ORCID Profile
0000-0003-0365-0087
Current Organisation
University of Adelaide
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Publisher: Wiley
Date: 06-2012
Publisher: Elsevier BV
Date: 09-2019
Publisher: MDPI AG
Date: 09-09-2020
DOI: 10.3390/MIN10090797
Abstract: High-tech metals including Ge, Ga and In are often sourced as by-products from a range of ore minerals, including sphalerite from Zn-Pb deposits. The Hilton Zn-Pb (Ag) deposit in the Mount Isa Inlier, Queensland, contains six textural varieties of sphalerite that have formed through a erse range of processes with variable co-crystallising sulphides. This textural complexity provides a unique opportunity to examine the effects of co-crystallising sulphides and chemical remobilisation on the trace element geochemistry of sphalerite. Early sphalerite (sph-1) is stratabound and coeval with pyrrhotite, pyrite and galena. Disseminated sphalerite (sph-2) occurs as isolated fine-grained laths rarely associated with co-crystallising sulphides and represents an alteration selvage accompanying the precipitation of early stratabound sphalerite (sph-1). Sphalerite (sph-3) occurs in early ferroan-dolomite veins and formed from the chemical remobilisation of stratabound sphalerite (sph-1) during brittle fracturing and interstitial fluid flow. This generation of veins terminate at the interface, and occurs within clasts of the paragenetically later sphalerite-dominated breccias (sph-4). Regions of high-grade Cu ( %) mineralisation contain a late generation of sphalerite (sph-5), which formed from the recrystallisation of breccia-type sphalerite (sph-4) during the infiltration of a paragenetically late Cu- and Pb-rich fluid. Late ferroan-dolomite veins crosscut all previous stages of mineralisation and also contain chemically remobilised sphalerite (sph-6). Major and trace elements including Fe, Co, In, Sn, Sb, Ag and Tl are depleted in sphalerite associated with abundant co-crystallised neighbouring sulphides (e.g., pyrite, pyrrhotite, galena and chalcopyrite) relative to sphalerite associated with minor to no co-crystallising sulphides. This depletion is attributed to the incorporation of the trace elements into the competing sulphide minerals. Chemically remobilised sphalerite is enriched in Zn, Cd, Ge, Ga and Sn, and depleted in Fe, Tl, Co, Bi and occasionally Ag, Sb and Mn relative to the primary minerals. This is attributed to the higher mobility of Zn, Ge, Ga and Sn relative to Fe and Co during the chemical remobilisation process, coupled with the effect of co-crystallising with galena and ferroan-dolomite. Results from this study indicate that the consideration of co-crystallising sulphides and post-depositional processes are important in understanding the trace element composition of sphalerite on both a microscopic and deposit-scale, and has implications for a range of Zn-Pb deposits worldwide.
Publisher: Society of Economic Geologists
Date: 12-2021
DOI: 10.5382/ECONGEO.4853
Abstract: Tasmania is the most important tin province in Australia, having been endowed with & .65 Mt Sn. Some granitic intrusions in western Tasmania have distinctive tourmaline- and quartz-rich magmatic-hydrothermal features, whether they are mineralized (e.g., Heemskirk Granite) or barren (Pieman Heads Granite). The Devonian Heemskirk and Pieman Heads plutons crop out on the western coast of Tasmania and are characterized by similar mineralogical and geochemical compositions and ages. The magmatic-hydrothermal textural features include tourmaline patches, tourmaline orbicules, and tourmaline-muscovite veins, as well as miarolitic cavities and quartz-fluorite-sulfide veins in the Heemskirk Granite. Cathodoluminescence (CL) imaging, laser ablation-inductively coupled plasma-mass spectrometry, and microthermometric analyses of quartz have revealed the physicochemical evolution of the magmatic-hydrothermal fluids from which these tourmaline- and quartz-bearing assemblages precipitated. High Ti quartz (20–28 ppm) in tourmaline patches, orbicules, and cavities typically have homogeneous CL-bright intensity, whereas CL-dark fractures have cut and/or offset the CL-bright and -gray domains that characterize low Ti quartz (3.4–8.5 ppm) from the tourmaline veins. The earliest fluid inclusion assemblages in the quartz-tourmaline orbicules and cavities have a salinity range from 3 to 14 wt % NaCl equiv with intermediate density and were probably trapped at lithostatic pressures of 1.57 ± 0.2 kbar and temperatures of 550° to 570°C, suggesting a depth of 5.9 ± 0.8 km. Prolonged depressurization and cooling may have led to the evolution of a brine (~39 wt % NaCl equiv salinity) from the primary magmatic liquid, which formed halite-bearing hypersaline inclusions in the tourmaline orbicules. Continuous pressure decrease explains the intense brittle failure and fluid migration outward from the apical portions of the pluton, where magmatic fluids partially mixed with and were cooled by external meteoric water. These mechanisms triggered the formation of tourmaline-muscovite-quartz veins and local cassiterite-bearing greisens from a moderate-salinity fluid (~12 wt % NaCl equiv) at temperatures of ~300°C and hydrostatic pressures of 120 bars. Retrograde dissolution textures evident from CL-bright quartz cores surrounded by oscillatory growth zones with gray CL response characterize the low Ti (& ppm) and high Al (500–1,000 ppm) quartz from the fluorite-sulfide veins that precipitated from a low-salinity (5.7 wt % NaCl equiv) acidic fluid at temperatures of 200° ± 25°C and hydrostatic pressures of & bars. High Sb concentrations (up to 80 ppm) in quartz may be an indicator of low-temperature base metal mineralization related to granitic intrusions. Abundant fluid percolation, protracted fractional crystallization, and high tin concentrations in exsolved hydrothermal fluids may explain why the Heemskirk Granite is well endowed in Sn and base metal deposits, whereas the Pieman Heads Granite is barren.
Publisher: Springer Science and Business Media LLC
Date: 27-04-2019
Publisher: Elsevier BV
Date: 03-2014
Publisher: Mineralogical Society of America
Date: 06-2020
DOI: 10.2138/AM-2020-7194
Abstract: Scheelite from the Tongshankou porphyry-skarn Cu-Mo(-W) deposit occurs mainly as disseminated grains in the altered granodiorite porphyries at depth (Sch A), in the skarn coeval with retrograde alteration (Sch B) and in distal quartz veins crosscutting marbles (Sch C). Cathodoluminescence (CL) responses within a single Sch A grain reveal two subtypes: CL-clear Sch A-I and CL-turbid, densely veined Sch A-II. The CL contrast, coupled with geochemical data, suggest Sch A-I was metasomatized to form Sch A-II. CL images reveal that Sch A-I, Sch B and Sch C are all homogenous, with blue luminescence and are depleted in heavy rare earth elements (HREE), indicating a primary origin. However, Sch A-II is characterized by higher contents of light REE and heavy REE as well as higher Sr isotopes (0.7080–0.7100) than the primary scheelite (& .7080). These differences indicate that Sch A-II formed through dissolution-reprecipitation. The Sr isotopes of the primary scheelite (0.7073–0.7078) are generally consistent with those of the mineralized granodiorite porphyries (0.7061–0.7063) and mafic enclaves (0.7058–0.7073). The granodiorite porphyries contain low tungsten contents (3–11 ppm), whereas high tungsten contents were detected in mafic enclaves (48–75 ppm). The coexistence of mafic enclaves and tungsten mineralization at depth, and their consistent Sr isotopes, indicates that the interaction of mafic enclaves and exsolved magmatic fluids from the granodiorite porphyries may have played an important role in the extraction of tungsten from the mafic enclaves and formation of scheelite mineralization. Our work shows that scheelite geochemistry can be used to trace the mineralizing conditions but the compositions may be significantly modified during the ore-forming process. Thus, detailed textural relationships should be investigated before using scheelite geochemistry to constrain the hydrothermal fluids and ore genesis.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 06-2020
No related grants have been discovered for Wei Hong.