Melt-related metasomatism in mafic granulites of the Quetico subprovince, Ontario: constraints from O-Sr-Nd isotopic and fluid inclusion data

1999 ◽  
Vol 36 (9) ◽  
pp. 1449-1462 ◽  
Author(s):  
Y Pan ◽  
M E Fleet ◽  
F J Longstaffe
Keyword(s):  
Fluid Inclusions ◽  
Diffusion Processes ◽  
Spatial Association ◽  
Central Zone ◽  
Granulite Facies ◽  
Nd Isotope ◽  
Granulite Facies Metamorphism ◽  
Metasedimentary Rocks ◽  
Isotope Data ◽  
Facies Metamorphism

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.

scholarly journals Dating the Sedimentary Protolith of the Daldyn Group Quartzite, Anabar Shield, Russia: New Detrital Zircon Constraints

Geosciences ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 208
Author(s):  
Nikolay I. Gusev ◽  
Lyudmila Yu. Sergeeva ◽  
Sergey G. Skublov
Keyword(s):  
Detrital Zircon ◽  
Granulite Facies ◽  
Detrital Zircons ◽  
Nd Isotope ◽  
Granulite Facies Metamorphism ◽  
Metasedimentary Rocks ◽  
Archean Rock ◽  
Facies Metamorphism ◽  
Anabar Shield ◽  
Isotope Systematics

Quartzites and paragneisses of the Archean granulite series of the Anabar Shield (Siberian Craton, Russia) are described geochemically. The Sm-Nd isotope systematics of the rocks and the U-Pb age (SHRIMP II) and geochemistry of zircons from quartzites and paragneisses are studied. Newly formed zircons from quartzites display geochemical characteristics of the magmatic type and were produced by rock anatexis upon granulite-facies metamorphism. The Paleoproterozoic age of the latest detrital zircons, 2250 ± 24 Ma, constrains the maximum age of sedimentary rock deposition. The anatectic rims around detrital zircons were formed ca. 2000 ± 9 Ma ago. The time of deposition of the sedimentary protolith of gneisses and quartzites falls within the age interval of the above-mentioned dates and is tentatively accepted as 2.1 Ga. The presence of Paleoproterozoic metasedimentary rocks in the Daldyn Group implies the tectonic heterogeneity of the series and the existence of Paleoproterozoic rock bodies among the predominant Archean rock sequences.

New constraints on metamorphism in the Highjump Archipelago, East Antarctica

2016 ◽  
Vol 28 (6) ◽  
pp. 487-503 ◽  
Author(s):  
Naomi M. Tucker ◽  
Martin Hand
Keyword(s):  
Granulite Facies ◽  
East Antarctica ◽  
Partial Replacement ◽  
Granulite Facies Metamorphism ◽  
Metasedimentary Rocks ◽  
Facies Metamorphism ◽  
Antarctic Expedition ◽  
Higher Temperature ◽  
Temperature And Pressure

AbstractThe age and conditions of metamorphism in the Highjump Archipelago, East Antarctica, are investigated using samples collected during the 1986 Australian Antarctic expedition to the Bunger Hills–Denman Glacier region. In situ U-Pb dating of monazite from three metasedimentary rocks yields ages between c. 1240–1150 Ma and a weighted mean 207Pb/206Pb age of 1183±8 Ma, consistent with previous constraints on the timing of metamorphism in this region and Stage 2 of the Albany–Fraser Orogeny in south-western Australia. This age is interpreted to date the development of garnet ± sillimanite ± rutile-bearing assemblages that formed at c. 850–950°C and 6–9 kbar. Peak granulite facies metamorphism was followed by decompression, evidenced largely by the partial replacement of garnet by cordierite. These new pressure–temperature determinations suggest that the Highjump Archipelago attained slightly higher temperature and pressure conditions than previously proposed and that the rocks probably experienced a clockwise pressure–temperature evolution.

Fluid inclusions in granulites and eclogites from the Bergen Arcs, Caledonides of W. Norway

1990 ◽  
Vol 54 (375) ◽  
pp. 145-158 ◽  
Author(s):  
T. Andersen ◽  
H. Austrheim ◽  
E. A. J. Burke
Keyword(s):  
Fluid Inclusions ◽  
Shear Zones ◽  
Granulite Facies ◽  
Mole Percent ◽  
Molar Volumes ◽  
Granulite Facies Metamorphism ◽  
Laser Raman ◽  
Granulite Metamorphism ◽  
Facies Metamorphism ◽  
Eclogite Facies

AbstractThe Grenvillian granulite-facies complex on Holsnøy island, Bergen Arcs, W. Norway, has been metamorphosed at eclogite-facies conditions during the Caledonian orogeny (ca. 425 Ma). The granulite-eclogite facies transition takes place along shear zones and fluid pathways. Mineral thermobarometry indicates PT conditions of 800–900°C and 8–10 kbar for the Proterozoic granulite facies metamorphism and 700–800°C and 16–19 kbar for the eclogite-forming event. Quartz in the granulite facies complex contains CO2 fluid inclusions with less than 2.5 mole percent N2; the molar volumes are compatible with the PT conditions of the Proterozoic granulite metamorphism. Quartz in pegmatitic quartz + omphacite and quartz + phengite/paragonite veins coeval with shear-zone eclogites contain N2 ± CO2 fluid inclusions. Combined laser Raman microanalysis and microthermometry show that the least disturbed inclusions have XCO2 = 0.1–0.3, and molar volumes less than 40 cm3/mole, which may agree with the PT conditions during Caledonian high-pressure metamorphism. Younger, low-density N2 and N2-H2O fluid inclusions are the results of decrepitation and redistribution of early inclusions during the retrograde PT evolution of the eclogites.

Granulite-facies metamorphism in the Quetico Subprovince, north of Manitouwadge, Ontario

1994 ◽  
Vol 31 (9) ◽  
pp. 1427-1439 ◽  
Author(s):  
Yuanming Pan ◽  
Michael E. Fleet ◽  
Howard R. Williams
Keyword(s):  
Equilibrium Phase ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Granulite Facies Metamorphism ◽  
Metasedimentary Rocks ◽  
Thermal Peak ◽  
Mineral Assemblages ◽  
Facies Metamorphism ◽  
Peak Event ◽  
High Temperature Metamorphism

A zone of granulites, defined by an orthopyroxene-in isograd and extending more than 100 km in length and about 10 km in width, occurs near the southern margin of the Quetico Subprovince, north of Manitouwadge, Ontario. Mineral assemblages in metasedimentary rocks and associated migmatites consist of quartz, plagioclase, garnet, orthopyroxene, biotite, cordierite, sillimanite, K-feldspar, hercynite, magnetite, ilmenite, and other accessory phases. Minor mafic gneisses and calc-silicate pods or lenses are also present. From equilibrium phase relations and thermobarometry, the granulites experienced a thermal-peak event (4–6 kbar (1 bar = 100 kPa), 680–770 °C, a(H2O) of 0.15–0.25 and fO2 of 1–2 log units above the FMQ buffer) in association with D2 deformation, followed by a retrogression (550–660 °C and 3–4 kbar) and a later hydrothermal alteration (1–2 kbar and 200–400 °C). The distribution and calculated peak metamorphic conditions of the granulite zone in the Quetico Subprovince are similar to those of granulites in the English River Subprovince and other proposed accretionary terranes. The low-pressure, high-temperature metamorphism in the Quetico Subprovince is interpreted to be related to both crustal thickening and addition of heat from subduction-related magmatism.

SHRIMP U–Pb zircon geochronology of gneisses from the Gweta borehole, northeast Botswana: implications for the Palaeoproterozoic Magondi Belt in southern Africa

2001 ◽  
Vol 138 (3) ◽  
pp. 299-308 ◽  
Author(s):  
R. B. M. MAPEO ◽  
R. A. ARMSTRONG ◽  
A. B. KAMPUNZU
Keyword(s):  
Central Zone ◽  
Granulite Facies ◽  
Eastern Africa ◽  
High Grade ◽  
Zircon Geochronology ◽  
Granulite Facies Metamorphism ◽  
Grade Metamorphism ◽  
Facies Metamorphism ◽  
High Grade Metamorphism ◽  
Limpopo Belt

This paper presents new U–Pb zircon analyses from garnet–sillimanite paragneisses from the Gweta borehole in northeast Botswana. Concordant to near-concordant analyses of zircon from these rocks reveal a billion year history from 3015 ± 21 Ma for the oldest detrital grain measured, to the age of high-grade metamorphism, 2027 ± 8 Ma. The maximum age of sedimentation in the Magondi belt is constrained by the age of the youngest concordant detrital zircon at 2125 ± 6 Ma. This contrasts with the age of sedimentation in the Central Zone of the Limpopo belt which is Archaean. The comparison of our results with U–Pb zircon data from the Magondi belt in Zimbabwe suggests that the granulite-facies metamorphism in this belt extended between c. 2027–1960 Ma. Granulite-facies rocks with U–Pb zircon ages in this interval are also known in the Ubendian belt and lend support to the correlation of these two segments of Palaeoproterozoic belts in southern and central–eastern Africa. The granulite facies metamorphism in the Magondi belt is coeval with the high-grade metamorphism and granitoids documented further south in the Central Zone of the Limpopo Belt.

scholarly journals Supracrustal rocks in the Ammassalik region, South-East Greenland

1989 ◽  
Vol 146 ◽  
pp. 17-22
Author(s):  
R.P Hall ◽  
B Chadwick ◽  
J.C Escher ◽  
V.N Vasudev
Keyword(s):  
Relative Stability ◽  
Granulite Facies ◽  
Ultramafic Rocks ◽  
Granulite Facies Metamorphism ◽  
East Greenland ◽  
Great Thickness ◽  
Metasedimentary Rocks ◽  
The North ◽  
Facies Metamorphism ◽  
Pelitic Rocks

Large belts of supracrustal rocks are abundant in the Ammassalik region of S.E. Greenland, and are referred to collectively as the Siportoq supracrustal association. They comprise overwhelmingly metasediments, mainly of quartz-rich or semipelitic composition, with variable proportions of quartz, kyanite, sillimanite, garnet and biotite. Graphitic schists are also common and marble horizons occur up to a kilometre thick. Garnet amphibolites are volumetrically minor, and ultramafic rocks are extremely rare. Lithological banding representing relict bedding and rare cross-bedding are locally well preserved. The compositions of the metasedimentary rocks suggest that their provenance was dominantly sialic and the great thickness of semi-pelitic rocks suggests that additions of immature minerals kept pace with gentle subsidence of a basin or shelf environment. The thick marble horizons indicate periods of relative stability. Unlike the surrounding quartzo-feldspathic gneisses in the north of the area, the supracrustal rocks do not appear to have undergone granulite facies metamorphism.

scholarly journals Geochemistry of greenstones in the Tasiusarsuaq terrane, southern West Greenland

2008 ◽  
Vol 15 ◽  
pp. 69-72 ◽  
Author(s):  
Anders Scherstén ◽  
Henrik Stendal ◽  
Tomas Næraa
Keyword(s):  
Spatial Association ◽  
Granulite Facies ◽  
Mineral Deposits ◽  
Base Metals ◽  
Layered Intrusions ◽  
Granulite Facies Metamorphism ◽  
West Greenland ◽  
Facies Metamorphism ◽  
Greenstone Belts ◽  
Green Land

Tonalite-trondhjemite–granodiorite (TTG) gneisses and mela nocratic to ultramafic greenstones dominate the Arc haean basement of southern West Greenland. The greenstones are likely to represent different original environments, which is important as the mineral deposits they may host depend on this. For example, massive sulphide deposits associated with gold and base metals are commonly volcan og enic, while chrome, nickel and platinum group elements are more commonly associated with layered intrusions (Robb 2005). Cur rent investigations by the Geological Survey of Denmark and Greenland (GEUS) in southern West Greenl and are therefore focused on the origin of greenstones and their relationship to associated TTG gneisses. Here, we report on work in progress on greenstones within the Tasiusarsuaq terrane (Fig. 1; Friend et al. 1996). They differ from many other greenstone belts in southern West Green land in their spatial association with the TTG gneisses. Unlike the Isua, Ivisârtoq and Storø greenstone belts in the central and northern Nuuk region, the Tasiusarsuaq greenstones are not proximal to terrane boundaries but form dismembered blocks and slivers within the terrane (Fig. 1). Contact relationships to the gneisses are almost exclusively tectonic, and primary textures are, with rare exceptions, ob literated by amphibolite to granulite facies metamorphism.

Fluid and mineral inclusions in corundum from gem gravels in Sri Lanka

1989 ◽  
Vol 53 (373) ◽  
pp. 539-545 ◽  
Author(s):  
A. A. de Maesschalck ◽  
I. S. Oen
Keyword(s):  
Sri Lanka ◽  
Fluid Inclusions ◽  
Granulite Facies ◽  
Granulite Facies Metamorphism ◽  
Source Areas ◽  
Mineral Inclusions ◽  
Primary Fluid ◽  
Facies Metamorphism ◽  
Secondary Fluid

AbstractMineral and fluid inclusions were studied in seven gem corundums from gravels of three areas in Sri Lanka. All fluid inclusions are pure CO2. Microthermometry results on primary fluid inclusions suggest formation of corundum under granulite facies metamorphism (>630°C, 5.5 kbar). Secondary fluid inclusions indicate different retrograde events of post-metamorphic cooling and uplift for different source areas.

Petrological evolution in the roof of the high-grade metamorphic Central Zone of the Limpopo Belt, South Africa

2005 ◽  
Vol 142 (3) ◽  
pp. 229-240 ◽  
Author(s):  
ARMIN ZEH ◽  
REINER KLEMD ◽  
JAY M. BARTON
Keyword(s):  
South Africa ◽  
Temperature Increase ◽  
Central Zone ◽  
Granulite Facies ◽  
High Grade ◽  
Metamorphic Overprint ◽  
Granulite Facies Metamorphism ◽  
Facies Metamorphism ◽  
Zonation Patterns ◽  
Limpopo Belt

In this study we present new petrological results from the Endora Klippe in the Central Zone of the Limpopo Belt, which may result from horizontal tectonics during the Proterozoic at c. 2.0Ga. Microstructures, assemblages and garnet zonation patterns observed in metapelitic rocks provide evidence that the Endora Klippe rocks underwent a contemporaneous pressure–temperature increase from c. 600°C/5kbar to 650°C/6.5kbar. This is inferred by the use of conventional geothermobarometry and interpretations based on quantitative phase diagrams in the system MnO–(TiO2)–(CaO)–(Na2O)–K2O–MgO–Al2O3–SiO2–H2O. Thus, the petrological results indicate that this part of the Central Zone only underwent a medium-grade metamorphic overprint during a single orogenic event and was never affected by granulite-facies metamorphism, as reported from other parts of the Limpopo Belt. The inferred P–T path, in combination with previous structural and petrological results, leads to the conclusion that the area surrounding the Endora Klippe forms the roof zone of the c. 2.0Ga old granulite-facies rocks forming wide parts of the Limpopo Central Zone.

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