Thermobarometry and Mineral Chemistry of Granulite Facies Rocks from Eastern Ghats, India

1998 ◽  
Vol 1 (2) ◽  
pp. 267-274 ◽  
Author(s):  
V. Divakara Rao ◽  
N.N. Murthy
Keyword(s):  
Granulite Facies ◽  
Mineral Chemistry ◽  
Eastern Ghats

Mineral chemistry and reaction textures in metabasites from the Eastern Ghats belt, India and their implications

1993 ◽  
Vol 57 (386) ◽  
pp. 113-120 ◽  
Author(s):  
Somnath Dasgupta ◽  
Pulak Sengupta ◽  
A. Mondal ◽  
M. Fukuoka
Keyword(s):  
Granulite Facies ◽  
Mineral Chemistry ◽  
Eastern Ghats ◽  
Thermal Perturbation ◽  
Granulite Facies Metamorphism ◽  
Eastern Ghats Belt ◽  
Facies Metamorphism ◽  
Garnet Granulite ◽  
C 32 ◽  
Enclosing Rocks

AbstractThree types of mafic granulites, namely two pyroxene-plagioclase granutite (MG), two pyroxeneplagioclase-garnet granulite (GMG) and spinel-olivine-plagioclase-two pyroxene granulite (SMG) are exposed at Sunkarimetta, Eastern Ghats belt, India. The marie granulites exhibit a foliation concordant with that in associated granulite facies quartzofeldspathic gneisses. Textural characteristics and mineral chemical data suggest the following mineral reactions: olivine + plagioclase = spinel + orthopyroxene + clinopyroxene (SMG), orthopyroxene + plagioclase = garnet + quartz (GMG), clinopyroxene + plagioclase = garnet + quartz (GMG) and plagioclase + hemoilmenite + quartz = garnet + ilmenite + 02 (GMG). Geothermobarometry indicates maximum P-T conditions of metamorphism at c. 8.5 kbar, 950°C The marie granulites later suffered nearly isobaric cooling to c. 7.5 kbar, 750°C Bulk compositional characteristics suggest that SMG is of cumulate origin. The protoliths of the mafic granulites, emplaced at c. 32 km depth, are probably responsible for thermal perturbation causing granulite facies metamorphism of the enclosing rocks.

Geochemistry and original nature of Precambrian khondalites in the Eastern Ghats, Orissa, India

1987 ◽  
Vol 78 (2) ◽  
pp. 115-127 ◽  
Author(s):  
B. Dash ◽  
K. N. Sahu ◽  
D. R. Bowes
Keyword(s):  
Soil Profile ◽  
Granulite Facies ◽  
Climatic Conditions ◽  
Eastern Ghats ◽  
Mass Wasting ◽  
Groundwater Movement ◽  
Weathered Soil ◽  
Average Analysis ◽  
Order Of Magnitude ◽  
Alkaline Earths

ABSTRACTThe quartz-sillimanite-garnet rocks of the Precambrian khondalite assemblage of Orissa consist dominantly of SiO2 + Al2O3 + Fe2O3 + FeO (average c. 95%) with Fe2O3 > FeO. An average analysis (H2O and CO2 free) also shows MgO, CaO and Na2O having 1·0, 0·5 and 0·4%, respectively. Compared with average crustal abundances, enrichment is shown in SiO2, Al2O3 and Fetot and depletion shown in MgO, CaO, Na2O and P2O5 with that for CaO being more than an order of magnitude and that for Na2O being a factor of >7. On an SiO2–Al2O3–Fetot plot a clearly defined field, elongate nearly parallel to the SiO2–Al2O3 sideline, is similar to that for deeply weathered soil profiles in Brazil. This correspondence also extends to enrichment, stability or depletion, compared to crustal averages, for Ce, Co, Cu, Ga, La, Ni, Nb, Th, U, Y, Zn and Zr, but not for Ba, Cr and Rb. In addition comparison of the proportions and ratios of alkalis and alkaline earths in average khondalite and in a weathering profile over a granodiorite, considered to be typical of the weathering of continents, shows remarkable similarities.The major and trace element data are consistent with the khondalites being granulite facies—upper amphibolite facies metamorphic equivalents of a deeply weathered soil profile. Associated quartzites and calc-silicate granulites are interpreted as having been silcretes and calcretes, respectively. This interpretation implies (1) the previous existence of a large stable cratonic mass on which the soil profile formed, (2) climatic conditions suitable for the development of such a profile, (3) topography, drainage systems and groundwater movement in Precambrian times similar to those of present day peneplane regions, (4) the presence of free oxygen in the atmosphere, (5) rapid covering (e.g. by products of volcanism) to preclude mass wasting, (6) a Precambrian stratigraphy in the crystalline rocks of the Eastern Ghats region similar to that of South India, and (7) orogenesis that involved tectonic repetition of lithological units and a mechanism for taking products of surface weathering down to granulite facies P–T conditions and subsequently elevating them.

Late Paleozoic detrital history of eastern Gondwanaland: petrofacies and detrital geochronology of Permo-Carboniferous intracratonic sequences of the northwest Bengal Basin

2020 ◽  
Vol 90 (4) ◽  
pp. 389-402 ◽  
Author(s):  
Md. Iftekhar Alam ◽  
Ashraf Uddin ◽  
Willis E. Hames
Keyword(s):  
Sediment Cores ◽  
Granulite Facies ◽  
Mineral Chemistry ◽  
Dominant Mode ◽  
Heavy Minerals ◽  
Bengal Basin ◽  
Peninsular India ◽  
History Of ◽  
Age Range ◽  
Sandstone Petrography

ABSTRACT Permo-Carboniferous Gondwanan sequences have been reported from several isolated basins of Peninsular India. These siliciclastic sequences were preserved in several intracratonic basins in northwest Bangladesh. Sandstone petrography, heavy-mineral assemblages, mineral chemistry, and 40Ar/39Ar geochronology of sediment cores were used in this study to decipher the provenance history of Gondwanan sediments at two localities (Khalashpir and Barapukuria). Petrographic studies suggest that these sequences are mostly immature and poorly sorted arkosic sandstones (Khalashpir-Qt60F27L13, Barapukuria-Qt52F31L17), with compositions ranging from quartzarenite to litharenite. Among lithic fragments, sedimentary types are abundant. Heavy minerals are volumetrically rare and of low diversity in sediments of northwest Bangladesh. Garnet geochemistry indicates that metamorphic grades in the source terranes were of the amphibolite to granulite facies. Laser 40Ar/39Ar ages for single crystals of detrital muscovite from the deepest drilled Gondwanan sequences yielded the broadest age range, with a dominant mode at circa 515 Ma and lesser clusters of ages at circa 550, 570, and 600 Ma. The other two shallower samples are dominated by ages with similar single modes at circa 495–500 Ma. The oldest muscovite crystals may have been derived from the adjacent Indian craton and/or the Meghalayan craton. Younger muscovite crystals may have been contributed from the Pinjarra Orogen, formed during episodes of Neoproterozoic to early Paleozoic collision among India, Antarctica, and Australia.

Origin of orthopyroxene-bearing felsic gneiss from the perspective of ultrahigh-temperature metamorphism: an example from the Chilka Lake migmatite complex, Eastern Ghats Belt, India

2020 ◽  
Vol 84 (5) ◽  
pp. 712-737 ◽  
Author(s):  
Sankar Bose ◽  
Kaushik Das ◽  
Junji Torimoto ◽  
Daniel Dunkley
Keyword(s):  
Partial Melting ◽  
Tectonic Setting ◽  
Granulite Facies ◽  
Time Frame ◽  
Eastern Ghats ◽  
Chilka Lake ◽  
Granulite Facies Metamorphism ◽  
Eastern Ghats Belt ◽  
Facies Metamorphism ◽  
Show Evidence

AbstractOrthopyroxene-bearing felsic gneiss occurs as foliation-parallel layers and bands together with aluminous granulite, mafic granulite, and quartzofeldspathic granulite in the Chilka Lake migmatite complex of the Proterozoic Eastern Ghats Belt, India. The rock was classified previously as charnockite which underwent granulite-facies metamorphism. Field and textural features of this rock show evidence of the partial melting of a biotite-bearing greywacke protolith. Orthopyroxene with/without garnet and cordierite were produced with K-feldspar as peritectic phases of incongruent melting of presumed metaluminous sediments. Fluid-inclusion data suggest the presence of high-density CO2-rich fluids during peak metamorphism, which are similar to those found in associated aluminous granulite. Whole-rock major and trace element data show wide variability of the source materials whereas REE distributions show enriched LREE and flat HREE patterns. Zircon grains from representative samples show the presence of inherited cores having spot dates (SHRIMP) in the range c. 1790–3270 Ma. The overgrowth on zircon was formed predominantly during c. 780–730 Ma and sporadically during c. 550–520 Ma. Some neoblastic zircons with c. 780–730 Ma ages are also present. U-rich dark zones surrounding cores appear partially metamictised, but spot ages from this zone vary within c. 1000–900 Ma. The <1000 Ma ages represent metamorphism that mirrors the events in associated aluminous granulite. The sources of metaluminous sediments are speculative as the rock compositions are largely modified under granulite-facies metamorphism and partial melting. Considering the accretionary tectonic setting of the Eastern Ghats Belt during the c. 1000–900 Ma time frame, a greywacke-type protolith for the migmatite complex has been proposed.

Charnockite and related neosome development in the Eastern Ghats, Orissa, India: petrographic evidence

1984 ◽  
Vol 75 (3) ◽  
pp. 341-352 ◽  
Author(s):  
Adrian F. Park ◽  
B. Dash
Keyword(s):  
Structural Control ◽  
Late Phase ◽  
Shear Zones ◽  
Granulite Facies ◽  
Potassium Feldspar ◽  
Eastern Ghats ◽  
Late Archaean ◽  
Deep Crust ◽  
Planar Shear ◽  
Mineral Assemblages

ABSTRACTCharnockite and homophanous leptynite are two quartz–feldspar neosomes in the late Archaean granulite-migmatite Eastern Ghats terrane of Orissa, India. Three phases of deformation and metamorphism are recognised to have preceded a late phase, or phases in which deformation was not intense. An early granulite facies event (D1–M1) produced basic granulites and khondalite (sillimanite-garnet aluminous paragneiss). A second event (D2–M2) involved some retrogression but temperatures and pressures remained high (possibly c. 750°C—>5 kb). D3–M3 was associated with the development of open folds (F3) with axial planar shear zones in pinched antiforms; temperatures and pressures were also falling (c. 650°C— 4kb), but the shear zones acted as a control on the development of firstly homophanous leptynite, and secondly charnockite. In both cases, neosomes of quartz and potassium feldspar have myrmekitic textures and intergranular occurrence. The palaeosome became strained and garnet–biotite and garnet–biotite–clinopyroxene ± orthopyroxene mineral assemblages were formed in association with the development, respectively, of homophanous leptynite and charnockite. The persistence of straining in the palaeosome and the presence of poikilitic textures indicate that this typical assemblage does not represent one in thermodynamic equilibrium. This has important consequences for geothermobarometry.The structural control on neosome development reflects a regional characteristic where shear zones are the site of peralkaline plutons, fenitisation, carbonatites and epigenetic graphite development. The peculiar features of charnockite are seen as just one of several aspects related to the fluxing of hot CO2-dominated fluids from either the deep crust or mantle during the late Archaean development of the Indian craton.

Late Paleoproterozoic granulite-facies metamorphism in the North Altyn Tagh area, southeastern Tarim craton: Pressure-temperature paths, zircon U-Pb ages, and tectonic implications

2019 ◽  
Vol 131 (9-10) ◽  
pp. 1591-1606 ◽  
Author(s):  
Hailin Wu ◽  
Wenbin Zhu ◽  
Rongfeng Ge
Keyword(s):  
Granulite Facies ◽  
Mineral Chemistry ◽  
Crustal Thickening ◽  
Granulite Facies Metamorphism ◽  
Magmatic Arc ◽  
Collisional Orogen ◽  
The North ◽  
Altyn Tagh ◽  
Facies Metamorphism ◽  
Tarim Craton

Abstract Granulite occupies the root of orogenic belts, and understanding its formation and evolution may provide critical information on orogenic processes. Previous studies have mainly focused on garnet-bearing high-pressure and medium-pressure granulites, whereas the metamorphic evolution and pressure-temperature (P-T) paths of garnet-absent, low-pressure granulites are more difficult to constrain. Here, we present zircon U-Pb ages and mineral chemistry for a suite of newly discovered two-pyroxene granulites in the North Altyn Tagh area, southeastern Tarim craton, northwestern China. Conventional geothermobarometry and phase equilibrium modeling revealed that these rocks experienced a peak granulite-facies metamorphism at T = 790–890 °C and P = 8–11 kbar. The mineral compositions and retrograde symplectites record a clockwise cooling and exhumation path, possibly involving near-isothermal decompression followed by near-isobaric cooling. Zircon U-Pb dating yielded a ca. 1.97 Ga metamorphic age, which likely represents the initial cooling age, based on Ti-in-zircon thermometry. Combined with regional geological records, we interpret that these granulites originated from the basement rocks of a late Paleoproterozoic magmatic arc that was subsequently involved in a collisional orogen in the southern Tarim craton, presumably related to the assembly of the Columbia/Nuna supercontinent. The clockwise P-T paths of the granulites record crustal thickening and burial followed by crustal thinning and exhumation in the upper plate of the collisional orogen. Our data indicate that the initial exhumation of this orogen probably occurred no later than ca. 1.97 Ga, which is supported by widespread 1.93–1.85 Ga postorogenic magmatism in this area.

Metamorphism of the Arseno Lake area, N.W.T., Canada: an Abukuma facies series of Aphebian age

1986 ◽  
Vol 23 (5) ◽  
pp. 646-669
Author(s):  
Peter A. Nielsen
Keyword(s):  
Northwest Territories ◽  
Electron Microprobe ◽  
Granulite Facies ◽  
Mineral Chemistry ◽  
Metamorphic Grade ◽  
Lake Area ◽  
Metamorphic Fluid ◽  
Physical Conditions ◽  
Fe Content ◽  
Metamorphic Series

Progressive mineralogical and mineral–chemical changes are described for metapelitic rocks from an Abukuma-type metamorphic series ranging from greenschist to upper amphibolite – granulite facies in the Bear Structural Province, Northwest Territories, Canada.The first appearance of the following minerals defines six isograds: biotite; andalusite; cordierite (muscovite + chlorite out); sillimanite (andalusite out); sillimanite + K-feldspar (muscovite + quartz out); and almandine + K-feldspar ± cordierite (biotite + sillimanite + quartz out).Electron microprobe analyses of the Fe–Mg silicates, biotite, cordierite, and garnet, display two distinct trends of mineral chemistry with increasing metamorphic grade. In the almandine + K-feldspar ± cordierite zone, where garnet is present, Fe/(Fe + Mg) decreases in all of the Fe–Mg silicates observed. However, in the cordierite zone and in the higher grade rocks where garnet is absent, Fe/(Fe + Mg) increases in both biotite and cordierite. Ilmenite and rutile are involved in all continuous reactions and lead to increasing Fe/Mg with grade unless garnet is a product of reaction. There is also a displacement towards lower Fe content at the sillimanite + K-feldspar isograd.The scale of equilibration decreases to 1–2 mm in the almandine + K-feldspar ± cordierite zone, which is most probably a function of the decrease of [Formula: see text] and therefore [Formula: see text]in the metamorphic fluid with increasing metamorphic grade.The physical conditions of metamorphism in the Arseno Lake area range from [Formula: see text] at 2–2.5 kbar with[Formula: see text] in the chlorite zone to ≥650 °C at 3.5–4.0 kbar where [Formula: see text] in the almandine + K-feldspar ± cordierite zone.

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