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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 l.r.e 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.r.actions 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 ul.r.high-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 ul.r.mylonites 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

How everything started:A retrospective

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Geoscience Frontiers 2014年第5期5卷 627-634页

作者： jacques touret 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

recalling some of the most important events and persons during his education and career, the author sketches his growth from a young engineer, educated in the sanctuary of solid state reactions, to an involved fully devoted scientific career for the study of fluids in the deep Earth. Most important in this respect was the discovery of C02 inclusions in granulites, which triggered years of discussion on fluid- absent or fluid-assisted granulite metamorphism. To some extent, this debate is a continuation of the former granite controversy, but it shows also how the famous battle of ＂soaks against pontiffs＂ could have been easily avoided.

关键词： Granite controversyMetamorphic petrologyFluid inclusionsJ touretGranulites

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 ul.r.maflc 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 chl.r.des, 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 infil.r.tion 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 infil.r.ted the Southern Marginal Zone during exhumation. The formation of anthophyllite after orthopyroxene established a regional.r.trograde 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

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 l.r.e 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

Composition and evolution of the continental crust:retrospect and prospect

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Geoscience Frontiers 2022年第5期13卷 1-15页

作者： J.l.r.touret M.Santosh J.M.Huizenga Institut de Minéralogie Physique des MatériauxCosmochimieSorbonne Universités4 Place JussieuF-75005 ParisFrance 121 rue de la réunion 75020 ParisFrance School of Earth Sciences and resources China University of GeosciencesBeijing 100083China Department of Earth Science University of AdelaideAdelaideSA 5005Australia Faculty of Environmental Sciences and Natural.r.source Management Norwegian University of Life SciencesP.O.Box 5003NO-1432ÅsNorway EGrU(Economic Geology research Centre) James Cook UniversityTownsvilleQueensland 4811Australia Department of Geology University of JohannesburgPO Box 524Auckland Park 2006South Africa

Until the middle of the 20th century,the continental crust was considered to be dominantly *** hypothesis was revised after the Second World War when several new studies led to the realization that the continental crust is dominantly made of metamorphic *** rocks were emplaced at peak metamorphic conditions in domains,which can be defined by geophysical *** to medium-grade metamorphic rocks constitute the upper crust,granitic migmatites and intrusive granites occur in the middle crust,and the lower crust,situated between the Conrad and Moho discontinuities,comprises charnockites and *** continental crust acquired its final structure during metamorphic episodes associated with mantle upwelling,which mostly occurred in supercontinents prior to their disruption,during which the base of the crust experienced ul.r.high temperatures(>1000℃,ul.r.high temperature granulite-facies metamorphism).Heat is provided by underplating of mantle-derived mafic magmas,as well as by a massive influx of low H_(2)O activity mantle fluids,***-density CO_(2) and highsalinity *** fluids are initially stored in ul.r.high temperature domains,and subsequently infil.r.te the lower crust,where they generate anhydrous granulite mineral *** brines can reach upper crustal levels,possibly even the surface,along major shear zones,where granitoids are generated through brine streaming in addition to those formed by dehydration melting in upper crustal levels.

关键词： Brines CO_(2) Continental crust Granulite lower crust

High-temperature granulites and supercontinents

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Geoscience Frontiers 2016年第1期7卷 101-113页

作者： J.l.r.touret M.Santosh J.M.Huizenga Institut de Mineralogie Physique des MateriauxCosmochimie(IMPMC)Sorbonne Universites et UPMC Univ Paris 06UMR CNRS 7590Museum National d'Histoire NaturelleIRD UMR 2064 Place JussieuF-FS005 ParisFrance School of the Earth Sciences and resources China University of Geosciences(Beijing)29 Xueyuan RoadBeijing 100083China Economic Geology research Institute(EGrU) College of ScienceTechnology and EngineeringJames Cook UniversityTownsvilleQueensland4811Australia Unit for Environmental Sciences and Management North-West UniversityPrivate Bag X60012520South Africa

The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature（P-T）conditions of（ul.r.） high-temperature granulites and magmatic rocks are simil.r. Continents grow laterally, by magmatic activity above oceanic subduction zones（high-pressure metamorphic setting）, and vertically by accumulation of mantle-derived magmas at the base of the crust（high-temperature metamorphic setting）. Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by l.r.e amounts of low H2O-activity fluids including high-density CO2 and concentrated saline solutions（brines）. These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ul.r.-high temperature metamorphism involving l.r.e-scale accumulation of these low-water activity fluids in the lower *** accumulation causes tectonic instability, which together with the heat input from the subcontinental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.

关键词： Continents Supercontinents Magmatism and metamorphism Fluids Tectonics

SPECTrAl IMAGING AND ANAlYSIS TO YIElD TISSUE OPTICAl PrOPErTIES

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Journal of Innovative Optical Health Sciences 2009年第2期2卷 123-129页

作者： STEVEN l.jacques Departments of Dermatology and Biomedical Engineering Oregon Health&Science University PortlandOregonUSA

An introduction to the basics of spectral imaging as applied to biological tissues is *** example of a spectral image of a face is used to demonstrate the data and spectral analysis that specify the melanin content(M),blood content(B),tissue oxygen saturation(S),water content(W),fraction of scattering due to rayleigh scattering(f)and due to Mie scattering(1−f),and the reduced scattering coefficient at 500-nm wavelength(µs 500 nm).The sensitivity of reflectance spectra to variation in the various parameters is illustrated.

关键词： Spectroscopy spectral imaging tissue optical properties optical diagnostics.

FrACTAl NATUrE OF lIGHT SCATTErING IN TISSUES

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Journal of Innovative Optical Health Sciences 2011年第1期4卷 1-7页

作者： STEVEN l.jacques Dermatology and Biomedical Engineering Oregon Health and Science University 3303 SW Bond Ave Portland OR97239USA

light scattering by a tissue has a wavelength dependence that depends on the size distribution of scatterers in the *** measuring the wavelength dependence of scattering,one can deduce changes in the nanoscale architecture of cells and *** report discusses the connection between nanoscale architecture and measurable light *** significance of this work is to develop label-free optical imaging that describes tissue structure,to complement the absorption,fluorescence,and raman scattering spectra that describe the chemical constituents of a tissue.

关键词： Optical scattering fractal biomedical optics