Graphite as an electrically conductive indicator of ancient crustal-scale fluid flow within mineral systems

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Geological features of the Jiaoxi tungsten deposit in the western Bangong-Nujiang metallogenic belt, Tibet, China

The Tibetan Plateau includes two important metallogenic belts, the Gangdese metallogenic zone in southern Tibet and the newly delimited Bangong-Nujiang metallogenic belt in central Tibet (Geng et al., 2016). The BangongNujiang metallogenic belt is considered to be a FeCu-Au metallogenic belt since the discovery of the Tiegelongnan giant porphyry-epithermal Cu-Au deposit (Tang et al., 2014), the Duobuza large porphyry deposit (Li et al., 2012) and the Ga’erqiong-Galale large skarn Cu-Au deposit (Zhang et al., 2015). The Jiaoxi quartz vein-type tungsten deposit (WO3 : 39,000 t, Wang et al., 2018) is the first quartz-vein type tungsten deposit found in this belt

Composition and evolution of the continental crust: Retrospect and prospect

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The Watershed tungsten deposit, NE Queensland, Australia: an example of a Permian metamorphic tungsten upgrade after a Carboniferous magmatic-hydrothermal mineralisation event

Tungsten is considered a strategic metal by various countries, including Australia. Between 1998 and 2016 Australia has been steadily increasing its tungsten production, but it is still far smaller than those of the main producers (e.g., China, Russia). Watershed with its current resources of 49.2 Mt averaging 0.14% WO3 is considered one of the biggest undeveloped tungsten deposits outside of China, and if developed would boost Australia’s tungsten production. We will be presenting the geological, geochemical and structural characteristics of the Watershed deposit, as well as the timing, mineral paragenesis and fluid characteristics of the mineralizing system; with the main goal of improving our understanding of the Watershed tungsten deposit and how to explore for similar deposits in northeast Queensland

Diamond formation by carbon saturation in C-O-H fluids at Lago di Cignana UHPM unit (western Alps, Italy)

Microdiamonds in garnet of graphite-free ultrahigh pressure metamorphic (UHPM) rocks from Lago di Cignana (western Alps, Italy) represent the first occurrence of diamond in a low temperature subduction complex of oceanic origin (T = 600°C; P ≥ 3.2 GPa). The presence of diamonds in fluid inclusions provides evidence for carbon transport and precipitation in an oxidized H2O-rich C-O-H crustal fluid buffered by mineral equilibria at sub-arc mantle depths. The structural state of carbon in fluid-precipitated diamonds was analyzed with 514 nm excitation source confocal Raman microspectroscopy. The first order peak of sp3-bonded carbon in crystalline diamonds lies at 1331 (±2) cm-1, similar to diamonds in other UHPM terranes. The analysis of the spectra shows additional Raman features due to sp2 carbon phases indicating the presence of both hydrogenated carbon (assigned to trans-polyacetylene segments) in grain boundaries, and graphite-like amorphous carbon in the bulk, i.e. showing a structural disorder much greater than that found in graphite of other UHPM rocks. In one rock sample, defective microdiamonds are recognized inside fluid inclusions by the presence of a weaker and broader Raman band downshifted from 1332 to 1328 cm−1. The association of sp3- with sp2-bonded carbon indicates variable kinetics during diamond precipitation. We suggest that precipitation of disordered sp2-bonded carbon acted as a precursor for diamond formation outside the thermodynamic stability field of crystalline graphite. Diamond formation started when the H2O-rich fluid reached the excess concentration of C required for the spontaneous nucleation of diamond. The interplay of rock buffered fO2 and the prograde P-T path at high pressures controlled carbon saturation (aC=1) in the fluid phase. Thermodynamic modeling confirms that the C-O-H fluids from which diamond precipitated must have been water- rich(0.992 < XH2O < 0.997), assuming that fO2 is fixed by the EMOD equilibrium

Geology, paragenesis, and alteration patterns of the E1 group of iron oxide-Cu-Au deposits, Cloncurry district, northwest Queensland, Australia

The Proterozoic E1 Group of iron oxide-Cu-Au deposits, composed of E1 North, East, and South, is located 8 km east of the world-class Ernest Henry IOCG deposit in the Cloncurry district of northwest Queensland, and contains estimated resources of 48 Mt averaging 0.72% Cu and 0.21 g/t Au. The E1 Group has been recently discovered below 20-50 m of Mesozoic sedimentary rocks near the world-class Ernest Henry IOCG, but its relationship to that deposit is not clear. Modelling of drill data indicates that the orebody is stratigraphically controlled within a series of folded, discontinuous metatuff, metasiltstone, marble and metapsammite lenses intercalated with metabasalt and glomerophyric metaandesite. The metaandesite is likely equivalent to the intermediate volcanic rocks hosting the Ernest Henry deposit. The E1 North orebody is controlled by a NW-plunging antiform, with mineralization occurring in a single major, discontinuous metatuff lens on the east limb, and in two discontinuous metatuff lenses on the west limb. The west limb of the antiform is truncated by Corella Breccia, and the east limb continues to the southeast to form the west limb of the E1 South synform. The E1 South orebody is comprised of three discontinuous lenses within this synform, with the upper lenses hosted in metasiltstone and the lowermost lens hosted in metatuff continuing from the E1 North antiform east limb. The uppermost ore lens of E1 South grades into barren carbonaceous metapelite, and the entire E1 South system is truncated to the southeast by the Mount Margaret Fault Zone. E1 East ores are hosted in two steeply east-dipping lenses of metasilts intercalated with metabasalt and surrounded by Corella Breccia. E1 Group mineralization is characterized dominantly by fine (0.05 mm) to coarse (3 mm)-grained layer-controlled magnetite-chalcopyrite-pyrite±Fe-Mn-carbonate±barite±fluorite±biotite±albite±chlorite±apatite±arsenopyrite±pyrrhotite±monazite (tr.) ±coffinite (tr.) ±uraninite(tr.) replacement of layered metatuff and metasilt, and matrix-controlled replacement of volcaniclastic metatuff, associated with Fe-Mn-carbonate-quartz-barite-fluoritealbite-chalcopyrite-magnetite-biotite-chlorite-apatite veining. Very high-grade ores (>2% Cu) typically exhibit a massive texture which completely overprints earlier layering. This replacementdominated mineralization style is substantially different from that of the hydrothermal brecciahosted Ernest Henry orebody. The E1 paragenetic sequence is comprised of four major stages: 1) Sodic-calcic: albite-quartzhematite±actinolite±magnetite; 2) Potassic(-Fe): K-feldspar-biotite-magnetite; 3) Ore stage A: magnetite-Fe-carbonate-chalcopyrite-pyrite-quartz-barite-fluorite-biotite (±Ba-Cl)-chloriteapatite-muscovite (±Ba)-monazite; and 4) Ore stage B: Mn-(Fe)-carbonate-barite-fluorite-chalcopyrite-pyrite-quartz-sericite-arsenopyrite-pyrrhotite. Stage 1 and 2 alterations are heavily overprinted by mineralization, and are most visible immediately outside the orebody and within and proximal to the Corella Breccia. Stages 3-4 carbonate veins, accompanied by chlorite and sericite alteration, are widespread throughout the mine lease, but are most prevalent outside the orebody in the more brittle metabasalts, metaandesites and Corella Breccia. In the west limb of the E1 North antiform the carbonate veins contain abundant apatite, magnetite, and pyrite, forming a magnetic and Fe-P-rich geochemical anomaly extending 150-200m southwest from the orebody. The E1 Group and Ernest Henry share a similar paragenetic sequence of early sodic (-Ca), intermediate potassic (-Fe), and late mineralization alteration, suggesting a similar genetic origin. The reason(s) for differing mineralization styles between the two systems, despite being hosted in similar rock types, is under investigation

The evolution and potential sources of mineralizing fluids of the E1 group of IOCG deposits, Cloncurry District, Northwest Queensland, Australia: implications from fluid inclusion and SHRIMP S isotope analyses

The E1 Group of Proterozoic iron oxide-Cu-Au deposits—E1 North, East, and South—is located 6 km east of the Ernest Henry IOCG deposit, in the far northeast of the polymetallic Cloncurry district of northwest Queensland, and hosts a total resource of 48 Mt of 0.72% Cu and 0.21 g/t Au. The mineralizing fluids of the E1 Group have not been studied in great detail and offer additional insight into the complex evolution of Cloncurry district iron oxide-associated Cu-Au deposits. We present a fluid evolution of the E1 Group hydrothermal system based on fluid inclusion microthermometrics of pre-ore, syn-early ore, and syn-late ore mineral assemblages, and ore formation temperatures calculated from in situ SHRIMP-measured sulfur isotopes in cogenetic late ore barite and chalcopyrite. The E1 Group is hosted in variably porphyritic intermediate-mafic metavolcanic rocks, marbles, metasiltstones, and carbonaceous pelites of the ~1740 Ma Corella Formation and Mount Fort Constantine Volcanics, and mineralization is characterized by layer- and matrix-controlled magnetite-carbonate-chalcopyrite ± barite ± fluorite replacement and veining of strongly sheared metasediments and metavolcanic breccias. The paragenetic sequence is characterized by four major stages: (1) early regional Na-Ca, composed mainly of albite and actinolite, (2) pre-ore K-Fe in magnetite, biotite K-feldspar, and minor quartz, (3) early Mg-Fe-carbonate-quartz-magnetite-associated mineralization, and (4) late Fe-Mn carbonate-barite-fluorite-associated mineralization. Stage 2 quartz, associated with the main phase of magnetite input, contains heterogeneously trapped, liquid-vapor ± halite, primary fluid inclusions which melt at –14°C. Stage 3 quartz, hosted in carbonate-quartz-chalcopyrite veins, is characterized by heterogeneously trapped primary, halite-saturated, hypersaline liquid-multisolid-vapor inclusions. Both stages 3 and 4 fluid inclusions homogenize above 450°C. Barite and calcite from stage 4 contain metastable liquid ± vapor inclusions with initial melting between –50° and –40°C, and final melting of ice ranging from –23° to –13°C, indicating the presence of NaCl-CaCl2–rich brine. Homogenization into the liquid phase in most inclusions occurs at temperatures >150°C, though some homogenize at ~95°C. Stage 4 chalcopyrite from E1 North, the largest of the three orebodies, shows δ34SCDT values in a narrow range between –2.2‰ and +1.9‰, while chalcopyrite δ34SCDT from E1 South are characterized by higher values ranging from 6.8‰ to 14.1‰. Sulfur in barite coeval with the chalcopyrite exhibits similar trends, with E1 North δ34SCDT of barite ranging from 16.4‰ to 21.2‰ CDT, and E1 South varying between 18.2‰ and 27.7‰. The formation temperature of stage 4 barite-chalcopyrite, calculated from sulfur isotope pairs, is constrained to 300° to 420°C in both orebodies. The transition in fluid inclusion composition from stage 3 (halite rich) to stage 4 (NaCl-CaCl2 rich), along with the decrease in minimum formation temperature (>450°C to as low as 320°C), is interpreted to represent the dilution of an early, relatively hot, sulfate-rich, and hypersaline fluid with a separate Ca-Ba–rich fluid, which was synchronous with cooling. This early fluid was likely magmatic, based on the low δ34SCDT values of E1 North chalcopyrite. Higher δ34SCDT values at E1 South may be explained by fractionation from the E1 North hydrothermal center, though the influence of primary sulfide-bearing graphitic pelites found at E1 South cannot be excluded

Geology, paragenesis, and alteration patterns of the E1 group of iron oxide-Cu-Au deposits, Cloncurry district, northwest Queensland, Australia

The Proterozoic E1 Group of iron oxide-Cu-Au deposits, composed of E1 North, East, and South, is located 8 km east of the world-class Ernest Henry IOCG deposit in the Cloncurry district of northwest Queensland, and contains estimated resources of 48 Mt averaging 0.72% Cu and 0.21 g/t Au. The E1 Group has been recently discovered below 20-50 m of Mesozoic sedimentary rocks near the world-class Ernest Henry IOCG, but its relationship to that deposit is not clear. Modelling of drill data indicates that the orebody is stratigraphically controlled within a series of folded, discontinuous metatuff, metasiltstone, marble and metapsammite lenses intercalated with metabasalt and glomerophyric metaandesite. The metaandesite is likely equivalent to the intermediate volcanic rocks hosting the Ernest Henry deposit. The E1 North orebody is controlled by a NW-plunging antiform, with mineralization occurring in a single major, discontinuous metatuff lens on the east limb, and in two discontinuous metatuff lenses on the west limb. The west limb of the antiform is truncated by Corella Breccia, and the east limb continues to the southeast to form the west limb of the E1 South synform. The E1 South orebody is comprised of three discontinuous lenses within this synform, with the upper lenses hosted in metasiltstone and the lowermost lens hosted in metatuff continuing from the E1 North antiform east limb. The uppermost ore lens of E1 South grades into barren carbonaceous metapelite, and the entire E1 South system is truncated to the southeast by the Mount Margaret Fault Zone. E1 East ores are hosted in two steeply east-dipping lenses of metasilts intercalated with metabasalt and surrounded by Corella Breccia. E1 Group mineralization is characterized dominantly by fine (0.05 mm) to coarse (3 mm)-grained layer-controlled magnetite-chalcopyrite-pyrite±Fe-Mn-carbonate±barite±fluorite±biotite±albite±chlorite±apatite±arsenopyrite±pyrrhotite±monazite (tr.) ±coffinite (tr.) ±uraninite(tr.) replacement of layered metatuff and metasilt, and matrix-controlled replacement of volcaniclastic metatuff, associated with Fe-Mn-carbonate-quartz-barite-fluoritealbite-chalcopyrite-magnetite-biotite-chlorite-apatite veining. Very high-grade ores (>2% Cu) typically exhibit a massive texture which completely overprints earlier layering. This replacementdominated mineralization style is substantially different from that of the hydrothermal brecciahosted Ernest Henry orebody. The E1 paragenetic sequence is comprised of four major stages: 1) Sodic-calcic: albite-quartzhematite±actinolite±magnetite; 2) Potassic(-Fe): K-feldspar-biotite-magnetite; 3) Ore stage A: magnetite-Fe-carbonate-chalcopyrite-pyrite-quartz-barite-fluorite-biotite (±Ba-Cl)-chloriteapatite-muscovite (±Ba)-monazite; and 4) Ore stage B: Mn-(Fe)-carbonate-barite-fluorite-chalcopyrite-pyrite-quartz-sericite-arsenopyrite-pyrrhotite. Stage 1 and 2 alterations are heavily overprinted by mineralization, and are most visible immediately outside the orebody and within and proximal to the Corella Breccia. Stages 3-4 carbonate veins, accompanied by chlorite and sericite alteration, are widespread throughout the mine lease, but are most prevalent outside the orebody in the more brittle metabasalts, metaandesites and Corella Breccia. In the west limb of the E1 North antiform the carbonate veins contain abundant apatite, magnetite, and pyrite, forming a magnetic and Fe-P-rich geochemical anomaly extending 150-200m southwest from the orebody. The E1 Group and Ernest Henry share a similar paragenetic sequence of early sodic (-Ca), intermediate potassic (-Fe), and late mineralization alteration, suggesting a similar genetic origin. The reason(s) for differing mineralization styles between the two systems, despite being hosted in similar rock types, is under investigation

Clinical aspects of glucocorticoid sensitivity

Recent studies demonstrate that primary (hereditary) abnormalities in the glucocorticoid receptor gene make 6.6% of the normal population relatively 'hypersensitive' to glucocorticoids, while 2.3% are relatively 'resistant.' These abnormalities might explain why some individuals develop severe adverse effects during low dose glucocorticoid therapy, while others do not develop side effects even during long-term therapy with a much higher dose. Awareness of this heterogeneity in glucocorticoid sensitivity in the normal population might eventually allow the prediction of a 'safe' dose of glucocorticoid in individual patients. 'Resistance' to the beneficial clinical effects of glucocorticoid therapy in part of the patients with severe rheumatoid arthritis and asthma is probably rarely related to generalized primary (hereditary) glucocorticoid resistance. In the majority of patients this 'resistance' seems to be acquired and localized to the sites of inflammation, where it reflects high local cytokine production, which interferes with glucocorticoid action. Recognition of localized, acquired glucocorticoid resistance is of great importance indicating as alternative drug therapy with other immune-modulating drugs like cyclosporin and methotrexate. Chronic high dose glucocorticoid treatment in such patients is ineffective in alleviating symptomatology, while generalized side effects occur, reflecting the patient's normal systemic sensitivity to these drugs

Petrogenesis of the quartz diorite from the Lietinggang-Leqingla Pb-Zn-Fe-Cu- (Mo) deposit in southern Tibet: implications for the genesis of a skarn-type polymetallic deposit in the Tibetan-Himalayan collisional orogen

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