Granulite facies metamorphism of metabasic and intermediate rocks in the Highland Series of Sri Lanka

Schumacher, Renate; Schenk, Volker; Raase, P.; Vitanage, P.W.

doi:10.1007/978-94-015-3929-6_10

Cited by 47 publications

(42 citation statements)

References 35 publications

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“…This suggests that during the Grenviile Orogeny, very high temperature conditions were achieved, overthickened crust formed, and extension occurred after the original compressional event of the collision. These conditions are not pervasive throughout the entire Grenville Province, however, they are suggested in the studies of Araku, Eastern Ghats, India (Sengupta et al 1991a), the Highland Series, Sri Lanka (Schumacher et al 1990), and in Madagascar (Nicollet 1988;.…”

Section: Return To the Srenville Concluding Remarksmentioning

confidence: 91%

“…Aussi, le Grenville, î'Araku du Ghats en Inde (Sengupta et al 1991), le Series Highland au Sri Lanka (Schumacher et al 1990), Madagascar (Nicollet 1988), et les Himalayas ont tous eu une croûte surépaissie. La méthode d'analyse des résultats d'un thermomètre en fonction de la taille des minéraux pour établir les températures maximales dans les conditions de haut grade métamorphique, développée ici, est peut-être applicable dans ces autres terrains granulitiques.…”

Section: Retrograde Cation Exchange In Garnets During Slow Cooling Ofunclassified

“…The granulitic faciès Highland Series occurs in the central part of the island. It is composed of metasediments (marbles, calc-silicates, metapelites and quaitzites) and granitic to basic metaigneous rocks (Schumacher et al 1990). High-grade metamorphism there occurred at 1100…”

Section: 4aii Highland Series Sri Lankamentioning

confidence: 99%

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Retrograde cation exchange in garnets during slow cooling of mid crustal granulites and the P-T-t trajectories from the Mont Laurier region, Grenville province Quebec

Boggs¹

1996

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During the past decade, there have been many advances in the domain of metamorphic geology that have rendered previous P-T results questionable. For example, Spear (1991) demonstrated that the widely used gamet-biotite Fe-Mg ion-exchange thermometer can underestimate temperatures by as much as 200°C due to retrograde diffusion between the garnet and biotite. Holdaway and Mukhopadhyay (1993) noted that exchange geothermometers are easily reset at granulite-grade metamorphism. Thus, all geothermobarometers would record lower diffasion-based post-peak metamorphic pressures and temperatures, particularly those such as the biotite-garnet Fe-Mg exchange geothermometer which are expecially sensitive to retrograde cation exchange. One objective of this thesis is to quantify this effect of resetting as a function of mineral grain size.The field area is located 100 km north of the Ottawa River between Ottawa and Montreal in the Central Metasedimentary Belt (CMB) of the Grenville Province. It contains the largest granulite terrane within the CMB. The western two thirds of the field area is dominated by the Bondy Gneiss Complex (BGC), a granulitic dome, consisting principally of orthogneisses with quartzites, a tonalitic pluton and metapelites. The northsouth trending Nominingue-Chénévilie Deformation Zone (NCDZ), cuts through the structural trend of the BGC and dominates the eastern third of the field area.The morphology and textures of migmatites in the area vary greatly from layers of leucosomes with granitic composition flanked by garnet-rich layers, and biotite-rich melanosomes through thin (1mm) wispy-discontinuous leucosomes and felsic moats surrounding garnets to continuous leucosomes greater than lcm thick. Many thin sections contain embayed K-feldspar or plagioclase grains with inclusions of biotite mat formed from a melt-producing reaction. Biotite is present throughout the field area, which limits the peak temperature to below 980°C. One outcrop contains garnets with spinel inclusions, suggesting the reaction Als + Grt = Spl + Qtz, which implies peak temperatures above 850°C. The Krn-Opx-Tur-Crd-Pl assemblage occurs in the BGC implying the komerupine-forming reaction Tur + Opx + Crd = Km + PL It has been proposed that the Bondy Gneiss Complex was hydrothermally altered. The plagioclase composition from the BGC are unusually diverse (between Anjs and An88), possibly due to this hydrothermal alteration. Cordierite, orthopyroxene, and spinel were only observed in the NCDZ. The spinel analyses were similar to literature values from the reconstructed Grenville Orogen at 0.8 Ga. Calcite was only observed in metapelites from the NCDZ, possibly due to fluid flow along this deformation zone during deformation. AFM projections also demonstrate this diversity between these two tectonostratigraphic domains. Garnets in the BGC are up to 20% more Mg-rich than those in the NCDZ, and the BGC biotites are also up to 30% more Mg-rich than the NCDZ biotites. VIGarnets were the only mineral found to exhibit regular zonin...

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Section: Return To the Srenville Concluding Remarksmentioning

confidence: 91%

Section: Retrograde Cation Exchange In Garnets During Slow Cooling Ofunclassified

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Retrograde cation exchange in garnets during slow cooling of mid crustal granulites and the P-T-t trajectories from the Mont Laurier region, Grenville province Quebec

Boggs¹

1996

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“…comm.). Pressures and temperatures range from 8-9 kb, 800-900~ in the deepest levels to 5 kb, -800~ in the structurally highest levels (ScHuMACHER et al, 1990;FAULHABER & RAITH, 1991). Recent U-Pb zircon (BAuR et al, 1990;HOLZL & K6nLER, 1989) radiometric work indicates that the age of high-grade metamorphism can be bracketed between 550-650 Ma, although Sm-Nd garnet data yield slightly younger (500-550 Ma) ages (H. KOnLER, pers.…”

Section: The Lewisian Nuk and Sri Lanka Terrains: Evolution And Pb Imentioning

confidence: 99%

Isotopic contrasts, chronology of elemental transfers and high-grade metamorphism: the Sri Lanka Highland granulites, and the Lewisian (Scotland) and Nuk (SW Greenland) gneisses

1991

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“…Temperatures in the metamorpbic aureole have been estimated from the Ti content of amphiboles (Schumaker et al 1990) and the plagloclase-amphibole geothermometer of Holland & Blundy (1994). Temperatures obtained from the former method vary from 540 to 696°C, whereas those from the latter gave higher results (between 662 and 823°C).…”

Section: Kmmentioning

confidence: 99%

Géométrie structurale et évolution tectonique de la ceinture de roches vertes de l'Abitibi (partie nord-ouest) :

Lacroix¹

1998

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Granulite facies metamorphism of metabasic and intermediate rocks in the Highland Series of Sri Lanka

Cited by 47 publications

References 35 publications

Retrograde cation exchange in garnets during slow cooling of mid crustal granulites and the P-T-t trajectories from the Mont Laurier region, Grenville province Quebec

Retrograde cation exchange in garnets during slow cooling of mid crustal granulites and the P-T-t trajectories from the Mont Laurier region, Grenville province Quebec

Isotopic contrasts, chronology of elemental transfers and high-grade metamorphism: the Sri Lanka Highland granulites, and the Lewisian (Scotland) and Nuk (SW Greenland) gneisses

Géométrie structurale et évolution tectonique de la ceinture de roches vertes de l'Abitibi (partie nord-ouest) :

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