arc-like trace element distribution patterns, indicating that these ultramafic igneous rocks crystallized from arc magma. Additionally, the modeled melts showed enrichment in melt-mobile elements such as Ba, Pb, Sr, Th, and light rare earth elements (LREE), and higher Th/Yb ratios, as compared with normal mid-ocean ridge basalt (MORB). These geochemical properties can be explained by the metasomatism of depleted MORB mantle peridotites by hydrous melts derived from subducted seafloor sediments. Whole rock Sr isotopes show correlations with Ba/Nb and Th/La ratios for the modeled melts, showing that fluids from the basaltic igneous crust, in addition to hydrous melts from the seafloor sediments, contribute to their mantle source. In addition, the heterogeneity of whole rock δ7Li values for ultramafic igneous rocks also indicates that their mantle sources have been metasomatized by terrigenous sediment- and altered oceanic crust-derived fluids. Depleted MORB mantle peridotites react with the mixed fluids at sub-arc depths to produce ultramafic metasomatites, and model calculations for trace element contents and Sr–Nd–Li isotopic compositions further validate that the geochemical compositions of the Lilong ultramafic rocks can be clarified by this process. The results show that the deeply subducted oceanic crust may have played an important role in the formation of sulfide-bearing juvenile mafic lower crust of this magmatic arc. [ABSTRACT FROM AUTHOR]

[Display omitted] • Constructed a geochemical big data platform on the Tibetan Plateau. • Using GIS analysis, a filling map of geochemical elements was carried out. • The HF and Nd isotopic packing characteristics were explored. • Multivariate statistics were applied to explore mineralization characteristics. Tibet has received much attention as a pivotal area to explore the genesis of ore deposits. So far, a large number of researchers have conducted a lot of discussions on the geological conditions, genesis, distribution and scale of ore deposits in Tibet, and accumulated a plenty of isotopic test data. Isotopic data can reveal the geological changes of an area and analyze the metallogenic regularity. In this paper, combined with GIS (Geographic Information System) spatiotemporal analysis technology, Hf and Nd isotopic data mapping analysis has been carried out in Tibet. The mapping shows high zircons ε Hf (t) value and high whole rock ε Nd (t) value and low T DM c value on both sides of the Eastern Yarlung Zangbo Suture Zone and the Western Bangong-Nujiang Suture Zone. It indicates that the terranes in these two areas are relatively young and have typical characteristics of Cu and Au mineralization, which are favorable areas for the prospecting of Cu and Au. Combined with the geological fault characteristics of Tibet Plateau, the influence of terrane boundary on the deposit and the relevant characteristics of geochemical elements, three favorable targets for Cu and Au prospecting in Tibet Plateau are delineated by GIS analysis. The results show that the characteristics of isotopic data in Tibet Plateau are quite different in disparate terranes, and the isotopic analysis can quickly delineate the strategic prospecting targets. Therefore, using GIS technology for isotope analysis and metallogenic prediction provides important guiding significance for scientific prospecting. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-temperature springs in the Yadong-Gulu rift are related to the deep circulation of groundwater. • Infiltrating water could reach the middle crust in the case of deep fault activity with high permeability. • Rare-alkali metals contributed from deep magma are enriched along upward pathways of hydrothermal circulation, providing new insight for future exploration. Geothermal water from the hot springs in the Yadong-Gulu rift (YGR) of southern Tibet is extremely enriched in rare-alkali metal (RAM) elements; however, the mechanism of enrichment has long been debated. Much attention has been given to the deep melting magma of the YGR, but no direct evidence indicates whether and how it is connected to the RAM anomaly of hot springs. Determining the mechanism of RAM enrichment and its variations with the time and space of hot springs will contribute to the exploration of the hydrothermal metallogenic systems. This paper presents numerical hydrothermal numerical circulation models constrained by the geological data and the geophysical structure of the YGR. The results illustrate that the depths of boundary faults control the anomalous temperatures of hot springs. High-temperature springs (such as Yangbajing) could be induced by deep faults extending to the middle crust, whereas magma at a depth greater than 10 km has a limited effect on geothermal anomalies. Secondary faults define the extent of hydrothermal circulation and further determine the distribution of thermal anomalies across the rift. We simulate the enrichment and distribution of RAMs from a deep magma source. The pathways of RAMs from the source are consistent with hydrothermal circulation. RAM concentrations are lower in infiltrating groundwater and higher in ascending hot water. In general, deep faults control the hydrothermal circulation of geothermal groundwater. Deep faults and magma further constrain the distribution of RAM anomalies. [ABSTRACT FROM AUTHOR]