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Geofluids:Developments in Microthermometry,Spectroscopy,Thermodynamics and Stable Isotopes

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Geoscience Frontiers 2016年第1期7卷 151-151页

作者： V.Hurai M.Huraiovà M.Slobodnik R.Thomas jacques touret Institut de Mineralogie Physique des MateriauxCosmochimie(IMPMC)Sorbonne Universités et UPMC Univ Paris 06UMR CNRS7590 Museum National d'Histoire Naturelle IRD UMR 2064 Place JussieuF-75005 ParisFrance 不详

Fluid （and melt） inclusion studies have shown a marked devel- opment in the last decades, as indicated by the increasing number of papers and as covered under major themes in specialized meetings （e.g. ECROFI in Europe, PACROFI in America, ACROFI in Asia）. However, a basic text book is lacking in current literature, available information being either somewhat outdated （e,g. Roedder, 1984） or scattered in multi-author ＂short course＂, mainly organized by the Mineralogical Societies of Canada, America or Europe. A result is that basic features of fluid inclusion studies, notably its key technique, microthermometry, and recently supplemented by micro Raman of infrared spectroscopy, is rarely taught in most universities, leaving the student alone to discover a field of study which has grown to the dimensions of a major science.

关键词： Geofluids Spectroscopy,Thermodynamics and Stable Isotopes

From granulite fluids to quartz-carbonate megashear zones:The gold rush

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Geoscience Frontiers 2014年第5期5卷 747-758页

作者： Bin Fu jacques L.R.touret Research School of Earth Sciences The Australian National University Institut de Mineralogie.de Physique des Materiaux et de Cosmochimie(IMPMC) Sorbonne Universites UPMC Univ Paris 06.UMR CNRS 7590 Museum National d'Histoire Naturelle IRD UMR 206.4 Place Jussieu.F-75005 Paris.France

At peak granulite-facies metamorphic conditions, lower continental crust is arguably fluxed by large amounts of two key low water activity fluids：（i） high-density CO2 and/or （ii） concentrated saline so- lutions. These fluids are either internally-derived, generated by mineral reactions or dehydration melting or, notably for CO2, externally-derived, issued from the underlying mantle. Postmetamorphic evolution results in complete disappearance of these fluids, except for minute remnants preserved in minerals as fluid inclusions. Two major processes are involved：（i） at peak conditions, granitoid magmas form, migrate upward, and crystallize as shallow intrusions in the upper crust （mineralized porphyry types or reduced intrusions）; （ii） during the rapid decompression which almost systematically follows a period of post-peak isobaric cooling, especially for ultrahigh-temperature granulites （anticlockwise P-T paths）, quartz-carbonate megashear zones are formed by repeated periods of seismic activity. Seismic activity may continue until all free fluids have disappeared, resulting in the ultramylonites and pseudotachylites that are found in many granulite domes. A great majority of vein-type Au deposits worldwide occur in the above-mentioned settings or nearby. We suggest that the Au has been scavenged by the granulite fluids, then redistributed and concentrated during the formation of veins and related phenomena.

关键词： Granulite CO2 BrinesMegashear zonesAu mineralization

CO_2,carbonate-rich melts,and brines in the mantle

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Geoscience Frontiers 2014年第5期5卷 697-710页

作者： Maria-Luce Frezzotti jacques L.R.touret Department of Earth and Environmental Sciences University Milano Bicocca.P.za Della Scienza 4.20126 Milano.Italy Mineralogy Universite Pierre et Marie Curie4 Place Jussieu 75272 Paris Cedex 05France

This paper reviews the origin and evolution of fluid inclusions in ultramaflc xenoliths, providing a framework for interpreting the chemistry of mantle fluids in the different geodynamic settings. Fluid inclusion data show that in the shallow mantle, at depths below about 100 km, the dominant fluid phase is CO2 ± brines, changing to alkali-, carbonate-rich （silicate） melts at higher pressures. Major solutes in aqueous fluids are chlorides, silica and alkalis （saline brines; 5-50 wt.% NaCl eq.）. Fluid inclusions in peridotites record CO2 fluxing from reacting metasomatic carbonate-rich melts at high pressures, and suggest significant upper-mantle carbon outgassing over time. Mantle-derived CO2 （±brines） may eventually reach upper-crustal levels, including the atmosphere, independently from, and additionally to magma degassing in active volcanoes.

关键词： Fluid inclusionPeridotiteMantle metasomatismCarbonate-rich meltCO2Saline brine

Fluid-rock interaction in retrograde granulites of the Southern Marginal Zone,Limpopo high grade terrain,South Africa

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Geoscience Frontiers 2014年第5期5卷 673-682页

作者： Jan Marten Huizenga Dirk van Reenen jacques L.R.touret Unit of Environmental Sciences and Management North-West UniversityPrivate Bag X60012520South Africa Economic Geology Research Institute(EGRU) School of Earth and Environmental SciencesJames Cook UniversityTownsvilleQLD 4811Australia Department of Geology University of JohannesburgJohannesburgSouth Africa Institut de Mineralogie.de Physique des Materiaux et de Cosmochimie(IMPMC) Sorbonne Universites UPMC Univ Paris 06UMR CNRS 7590 Museum National d'Histoire Naturelle.IRD UMR 206.4 Place Jussieu.F-75005

Fluid infiltration into retrograde granulites of the Southern Marginal Zone （Limpopo high grade terrain） is exemplified by hydration reactions, shear zone hosted metasomatism, and lode gold mineralisation. Hydration reactions include the breakdown of cordierite and orthopyroxene to gedrite ＋ kyanite, and anthophyllite, respectively. Metamorphic petrology, fluid inclusions, and field data indicate that a low H2O-activity carbon-saturated CO2-rich and a saline aqueous fluid infiltrated the Southern Marginal Zone during exhumation. The formation of anthophyllite after orthopyroxene established a regional retrograde anthophyllite-in isograd and occurred at P-Tconditions of -6 kbar and 610 ℃, which fixes the minimum mole fraction of H20 in the CO2-rich fluid phase at ~ 0.1. The maximum H20 mole fraction is fixed by the lower temperature limit （~800 ℃） for partial melting at -0.3. C-O-H fluid calculations show that the CO2-rich fluid had an oxygen fugacity that was 0.6 log10 units higher than that of the fayalite-magnetite- quartz buffer and that the CO2/（CO2＋CH4） mole ratio of this fluid was 1. The presence of dominantly relatively low density CO2-rich fluid inclusions in the hydrated granulites indicates that the fluid pressure was less than the lithostatic pressure. This can be explained by strike slip faulting and/or an increase of the rock permeability caused by hydration reactions.

关键词： GranuliteFluidLimpopoRetrogradeSouthern Marginal Zone

Incipient charnockites from southern India:The role of brines

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Geoscience Frontiers 2019年第5期10卷 1789-1801页

作者： jacques L.R. touret Robert C. Newton Michel Cuney 121 Rue de la Réunion F-75020ParisFrance Department of Earth Planetary and Space SciencesUCLALos AngelesCAUSA Université de Lorraine CNRS-CREGUGeoRessources BP70239F-54506Vandoeuvre-les-Nancy CedexFrance

Southern India and Sri-Lanka are the places where “incipient charnockites”,*** local transformation of amphibolite-facies gneisses into orthopyroxene-bearing,igneous looking charnockites,have been discovered in the early *** fact that some incipient charnockites occur along a network of brittle fractures,together with CO2 remnants preserved in mineral inclusions,had called for the role of fluids during charnockite *** present work presents new observations on fluid inclusions and microtextures of incipient charnockites from type localities in southern *** addition to CO2-rich fluid inclusions in quartz and feldspar,all of the occurrences have disrupted remnants of concentrated aqueous alkali chloride ***2 inclusions are more abundant in paragneiss (Kerala) than in orthogneiss (Karnataka/Tamil Nadu).The finding of disrupted brine inclusions in the Kabbal charnockite is a key link between closely associated massive charnockites and Closepet Granite,both of which also share the brine *** of the occurrences studied here have feldspar or feldspar-quartz microvein networks along grain boundaries of recrystallized quartz,feldspar and *** metasomatic veins again indicate the action of alkali-exchanging fluids (i.e.,saline solutions).Feldspar microveins,which have been found in most “massive” charnockites,along with the CO2-rich fluid inclusions,suggest a commonality of incipient charnockite and massive charnockite,both types differing in intensity of interaction with metasomatizing pore fluids.

关键词： Incipient charnockite High-grade crustal metamorphism CO2 Brine metasomatism

Charnockite microstructures:From magmatic to metamorphic

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Geoscience Frontiers 2012年第6期3卷 745-753页

作者： jacques L.R.touret Jan Marten Huizenga Musee de Mineralogie MINES ParisTech75272 Paris Cedex 06France Department of Geology.School of Environmental Sciences and Development North-West UniversityPrivate Bag X6001Potchefstroom 2520South Africa

Charnockites sensu lato （charnockite-enderbite series） are lower crustal felsic rocks typically characterised by the presence of anhydrous minerals including orthopyroxene and garnet. They either represent dry （H2O-poor） felsic magmas that are emplaced in the lower crust or granitic intrusions that have been dehydrated during a subsequent granulite facies metamorphic event. In the first case, post- magmatic high-temperature recrystallisation may result in widespread metamorphic granulite microstruc- tures, superimposed or replacing the magmatic microstructures. Despite recrystallisation, magmatic remnants may still be found, notably in the form of melt-related microstructures such as melt inclusions. For both magmatic charnockites and dehydrated granites, subsequent fluid-mineral interaction at inter- grain boundaries during retrogradation are documented by microstructures including K-feldspar micro- veins and myrmekites. They indicate that a large quantity of low-H2O activity salt-rich brines, were present （together with CO2 under immiscible conditions） in the lower crust.

关键词： Charnockite Petrology Microstructure Melt inclusions