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.

Geology and U–Pb geochronology of the Neoarchean Snare River terrane: tracking evolving tectonic regimes and crustal growth mechanisms

2005 ◽  
Vol 42 (6) ◽  
pp. 895-934 ◽  
Author(s):  
Venessa Bennett ◽  
Valerie A Jackson ◽  
Toby Rivers ◽  
Carolyn Relf ◽  
Pat Horan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Ionization Mass ◽  
Granulite Facies Metamorphism ◽  
Zircon Crystallization ◽  
Facies Metamorphism ◽  
Turbidite Sedimentation

U–Pb zircon crystallization ages determined by isotope dilution – thermal ionization mass spectrometry (ID–TIMS) and laser ablation microprobe – inductively coupled plasma – mass spectrometry (LAM–ICP–MS) for 13 intrusive units in the Neoarchean Snare River terrane (SRT) provide tight constraints on the timing of crust formation and orogenic evolution. Seven metaluminous plutons were emplaced over ~80 Ma from ca. 2674 to 2589 Ma, whereas six peraluminous bodies were emplaced in a ~15 Ma interval from ca. 2598 to 2585 Ma. A detrital zircon study yielded an age spectrum with peaks correlative with known magmatic events in the Slave Province, with the ca. 2635 Ma age of the youngest detrital zircon population providing a maximum estimate for the onset of sedimentation. This age contrasts with evidence for pre-2635 Ma sedimentation elsewhere in the SRT, indicating that sedimentation was protracted and diachronous. Evolution of the SRT can be subdivided into four stages: (i) 2674–2635 Ma — formation of a metaluminous protoarc in a tonalite–trondhjemite–granodiorite (TTG) – granite–greenstone tectonic regime (TR1) and coeval with early turbidite sedimentation; (ii) 2635–2608 Ma — continued turbidite sedimentation, D1/M1 juxtaposition of turbidites and protoarc lithologies prior to ~2608 Ma, and metaluminous granitoid plutonism; (iii) 2608–2597 Ma — onset of TR2, collision of Snare protoarc with Central Slave Basement Complex, D2/M2 crustal thickening and mid-crustal granulite-facies metamorphism, sychronous with metaluminous and peraluminous plutonism; and (iv) 2597–2586 Ma — orogenic collapse, D3/M3 mid-crustal uplift, granulite-facies metamorphism, and waning metaluminous and peraluminous plutonism. The distribution of igneous rocks yields an "orogenic stratigraphy" with an older upper crust underlain by a younger synorogenic mid-crust. These data can be used to provide constraints for the interpretation of the Slave – Northern Cordillera Lithospheric Evolution (SNORCLE) Lithoprobe transect.

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.

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.

Extensional exhumation of a high-pressure granulite terrane in Payer Land, Greenland Caledonides: structural, petrologic, and geochronologic evidence from metapelites

2002 ◽  
Vol 39 (8) ◽  
pp. 1169-1187 ◽  
Author(s):  
Jane A Gilotti ◽  
Synnøve Elvevold
Keyword(s):  
High Pressure ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Low Grade ◽  
Granulite Facies Metamorphism ◽  
High Pressure High Temperature ◽  
High Pressure Granulite ◽  
Two Samples ◽  
Facies Metamorphism ◽  
Southern Half

The Payer Land gneiss complex is unique among the mostly amphibolite-facies, mid-crustal gneiss complexes in the East Greenland Caledonides due to its well-preserved, regional high-pressure (HP) granulite-facies metamorphism. High-pressure – high-temperature (HP–HT) assemblages are recognized in mafic, ultramafic, granitic, and metasedimentary lithologies. Anatectic metapelites contain the assemblage garnet + kyanite + K-feldspar + antiperthite (exsolved ternary feldspar) + quartz ± biotite ± rutile and record approximately the same peak metamorphic conditions (pressure (P) = 1.4–1.5 GPa, temperature (T) = 800–850°C) as those of the neighboring mafic HP granulites. The HP granulite-facies metamorphism is Caledonian based on in situ U–Th–Pb electron microprobe dating of monazite from two samples of the aluminous paragneiss. The monazites are found along garnet–kyanite phase boundaries, as inclusions in garnet and kyanite, and within small leucocratic melt pods (K-feldspar + plagioclase + kyanite ± garnet) within the HP–HT paragneisses. Mylonitic equivalents of the metapelites contain a detrital monazite age signature that suggests the Payer Land paragneisses correlate with other Mesoproterozoic metasedimentary sequences in the area. The gneisses form a metamorphic core complex that is separated from the overlying low-grade sedimentary rocks of the Neoproterozoic Eleonore Bay Supergroup by an extensional detachment. This newly recognized Payer Land detachment is part of a system of prominent extensional faults located in the southern half of the Greenland Caledonides (i.e., south of 76°N). The HP granulites preserve the deepest level of crust exposed in this southern segment of the orogen and attest to significant crustal thickening.

Granulite-facies metamorphism of the Palaeoproterozoic – early Palaeozoic gneiss domains of NE Mozambique, East African Orogen

2016 ◽  
Vol 154 (3) ◽  
pp. 491-515 ◽  
Author(s):  
A. K. ENGVIK ◽  
B. BINGEN
Keyword(s):  
High Pressure ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Northwestern Part ◽  
Granulite Facies Metamorphism ◽  
Medium Pressure ◽  
Nappe Complex ◽  
High Pressure Granulite ◽  
Facies Metamorphism ◽  
Early Palaeozoic

AbstractGranulite-facies metamorphism recorded in NE Mozambique is attributed to three main tectonothermal events, covering more than 1400 Ma from Palaeoproterozoic – early Palaeozoic time. (1) Usagaran–Ubendian high-grade metamorphism of Palaeoproterozoic age is documented in the Ponta Messuli Complex by Grt-Sil-Crd-bearing metapelites, estimated to pressure (P) 0.75 ± 0.08 GPa and temperature (T) 765 ± 96°C. The post-peak P-T path is characterized by decompression followed by near-isobaric cooling. (2) Irumidian medium- to high-pressure granulite-facies metamorphism is evident in the Unango and Marrupa complexes of late Mesoproterozoic – early Neoproterozoic age. High-pressure granulite-facies is documented by Grt-Cpx-Pl-Rt-bearing mafic granulites in the northwestern part of the Unango Complex, with peak conditions up to P = 1.5 GPa and T = 850°C. Medium-pressure granulite-facies conditions recording P of c. 1.15 GPa and T of 875°C are documented by Grt-Opx-Cpx-Pl assemblage in mafic granulites and charnockitic gneisses of the central part of the Unango Complex. (3) Tectonothermal activity during the Ediacaran–Cambrian Kuunga Orogeny is recorded in the Mesoproterozoic gneiss complexes as amphibolite facies to medium-pressure granulite-facies metamorphism. Granulite facies are documented by Grt-Opx-Cpx-Pl-bearing mafic granulites and charnockitic gneisses, reporting P = 0.99 ± 13 GPa at T = 738 ± 84°C in the Unango Complex and P = 0.92 ± 18 GPa at T = 841 ± 135°C in the Marrupa Complex. This metamorphism is attributed to crustal thickening related to overriding of the Cabo Delgado Nappe Complex, and shorthening along the Lurio Belt during the early Palaeozoic Kuunga Orogeny.

Stable coexistence of grandidierite and kornerupine during medium pressure granulite facies metamorphism

1995 ◽  
Vol 59 (395) ◽  
pp. 327-339 ◽  
Author(s):  
C. J. Carson ◽  
M. Hand ◽  
P. H. G. M. Dirks
Keyword(s):  
Granulite Facies ◽  
Crustal Thickening ◽  
Coarse Grained ◽  
Granulite Facies Metamorphism ◽  
Larsemann Hills ◽  
Facies Metamorphism ◽  
Peak Metamorphism ◽  
Isothermal Decompression ◽  
The Stability ◽  
New Occurrences

AbstractPetrological and mineral chemical data are presented for two new occurrences of co-existing borosilicate minerals in the Larsemann Hills, East Antarctica. The assemblages contain kornerupine and the rare borosilicate, grandidierite (Mg,Fe)A13BSiO9. Two distinct associations occur: (1) At McCarthy Point, 1–10 mm thick tourmaline-kornerupine-grandidierite layers are hosted within quartzofeldspathic gneiss; and (2) Seal Cove, where coexisting kornerupine and grandidierite occur within coarse-grained, metamorphic segregations with Mg-rich cores of cordierite-garnet-spinel-biotite-ilmenite and variably developed plagioclase halos. The segregations are hosted within biotite-bearing, plagio-feldspathic gneiss. Textural relationships from these localities indicate the stability of co-existing kornerupine and grandidierite.The grandidierite- and kornerupine-bearing segregations from Seal Cove largely postdate structures developed during a crustal thickening event (D2) which was coeval with peak metamorphism. At McCarthy Point, grandidierite, kornerupine and late-tourmaline growth predates, or is synchronous, with F3 fold structures developed during a extensive granulite grade, normal shearing event (D3) which occurred prior to, and synchronous with, near-isothermal decompression. Average pressure calculations on assemblages that coexist with the borosilicates at Seal Cove, indicate the prevailing conditions were 5.2–5.5 kbar at ∼ 750°C for formation of the grandidierite-kornerupine assemblage.

Granulite Facies Metamorphism in the Coast Range Crystalline Belt

1975 ◽  
Vol 12 (11) ◽  
pp. 1953-1955 ◽  
Author(s):  
Lincoln S. Hollister
Keyword(s):  
British Columbia ◽  
Granulite Facies ◽  
Coast Range ◽  
Geologic History ◽  
Granulite Facies Metamorphism ◽  
Mineral Assemblages ◽  
Facies Metamorphism ◽  
History Of

Mineral assemblages diagnostic of the granulite facies of metamorphism occur between Terrace and Prince Rupert, British Columbia. The estimated pressure (5–8 kb) and temperature (750–850 °C) of metamorphism are important constraints in unravelling the geologic history of the Coast Range batholithic complex.

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.

Early Archaean continental crust in the Eastern Ghats granulite belt, India: isotopic evidence from a charnockite suite

2001 ◽  
Vol 138 (5) ◽  
pp. 609-618 ◽  
Author(s):  
S. BHATTACHARYA ◽  
RAJIB KAR ◽  
S. MISRA ◽  
W. TEIXEIRA
Keyword(s):  
Continental Crust ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Eastern Ghats ◽  
Mobile Belt ◽  
Granulite Facies Metamorphism ◽  
Granulite Belt ◽  
Facies Metamorphism ◽  
Geochemical Studies ◽  
Lower Crustal

The Eastern Ghats granulite belt of India has traditionally been described as a Proterozoic mobile belt, with probable Archaean protoliths. However, recent findings suggest that synkinematic development of granulites took place in a compressional tectonic regime and that granulite facies metamorphism resulted from crustal thickening. The field, petrological and geochemical studies of a charnockite massif of tonalitic to trondhjemitic composition, and associated rocks, document granulite facies metamorphism and dehydration partial melting of basic rocks at lower crustal depths, with garnet granulite residues exposed as cognate xenoliths within the charnockite massif. The melting and generation of the charnockite suite under granulite facies conditions have been dated c. 3.0 Ga by Sm–Nd and Rb–Sr whole rock systematics and Pb–Pb zircon dating. Sm–Nd model dates between 3.4 and 3.5 Ga and negative epsilon values provide evidence of early Archaean continental crust in this high-grade terrain.

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.

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