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1
Poutiainen, Matti. "Evolution of a metamorphic fluid during progressive metamorphism in the Joroinen-Sulkava area, southeastern Finland, as indicated by fluid inclusions." Mineralogical Magazine 54, no. 375 (June 1990): 207–18. http://dx.doi.org/10.1180/minmag.1990.054.375.07.
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AbstractFluid inclusions in the progressively metamorphosed rocks of the Joroinen-Sulkava area, located in the south-eastern end of the Raahe-Ladoga zone near the Archaean-Proterozoic boundary, southeastern Finland, fall into four main categories: (1) H2O-rich, (2) CO2-rich, (3) mixed H2O-CO2 and (4) CH4-N2 inclusions. The samples were collected from quartz veins associated with different deformation phases (D2-D4) and from metapelites. The progressive stage of metamorphism took place mainly during the D2 deformation. The age of metamorphism and D2 deformation becomes younger with increase in metamorphic grade from amphibolite to granulite facies.Regional distribution of the different fluid types indicates a change in fluid regime from H2O to CO2-dominant during the progressive stage of the metamorphism. H2O entered preferentially into the anatectic melt. The possibility of CO2 infiltration from deeper crust can not be excluded, because granulite facies rocks occur most probably below the lower grade zones. A zone enriched in CH4-N2 fluids is located near the lineament zones caused by the D3 deformation. This fluid type dominates the Au-bearing D2–D3 quartz lenses in the K-feldspar-sillimanite zone. Density data of early CO2 inclusions in combination with estimates of metamorphic temperatures (645–750°C) in the different metamorphic zones indicate a pressure range of 3.0–4.5 kbar, which is consistent with data derived from mineral geobarometry. The diversity of fluid types encountered in the D2–D4 quartz veins are a result of the passage of different fluids through veins at different times without re-equilibrating with the wall rocks. However, it is supposed that the CH4-N2 fluid is derived from a CO2-rich fluid with XCH4 ⩽ 0.4 by re-equilibration during its passage through the rocks.
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Moritz, Robert P., and Serge R. Chevé. "Fluid-inclusion studies of high-grade metamorphic rocks of the Ashuanipi complex, eastern Superior Province: constraints on the retrograde P–T path and implications for gold metallogeny." Canadian Journal of Earth Sciences 29, no. 10 (October 1, 1992): 2309–27. http://dx.doi.org/10.1139/e92-180.
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The high-grade metamorphic rocks of the Ashuanipi complex have been the subject of a microthermometric fluid-inclusion study. Four types of fluid inclusions were observed: CO2-rich fluids; low-temperature, high-salinity H2O fluids; CH4 ± N2-rich fluids; and high-temperature, low-salinity H2O fluids. The regionally distributed CO2-rich fluids are the earliest fluids, and their calculated isochores indicate a clockwise post-peak metamorphic P–T–t path for the Ashuanipi complex. The low-temperature, high-salinity aqueous fluid inclusions are also distributed regionally and can be interpreted as late brines, retrograde metamorphic fluids, or the wicked-off aqueous component of H2O–CO2 fluid inclusions. Both CH4 ± N2-rich fluids and the high-temperature, low-salinity aqueous fluid inclusions were found only locally in gold-bearing metamorphosed banded iron formations. Fluid-inclusion microthermometry, arsenopyrite thermometry, and metamorphic petrologic study at Lac Lilois, one of the principal gold showings, suggest that some gold deposition may have occurred during regional post-peak metamorphic exhumation and cooling at P–T conditions near the amphibolite–greenschist transition. However, it is possible that gold deposition began at higher near-peak metamorphic P–T conditions. Another major gold showing, Arsène, is characterized by CH4 ± N2-rich fluid inclusions, tentatively inferred to be either directly related to gold deposition or responsible for secondary gold enrichment. The association of CH4 ± N2-rich fluids with gold occurrences in the Ashuanipi complex is comparable to gold deposits of the Abitibi greenstone belt and of Wales, Finland, and Brazil.
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Thomas, L. J., R. S. Harmon, and G. J. H. Oliver. "Stable isotope compositions of alteration fluids in low-grade Lower Palaeozoic rocks, English Lake District." Mineralogical Magazine 49, no. 352 (June 1985): 425–34. http://dx.doi.org/10.1180/minmag.1985.049.352.13.
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AbstractA combination of hydrogen and oxygen isotope analyses and fluid inclusion studies has defined the composition of fluids involved in the metamorphism of Lower Palaeozoic rocks in the English Lake District. Three fluid fields have been defined from secondary phases: 1, syn-burial metamorphic D-enriched fluids from epidote and chlorite at a temperature between 250 and 350°C; D-depleted fluid measured from groundmass and quartz inclusions; 3, a mixed magmatic-meteoric fluid with an intermediate H-isotopic composition estimated from W/R granite data and calculated from illite.
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Krenn, Kurt, Martina Husar, and Anna Mikulics. "Fluid and Solid Inclusions in Host Minerals of Permian Pegmatites from Koralpe (Austria): Deciphering the Permian Fluid Evolution during Pegmatite Formation." Minerals 11, no. 6 (June 16, 2021): 638. http://dx.doi.org/10.3390/min11060638.
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Fluid inclusions (FIs) and associated solids in host minerals garnet, tourmaline, spodumene, and quartz from six pegmatite fields of Permian origin at Koralpe (Eastern Alps) have been investigated. Although pegmatites suffered intense Eoalpine high-pressure metamorphic overprint during the Cretaceous period, the studied samples originate from rock sections with well-preserved Permian magmatic textures. Magmatic low-saline aqueous FIs in garnet domains entrapped as part of an unmixed fluid together with primary N2-bearing FIs that originate from a host rock-derived CO2-N2 dominated high-grade metamorphic fluid. This CO2-N2 fluid is entrapped as primary FIs in garnet, tourmaline, and quartz. During host mineral crystallization, fluid mixing between the magmatic and the metamorphic fluid at the solvus formed CO2-N2-H2O–rich FIs of various compositional degrees that are preserved as pseudo-secondary inclusions in tourmaline, quartz, and as primary inclusions in spodumene. Intense fluid modification processes by in-situ host mineral–fluid reactions formed a high amount of crystal-rich inclusions in spodumene but also in garnet. The distribution of different types of FIs enables a chronology of pegmatite host mineral growth (garnet-tourmaline/quartz-spodumene) and their fluid chemistry is considered as having exsolved from the pegmatite parent melt together with the metamorphic fluid from the pegmatite host rocks. Minimum conditions for pegmatite crystallization of ca. 4.5–5.5 kbar at 650–750 °C have been constrained by primary FIs in tourmaline that, unlike to FIs in garnet, quartz, and spodumene, have not been affected by post-entrapment modifications. Late high-saline aqueous FIs, only preserved in the recrystallized quartz matrix, are related to a post-pegmatite stage during Cretaceous Eoalpine metamorphism.
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Vry, Julie K., and Philip E. Brown. "Evidence for early fluid channelization, Pikwitonei granulite domain, Manitoba, Canada." Canadian Journal of Earth Sciences 29, no. 8 (August 1, 1992): 1701–16. http://dx.doi.org/10.1139/e92-134.
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The results of field mapping and carbon isotope and phase equilibria studies suggest that two different, locally controlled fluid regimes existed during at least the early phases of high-grade metamorphism in the north Cauchon Lake region, Pikwitonei granulite domain, Manitoba, Canada. During the prograde stages of high-grade "anticlockwise" regional metamorphism, rocks already metamorphosed to at least sillimanite grade were thermally metamorphosed at temperatures near 900 °C by the intrusion of a charnockitic magma. It is likely that this magma released an oxidizing, CO2-bearing, probably CO2-rich fluid phase while the region was still at relatively shallow depths. Fluid migration was channelized along the intrusive contact, and local fluid buffering characterized many of the country rocks. The light carbon isotope values of graphites (gr) and CO2 in cordierites (crd) in pelitic lithologies (δ13Cgr = −41.8 to −30.4; δ13Ccrd = −31.8 to −34.9), and the low oxygen fugacities in many samples rule out infiltration of these units by large amounts of an externally derived CO2-rich fluid phase. Texturally early CO2-rich fluid inclusions occur in the cores of garnets in a variety of rock types along the intrusive contact. These fluid inclusions were probably trapped during early garnet growth at high temperatures and relatively low pressures, and appear to have undergone limited or no subsequent reequilibration. They do not appear to provide direct information about the highest regional metamorphic temperature and pressure conditions to have affected the region (750 °C and 7 kbar (1 kbar = 100 MPa)) but may instead retain evidence of the prograde metamorphic path. These studies demonstrate the importance of local controls on the sources, compositions, timing, and transport of metamorphic fluids in the north Cauchon Lake region.
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Powell, Wayne G., and Edward D. Ghent. "Low-pressure metamorphism of the mafic volcanic rocks of the Rossland Group, southeastern British Columbia." Canadian Journal of Earth Sciences 33, no. 10 (October 1, 1996): 1402–9. http://dx.doi.org/10.1139/e96-105.
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Mafic volcanic rocks of the Rossland Group have been metamorphosed in the subgreenschist to lower amphibolite faciès. Subgreenschist-facies regional metamorphic rocks are subdivided into prehnite–pumpeilyite zone and prehnite–epidote zone. Fluid inclusions in two subgreenschist-facies veins yielded mean homogenization temperatures of 139 and 151 °C. Assuming a reasonable maximum temperature limit of 275 °C for the subgreenschist fades, the fluid-inclusion isochores indicate a pressure <250 MPa for regional metamorphism in the subgreenschist facies. This is consistent with the widespread occurrence of prehnite–chlorite-bearing assemblages. Metamorphic grade increases sharply northward approaching the large plutons of the Nelson suite. The contact aureoles of the Nelson batholith and the related Bonnington pluton encompass most of the region, producing an extensive region underlain by rocks within the hornblende–oligoclasc zone. Intrusion of the Nelson plutonic suite overlapped with the development of the Hall Creek syncline and Silver King shear zone. The pattern of isograds across the Rossland Group indicates superimposed contact and regional metamorphism rather than progressively deeper structural levels northward.
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SATISH-KUMAR, M., and M. SANTOSH. "A petrological and fluid inclusion study of calc-silicate–charnockite associations from southern Kerala, India: implications for CO2 influx." Geological Magazine 135, no. 1 (January 1998): 27–45. http://dx.doi.org/10.1017/s0016756897008145.
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Recent discovery of wollastonite-bearing calc-silicate assemblages adjacent to gneiss–charnockite horizons in the supracrustal terrain of the Kerala Khondalite Belt, southern India, provides an opportunity to evaluate the carbonic fluid infiltration model proposed for charnockite formation. Petrological and fluid inclusion studies across these horizons in three representative localities are presented in this study. The calc-silicate assemblages define peak metamorphic conditions of ∼800°C at 5 kbar and define a low aCO2. Adjacent charnockite assemblages developed through dehydration involving the breakdown of garnet, biotite and quartz to produce orthopyroxene under low aH2O conditions. Retrograde reactions preserved in the calc-silicate rocks, such as scapolite–quartz symplectites, and the partial breakdown of wollastonite previously has been attributed to a near isothermal decompression during which infiltration of CO2-rich fluids occurred. Fluid inclusion studies indicate that the earliest generation of fluids preserved in the calc-silicate assemblages are aqueous (with salinity ∼8 wt% NaCl equivalent), consistent with mineral phase equilibria defining low aCO2. The estimation of NaCl content in brines coexisting with scapolite, based on the Cl content of the scapolite, indicates the presence of up to 20 wt % NaCl during the formation of scapolite consistent with the saline primary fluid inclusions. Primary carbonic inclusions occur within the retrogressed calcite+quartz assemblage after wollastonite, and are considered to represent the post-peak metamorphic carbonic fluid infiltration event, synchronous with the development of charnockites in the adjacent gneisses. These inclusions have identical characteristics to those in the charnockites. We envisage that the Kerala Khondalite Belt fluid regime was largely internally buffered during the prograde path, and that CO2 infiltration post-dated peak metamorphism. Influx of CO2 was mostly structurally controlled, and occurred along a near-isothermal uplift path. Graphite-bearing pegmatitic dykes with abundant CO2-rich inclusions in these localities attest to the transfer of carbonic fluids through magmatic conduits.
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MUKHERJEE, BARUN K., and HIMANSHU K. SACHAN. "Fluids in coesite-bearing rocks of the Tso Morari Complex, NW Himalaya: evidence for entrapment during peak metamorphism and subsequent uplift." Geological Magazine 146, no. 6 (July 15, 2009): 876–89. http://dx.doi.org/10.1017/s0016756809990069.
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AbstractFluid inclusions trapped in coesite-bearing rocks provide important information on the fluid phases present during ultrahigh-pressure metamorphism. The subduction-related coesite-bearing eclogites of the Tso Morari Complex, Himalaya, contain five major types of fluids identified by microthermometry and Raman spectroscopy. These are: (1) high-salinity brine, (2) N2, (3) CH4, (4) CO2and (5) low-salinity aqueous fluids. These fluids were trapped during both deep subduction and exhumation processes. The coesite-bearing rocks are inferred to have been buried to a depth of >120 km, where they experienced ultrahigh-pressure metamorphism. The fluid–rock interaction provides direct evidence for fluid derivation during a deep subduction process as demonstrated by silica–carbonate assemblages in eclogite. High salinity brine, N2and CH4inclusions are remnants of prograde and peak metamorphic fluids, whereas CO2and low-salinity aqueous fluids appear to have been trapped late, during uplift. The high-salinity brine was possibly derived from subducted ancient metasedimentary rocks, whereas the N2and CH4fluids were likely generated through chemical breakdown of NH3-bearing K minerals and graphite. Alternatively, CH4might have been formed by a mixed fluid that was released from calcareous sediments during subduction or supplied through subducted oceanic metabasic rocks. High density CO2is associated with matrix minerals formed during granulite-facies overprinting of the ultrahigh-pressure eclogite. During retrogression to amphibolite-facies conditions, low-salinity fluids were introduced from external sources, probably the enclosing gneisses. This source enhances salinity differences as compared to primary saline inclusions. The subducting Indian lithosphere produced brines prior to achieving maximal depths of >120 km, where fluids were instead dominated by gaseous phases. Subsequently, the Indian lithosphere released CO2-rich fluids during fast exhumation and was then infiltrated by the low-salinity aqueous fluids near the surface through external sources. Elemental modelling may improve quantitative understanding of the complexity of fluids and their reactions.
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Clarke, D. B. "Cordierite in felsic igneous rocks: a synthesis." Mineralogical Magazine 59, no. 395 (June 1995): 311–25. http://dx.doi.org/10.1180/minmag.1995.059.395.15.
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AbstractCordierite is a characteristic mineral of many peraluminous felsic igneous rocks. A combination of T-P-X parameters, which overlap the stability conditions for felsic magmas, control its formation. Critical among these parameters are relatively low T, low P, and typically high (Mg+Fe2+), Mg/Fe2+, A/CNK, aAl2O3, and fO2. Spatial and textural information indicate that cordierite may originate in one of three principal ways in felsic igneous rocks: Type 1 Metamorphic: (a) xenocrystic (generally anhedral, many inclusions, spatial proximity to country rocks and pelitic xenoliths); (b) restitic (generally anhedral, high-grade metamorphic inclusions); Type 2 Magmatic: (a,b) peritectic (subhedral to euhedral, associated with leucosomes in migmatites or as reaction rims on garnet); (c) cotectic (euhedral, grain size compatibility with host rock, few inclusions); (d) pegmatitic (large subhedral to euhedral grains, associated with aplite-pegmatite contacts or pegmatitic portion alone); and Type 3 Metasomatic (spatially related to structural discontinuities in host, replacement of feldspar and/or biotite, intergrowths with quartz). Of these, Type 2a (peritectic) and Type 2c (cotectic) predominate in granitic and rhyolitic rocks derived from fluid-undersaturated peraluminous magmas, and Type 2d (pegmatitic) may be the most common type in fluid-saturated systems.
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Cheng, Xi-hui, Jiu-hua Xu, Jian-xiong Wang, Qing-po Xue, and Hui Zhang. "Carbonic fluids in the Hamadi gold deposit, Sudan: origin and contribution to gold mineralization." Canadian Journal of Earth Sciences 54, no. 5 (May 2017): 494–511. http://dx.doi.org/10.1139/cjes-2016-0058.
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The Hamadi gold deposit is located in North Sudan, and occurs in the Neoproterozoic metamorphic strata of the Arabian–Nubian Shield. Two types of gold mineralization can be discerned: gold-bearing quartz veins and altered rock ores near ductile shear zones. The gold-bearing quartz veins are composed of white to gray quartz associated with small amounts of pyrite and other polymetallic sulfide minerals. Wall-rock alterations include mainly beresitization, epidotization, chloritization, and carbonatization. CO2-rich inclusions are commonly seen in gold-bearing quartz veins and quartz veinlets from gold-bearing altered rocks; these include mainly one-phase carbonic (CO2 ± CH4 ± N2) inclusions and CO2–H2O inclusions with CO2/H2O volumetric ratios of 30% to ∼80%. Laser Raman analysis does not show the H2O peak in carbonic inclusions. In quartz veins, the melting temperature of solid CO2 (Tm,CO2) of carbonic inclusions has a narrow range of −59.6 to −56.8 °C. Carbonic inclusions also have CO2 partial homogenization temperatures (Th,CO2) of −28.3 to +23.7 °C, with most of the values clustering between +4.0 and +20 °C; all of these inclusions are homogenized into the liquid CO2 state. The densities range from 0.73 to 1.03 g/cm3. XCH4 of carbonic fluid inclusions ranges from 0.004 to 0.14, with most XCH4 around 0.05. In CO2–H2O fluid inclusions, Tm,CO2 values are recorded mostly at around −57.5 °C. The melting temperature of clathrate is 3.8–8.9 °C. It is suggested that the lowest trapping pressures of CO2 fluids would be 100 to ∼400 MPa, on the basis of the Th,CO2 of CO2-bearing one-phase (LCO2) inclusions and the total homogenization temperatures (Th,tot) of paragenetic CO2-bearing two-phase (LCO2–LH2O) inclusions. For altered rocks, the Tm,CO2 of the carbonic inclusions has a narrow range of −58.4 to ∼−57.0 °C, whereas the Th,CO2 varies widely (−19 to ∼+29 °C). Most carbonic inclusions and the carbonic phases in the CO2–H2O inclusions are homogenized to liquid CO2 phases, which correspond to densities of 0.70 to ∼1.00 g/cm3. Fluid inclusions in a single fluid inclusion assemblage (FIA) have narrow Tm,CO2 and Th,CO2 values, but they vary widely in different FIAs and non-FIAs, which indicates that there was a wide range of trapping pressure and temperature (P–T) conditions during the ore-forming process in late retrograde metamorphism after the metamorphism peak period. The carbonic inclusions in the Hamadi gold deposit are interpreted to have resulted from unmixing of an originally homogeneous aqueous–carbonic mixture during retrogress metamorphism caused by decreasing P–T conditions. CO2 contributed to gold mineralization by buffering the pH range and increasing the gold concentration in the fluids.
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Rao, D. Rameshwar, Rajesh Sharma, and N. S. Gururajan. "Mafic granulites of the Schirmacher region, East Antarctica: fluid inclusion and geothermobarometric studies focusing on the Proterozoic evolution of the crust." Transactions of the Royal Society of Edinburgh: Earth Sciences 88, no. 1 (1997): 1–17. http://dx.doi.org/10.1017/s0263593300002285.
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AbstractIn the Proterozoic complex of the Schirmacher region of East Antarctica, a retrograde pressure–temperature (P–T) history has been inferred through quantitative geothermobarometry and fluid inclusion studies of the mafic granulites. Microthermometric investigations of the fluid phases trapped in quartz and garnet identified three types of inclusions, namely, earliest pure CO2 inclusions (0·987–1·057 g cm−3), CO2–H2O inclusions and aqueous inclusions.The temperature and pressure of metamorphism have been estimated through different calibrations of geothermometers and geobarometers. The mineral reactions and compositional zoning in the minerals record P–T conditions from nearly 837 ± 26°C, 7·1±0·2 kbar to 652 ± 33°C, 5·9 ± 0·3 kbar. A good correlation between the fluid and mineral data is observed. The isochores typical of highdensity CO2 fluids fall well within the P–T box estimated by mineral thermobarometry. The abundance of primary CO2 inclusions in early metamorphic minerals (notably quartz and primary garnet) and the general correspondence between fluid and mineral P–T data indicate a ‘fluid-present’ carbonic regime for the high-grade metamorpism; however, from the present data largescale CO2 advection could not be envisaged. The subsequent stages involved a decrease in CO2 density, a progressive influx of hydrous fluids and the generation of retrograde amphibolite facies metamorphism in the area.The estimated P–T conditions of the region suggest that the rocks were metamorphosed at a depth of 19–24 km, with a geothermal gradient of c. 3°5C km−1. The estimated P–T conditions of the rocks imply a clockwise P–T–t path with a gradual decrease in temperature of around 250°C and a decrease in pressure of around 1700 bar. They have a dP/dT gradient of ≈7 ± l bar °C−1, arguing for an isobaric cooling history of the terrane under normal thickened crust after the underplating of mantle-derived material.
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Fintor, Krisztián, and Andrea Varga. "Paleofluid Fingerprint as an Independent Paleogeographic Correlation Tool: An Example from Pennsylvanian Sandstones and Neighboring Crystalline Rocks (Tisia Composite Terrane, S Hungary)." Geofluids 2020 (March 17, 2020): 1–24. http://dx.doi.org/10.1155/2020/3568986.
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In the basement areas of the southern Pannonian Basin, Central Europe (Tisia Composite Terrane, Hungary), Variscan blocks are essential components. The existing paleogeographic reconstructions, however, are often unclear and contradictory. This paper attempts to give a contribution for paleogeographic correlation of the Tisia using paleohydrological features (e.g., vein mineralization types, inclusion fluid composition and origin) of the Pennsylvanian continental succession and neighboring crystalline complexes. Vein-type mineralization in the studied samples dominantly forms blocky morphological types with inclusion-rich quartz and carbonate crystals. The evolution of hydrothermal mineralization and host rock alteration in the study area comprises three major stages. The first one is characterized by chloritization, epidotization, and sericitization of metamorphic rocks together with subsequent formation of Ca-Al-silicate and quartz-sulfide veins (clinopyroxene-dominant and epidote-dominant mineralization). The related fluid inclusion record consists of high-temperature and low-salinity aqueous inclusions, corresponding to a reduced retrograde-metamorphic fluid phase during the Late Westphalian (~310 Ma). The next mineralization stage can be related to a generally oxidized alkaline fluid phase with a cross-formational character (hematite-rich alkali feldspar-dominant and quartz-dolomite veins). High-salinity primary aqueous inclusions probably were originated from the Upper Permian playa fluids of the region. The parent fluid of the third event (ankerite-hosted inclusions) was derived from a more reductive and low-salinity environment and can represent a post-Variscan fluid system. Fluid evolution data presented in this paper support that the W Tisia (Mecsek–Villány area) belonged to the Central European Variscan belt close to the Bohemian Massif up to the Early Alpine orogenic phases. Its original position is presumably to the northeast from the Bohemian Massif at the Late Paleozoic, north to the Moravo-Silesian Zone. The presented paleofluid evolution refines previous models of the paleogeographic position of the Tisia and puts constraints on the evolution of the Variscan Europe.
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Ma, Ying, Suo-Fei Xiong, Hua-Liang Li, and Shao-Yong Jiang. "Origin and Evolution of the Ore-Forming Fluids in the Liyuan Gold Deposit, Central North China Craton: Constraints from Fluid Inclusions and H-O-C Isotopic Compositions." Geofluids 2017 (2017): 1–21. http://dx.doi.org/10.1155/2017/3107280.
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The Liyuan gold deposit is hosted within Archean basement metamorphic rocks and controlled by the NNE-trending faults in the central North China Craton. The ore-forming processes can be divided into three stages (early, middle, and late). Three types of primary fluid inclusions (FIs) are identified in the Liyuan, including pure carbonic, carbonic-aqueous, and aqueous inclusions. The primary FIs of three stages are mainly homogenized at temperatures of 318–408°C, 201–329°C, and 136–229°C, with salinities of 2.1–8.9, 0.5–12.4, and 0.4–6.3 wt.% NaCl equivalent, respectively. The main Au mineralization is related to the middle stage, and water-rock interaction caused rapid precipitation of gold in this stage. The initial ore-forming fluids were likely magmatic water or metamorphic fluid and mixed with meteoric water at later stages. Due to the lack of granite body at the present mining levels, we speculate that it was magmatic water that might have been exsolved from a concealed granite body at greater depth or it was metamorphic fluid that was directly transported from depth via deep faults. Based on all the available geological and geochemical evidence, we suggest that the Liyuan deposit belongs to orogenic gold deposit that located in the interior North China Craton.
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Korsakov, A. V., A. V. Golovin, T. Dieing, and J. Toporski. "Fluid inclusions in rock-forming minerals of ultrahigh-pressure metamorphic rocks (Kokchetav massif, Northern Kazakhstan)." Doklady Earth Sciences 437, no. 2 (April 2011): 473–78. http://dx.doi.org/10.1134/s1028334x11040040.
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HOSHINO, Kenichi, Ai NAGATOMI, Makoto WATANABE, Takamoto OKUDAIRA, and Yuki BEPPU. "Nahcolite in fluid inclusions from the Ryoke metamorphic rocks and its implication for fluid genesis." Journal of Mineralogical and Petrological Sciences 101, no. 5 (2006): 254–59. http://dx.doi.org/10.2465/jmps.101.254.
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Török, Kálmán. "Multiple fluid migration events and REE+Th mineralisation during Alpine metamorphism in the Sopron micaschist from the Eastern-Alps (Sopron area, Western Hungary)." Földtani Közlöny 150, no. 1 (March 22, 2020): 45. http://dx.doi.org/10.23928/foldt.kozl.2020.150.1.45.
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Four fluid migration events were recorded during the Alpine metamorphism in the Sopron micaschist from the Grob gneiss series of the Lower Austroalpine Unit of the Eastern Alps near Sopron, using mineral chemistry data, geothermo-barometry and fluid inclusion studies.1. Tourmaline mineralisation in quartz veins and to some extent in the host rock. Similar mineral compositions in the quartz-tourmaline veins and in the host rock show equilibrium between fluid and the host rock. Geothermo-barometry gives 560-610oC temperature and 950-1230 MPa pressure for the formation of quartz-tourmaline veins which is the same as the determined P-T peak (T=560 and 600°C p= 840-1230 MPa).2. Fluids causing Mg-metasomatism in the shear zones. The result of this fluid invasion was the formation of leucophyllite in the shear zones and Mg-enrichment of some minerals (chlorite, muscovite, garnet) in the close vicinity of the shear zone. The effect of this fluid was confined to the shear zones and the neighbouring host rock.3. The rock was infiltrated along the shear zones and quartz veins with CO2-bearing hypersaline fluids during retrograde metamorphism. The presence of this fluid is evidenced by secondary CO2 inclusions and hypersaline aqueous fluid inclusions ± CO2. The aqueous fluid had high concentrations of Na, Ca, Fe, Al, Cl and contained moderate amounts of Mg, Zn, Ti, K, Mn, S and P. This fluid was the carrier of the REE and Th and locally precipitated florencite, monazite, allanite, apatite, thorite and thorianite in the shear zone. Traces of this mineralisation are found in quartz-tourmaline veins, postdating the tourmaline mineralisation.4. Late retrograde metamorphic fluid represented by two phase (liquid+vapor) aqueous inclusions of the NaCl-CaCl2-H2O system with total salinity between 25 and 28.5% and homogenisation temperatures between 229.6 and 322oC
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OHYAMA, Hiroyuki, and Toshiaki TSUNOGAE. "Fluid inclusions study of Abukuma metamorphic rocks from the Hanazono district, northeast Japan." Journal of Mineralogical and Petrological Sciences 102, no. 6 (2007): 325–36. http://dx.doi.org/10.2465/jmps.061113.
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Harris, Chris, and Lucrecia Maboane. "The Garies wollastonite deposit, Namaqualand, South Africa: High-Temperature metamorphism of a low-δ18O skarn?" Canadian Mineralogist 59, no. 3 (May 1, 2021): 495–510. http://dx.doi.org/10.3749/canmin.2000071.
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ABSTRACT The Garies wollastonite deposit is located in the Bushmanland terrane of the Namaqualand Metamorphic Province and is part of a discontinuous calc-silicate unit bounded by granulite facies gneiss that experienced peak metamorphic temperatures above 800 °C. In bulk, the deposit is dominated by wollastonite, but varied proportions of garnet, diopside, quartz, calcite, and vesuvianite are also present. Mineral chemistry variations across the deposit are minor, and the absence of inclusions indicates textural and chemical equilibrium. The wollastonite-bearing rocks have unusually low mineral δ18O values: –0.6 to +2.2‰ for garnet, –0.2 to +2. 6‰ for clinopyroxene, and –0.2 to +0.4‰ for wollastonite. Calcite δ18O values range from 6.8 to 11. 8‰ and δ13C values from –6.4 to –3.2‰. Calcite δ18O values are unusually low for calc-silicate rocks, but Δcalcite-garnet values from 3 to 12‰ indicate O-isotope disequilibrium between calcite and the silicate minerals. Garnet-biotite metapelitic and diopside gneisses have unexpectedly low δ18O values (<7‰). The approach to O-isotope equilibrium displayed by coexisting silicate minerals, and low mineral δ18O values in calc-silicate and metapelite and metapsammite gneisses, is consistent with low δ18O values being acquired before peak metamorphism. Low δ18O values in the minerals of the calc-silicate rocks require interaction with external fluid at high water/rock ratio. We suggest that the deposit represents a metamorphosed skarn that developed at the contact between the original carbonate rocks and intruding felsic magmas.
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Nesbitt, Bruce E., and Karlis Muehlenbachs. "Geochemistry of syntectonic, crustal fluid regimes along the Lithoprobe Southern Canadian Cordillera Transect." Canadian Journal of Earth Sciences 32, no. 10 (October 1, 1995): 1699–719. http://dx.doi.org/10.1139/e95-134.
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In conjunction with the Lithoprobe southern Canadian Cordillera program, an extensive examination of geochemical indicators of origins, movement, chemical evolution, and economic significance of paleocrustal fluids was conducted. The study area covers approximately 360 000 km2from the Canadian Rockies to Vancouver Island. Research incorporated petrological, mineralogical, fluid-inclusion, δ18O, δD, δ13C, and Rb/Sr studies of samples of quartz ± carbonate veins and other rock types. The results of the study document a variety of pre-, syn-, and postorogenic, crustal fluid events. In the Rockies, a major pre-Laramide hydrothermal event was identified, which was comprised of a west to east migration of warm, saline brines. This was followed by a major circulation of meteoric water in the Rockies during Laramide uplift. In the southern Omineca extensional zone, convecting surface fluids penetrated to the brittle–ductile transition at 350–450 °C and locally into the underlying more ductile rocks. A principal conclusion of the study is that most quartz ± carbonate veins in metamorphic rocks in the southern Canadian Cordillera precipitated from deeply converted surface fluids. This conclusion supports a surface fluid convection model for the genesis of mesothermal Au–quartz veins, common in greenschist-facies rocks worldwide. The combination of our geochemical results with the results of other Lithoprobe studies indicates that widespread and deep convection of surface fluids in rocks undergoing active metamorphism is a commonplace phenomena in extensional settings, while in compressional-thrust settings the depth of penetration of surface fluids is more limited.
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Makoundi, Charles, Khin Zaw, and Zakaria Endut. "Fluid Inclusion Study of the Penjom, Tersang, and Selinsing Orogenic Gold Deposits, Peninsular Malaysia." Minerals 10, no. 2 (January 28, 2020): 111. http://dx.doi.org/10.3390/min10020111.
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Ore-forming fluids in the auriferous district of the Central gold belt in Peninsular Malaysia were studied for their temperature, salinity, and relationship to the surrounding geology. Microthermometric analysis carried out showed homogenisation temperatures range from 210 to 348 °C (Tersang), between 194 and 348 °C (Selinsing), and from 221 to 346 °C (Penjom). Salinities range from 2.41 to 8.95 wt % NaCl equiv (Tersang), between 1.23 and 9.98 wt % NaCl equiv (Selinsing), and from 4.34 to 9.34 wt % NaCl equiv (Penjom). Laser Raman studies indicated that at the Tersang gold deposit, most inclusions are either pure or nearly pure CO2-rich (87–100 mol %), except for one inclusion, which contains CH4 gas (13 mol %). In addition, at Selinsing, most inclusions are CO2-rich (100 mol %). However, an inclusion was found containing CO2 (90 mol %), with minor N2 and CH4. Additionally, at the Penjom gold deposit, most fluid inclusions are CO2-rich (91–100 mol %), whereas one fluid inclusion is N2-rich (100 mol %) and another one has minor N2 and CH4. At a basin scale, homogenisation temperatures against salinity suggests an isothermal mixing of fluids. Most fluids are CO2-rich and are interpreted to be of metamorphic origin. The evidence further indicates involvement of magmatic fluids that is supported by the association of sandstone and carbonaceous black shales with magmatic rocks, such as rhyolite, rhyolite-dacite, and trachyte-andesite at the Tersang and Penjom orogenic gold deposits.
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Torimoto, Junji, Hiroharu Matsueda, Sachihiro Taguchi, and Takamura Tsuchiya. "Preliminary Study of Fluid Inclusions in the High-Grade Metamorphic Rocks of Sri Lanka." Gondwana Research 4, no. 4 (October 2001): 803. http://dx.doi.org/10.1016/s1342-937x(05)70588-8.
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Lajoie, Marie-Ève, Stephen J. Piercey, James Conliffe, and Daniel Layton-Matthews. "Geology, mineralogy, S and Sr isotope geochemistry, and fluid inclusion analysis of barite associated with the Lemarchant Zn–Pb–Cu–Ag–Au-rich volcanogenic massive sulphide deposit, Newfoundland, Canada." Canadian Journal of Earth Sciences 57, no. 1 (January 2020): 133–66. http://dx.doi.org/10.1139/cjes-2018-0161.
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Barite in the approximately 513 Ma Lemarchant volcanogenic massive sulphide (VMS) deposit, Newfoundland, consists of granular and bladed barite intimately associated with mineralization. Regardless of type, the composition of barite is homogeneous at bulk rock and mineral scale containing predominantly Ba, S, and Sr, with minor Ca and Na. The barite has homogeneous sulphur isotope compositions (δ34Smean = 27‰), similar to Cambrian seawater sulphate (25–35‰) and Sr isotope compositions (87Sr/86Sr = 0.706905 to 0.707485). These results are consistent with barite having formed from fluid–fluid mixing between Cambrian seawater and VMS-related hydrothermal fluids. The 87Sr/86Sr values in the barite are lower than mid-Cambrian seawater, which suggests that some of the Sr was derived from the underlying Neoproterozoic basement. Fluid inclusions in bladed barite are low-salinity, CO2-rich inclusions with homogenization temperatures between 245°–250 °C, and average salinity of 1.2 wt.% NaCl equivalent. Estimated minimum trapping pressures of between 1.7 to 2.0 kbars were calculated from aqueous–carbonic fluid inclusion assemblages. The fluid inclusion results reflect regional metamorphic reequilibration during younger Silurian regional metamorphism, rather than primary fluid signatures, despite the preservation of primary barite and fluid inclusion textures. These results illustrate that barite in VMS deposits records the physicochemical processes associated with VMS formation and the sources of fluids in ancient VMS deposits, as well as seawater sulphate and basement isotopic compositions. The results herein are not only relevant for the Lemarchant deposit but also for other barite-rich VMS deposits globally.
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Mihalynuk, M. G., and E. D. Ghent. "Regional depth-controlled hydrothermal metamorphism in the Zymoetz River area, British Columbia." Canadian Journal of Earth Sciences 33, no. 8 (August 1, 1996): 1169–84. http://dx.doi.org/10.1139/e96-088.
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An estimated 6 km of basic to silicic volcanic flows and clastic rocks of the Early Jurassic Telkwa Formation is exposed in moderately east-dipping fault blocks along the Zymoetz River, British Columbia. Extensive wholesale zeolitic replacement of porous tuff beds suggests widespread hydrothermal activity. Metamorphic grade increases regionally from laumontite–albite facies to prehnite–pumpellyite facies with increasing stratigraphic depth. Telkwa Formation strata and the imparted metamorphic zonation are cut and tilted by rotational block faulting, and are repeated in each of the upturned blocks. Late Mesozoic to Tertiary plutonism locally thermally overprinted the regional facies, particularly in the western part of the area. Fluid-inclusion isochores, combined with calculated mineral equilibria, suggest that metamorphism took place at fluid pressures of 2 kbar (1 kbar = 100 MPa) or less, consistent with estimates of stratigraphic burial. Metamorphic fluids were H2O rich and low in dissolved salts. Maximum temperatures during regional depth-controlled hydrothermal metamorphism, based upon the widespread presence of laumontite and the lack of wairakite in the middle to upper parts of the Telkwa Formation, probably did not exceed about 250 °C at H2O pressures of 2 kbar. Mineral zones, estimated paleotemperatures, and geothermal gradients are comparable to regional hydrothermal metamorphism in active volcanic settings such as Iceland.
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Seccombe, P. K., J. Ju, A. S. Andrew, B. L. Gulson, and K. J. Mizon. "Nature and evolution of metamorphic fluids associated with turbidite-hosted gold deposits: Hill End goldfield, NSW, Australia." Mineralogical Magazine 57, no. 388 (September 1993): 423–36. http://dx.doi.org/10.1180/minmag.1993.057.388.06.
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AbstractThe Hill goldfield, NSW, Australia, is an example of a syntectonic, slate-belt gold deposit formed in a multiply deformed, Late Silurian slate-metagreywacke turbidite sequence. Gold is confined to bedding-parallel veins and discordant leader veins composed of as many as four generations of quartz, accompanied by phyllosilicates, carbonates and minor sulphides. Vein formation and gold deposition was apparently synchronous with Early Carboniferous metamorphism and deformation. Homogenisation temperatures (Th) for fluid inclusions in vein quartz demonstrate five groupings in the temperature intervals 350-280°C 280-250°C 250-190°C 190-150°C and 150-110°C corresponding to a variety of primary and secondary inclusions developed during four periods of vein quartz deposition under a generally declining temperature regime. Inclusion fluids are characterised by a low salinity of around 0.1 to 3.6 wt. % NaCl equivalent. The dominant gas phase present in the inclusion fluids varies from N2 in the early stages of the paragenesis, through CH 4 during the main episode of gold deposition, to CO2- rich fluids associated with late-stage mineralisation. δ18O values for vein quartz (range 15.1-17.1‰) and vein carbonate (range 11.3-13.4‰) are typical of metamorphic mineralisation. δD composition of hydrous minerals and inclusion fluids (range −53 to −138‰) suggest an influx of meteoric water in the later mineralising fluids. This conclusion is supported by δ13C data for vein calcite (range −2.5 to −9.7%0). δ34S composition of vein pyrrhotite and pyrite ranges from 6.9 to 7.8‰ early in the paragenesis, to lighter values (around 4.2 to 5.8%0) accompanying late gold deposition from more oxidising fluids. Sulphur isotope data imply a sulphur source from underlying turbidites and an increase in fluid oxidation state during mineralisation . Lead isotope measurements on vein pyrite, arseno py rite, galena and gold are characterised by two isotope populations with 207Pb/206Pb ratios of 0.862 and 0.860, which define two discrete mineralising events during vein formation. Consistency between data from vein minerals and lead isotope signatures for potential source rocks indicate that lead was derived from the sedimentary pile.
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Chen, Zhen-Yu, Li-Fei Zhang, Zeng Lü, and Jin-Xue Du. "Episodic Fluid Action in Chinese Southwestern Tianshan HP/UHP Metamorphic Belt: Evidence from U–Pb Dating of Zircon in Vein and Host Eclogite." Minerals 9, no. 12 (November 25, 2019): 727. http://dx.doi.org/10.3390/min9120727.
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Fluid plays a key role in metamorphism and magmatism in subduction zones. Veins in high-pressure (HP) to ultrahigh-pressure (UHP) rocks are the products of fluid–rock interactions and can thus provide important constraints on fluid processes in subduction zones. In this study, we present an integrated study of zircon in situ U–Pb dating, trace element and mineral inclusion analysis for a complex vein and its host eclogite in the southwestern Tianshan UHP terrane, aiming to decipher the episodic fluid action during slab subduction and exhumation. Both zircon in eclogite and vein have euhedral, prismatic morphology similar to those crystallized from metamorphic fluid. Zircon in eclogite shows core–rim structures with distinct bounds and mineral inclusions. Zircon in the vein shows sector zoning or weak zoning, with bright rims around most zircon grains, which suggests recrystallization of the zircon crystals after their formation and multiple evolution of the vein. Eclogite zircon rims yield a weighted mean of 311 ± 3 Ma and cores yield a range from 413 ± 4 to 2326 ± 18 Ma, respectively. Vein zircon yields four groups of age (~355 Ma, ~337 Ma, ~315 Ma, and ~283 Ma), which date four episodes of fluid flow involving zircon growth. The first two groups of age may represent prograde epidote–amphibolite facies and amphibolite/blueschist facies metamorphism stage, respectively. The third group is similar to that of eclogite zircon rims, which is thought to date the eclogitic facie metamorphism (320–305 Ma), and the fourth group dates a later retrograde metamorphism after greenschist facies. The vein-forming fluid system was supposed to be an open system indicated by trace element of vein zircon and mineral assemblage of the vein. The coexistence of rutile, zircon, and garnet in prograde vein and the heavy rare earth elements (HREE) enrichment characteristic of vein zircon suggest that the vein-forming fluid are enriched in high field strength elements (HFSE) and HREE, and such fluid could be formed under low P–T conditions.
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Craw, D., and Y. A. Cook. "Retrogressive fluids and vein formation during uplift of the Priestley metamorphic complex, north Victoria Land, Antarctica." Antarctic Science 7, no. 3 (September 1995): 283–91. http://dx.doi.org/10.1017/s0954102095000393.
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The poly-deformed Priestley schist (Wilson Terrane) of north Victoria Land, Antarctica ranges in metamorphic grade from lower greenschist facies to upper amphibolite facies. All grades of schist have been affected by structurally controlled retrogressive H2O-CO2 fluids with 45–70 mole % CO2. The fluids have deposited quartz-carbonate veins with pyrite and chlorite or biotite in late stage structures. Veins typically constitute < 1% of the rock mass, but in one greenschist facies area > 10% of the rock is vein. Veins in higher grade schists have been boudinaged after formation, and many have been annealed. Primary fluid inclusions are preserved in veins in biotite zone schists in two localities. At one locality, entrapment of immiscible fluids (water with c. 8 and 45 mole % CO2) occurred during vein formation, at about 280–300°C and 700 ± 200 bars fluid pressure. The aqueous fluid is slightly saline (4 wt % NaCl equivalent). At the other primary fluid inclusion locality, veins were formed from a single phase fluid (c. 70 mole % CO2) at 200–350°C and 1600 ± 500 bars fluid pressure. Both these vein systems are inferred to have formed between 2 and 8 km depth, near the brittle-ductile transition. Retrogressive fluid mobility and vein formation occurred throughout schist in the Priestly metamorphic complex during uplift in the latter part of the Ross Orogeny (c. 490 Ma), following near-isobaric cooling at metamorphic depths.
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Fernández-Caliani, Juan C., Cesar Casquet, and Emelio Galan. "Complex multiphase fluid inclusions in wollastonite from the Mérida contact-metamorphic deposit, Spain: evidence for rock/HCl-rich fluid interaction." European Journal of Mineralogy 8, no. 5 (October 30, 1996): 1015–26. http://dx.doi.org/10.1127/ejm/8/5/1015.
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FAN, Hongrui. "Fluid inclusions evidence for differential exhumation of ultrahigh pressure metamorphic rocks in the Sulu terrane." Chinese Science Bulletin 50, no. 11 (2005): 1139. http://dx.doi.org/10.1360/982004-541.
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Lamadrid, H. M., W. M. Lamb, M. Santosh, and R. J. Bodnar. "Raman spectroscopic characterization of H2O in CO2-rich fluid inclusions in granulite facies metamorphic rocks." Gondwana Research 26, no. 1 (July 2014): 301–10. http://dx.doi.org/10.1016/j.gr.2013.07.003.
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Cai, Pengjie, Rongke Xu, Youye Zheng, Yueming Yin, Xin Chen, Xianbin Fan, and Chao Ma. "Fluid Inclusion and H–O–S–Pb Isotope Geochemistry of the Yuka Orogenic Gold Deposit, Northern Qaidam, China." Geofluids 2019 (October 7, 2019): 1–17. http://dx.doi.org/10.1155/2019/6912519.
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The Yuka gold deposit, located in the western part of northern Qaidam, contains Au orebodies hosted in early Paleozoic metamorphic basic volcaniclastic rocks. The Yuka mineralization can be divided into three stages: early quartz-pyrite (stage-I), middle quartz-gold-polymetallic sulfide (stage-II), and late quartz-carbonate (stage-III). Gold deposition is primarily contained within stage-II. Three types of fluid inclusions were identified in the vein mineral assemblages using petrography and laser Raman spectroscopy: H2O-CO2-NaCl (C-type), H2O-NaCl (W-type), and pure CO2 (PC-type). Stage-I fluids record medium temperatures (205.2°C to 285.5°C) and H2O-CO2-NaCl±CH4 fluids with variable salinities (0.6–8.5 wt.% NaCl equiv.). Stage-II fluids evolved towards a more H2O-rich composition within a H2O-CO2-NaCl±CH4 hydrothermal system at medium temperatures (193.1°C to 271.1°C), with variable salinities (0.4–11.7 wt.% NaCl equiv.). Stage-III fluids are almost pure H2O and characterized by low temperatures (188.1°C to 248.5°C) and salinities (0.4–16.1 wt.% NaCl equiv.). These data indicate that ore-forming fluids are characterized by low to medium homogenization temperatures and low salinity and are evolved from a CO2-rich metamorphogenic fluid to a CO2-poor fluid due to inputs of meteoric waters, which is similar to orogenic-type gold deposits. The average δ18OW of quartz varies from 3.3‰ in stage-I to 2.1‰ in stage-II and to 1.4‰ in stage-III, with the δD values ranging from −41.6‰ to −58.5‰, suggesting that ore-forming fluids formed from metamorphic fluids mixed with meteoric waters. Auriferous pyrite δ34S ranges from 0.5 to 7.4‰ with a mean value of 4.43‰, suggesting that fluids were partially derived from Paleozoic rocks via fluid-wall rock interactions. Auriferous pyrites have 206Pb/204Pb of 18.238–18.600 (average of 18.313), 207Pb/204Pb of 15.590–15.618 (average of 15.604), and 208Pb/204Pb of 38.039–38.775 (average of 38.1697) and stem from the upper crust. Basing on geological characteristics of the ore deposit as well as new data from the ore-forming fluids, and H-O-S-Pb isotopes, the Yuka gold deposit is best described as an orogenic-type gold deposit.
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ZHANG, Z., K. SHEN, Y. XIAO, J. HOEFS, and J. LIOU. "Mineral and fluid inclusions in zircon of UHP metamorphic rocks from the CCSD-main drill hole: A record of metamorphism and fluid activity." Lithos 92, no. 3-4 (December 2006): 378–98. http://dx.doi.org/10.1016/j.lithos.2006.04.003.
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Giuliani, Gaston, Lee A. Groat, Dan Marshall, Anthony E. Fallick, and Yannick Branquet. "Emerald Deposits: A Review and Enhanced Classification." Minerals 9, no. 2 (February 13, 2019): 105. http://dx.doi.org/10.3390/min9020105.
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Although emerald deposits are relatively rare, they can be formed in several different, butspecific geologic settings and the classification systems and models currently used to describeemerald precipitation and predict its occurrence are too restrictive, leading to confusion as to theexact mode of formation for some emerald deposits. Generally speaking, emerald is beryl withsufficient concentrations of the chromophores, chromium and vanadium, to result in green andsometimes bluish green or yellowish green crystals. The limiting factor in the formation of emeraldis geological conditions resulting in an environment rich in both beryllium and chromium orvanadium. Historically, emerald deposits have been classified into three broad types. The first andmost abundant deposit type, in terms of production, is the desilicated pegmatite related type thatformed via the interaction of metasomatic fluids with beryllium-rich pegmatites, or similar graniticbodies, that intruded into chromium- or vanadium-rich rocks, such as ultramafic and volcanic rocks,or shales derived from those rocks. A second deposit type, accounting for most of the emerald ofgem quality, is the sedimentary type, which generally involves the interaction, along faults andfractures, of upper level crustal brines rich in Be from evaporite interaction with shales and otherCr- and/or V-bearing sedimentary rocks. The third, and comparatively most rare, deposit type is themetamorphic-metasomatic deposit. In this deposit model, deeper crustal fluids circulate along faultsor shear zones and interact with metamorphosed shales, carbonates, and ultramafic rocks, and Beand Cr (±V) may either be transported to the deposition site via the fluids or already be present inthe host metamorphic rocks intersected by the faults or shear zones. All three emerald depositmodels require some level of tectonic activity and often continued tectonic activity can result in themetamorphism of an existing sedimentary or magmatic type deposit. In the extreme, at deepercrustal levels, high-grade metamorphism can result in the partial melting of metamorphic rocks,blurring the distinction between metamorphic and magmatic deposit types. In the present paper,we propose an enhanced classification for emerald deposits based on the geological environment,i.e., magmatic or metamorphic; host-rocks type, i.e., mafic-ultramafic rocks, sedimentary rocks, andgranitoids; degree of metamorphism; styles of minerlization, i.e., veins, pods, metasomatites, shearzone; type of fluids and their temperature, pressure, composition. The new classification accountsfor multi-stage formation of the deposits and ages of formation, as well as probable remobilizationof previous beryllium mineralization, such as pegmatite intrusions in mafic-ultramafic rocks. Suchnew considerations use the concept of genetic models based on studies employing chemical,geochemical, radiogenic, and stable isotope, and fluid and solid inclusion fingerprints. The emerald occurrences and deposits are classified into two main types: (Type I) Tectonic magmatic-relatedwith sub-types hosted in: (IA) Mafic-ultramafic rocks (Brazil, Zambia, Russia, and others); (IB)Sedimentary rocks (China, Canada, Norway, Kazakhstan, Australia); (IC) Granitic rocks (Nigeria).(Type II) Tectonic metamorphic-related with sub-types hosted in: (IIA) Mafic-ultramafic rocks(Brazil, Austria); (IIB) Sedimentary rocks-black shale (Colombia, Canada, USA); (IIC) Metamorphicrocks (China, Afghanistan, USA); (IID) Metamorphosed and remobilized either type I deposits orhidden granitic intrusion-related (Austria, Egypt, Australia, Pakistan), and some unclassifieddeposits.
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Carruzzo, Sarah, Daniel J. Kontak, and D. Barrie Clarke. "Granite-hosted mineral deposits of the New Ross area, South Mountain Batholith, Nova Scotia, Canada: P, T and X constraints of fluids using fluid inclusion thermometry and decrepitate analysis." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 91, no. 1-2 (2000): 303–19. http://dx.doi.org/10.1017/s0263593300007458.
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The 370 Ma peraluminous South Mountain Batholith (SMB) intrudes Meguma Supergroup metasedimentary rocks in Nova Scotia. The New Ross area of the SMB contains polymetallic mineralisation (Sn, W, U, Mo, Cu and Mn) in pegmatite, greisen and vein directly or indirectly associated with highly evolved fractions of the SMB. Eight mineral deposits from this area have several fluid inclusion types hosted by quartz: (1) monophase liquid (L); (2) monophase vapour (V); (3) aqueous, L-V (4) aqueous, L-rich + solids; (5) aqueous, L-rich + halite. Inclusions have irregular to equant shapes and are pseudo-secondary or secondary. The irregularity and variability of L:V ratios within fluid inclusion populations suggest post-entrapment modifications of inclusions (i.e. necking).Thermometric data indicate three distinct fluids in terms of salinity: (1) 19-25 wt. % equiv. NaCl (rarely 14-25 wt. % NaCl equiv.), (2) 29-43 wt. % equiv. NaCl, and (3) 0-9 wt. % equiv. NaCl. Temperatures of first melting and ice/hydrohalife melting indicate CaCl2 in solution. Proximity of the deposits to Meguma Supergroup metasedimentary rocks suggests that this Ca component may be externally derived. The majority of the low-salinity fluid population has the composition of meteoric water. Electron microprobe analyses of artificially decrepitated mounds identify Na, Ca and K as major solutes, with a continuum in terms of compositions. Other solute components in the mounds are Fe and Ba, and a variety of metals of unknown speciation also occur (Cu, Zn, Fe, Ni). Homogenisation temperatures (Th) range from c. 80°C to 370°C, but for inclusion assemblages the range is 10°C to 20°C. Given the 3 kbar depth of emplacement of the SMB, estimated entrapment temperatures are c. 200°C to 550°C. The fluid inclusion data appear to reflect: (1) trapping of mixed Na-K-Ca brines during isobaric cooling in pegmatite and greisen deposits as indicated by large ranges in Th; (2) formation of deposits at different ambient pressures (i.e. depth); and (3) mixing of fluids of different reservoirs (i.e. magmatic, metamorphic, meteoric).
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Pan, Y., M. E. Fleet, and F. J. Longstaffe. "Melt-related metasomatism in mafic granulites of the Quetico subprovince, Ontario: constraints from O-Sr-Nd isotopic and fluid inclusion data." Canadian Journal of Earth Sciences 36, no. 9 (September 1, 1999): 1449–62. http://dx.doi.org/10.1139/e99-041.
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Mafic granulites in the Archean Quetico subprovince, north of Manitouwadge, Ontario, occur as isolated lenses or discontinuous layers in spatial association with tonalitic leucosomes in metasedimentary rocks and exhibit concentric zoning from a biotite-rich margin to an orthopyroxene-rich outer zone and a clinopyroxene-rich central zone, with internal orthopyroxene-bearing leucosomes and, rarely, patches of relict amphibolites within the clinopyroxene-rich zone. Microstructural and microchemical evidence suggests that the mafic granulites formed from amphibolites by combined infiltration-diffusion processes in the presence of a P-F-bearing silicate melt ((P2O5)melt = 0.24-0.28 wt.%) and a CO2-rich (hypersaline?) fluid. The whole-rock and mineral δ18O values of the mafic granulites (8-9 V-SMOW) indicate oxygen-isotope equilibration between amphibolites (6.6-6.9) and associated tonalitic leucosomes (9.5-10) at 700-800°C. Strontium- and Nd-isotope data and U-Pb zircon ages confirm isotopic homogenization at the leucosome-amphibolite boundaries during the peak granulite-facies metamorphism at about 2650 Ma. Texturally, early CO2-rich fluid inclusions in quartz and garnet yield P-T conditions similar to those of the peak granulite-facies metamorphism. Hypersaline fluid inclusions occur in textural coexistence with the early CO2-rich inclusions, but are invariably low in homogenization temperatures (178-234°C). This study shows that silicate melts not only provide a conduit for CO2-rich fluids but also interact directly with country rocks for the formation of granulites. Also, the O-Sr-Nd isotope data show that the documented mobility of rare-earth elements in the Quetico granulite zone is localized in scale and related to anatexis of local metasedimentary rocks during the granulite-facies metamorphism.
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Ortega, L., E. Vindel, and C. Beny. "C-O-H-N fluid inclusions associated with gold-stibnite mineralization in low-grade metamorphic rocks, Mari Rosa mine, Caceres, Spain." Mineralogical Magazine 55, no. 379 (June 1991): 235–47. http://dx.doi.org/10.1180/minmag.1991.055.379.12.
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AbstractThe Mari Rosa mine lies within a low-grade Precambrian alternating series of black shales and metagreywackes in the Spanish Hercynian massif. There are two generations of mineralized veins: V2, gold-(stibnite)-bearing quartz veins, parallel to the main cleavage, and V3, stibnite-bearing quartz veins which postdate the main deformation event.Four main types of inclusions have been identified. Type I, II and IV are aqueous-carbonaceous inclusions, with variable degrees of filling, while type III are non-aqueous and typically single-phase at room temperature. Except for type I (absent in V3), similar inclusions have been observed in both V2 and V3 veins. Gas compositions are always characterised by CH4-N2-CO2 assemblages, ranging from CO2-rich mixtures in the earliest inclusions (type I), to N2-rich mixtures in the latest inclusions (type IV).Gold precipitation in V2 veins can be related to type I inclusions at T > 380°C (TH = 300–380°C). A subsequent drop in XCO2 and cooling are recorded in type II and III inclusions, interpreted to be the result of unmixing of a previously homogeneous fluid derived from type I. This boiling would provoke the precipitation of stibnite at 300°C and 1 kbar. The type IV inclusions, which are the richest in H2O, represent a late fluid circulation at lower temperatures (TH = 190–280°C).
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Li, Xu, Sun Xiaoming, Zhai Wei, Liang Jinlong, Liang Yeheng, Shen Kun, Zhang Zeming, and Tang Qian. "Fluid Inclusions in Quartz Veins from HP-UHP Metamorphic Rocks, Chinese Continental Scientific Drilling (CCSD) Project." International Geology Review 48, no. 7 (July 2006): 639–49. http://dx.doi.org/10.2747/0020-6814.48.7.639.
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Marsh, Erin E., Richard J. Goldfarb, Craig J. R. Hart, and Craig A. Johnson. "Geology and geochemistry of the Clear Creek intrusion-related gold occurrences, Tintina Gold Province, Yukon, Canada." Canadian Journal of Earth Sciences 40, no. 5 (May 1, 2003): 681–99. http://dx.doi.org/10.1139/e03-018.
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The Clear Creek gold occurrences lie within deformed lower greenschist-facies rocks of the western Selwyn basin. They consist of auriferous, sheeted quartz veins that cut six Cretaceous stocks and their hornfels. The veins contain 12% combined pyrite and arsenopyrite, with lesser pyrrhotite, bismuthinite, and scheelite, as well as 25 g/t Au. New 40Ar/39Ar geochronology of hydrothermal micas indicates that the veins formed within 12 million years of granitoid emplacement. Fluid inclusion microthermometry defines a parent ore fluid of ~81 mol.% H2O, 14 mol.% CO2, 4 mol.% NaCl ± KCl, and 1 mol.% CH4, which unmixed into a low- and high-salinity immiscible pair. This suggests a more saline parent fluid and a greater degree of fluid unmixing relative to the other occurrences in the eastern Tintina Gold Province. Inclusions trapped in As- and Bi-rich, high-gold grade veins have homogenization temperatures of 300350°C, whereas inclusions found in more Ag- and Pb-rich veins are characterized by temperatures of 250300°C. Fluid inclusion geobarometry suggests hydro-fracturing and gold deposition at 57 km depth. The δ18O values of quartz samples range from 1316 (per mil) and δ34S for sulfides are also consistent between 3.0 and 0, with the exception of some outliers from the Contact Zone of the Pukelman stock that indicate a lower temperature second phase of mineralization. It remains uncertain as to whether the Clear Creek ore fluids were exsolved from magmas at depth or from devolatilization reactions within the contact metamorphic aureoles of the intrusions.
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Sizaret, Stanislas, Eric Marcoux, Alice Boyce, Michel Jebrak, Roos Stevenson, and Rob Ellam. "Isotopic (S, Sr, Sm/Nd, D, Pb) evidences for multiple sources in the Early Jurassic Chaillac F-Ba ore deposit (Indre, France)." Bulletin de la Société Géologique de France 180, no. 2 (March 1, 2009): 83–94. http://dx.doi.org/10.2113/gssgfbull.180.2.83.
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AbstractDuring the earliest Jurassic, a widespread hydrothermal event occurred in western Europe producing large veins and stratiform F-Ba-Pb-Zn ore deposits. Previous work argued about genetic processes involving circulation of mineralising brines. Two main alternative genetic models are proposed. The first one proposes a convection of brines through the crust to produce ore deposits, the second an early infiltration of brine in the basement followed by expulsion during Mesozoic extension. In the northern French Massif Central, new data on the F-Ba Chaillac deposit suggest that the genesis of these mineralising brines requires a new discussion.Located in the northern French Massif Central, the Chaillac barite and fluorite ore deposit is an exceptional site where a stratiform deposit is rooted onto a vein. The ore deposition is split in two stages: 1) precipitation of green and purple fluorite within the vein (Fg-p stage), with associated fluid inclusions indicating 135°C for deposition from a low salinity fluid, and 2) yellow fluorite and barite stage (Fy-Ba) filling the vein and forming the stratiform deposit. Fluid inclusions depict a mineralising brine at 110°C. The 87Sr/86Sr and 143Nd/144Nd isotopic ratios measured in the fluorite are compared to those of French Massif Central rocks. The ratios in green and purple fluorite are similar to those of monzogranite and granodiorite of the basement; those measured in yellow fluorite involve the granulites and other metamorphic rocks of the basement. Measurements of the Sr isotopic ratio and δ34SCDT in barite and δD in fluorite fluid inclusions suggest a deposition process by the mixing of a hydrothermal fluid with meteoric water.At the scale of the northern Massif Central district, the successive hydrothermal fluid salinities are highly contrasted as in Chaillac deposit. We propose that the two types of hydrothermal fluids have been produced by the boiling of a single fluid at depth.
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Wei, Yu-Ji, Li-Qiang Yang, Jian-Qiu Feng, Hao Wang, Guang-Yao Lv, Wen-Chao Li, and Sheng-Guang Liu. "Ore-Fluid Evolution of the Sizhuang Orogenic Gold Deposit, Jiaodong Peninsula, China." Minerals 9, no. 3 (March 21, 2019): 190. http://dx.doi.org/10.3390/min9030190.
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The Sizhuang gold deposit with a proven gold resource of >120 t, located in northwest Jiaodong Peninsula in China, lies in the southern part of the Jiaojia gold belt. Gold mineralization can be divided into altered rock type, auriferous quartz vein type, and sulfide-quartz veinlet in K-feldspar altered granite. According to mineral paragenesis and mineral crosscutting relationships, three stages of metal mineralization can be identified: early stage, main stage, and late stage. Gold mainly occurs in the main stage. The petrography and microthermometry of fluid inclusion shows three types of inclusions (type 1 H2O–CO2 inclusions, type 2 aqueous inclusions, and type 3 CO2 inclusions). Early stage quartz-hosted inclusions have a trapped temperatures range 303–390 °C. The gold-rich main stage contains a fluid-inclusion cluster with both type 1 and 2 inclusions (trapped between 279 and 298 °C), and a wide range of homogenization temperatures of CO2 occurs to the vapor phase (17.6 to 30.5 °C). The late stage calcite only contains type 1 inclusions with homogenization temperatures between 195 and 289 °C. With evidences from the H–O isotope data and the study of water–rock interaction, the metamorphic water of the Jiaodong Group is considered to be the dominating source for the ore-forming fluid. The ore-fluid belonged to a CO2–H2O–NaCl system with medium-low temperature (160–360 °C), medium-low salinity (3.00–11.83 wt% NaCl eq.), and low density (1.51–1.02 g/cm3). Fluid immiscibility caused by pressure fluctuation is the key mechanism in inducing gold mineralization in the Sizhuang gold deposit.
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Uzel, Jessica, Yves Lagabrielle, Serge Fourcade, Christian Chopin, Pierre Monchoux, Camille Clerc, and Marc Poujol. "The sapphirine-bearing rocks in contact with the Lherz peridotite body: New mineralogical data, age and interpretation." BSGF - Earth Sciences Bulletin 191 (2020): 5. http://dx.doi.org/10.1051/bsgf/2019015.
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Sapphirine-bearing rocks are described in the Aulus Basin (Ariège, France) in a contact zone between the Lherz peridotitic body and Mesozoic metasediments which underwent the Pyrenean Cretaceous high-temperature, low-pressure metamorphic event (Monchoux, 1970, 1972a, 1972b). Sapphirine crystals occur in layered clastic deposits characterized by an uncommon suite of Al-Mg-rich minerals. A detailed petrographic study of sixteen samples representative of the diversity of the Lherz sapphirine-bearing rocks is presented. These rocks include breccias and microbreccias with various compositions. Some samples are composed of polymineralic clasts and isolated minerals that derive from regionally well-known protoliths such as ultramafic rocks, meta-ophites, “micaceous hornfels”, and very scarce Paleozoic basement rocks. Nevertheless, a large portion of the sapphirine-bearing clastic suite is composed of mono- and polymineralic debris that derive from unknown protolith(s). We define a "sapphirine-bearing mineral suite” (SBMS) composed of monomineralic debris including: sapphirine + enstatite + aluminous spinel + Mg-amphiboles + Ca-amphiboles + kornerupine + accessory minerals (apatite, diopside, rutile, serpentine, smectite, tourmaline, vermiculite and a white mica). We highlight the dominance of metamorphic Keuper clastic materials in the studied rocks and the presence of inclusions of anhydrite and F-, Cl-, Sr-rich apatite in minerals of the Al-Mg-rich suite. The brecciated texture and the presence of unequivocal sedimentary features suggest that the sapphirine-bearing rocks were mechanically disaggregated and then experienced winnowing in underwater conditions with poor mixing between the different sources. We measured U-Pb rutile age data in order to provide constraints on the age of (one of) the protolith(s) of those clastic deposits. The obtained age (98.6 + 1.2 Ma) is interpreted as the age of metamorphism of this protolith of the SBMS. Previous works interpreted the Lherz sapphirine-bearing rocks as crustal protoliths modified at depth along the contact with the ultramafic rocks of the Lherz body during their ascent towards shallower depths. These new data imply: (i) an Upper Triassic to Lower Jurassic origin for the main protolith of the sapphirine-bearing rocks; (ii) the metamorphism of this protolith along an active hot crust–mantle detachment during Cenomanian times with the involvement of metasomatic, brine-type fluids; and (iii) its brecciation during the exhumation of the material due to the evolution of the detachment, followed by subsequent sedimentary reworking of the metamorphic material.
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Esteves, Melina C. B., and Frederico M. Faleiros. "Fluid flow and syntectonic veining in an Ediacaran-Cambrian foreland fold–thrust zone, western margin of the São Francisco Craton, Brazil." Journal of the Geological Society 178, no. 3 (January 22, 2021): jgs2020–061. http://dx.doi.org/10.1144/jgs2020-061.
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The western margin of the São Francisco Craton, central Brazil presents a 1300 km long foreland fold–thrust belt where Ediacaran-Cambrian (560–520 Ma) metasedimentary rocks from the Bambuí Group were subsequently deformed during post-collisional stages (520–495 Ma) related to Gondwana assembly. This scenario provides an opportunity to quantify fluid flow regimes and fault-related processes that were active in exhumed foreland fold–thrust zones, which were estimated based on structural, microstructural and fluid inclusion studies of syntectonic veins and host rocks. Kaolinite-bearing synkinematic mineral assemblages from metasedimentary rocks, thermodynamic models and grain-scale deformation accommodated by dissolution–precipitation creep and intracrystalline deformation indicate metamorphic and deformational conditions of 250–270°C. Subhorizontal extensional veins formed under subhorizontal shortening and subvertical extension, supporting vein development under a fold–thrust regime that formed regional NW–SE-trending thrust fault zones and megafolds with NW–SE-trending axes. Orientation and growth microstructures indicate that NW–SE-trending subvertical cleavage-parallel veins formed under subhorizontal NE–SW extension, compatible with those inferred to produce mapped kilometre-scale gentle folds with NE–SW-trending traces. Two primary aqueous fluid inclusion assemblages (FIA) are distinguished by salinity variation: 2–21 wt% NaCleq. in subhorizontal veins and 6–0 wt% NaCleq. in cleavage-parallel subvertical veins. Fluid inclusion thermometry and microstructural analysis suggest that veins crystallized between 250 and 270°C under fluid pressure fluctuating within a range of 50–500 MPa (subhorizontal veins) and 80–320 MPa (cleavage-parallel subvertical veins), evidencing fault-valve behaviour. Trends of coupled decreases in salinity and homogenization temperatures in both FIA indicate downward mixing of meteoric fluids, which was more effective in subvertical veins and was in both cases enhanced by fault-valve behaviour. Dominance of moderate salinity and absence of CO2 and CH4 indicate that the fluids are dominated by formation waters. The salinity signature is similar to those of formation waters and metamorphic fluids derived from rocks of shallow marine environments worldwide.Supplementary material: Details of samples and analytical data are available at https://doi.org/10.6084/m9.figshare.c.5275031
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Idrus, Arifudin, Sukamandaru Prihatmoko, Ernowo Harjanto, Franz Michael Meyer, Irzal Nur, Wahyu Widodo, and Lia Novelia Agung. "Metamorphic rock-hosted orogenic gold deposit style at Bombana (Southeast Sulawesi) and Buru Island (Maluku): Their key features and significances for gold exploration in Eastern Indonesia." Journal of Geoscience, Engineering, Environment, and Technology 2, no. 2 (June 1, 2017): 124. http://dx.doi.org/10.24273/jgeet.2017.2.2.291.
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In Indonesia, gold is commonly mined from epithermal-, porphyry-, and skarn-type deposits that are commonly found in volcanic belts along island arcs or active continental margin settings. Numerous gold prospects, however, were recently discovered in association with metamorphic rocks. This paper focuses on metamorphic rock-hosted gold mineralization in Eastern Indonesia, in particular the Bombana (SE Sulawesi) and Buru Island (Maluku) prospects. At Bombana, gold-bearing quartz-veins are hosted by the Pompangeo metamorphic complex. Sheared, segmented veins vary in thickness from 2 cm to 2 m. Gold is mainly present in the form of ‘free gold’ among silicate minerals and closely related to cinnabar, stibnite, tripuhyite, and in places, minor arsenopyrite. The gold distribution is erratic, however, ranging from below detection limit up to 134 g/t. At least three generations of veins are identified. The first is parallel to the foliation, the second crosscuts the first generation of veins as well as the foliation, and the late-stage laminated deformed quartz-calcite vein represents the third mineralization stage. The early veins are mostly massive to crystalline, occasionally brecciated, and sigmoidal, whereas the second-stage veins are narrower than the first ones and less subjected to brecciation. Gold grades in the second- and third-stage veins are on average higher than that in the earlier veins. Microthermometric and Raman spectrometric studies of fluid inclusions indicate abundant H2O-NaCl and minor H2O-NaCl-CO2 fluids. Homogenization temperatures and salinities vary from 114 to 283 ºC and 0.35 to 9.08 wt.% NaCl eq., respectively. Crush-leach analysis of fluid inclusions suggests that the halogen fluid chemistry is not identical to sea water, magmatic or epithermal related fluids, but tends to be similar to fluids in mesothermal-type gold deposits. In Buru Island (Gunung Botak and Gogorea prospects), two distinct generations of quartz veins are identified. Early quartz veins are segmented, sigmoidal discontinuous and parallel to the foliation of the host rock. This generation of quartz veins is characterized by crystalline relatively clear quartz, and weakly mineralized with low sulfide and gold contents. The second type of quartz veins occurs within the ‘mineralized zone’ of about 100 m in width and ~1,000 m in length. Gold mineralization is intensely overprinted by argillic alteration. The mineralization-alteration zone is probably parallel to the mica schist foliation and strongly controlled by N-S or NE-SW-trending structures. Gold-bearing quartz veins are characterized by banded texture particularly following host rock foliation and sulphide banding, brecciated and rare bladed-like texture. Alteration types consist of propylitic (chlorite, calcite, sericite), argillic and carbonation represented by graphite banding and carbon flakes. Ore mineral comprises pyrite, native gold, pyrrhotite, and arsenopyrite. Cinnabar and stibnite are present in association with gold. Ore chemistry indicates that 11 out of 15 samples yielded more than 1 g/t Au, in which 6 of them graded in excess of 3 g/t Au. All high-grade samples are composed of limonite or partly contain limonitic material. This suggests the process of supergene enrichment. Interestingly, most of the high-grade samples contain also high concentrations of As (up to 991ppm), Sb (up to 885ppm), and Hg (up to 75ppm). Fluid inclusions in both quartz vein types consist of 4 phases including L-rich, V-rich, L-V-rich and L1-L2-V (CO2)-rich phases. The mineralizing hydrothermal fluid typically is CO2-rich, of moderate temperature (300-400 ºC), and low salinity (0.36 to 0.54 wt.% NaCl eq). Based on those key features, gold mineralization in Bombana and Buru Island tends to meet the characteristics of orogenic, mesothermal types of gold deposit. Metamorphic rock-hosted gold deposits could represent the new targets for gold exploration particularly in Eastern Indonesia.
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Dee, S. J., and S. Roberts. "Late-kinematic gold mineralisation during regional uplift and the role of nitrogen: an example from the La Codosera area, W. Spain." Mineralogical Magazine 57, no. 388 (September 1993): 437–50. http://dx.doi.org/10.1180/minmag.1993.057.388.07.
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AbstractVein formation occurred throughout a deformation sequence which involved early transpressive ductile deformation through to late-kinematic transpressive brittle structures which host a series of gold prospects. Fluid inclusion data from (S1) fabric parallel veins associated with early deformation suggest that a low-salinity aqueous fluid, with a mean salinity of 6.4 wt.%, was present during peak metamorphism, Pelite mineralogy and isochores constrain peak metamorphism to the lowermost part of the upper greenschist facies at 325 to 425°C and 1.4 to 3.4 kbar.Fluid inclusion data from auriferous and barren late-kinematic quartz veins, both containing unmixing assemblages of aqueo-carbonic inclusions with low salinities of ≈2.7 wt.% NaCl equiv., indicate unmixing occurred at 300°C and 1.5 kbar.Volatiles (CO2, N2, CH4) are observed in all the late-kinematic veins. The N2contents of veins with elevated gold grades are typically higher than those with low gold grades. N2reaches 8.7 mole% in a vein with 0.49−4.6 p.p.m. Au compared to <1 mole% in a vein with <0.05 p.p.m. Au. The CH4content of late kinematic veins is generally less than 1 mole% and shows no relative enrichment in mineralised veins. The generation of N2in the mineralising fluid most likely results from interaction of fluid with the ammonium ion, NH4+, in micas and feldspars. This interaction could take place either at source, due to metamorphic devolatisation reactions, or along those structures which acted as fluid conduits due to fluid-rock interaction.
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TSUNOGAE, Toshiaki, and Jean DUBESSY. "Ethane- and hydrogen-bearing carbonic fluid inclusions in a high-grade metamorphic rock." Journal of Mineralogical and Petrological Sciences 104, no. 5 (2009): 324–29. http://dx.doi.org/10.2465/jmps.090622f.
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Liu, Fulai, and Zhiqin Xu. "Fluid inclusions hidden in coesite-bearing zircons in ultrahigh-pressure metamorphic rocks from southwestern Sulu terrane in eastern China." Chinese Science Bulletin 49, no. 4 (February 2004): 396–404. http://dx.doi.org/10.1007/bf02900324.
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LIU, Fulai. "Fluid inclusions hidden in coesite-bearing zircons in ultrahigh-pressure metamorphic rocks from southwestern Sulu terrane in eastern China." Chinese Science Bulletin 49, no. 4 (2004): 396. http://dx.doi.org/10.1360/03wd0475.
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Yardley, B. W. D., D. A. Banks, S. H. Bottrell, and L. W. Diamond. "Post-metamorphic gold-quartz veins from N.W. Italy: the composition and origin of the ore fluid." Mineralogical Magazine 57, no. 388 (September 1993): 407–22. http://dx.doi.org/10.1180/minmag.1993.057.388.05.
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AbstractMulti-element crush-leach analysis of H2O-CO2 inclusion fluids from a suite of six vein samples from gold-quartz veins in the Brusson district demonstrates that their solute chemistry (c. 5 wt.% NaCl equivalent) is dominated by sodium chloride with lesser amounts of calcium bicarbonate, potassium chloride and sodium bicarbonate. The samples have been analysed both for gas species (CO2, H2O, N2 and H2S) and for Na, K, Li, Rb, Ca, Mg, Sr, Ba, Fe, Mn, Zn, Pb, Cu, Al, As, B, SO42−, F, Cl, Br and I. The fluids contain appreciable H2S (>10−3 molal), which correlates with the contents of As, CO2 and B. Concentrations of many cations remain similar irrespective of wall rock, but there is evidence of leaching of Li, and possibly I, from some wall rocks. Large variations in the K-content of the fluid may result from precipitation of sericite. The bicarbonate concentrations in the fluids, estimated from charge imbalance, are substantially less than their total CO2 content when trapped as single phase fluids, indicating a low pH. Sulphate : sulphide ratios suggest relatively reducing conditions, which is consistent with Fe concentrations significantly greater than Mn.The gold-quartz veins formed as H2O-CO2 fluids of modest salinity and very uniform composition ascended from depth. Halogen ratios of the fluids are consistent with an ultimate origin for these fluids from deep-penetrating surface or connate waters although such a model requires extremely low fluid : rock ratios, to account for the hydrogen isotope composition of many similar deposits. There is as yet insufficient reference data to use halogen ratios as a rigorous test for the alternative model of an origin for the fluid by metamorphic devolatilisation.
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PANTIA, Adrian-Iulian, and Andra-Elena FILIUȚĂ. "HEAT SENSITIVE BLUE QUARTZ – THE UNUSUAL OCCURRENCE OF ALBEȘTI, ROMANIA." Carpathian Journal of Earth and Environmental Sciences 16, no. 1 (2021): 175–86. http://dx.doi.org/10.26471/cjees/2021/016/165.
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The blue quartz of the Albești metagranite is an interesting and puzzling occurrence in the Romanian geological landscape, both in terms of rarity and available data. The body of literature on blue quartz attributes the color to the Rayleigh/Tyndall scattering of light by nanometer/submicron inclusions, commonly identified as ilmenite or rutile, and as a theoretical possibility, fluid inclusions. The Albești blue quartz undergoes a visible loss of color at temperatures as low as 300°C, and for this reason the most commonly cited light scattering inclusions cannot be the cause of the coloration. Furthermore, there are only a handful of occurrences known to exhibit such a thermal behavior, potentially placing the Romanian occurrence in a rather exclusive class of rock forming blue quartz. The data gathered by optical observations, heat treatment, powder diffraction, infrared spectroscopy, and scanning electron microscopy have shown that the blue color is produced by light scattering, the scattering particles are sensitive to heat, recrystallization can also affect the color, and that the color is likely metamorphic in origin. Despite the fact that the identity of the scattering particles is still unknown (although fluid inclusions, and molecular colloids are suggested as potential light scattering elements), there is strong indication that the color is metamorphic in origin and that it could be used as a marker for a specific set of metamorphic conditions. The results of the present study constitute a first significant step in the understanding of the Albești blue quartz and point in the direction of future research.
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Chai, Peng, Hong-rui Zhang, Zeng-qian Hou, Zhi-yu Zhang, and Lei-lei Dong. "Ore geology, fluid inclusion, and stable isotope constraints on the origin of the Damoqujia gold deposit, Jiaodong Peninsula, China." Canadian Journal of Earth Sciences 57, no. 12 (December 2020): 1428–46. http://dx.doi.org/10.1139/cjes-2018-0247.
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The Damoqujia gold deposit within the Zhaoping Fault Zone on Jiaodong Peninsula in eastern China is hosted primarily by Mesozoic granitoids and contains >60 t of gold, making it an important gold producer. Three mineralization stages are distinguished (early, middle, and late): (K-feldspar)–sericite–quartz–pyrite, quartz – gold – polymetallic sulfides, and quartz–carbonate. Gold deposition occurred mainly in the middle stage. The primary fluid inclusions of three stages are mainly homogenized at temperatures of 236–389, 191–346, and 104–251 °C, with salinities of 2.96–11.33, 1.39–17.28, and 0.53–11.48 wt.% NaCl equivalent, respectively. Fluid inclusion studies indicate that the metallogenic system evolved from CO2-rich mesothermal homogeneous fluids to CO2-poor aqueous fluids due to inputs of meteoric waters. The gold was carried as a bisulfide complex in the ore-forming fluids. Precipitation of gold was caused by a combination of fluid immiscibility and water–rock interaction. Studies of the fluid inclusion characteristics (medium temperature, CO2-rich, and low salinity H2O–CO2–NaCl homogeneous system), hydrogen and oxygen isotopes ([Formula: see text] = –1.0‰ to 7.6‰, δD = –109‰ to –77‰), sulfur values ([Formula: see text] = 4.5‰ to 8.5‰), and regional geological events show that the ore-forming fluids reservoir was likely metamorphic in origin. Based on the immiscibility of fluid inclusion assemblages, the estimated depth and pressure of trapping are 8.3–10.2 km and 83–276 MPa, respectively, corresponding to the depth and pressure of mineralization.
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Rezvukhina, Olga V., Sergey G. Skublov, Dmitriy I. Rezvukhin, and Andrey V. Korsakov. "Rutile in diamondiferous metamorphic rocks: New insights from trace-element composition, mineral/fluid inclusions, and U-Pb ID-TIMS dating." Lithos 394-395 (August 2021): 106172. http://dx.doi.org/10.1016/j.lithos.2021.106172.
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