Journal ArticleDOI
Regional Carbonate Alteration of the Crust by Mantle-Derived Magmatic Fluids, Tamil Nadu, South India
TLDR
In this paper, carbon, oxygen, and strontium isotope analyses of samples of ankerite and calcite, together with some of the coexisting silicate minerals, have been used to constrain the conditions of formation of the carbonate alteration and the origin of the fluids involved.Abstract:
Regional carbonate alteration of the crust associated with major shear zones provides direct evidence for $CO_{2}$-rich fluid mobility. A good example occurs within the Attur lineament, one of numerous Proterozoic shear zones which crosscut charnockitic gneisses and other lithologies of the southern Indian craton. At this locality, widespread carbonate alteration of silicate rocks has involved growth of ankerite and other carbonate minerals which replace preexisting silicates. Some of the ankerite was subsequently recrystallized to fine-grained calcite and iron oxide, accompanied by sericitization of feldspar. Carbon, oxygen, and strontium isotope analyses of samples of ankerite and calcite, together with some of the coexisting silicate minerals, have been used to constrain the conditions of formation of the carbonate alteration and the origin of the fluids involved. $\delta^{13}C$ values of ankerite are relatively homogeneous, ranging between -6.5 and -3.9 ‰ with a mean of -5.3 ‰. $\delta^{18}O$ is also ...read more
Citations
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Journal ArticleDOI
CO2 flushing: A plate tectonic perspective
M. Santosh,Soichi Omori +1 more
TL;DR: In this paper, the authors present results from thermodynamic computations in appropriate petrogenetic systems to quantitatively evaluate CO2 generation from calc-silicate rocks as well as model mantle peridotite, and demonstrate that CO2 release occurs in both cases under the P-T conditions and tectonic settings inferred for the formation of charnockites and ultrahigh-temperature granulites.
Journal ArticleDOI
The Chemistry of Carbon in Aqueous Fluids at Crustal and Upper-Mantle Conditions: Experimental and Theoretical Constraints
TL;DR: Carbon can be a major constituent of crustal and mantle fluids, occurring both as dissolved ionic species (e.g., carbonate ions or organic acids) and molecular species (i.e., CO2, CO, CH4, and more complex organic compounds) as discussed by the authors.
Journal ArticleDOI
Experimental determination of calcite solubility in H2O-NaCl solutions at deep crust/upper mantle pressures and temperatures: Implications for metasomatic processes in shear zones
TL;DR: In this article, the authors measured the solubility of calcite in NaCl-H 2 O solutions at 600-900 °C, 10kbar, at NaCl concentrations ranging from dilute to near halite saturation, and at 6-14 kbar, 700 °C in 30 mol% NaCl solutions.
Journal ArticleDOI
Role of saline fluids in deep‐crustal and upper‐mantle metasomatism: insights from experimental studies
TL;DR: In this paper, the authors investigated the role of brines in the deep crust and upper mantle of metamorphic and magmatic systems and provided new insights into fluid-rock interaction in a range of settings.
Journal ArticleDOI
Differentiation of Late Archean Crust in the Eastern Dharwar Craton, Krishnagiri-Salem Area, South India
TL;DR: The Late Archean crust south of Krishnagiri, Tamil Nadu, consists of tonalitic-trondhjemitic-granodioritic (TTG) gneisses with mafic and sedimentary enclaves, formed between 2.7 and 2.5 Ga and metamorphosed at amphibolite facies in the north to granulite faces in the south close to 2.4 Ga as mentioned in this paper.
References
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Book ChapterDOI
Magmas as a Source of Heat and Fluids in Granulite Metamorphism
TL;DR: In this article, it was shown that CO2-saturated silicic and mafic granulites can exsolve enough CO2 to dehydrate a volume of country rock approximately equal to 20% of the volume of the actual granulite itself.
Journal ArticleDOI
Hydrothermal dolomite marbles associated with charnockitic magmatism in the Proterozoic Bamble Shear Belt, south Norway
TL;DR: Deformed and metamorphosed dolomite marbles in the Kragero area of the Bamble Shear Belt occur as lenses within metasupracrustal sequences, as matrix in bodies resembling magmatic breccias, and as veins/dykes cutting amphibolites and metagabbros as mentioned in this paper.
Journal ArticleDOI
Charnockites of the type area near Madras; a reinterpretation
TL;DR: Charnockite as mentioned in this paper is defined as a hypersthene-quartz-feldspar rock, with or without garnet, characterized by greenish blue feldspars, with microperthite dominant.
Journal ArticleDOI
High-temperature hydration of ultramafic granulites from the Southern Marginal Zone of the Limpopo Belt by infiltration of CO2-rich fluid
TL;DR: In this article, the peak metamorphic assemblage of olivine + orthopyroxene + calcic amphibole + spinel is replaced by a variety of high-temperature retrograde assemblages in ultramafic granulites from the Southern Marginal Zone of the Limpopo Belt.
Book ChapterDOI
Temperature, Pressure and Metamorphic Fluid Regimes in the Amphibolite Facies to Granulite Facies Transition Zones
TL;DR: In this paper, high activities of F, CO2 and SO2 were recorded in fluorbiotite and scapolite and water activities were 0.35 and lower, based on calculations of orthopyroxene stability, fluid inclusions, and volatiles in cordierite.