Detrital footprint of the Mozambique ocean: U–Pb SHRIMP and Pb evaporation zircon geochronology of metasedimentary gneisses in eastern Madagascar

Collins, Alan S.; Kröner, Alfred; Fitzsimons, I. C. W.; Razakamanana, Théodore

doi:10.1016/s0040-1951(03)00334-2

Cited by 102 publications

(41 citation statements)

References 69 publications

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“…Although this model of western and eastern collisions at~0.65 and~0.53 Ga explains protracted Pan-African metamorphism, it has a number of problems including the 170 Myr gap from the end of continental arc magmatism at~0.70 Ga to ocean closure along the Malagasy suture, and the observation that Dharwar-like basement of the Masora Domain is overlain by supracrustal rocks with 2.2-1.8 Ga detritus and intruded by 0.85-0.78 Ga granite and gabbro Tucker et al, 2011a), both of which should only occur west of the Malagasy suture. Similar problems are created by supracrustal rocks deformed within the Malagasy suture, which locally contain detrital zircons of mixed Dharwar (3.3-3.1 Ga), Congo (2.2-1.8 Ga) and Azania (0.84-0.70 Ga) ancestry (Collins et al, 2003;Key et al, 2011), suggesting that these source terranes had assembled before metamorphism at 0.53-0.51 Ga (Tucker et al, 2011a). Finally, a Cambrian age for the Malagasy suture is difficult to reconcile with the age of high-T granulites between the two sutures.…”

Section: Discussionmentioning

confidence: 96%

“…4a). Collectively called the Malagasy suture, but known as the Betsimisaraka suture in Madagascar (Kröner et al, 2000;Collins and Windley, 2002;Collins et al, 2003;Key et al, 2011) and Palghat-Cauvery shear zone in India (Collins et al, 2007a;Clark et al, 2009;Santosh et al, 2012), this highly-deformed schist belt contains detrital zircons as young as 0.70 Ga and abundant mafic-ultramafic lenses. It is interpreted as a second strand of the Mozambique Ocean that subducted westwards under the inferred continental arc in southern India and Madagascar (Collins and Pisarevsky, 2005;Ishwar-Kumar et al, 2015), although others have argued that both 0.85-0.70 Ga plutons and ultramafic-decorated schist belt formed in a rift and not at a convergent margin (Tucker et al, 2011a;Brandt et al, 2014).…”

Section: Cryogenian Magmatic Arcs and Ophiolitementioning

confidence: 99%

“…Other igneous protoliths include~2.0, 1.7-1.6, and 1.0 Ga granite in the Nagercoil and northeastern and southern Madurai blocks of India (Plavsa et al, 2012;Brandt et al, 2014;Kröner et al, 2015), local 2.2-1.8 and~1.0 Ga mafic and felsic rocks in south-central Madagascar (Tucker et al, 2011b), and 0.94-0.90 Ga alkali granite and anorthosite in southern Madagascar (Boger et al, 2015). Most metasedimentary units in Madagascar and southern India contain abundant 2.7-2.4 and 2.2-1.8 Ga detrital zircons (Cox et al, 1998(Cox et al, , 2004Fitzsimons and Hulscher, 2005;Collins et al, 2007b;De Waele et al, 2011;Collins et al, 2012;Boger et al, 2014;Plavsa et al, 2014), but 1.1-0.9 Ga detritus dominates the Ikalamavony Domain of Madagascar (Tucker et al, 2011b) and southern Madurai Block and Achankovil Zone of India , and detritus in the Malagasy suture can have a mix of age populations including 3.3-3.1, 2.7-2.4, 2.2-1.8 and 0.84-0.70 Ga (Collins et al, 2003;Key et al, 2011).…”

Section: Reworked Crust Of the Southern East African Orogenmentioning

confidence: 99%

“…The age of metamorphism in the Malagasy suture is controversial with kyanite-staurolite schist west of the Antongil Domain dated both as Archean (Schofield et al, 2010;Tucker et al, 2011a) and Cambrian (Collins et al, 2003). A Cambrian age is confirmed by 0.52 Ga monazite included in staurolite and kyanite (Maxwell et al, 2014), consistent with high-strain rocks west of the Masora Domain that record metamorphic ages of 0.56-0.52 Ga and an eastwards P increase from 0.7-1.0 GPa and 700-750°C to 1.0-1.2 GPa and 600-650°C .…”

Section: Metamorphism Along the Malagasy Suturementioning

confidence: 99%

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Pan–African granulites of Madagascar and southern India: Gondwana assembly and parallels with modern Tibet

Fitzsimons

2016

Journal of Mineralogical and Petrological Sciences

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Granulites of the southern East African Orogen formed by continental collision during Gondwana assembly. The highest metamorphic gradients of 25-50°C km −1 were attained at 0.58-0.53 Ga in a microcontinental block that was sandwiched between two collisional sutures and is now exposed in Madagascar and southern India. The 50 Myr duration of extreme pressure-temperature (P-T) conditions and lack of coeval mantle magmatism suggest that metamorphism was driven by radiogenic heat accumulation beneath a long-lived orogenic plateau. Bounding sutures most likely record transfer of this microcontinent across the Neoproterozoic Mozambique Ocean, analogous to Gondwanan terranes that crossed Tethys before final India-Asia collision and, like Tibet, these sutures mark the edges of a plateau that formed following terminal ocean closure and collision. Both sutures record moderate metamorphic gradients of 15-25°C km −1 but with quite different ages. Metamorphism along the western suture at 0.65-0.61 Ga followed the end of magmatism in an adjacent 0.85-0.65 Ga ocean-arc terrane. It has an anti-clockwise P-T path that reflects preferential thickening of the hot arc during early stages of collision, and dates ocean closure at the western suture. Metamorphism along the eastern suture at 0.53-0.51 Ga has a clockwise P-T path and is widely assumed to date terminal collision in the East African Orogen. However, this event was coeval with rapid exhumation of granulites in the adjacent plateau and is more likely to reflect reactivation of a much older eastern suture during plateau collapse. Great care should be taken when using metamorphism to date ocean closure in ancient orogens. Rocks with hot metamorphic gradients give poor age constraints on initial collision because peak T is attained >50 Myr after ocean closure if radioactivity is a major part of the heat budget. Suture zone rocks with moderate metamorphic gradients can provide more reliable estimates for the time of ocean closure but are also prone to later reactivation in orogens with protracted histories.

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Section: Discussionmentioning

confidence: 96%

Section: Cryogenian Magmatic Arcs and Ophiolitementioning

confidence: 99%

Section: Reworked Crust Of the Southern East African Orogenmentioning

confidence: 99%

Section: Metamorphism Along the Malagasy Suturementioning

confidence: 99%

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Pan–African granulites of Madagascar and southern India: Gondwana assembly and parallels with modern Tibet

Fitzsimons

2016

Journal of Mineralogical and Petrological Sciences

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“…Shackleton 4 suggested that the high-grade terranes may even be younger than the granite-greenstone terranes and may represent uplifted mobile belts that evolved between greenstone belt terranes. U-Pb detrital zircon geochronology has been pursued extensively to resolve these complex relationships [10][11][12][13][14][15] . In polycyclic Archaean metamorphic assemblages, zircon grains may have grown during different geological processes and/or may have been affected by multiple alteration processes 16,17 .…”

mentioning

confidence: 99%

U–Pb and Lu–Hf Systematics of Zircons from Sargur Metasediments, Dharwar Craton, Southern India:New Insights on the Provenance and Crustal Evolution

et al. 2017

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A study of U-Pb and Lu-Hf-Yb isotope data in zircons from metamorphosed psammopelite and quartzite from the type area of Archaean Sargur Group, Dharwar Craton, India is carried out. Two age populations are observed: an older population with concordant U-Pb ages between 2.7 and 2.8 Ga, and a younger population with ages in the 2.4-2.6 Ga age range. The Hf values of 0 to +2.0 for the older zircon population suggest that they were derived from juvenile crust formed at 2.7-2.8 Ga. Sub-chondritic Hf values for the younger population indicate metamorphism and/or crustal reworking at ~2.5 Ga. Metasedimentary enclaves in the Sargur type area are therefore part of the gneiss-supracrustal complex of different antiquities and may not have an independent stratigraphic status.

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The evolution of a Gondwanan collisional orogen: A structural and geochronological appraisal from the Southern Granulite Terrane, South India

et al. 2015

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Gondwana amalgamated along a suite of Himalayan-scale collisional orogens, the roots of which lace the continents of Africa, South America, and Antarctica. The Southern Granulite Terrane of India is a generally well-exposed, exhumed, Gondwana-forming orogen that preserves a record of the tectonic evolution of the eastern margin of the East African Orogen during the Ediacaran-Cambrian (circa 600-500 Ma) as central Gondwana formed. The deformation associated with the closure of the Mozambique Ocean and collision of the Indian and East African/Madagascan cratonic domains is believed to have taken place along the southern margin of the Salem Block (the Palghat-Cauvery Shear System, PCSS) in the Southern Granulite Terrane. Investigation of the structural fabrics and the geochronology of the high-grade shear zones within the PCSS system shows that the Moyar-Salem-Attur shear zone to the north of the PCSS system is early Paleoproterozoic in age and associated with dextral strike-slip motion, while the Cauvery shear zone (CSZ) to the south of the PCSS system can be loosely constrained to circa 740-550 Ma and is associated with dip-slip dextral transpression and north side-up motion. To the south of the proposed suture zone (the Cauvery shear zone), the structural fabrics of the Northern Madurai Block suggest four deformational events (D 1 -D 4 ), some of which are likely to be contemporaneous. The timing of high pressure-ultrahigh temperature metamorphism and deformation (D 1 -D 3 ) in the Madurai Block (here interpreted as the southern extension of Azania) is constrained to circa 550-500 Ma and interpreted as representing collisional orogeny and subsequent orogenic collapse of the eastern margin of the East African Orogen. The disparity in the nature of the structural fabrics and the timing of the deformation in the Salem and the Madurai Blocks suggest that the two experienced distinct tectonothermal events prior to their amalgamation along the Cauvery shear zone during the Ediacaran/Cambrian.

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Detrital footprint of the Mozambique ocean: U–Pb SHRIMP and Pb evaporation zircon geochronology of metasedimentary gneisses in eastern Madagascar

Cited by 102 publications

References 69 publications

Pan–African granulites of Madagascar and southern India: Gondwana assembly and parallels with modern Tibet

Pan–African granulites of Madagascar and southern India: Gondwana assembly and parallels with modern Tibet

U–Pb and Lu–Hf Systematics of Zircons from Sargur Metasediments, Dharwar Craton, Southern India:New Insights on the Provenance and Crustal Evolution

The evolution of a Gondwanan collisional orogen: A structural and geochronological appraisal from the Southern Granulite Terrane, South India

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