Geochronology and petrogenesis of Miocene granitic intrusions related to the Zhibula Cu skarn deposit in the Gangdese belt, southern Tibet

Xu, Jing; Zheng, Youye; Sun, Xiang; Shen, Ya-hui

doi:10.1016/j.jseaes.2016.01.026

Cited by 23 publications

(20 citation statements)

References 94 publications

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“…The giant Gangdese metallogenic belt within the Lhasa terrane, one of the famous metallogenic belts in China, is composed of the Gangdese porphyry copper belt to the south and the Gangdese Pb–Zn polymetallic metallogenic belt (Cao, Zhang, Tang, et al, ; Hou, Duan, et al, ; Liu, Zheng, Gao, Jiang, & Cao, ; Sun et al, , ; Xu et al, , b; Xu et al, ; Zhang et al, ; Zheng et al, ; Zheng, Fu, Hou, Yang, & Huang, ). The well‐known Gangdese porphyry belt contains several world‐class porphyry Cu–(Mo) deposits, including the Jiama, Qulong, Bangpu, Lakang'e, Dabu, Tinggong, Gangjiang, Chongjiang, Jiru, and Zhunuo.…”

Section: Introductionsupporting

confidence: 62%

Sulphur and lead isotopic compositions of the Pb–Zn polymetallic deposits in the Linzizong volcanic area, Gangdese belt, Tibet: Implications for variation characteristics of ore‐forming material sources and exploration targeting

et al. 2019

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Relatively little attention has been given to variations in ore-forming metal sources of Pb-Zn polymetallic deposits hosted in or near the Linzizong volcanic rocks from the eastern to western Gangdese belt. Based on the S and Pb isotopic data of typical Pb-Zn polymetallic deposits from the eastern to western Gangdese, the oreforming sources are discerned. The δ 34 S V-CDT values of the typical Pb-Zn polymetallic deposits in the Gangdese metallogenic belt have a relatively large range of −11.6‰ to 6.0‰, different from those of the porphyry Cu ± Mo ± Au deposits (mainly vary from −2.0‰ to 1.0‰) in the Gangdese metallogenic belt, indicating that the sulphur in the ore-forming fluid of Pb-Zn polymetallic deposits was dominantly of magmatic origin, but also influenced by strata nearby. The Nuocang and Beina deposits in the western Gangdese have a predominantly upper crustal source of Pb (average values: 207 Pb/ 204 Pb = 15.705, 208 Pb/ 204 Pb = 39.102), while the Narusongduo and Dexin deposits in the central Gangdese and the Leqingla and Xingaguo deposits in the eastern Gangdese are characterized by a mixed source in which Pb was derived from both the subducted slab and the ancient Lhasa basement. From the eastern to western Gangdese, Pb isotopic data show a gradually increasing scale of crustal materials from the Lhasa terrane basement. Combined with the geochemical data of the ore-relatedintrusions and Linzizong volcanic rocks from the six deposits, or nearby, we proposed that the heterogeneity of Lhasa terrane crust resulted in more ancient Lhasa basement components contributing to ore-forming sources from the eastern to western Gangdese. Moreover, relatively higher contents of Au, Ag elements could be identified in the Linzizong volcanic rocks of the western Gangdese than those of in the central and eastern Gangdese. Therefore, in addition to finding the cryptoexplosive breccia, epithermal, skarn, hydrothermal vein-type Pb-Zn polymetallic deposits, there is exploration potential for epithermal Au-Ag deposits associated with the Linzizong volcanic rocks, western Gangdese. KEYWORDS lead isotope, Linzizong volcanic area, Pb-Zn polymetallic deposits, sulphur isotope, western Gangdese

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Section: Introductionsupporting

confidence: 62%

Sulphur and lead isotopic compositions of the Pb–Zn polymetallic deposits in the Linzizong volcanic area, Gangdese belt, Tibet: Implications for variation characteristics of ore‐forming material sources and exploration targeting

et al. 2019

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“…The skarn protolith is found in the limestone/dolomite sequences throughout the Yeba volcano-sedimentary sequence of Jurassic age (U-Pb zircon age 174.4 ± 1.7 Ma; [20]). Fluid inclusion data from Zhibula indicate fluids typical of skarn evolution, from relatively high temperature (405-667 • C), high salinity (up to 44.0 wt.% NaCl equiv.)…”

Section: Zhibula Cu Skarnmentioning

confidence: 99%

“…fluids to low temperature (194-420 • C), moderate salinity (10.1-18.3 and 30.0-44.2 wt.% NaCl equiv.) fluids, with a dominance of magmatic-hydrothermal fluids based upon sulphur, hydrogen and oxygen isotope data [20,21].…”

Section: Zhibula Cu Skarnmentioning

confidence: 99%

“…Copper-Mo mineralisation is often formed as paired porphyry-skarn systems associated with magmatism along subduction/post subduction settings in young Alpine belts, such as the Gangdese Belt in southern Tibet [23]. A good, well-studied example is represented by the Zhibula Cu skarn (0.32 Mt Cu, @ 1.64% Cu grade; Figure 1) and Qulong porphyry Cu-Mo deposit, which lie ~2 km apart [20][21][22]. Miocene magmatism at ~17 Ma was documented from both deposits, albeit from deeper monzogranite and granodiorite dikes at Zhibula [20,24].…”

Section: Zhibula Cu Skarnmentioning

confidence: 99%

“…In this contribution, we report micron-scale intergrowths among compositionally varied, intermediate members of the scheelite-powellite series, which occur as accessory phases in the Zhibula Cu skarn, Gangdese belt, southern Tibet [20][21][22]. We investigate, at the nanoscale, the boundaries between distinct domains with different mol.% powellite components within single grains of scheelite-powellite.…”

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confidence: 99%

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Crystals from the Powellite-Scheelite Series at the Nanoscale: A Case Study from the Zhibula Cu Skarn, Gangdese Belt, Tibet

Ciobanu

Cook

et al. 2019

Minerals

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Scheelite (CaWO4) and powellite (CaMoO4) are isostructural minerals considered as a non-ideal solid solution series. Micron- to nanoscale investigation of a specimen of skarnoid from Zhibula, Gangdese Belt, Tibet, China, was carried out to assess the identity of the phases within a broad scheelite-powellite (Sch-Pow) compositional range, and to place additional constraints on redox changes during ore formation. An electron probe microanalysis shows that Mo-rich domains within complex oscillatory-zoned single crystals, and as thin sliver-like domains, have a compositional range from 20 mol.% to 80 mol.% Pow. These occur within a matrix of unzoned, close-to-end-member scheelite aggregates (87 mol.%–95 mol.% Sch). Laser-ablation inductively coupled plasma mass spectrometry spot analysis and element mapping reveal systematic partitioning behaviour of trace elements in skarn minerals (grossular50, diopside80, anorthite, and retrograde clinozoisite) and scheelite-powellite aggregates. The Mo-rich domains feature higher concentrations of As, Nb, and light rare earth elements LREE, whereas W-rich domains are comparatively enriched in Y and Sr. Transmission electron microscopy (TEM) was carried out on focused-ion-beam-prepared foils extracted in situ from domains with oscillatory zoning occurring as slivers of 20 mol.%–40 mol.% Pow and 48 mol.%–80 mol.% Pow composition within an unzoned low-Mo matrix (20 mol.% Pow). Electron diffractions, high-angular annular dark field (HAADF) scanning-TEM (STEM) imaging, and energy-dispersive spectroscopy STEM mapping show chemical oscillatory zoning with interfaces that have continuity in crystal orientation throughout each defined structure, zoned grain or sliver. Non-linear thermodynamics likely govern the patterning and presence of compositionally and texturally distinct domains, in agreement with a non-ideal solid solution. We show that the sharpest compositional contrasts are also recognisable by variation in growth direction. Atomic-scale resolution imaging and STEM simulation confirm the presence of scheelite-powellite within the analysed range (20 mol.%–80 mol.% Pow). Xenotime-(Y) inclusions occur as nm-wide needles with epitaxial orientation to the host scheelite-powellite matrix throughout both types of patterns, but no discrete Mo- or W-bearing inclusions are observed. The observed geochemical and petrographic features can be reconciled with a redox model involving prograde deposition of a scheelite+molybdenite assemblage (reduced), followed by interaction with low-T fluids, leading to molybdenite dissolution and reprecipitation of Mo as powellite-rich domains (retrograde stage, oxidised). The observation of nanoscale inclusions of xenotime-(Y) within scheelite carries implications for the meaningful interpretation of petrogenesis based on rare earth element (REE) concentrations and fractionation patterns. This research demonstrates that HAADF-STEM is a versatile technique to address issues of solid solution and compositional heterogeneity.

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Petrogenesis and geodynamic implications of the intrusions related to the Pusangguo skarn Cu‐dominated polymetallic deposit in Tibet: Constraints from geochronology, geochemistry, and Sr–Nd–Pb–Hf isotopes

Lang

Zhang³

et al. 2020

Geological Journal

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Pusangguo is a high‐grade skarn‐type Cu‐dominated polymetallic deposit and the only large‐sized Cu‐Pb‐Zn‐(Co‐Ni) deposit in the Gangdese metallogenic belt (GMB); the magmatic rocks associated with this deposit are poorly documented, and their petrogenesis and geodynamic setting are unclear. To explore these issues, we present zircon U–Pb ages along with Hf isotopic, whole‐rock geochemical, and Sr–Nd–Pb isotopic data for Pusangguo biotite granodiorite (PBG) and Pusangguo diorite porphyrite (PDP) in this deposit. Zircon U–Pb dating for these rocks indicates that they were emplaced during the Miocene (13.6–14.6 Ma). Geochemically, both PBG and PDP show characteristics of adakites, with intermediate SiO2 (65.55–67.30 wt% and 60.56–58.27 wt%, respectively), relatively high Al2O3 (15.28–15.85 wt% and 17.71–16.71 wt%, respectively) and Sr (599–723 ppm and 687–1,616 ppm, respectively) and low Y and Yb. In addition, they show relatively low ratios of (87Sr/86Sr)i and (206Pb/204Pb)i, (207Pb/204Pb)i and (208Pb/204Pb)i and relatively low values of εNd(t) and εHf(t). The Sr‐Nd‐Pb‐Hf isotopes of PBG and PDP are similar to those of the Miocene adakitic rocks associated with the porphyry–skarn deposits in the GMB, indicating that they were predominantly generated by partial melting of the thickened juvenile Lhasa Terrane lower crust and the PDP were likely to be generated through mixing between the magma parental to the PBG and a mafic end‐member. By combining our results with the previously reported results, we suggest that the model of delamination of the overthickened mantle lithosphere of Lhasa Terrane and convective upwelling of mantle asthenosphere which may involve Indian continental lithosphere.

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Geochronology and petrogenesis of Miocene granitic intrusions related to the Zhibula Cu skarn deposit in the Gangdese belt, southern Tibet

Cited by 23 publications

References 94 publications

Sulphur and lead isotopic compositions of the Pb–Zn polymetallic deposits in the Linzizong volcanic area, Gangdese belt, Tibet: Implications for variation characteristics of ore‐forming material sources and exploration targeting

Sulphur and lead isotopic compositions of the Pb–Zn polymetallic deposits in the Linzizong volcanic area, Gangdese belt, Tibet: Implications for variation characteristics of ore‐forming material sources and exploration targeting

Crystals from the Powellite-Scheelite Series at the Nanoscale: A Case Study from the Zhibula Cu Skarn, Gangdese Belt, Tibet

Petrogenesis and geodynamic implications of the intrusions related to the Pusangguo skarn Cu‐dominated polymetallic deposit in Tibet: Constraints from geochronology, geochemistry, and Sr–Nd–Pb–Hf isotopes

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