Humite‐ and scapolite‐bearing assemblages in marbles and calcsilicates of Dronning Maud Land, Antarctica: new data for Gondwana reconstructions

Piazolo, Sandra; Markl,

doi:10.1046/j.1525-1314.1999.00179.x

Cited by 36 publications

(18 citation statements)

References 45 publications

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“…The fluid infiltration is dated around 485 Ma by U-Pb on zircons and titanites (Paulsson, 2003), giving the time where the crust was exhumed to about 2 kbar and the tectonic activity was decreasing. This shows that the Pan-African exhumation from peak granulite facies (7-8 kbar; Bucher-Nurminen & Ohta, 1993;Piazolo & Markl, 1999) was about 15-20 km. Later exhumation, brittle faulting and intrusion of mafic dykes are related to Permo-Triassic removal of crustal material and breakup of Gondwana around 200 Ma (e.g.…”

Section: A Pan-african Near-isothermal Uplift During Tectonic Extementioning

confidence: 83%

“…The high geotherm under the Pan-African event is recorded by metamorphic studies over large areas of the East Antarctic craton (Bucher-Nurminen & Ohta, 1993;Thost, Hensen & Motoyoshi, 1994;Piazolo & Markl, 1999). In addition, the late Pan-African syenitic magmas are voluminous in central Dronning Maud Land.…”

Section: B Late-orogenic Collapse Of the Pan-african East Antarctimentioning

confidence: 95%

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Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica

Engvik

Elvevold

2004

Geol. Mag.

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-The Mühlig-Hofmann-and Filchnerfjella in central Dronning Maud Land, Antarctica, consist of series of granitoid igneous rocks emplaced in granulite and upper amphibolite facies metamorphic rocks. The area has experienced high-temperature metamorphism followed by near-isothermal decompression, partial crustal melting, voluminous magmatism and extensional exhumation during the later phase of the late Neoproterozoic to Cambrian Pan-African event. Remnants of kyanitegarnet-ferritschermakite-rutile assemblages indicate an early higher-pressure metamorphism and crustal overthickening. The gneisses experienced peak granulite facies temperatures of 800-900 • C at intermediate pressures. Breakdown of garnet + sillimanite + spinel-bearing assemblages to cordierite shows subsequent re-equilibration to lower pressures. An E-W foliation dominating the gneisses illustrates transposition of migmatites and leucocratic melts which evolved during the near-isothermal decompression. Occurrence of extensional shear bands and shear zones evolving from the ductile partial melting stage through semiductile towards brittle conditions, shows that the uplift persisted towards brittle crustal conditions under tectonic W/SW-vergent extension. Late-orogenic Pan-African quartz syenites intruded after formation of the main gneiss fabric contain narrow semiductile to brittle shear zones, illustrating that the extensional exhumation continued also after their emplacement. The latest record of the Pan-African event is late-magmatic fluid infiltration around 350-400 • C and 2 kbar. At this stage the Pan-African crust had undergone 15-20 km exhumation from the peak granulite facies conditions. We conclude that the later phase of the Pan-African event in central Dronning Maud Land is characterized by a near-isothermal decompression P-T path and extensional structures indicating tectonic exhumation, which is most likely related to a late-orogenic collapsing phase of the Pan-African orogen.

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Section: A Pan-african Near-isothermal Uplift During Tectonic Extementioning

confidence: 83%

Section: B Late-orogenic Collapse Of the Pan-african East Antarctimentioning

confidence: 95%

Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica

Engvik

Elvevold

2004

Geol. Mag.

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“…Medium-P granulite-facies metamorphism is documented over a large part of the EAAO in DML, from the western DML (Board et al, 2005), through the central parts (Bucher-Nurminen and Ohta, 1993, Piazolo and Markl, 1999, Engvik and Elvevold, 2004, Colombo and Talarico, 2004, Bisnath and Frimmel, 2005 into the eastern DML (Shiraishi et al, 1997). The metamorphism in cDML reached conditions of 1.0 GPa, 800-900ºC.…”

Section: Discussionmentioning

confidence: 99%

“…Granulite-facies rocks of central Dronning Maud Land have been documented by Bucher-Nurminen and Ohta (1993), Piazolo and Markl (1999), Engvik and Elvevold (2004), Colombo and Talarico (2004) and Bisnath and Frimmel (2005). Geochronological studies in the area report a Mesoproterozoic crust formation and a Late Neoproterozoic/Early Paleozoic metamorphic event related to the Pan-African orogeny (e.g.…”

Section: Granulites Of Central Dronning Maud Landmentioning

confidence: 99%

Pan-African granulites of central Dronning Maud Land and Mozambique: A comparison within the East-African-Antarctic orogen

Engvik¹,

Elevevold²,

Jacobs³

et al. 2007

Open-File Report

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Granulite-facies metamorphism is extensively reported in Late Neoproterozoic/Early Palaeozoic time during formation of the East-African-Antarctic orogen (EAAO). Metamorphic data acquired from the Pan-African orogen of central Dronning Maud Land (cDML) are compared with data from northern Mozambique. The metamorphic rocks of cDML are characterised by Opx±Grt-bearing gneisses and Sil+Kfs-bearing metapelites which indicate medium-P granulite-facies metamorphism. Peak conditions, which are estimated to 800-900ºC at pressures up to 1.0 GPa, were followed by near-isothermal decompression during late Pan-African extension and exhumation. Granulite-facies lithologies are widespread in northern Mozambique, and Grt+Cpx-bearing assemblages show that high-P granulitefacies conditions with PT reaching 1.55 GPa and 900ºC were reached during the Pan-African orogeny. Garnet is replaced by symplectites of Pl+Opx+Mag indicating isothermal decompression, and the subsequent formation of Pl+amphibole-coronas suggests cooling into amphibolite facies. It is concluded that high-T metamorphism was pervasive in EAAO in Late Neoproterozoic/Early Paleozoic time, strongly overprinting evidences of earlier metamorphic assemblages.

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“…The metamorphic rocks in cDML are characterized by coexistence of granulite-facies and amphibolite-facies features (Rameshwar Rao et al 1997, Markl & Piazolo 1998, Piazolo & Markl 1999. The metamorphic grade was determined from the garnetpyroxene-plagioclase-quartz assemblage in marie granulite as 837+26C at 7.1+0.2kbar (granulite facies), and from the garnet-pyroxeneamphibole-biotite-quartz (amphibolite facies) as 652 -+-33 C at 5.9 4-0.3 kbar (Rameshwar Rao et al 1997).…”

Section: Pan-african Eventsmentioning

confidence: 99%

Pervasive Pan-African reactivation of the Grenvillian crust and large igneous intrusions in central Dronning Maud Land, East Antarctica

Paech

2001

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The geological history of central Dronning Maud Land (cDML) is described on the basis of age data, recent observations, and published data. The ages of both the protoliths of the metamorphic rocks of cDML and their primary metamorphism are Grenvillian (1200 to 1000 Ma). Following a long hiatus for which geochronological data are lacking, the Grenvillian crust of cDML was intruded by abundant Pan-African partly charnockitic granitoids and anorthosites of the Dronning Maud Land igneous province. These intrusions occurred predominantly in two Pan-African igneous episodes. The early igneous episode (about 600 Ma), in which the Grubergebirge anorthosite intruded, was followed by Pan-African highgrade metamorphism, intense ductile deformation and then medium-grade retrogression during later Pan-African events (570 to 520 Ma). The Grenvillian structures and metamorphic signature were pervasively overprinted or completely eradicated. The Pan-African metamorphism and tectonism were completed prior to the late Pan-African igneous episode (500 Ma), in which predominantly post-kinematic granitoids, as well as a small anorthosite, intruded. Thus, the present tectonic structure of the crust in cDML was formed during Pan-African events by overprinting of Grenvillian basement and intrusion of granitoids/syenites and anorthosites.

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Humite‐ and scapolite‐bearing assemblages in marbles and calcsilicates of Dronning Maud Land, Antarctica: new data for Gondwana reconstructions

Cited by 36 publications

References 45 publications

Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica

Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica

Pan-African granulites of central Dronning Maud Land and Mozambique: A comparison within the East-African-Antarctic orogen

Pervasive Pan-African reactivation of the Grenvillian crust and large igneous intrusions in central Dronning Maud Land, East Antarctica

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