Tectonic framework of the Precambrian of Madagascar and its Gondwana connections: a review and reappraisal

Windley, Brian F.; Razafiniparany, A.; Razakamanana, Théodore; Ackermand, D.

doi:10.1007/bf01083234

Cited by 198 publications

(27 citation statements)

References 29 publications

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“…Madagascar also hosts a number of crustal-scale shear zones, such as the Angavo, Ampanihy, Beraketa, Ifanadiana, Ihosy and Zazafotsy shear zones ( Fig. 1; e.g., Windley et al, 1994;Martelat et al, 2000Martelat et al, , 2013Raharimahefa and Kusky, 2010;Raharimahefa et al, 2013), that provide tectonic constraints on the assembly of the Gondwana supercontinent.…”

Section: Introductionmentioning

confidence: 99%

Crustal assembly of the Antananarivo and Masora domains, central–eastern Madagascar: constraints from U–Pb zircon geochronology and whole–rock geochemistry of meta–granitoids

Ichiki

Ishikawa

Kimura

et al. 2015

Journal of Mineralogical and Petrological Sciences

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Section: Introductionmentioning

confidence: 99%

Crustal assembly of the Antananarivo and Masora domains, central–eastern Madagascar: constraints from U–Pb zircon geochronology and whole–rock geochemistry of meta–granitoids

Ichiki

Ishikawa

Kimura

et al. 2015

Journal of Mineralogical and Petrological Sciences

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“…2) have been interpreted as ductile shear zones (e.g. Windley et al 1994;Martelat 1998;Martelat et al 2000;Nédélec et al 2000) that formed at high-grade metamorphic conditions during the late stages of the East African Orogen (Nicollet 1990;Martelat et al 1997;de Wit et al 2001). Although the steep ductile zones predominantly strike N-S (present-day coordinates), previous workers also postulated a NW-SE striking ductile shear zone that traverses the entire crystalline basement of southern Madagascar (e.g., Katz and Premoli 1979;Ackermand et al 1989;Martelat 1998).…”

Section: Introductionmentioning

confidence: 95%

“…1), e.g., the Achankovil Shear Zone (Drury et al 1984;Kriegsman 1993Kriegsman , 1995Paquette et al 1994;Windley et al 1994;Shackleton 1996;Windley and Razakamanana 1996;Martelat 1998;Rajesh et al 1998;Rajesh and Chetty 2006), the Palghat-Cauvery shear zone (de Wit et al 1995;Janardhan 1999;Janardhan et al 1997;Harris 1999), the Bhavani shear zone (Katz and Premoli 1979;Agrawal et al 1992), and the Karur-Kambam-Painavu-Trichur shear zone (de Wit et al 2001;Collins and Windley 2002;Ghosh et al 2004).…”

Section: Introductionmentioning

confidence: 97%

“…It is generally regarded as a *20-km-wide intra-crustal strike-slip shear zone (Martelat et al 2000) with a sinistral sense of shear (e.g. Nicollet 1990;Windley et al 1994;Martelat et al 1997;Martelat et al 2000;de Wit et al 2001) and an exposed length of about 350 km (Martelat et al 2000). Because of its oblique orientation with respect Reeves 2008, unpubl., model CR09MZRJ.rot, which is an updated version of model reev519c published in Reeves et al 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Kriegsman (1993Kriegsman ( , 1995 matches the Ranotsara shear zone with the Surma shear zone, whereas Shackleton (1996) and Müller (2000) trace the Ranotsara shear zone into the parallel Aswa shear zone (also known as AswaNandi shear zone). Windley et al (1994) consider that both the Surma and the Aswa shear zones are viable candidates for an extension of the Ranotsara shear zone. Martelat (1998), in contrast, suggests that the Mt.…”

Section: Introductionmentioning

confidence: 99%

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A new perspective on the significance of the Ranotsara shear zone in Madagascar

Schreurs

Giese

Berger³

et al. 2009

Int J Earth Sci (Geol Rundsch)

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The Ranotsara shear zone in Madagascar has been considered in previous studies to be a [350-km-long, intracrustal strike-slip shear zone of Precambrian/Cambrian age. Because of its oblique strike to the east and west coast of Madagascar, the Ranotsara shear zone has been correlated with shear zones in southern India and eastern Africa in Gondwana reconstructions. Our assessment using remote sensing data and field-based investigations, however, reveals that what previously has been interpreted as the Ranotsara shear zone is in fact a composite structure with a ductile deflection zone confined to its central segment and prominent NW-SE trending brittle faulting along most of its length. We therefore prefer the more neutral term ''Ranotsara Zone''. Lithologies, tectonic foliations, and axial trace trajectories of major folds can be followed from south to north across most of the Ranotsara Zone and show only a marked deflection along its central segment. The ductile deflection zone is interpreted as a result of E-W indentation of the Antananarivo Block into the less rigid, predominantly metasedimentary rocks of the Southwestern Madagascar Block during a late phase of the Neoproterozoic/Cambrian East African Orogeny (c. 550-520 Ma). The Ranotsara Zone shows significant NW-SE striking brittle faulting that reactivates part of the NW-SE striking ductile structures in the flexure zone, but also extends along strike toward the NW and toward the SE. Brittle reactivation of ductile structures along the central segment of the Ranotsara Zone, confirmed by apatite-fission track results, may have led to the formation of a shallow Neogene basin underlying the Ranotsara plain. The present-day drainage pattern suggests on-going normal fault activity along the central segment. The Ranotsara Zone is not a megascale intracrustal strike-slip shear zone that crosscuts the entire basement of southern Madagascar. It can therefore not be used as a piercing point in Gondwana reconstructions.

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Focused radiogenic heating of middle crust caused ultrahigh temperatures in southern Madagascar

et al. 2016

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Internal heating can cause melting, metamorphism, and crustal weakening in convergent orogens.This study evaluates the role of radiogenic heat production (RHP) in a Neoproterozoic ultrahigh-temperature metamorphic (UHTM) terrane exposed in southern Madagascar. Monazite and zircon geochronology indicates that the Paleoproterozoic Androyen and Anosyen domains (i) collided with the oceanic Vohibory Arc at~630 Ma, (ii) became incorporated into the Gondwanan collisional orogen by~580 Ma, and (iii) were exhumed during crustal thinning at 525-510 Ma. Ti-in-quartz and Zr-in-rutile thermometry reveals that UHTM occurred over >20,000 km 2 , mostly within the Anosyen domain. Assuming that U, Th, and K contents of samples from the field area are representative of the middle to lower crust during orogenesis, RHP was high enough-locally >5 μW/m 3 -to cause regional UHTM in <60 Myr. We conclude that, due in large part to the stability and insolubility of monazite at high crustal temperatures, RHP was the principal heat source responsible for UHTM, obviating the need to evoke external heat sources. Focused RHP probably thermally weakened portions of the middle crust, gravitationally destabilizing the orogen and facilitating thinning via lateral extrusion of hot crustal sections.

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Tectonic framework of the Precambrian of Madagascar and its Gondwana connections: a review and reappraisal

Cited by 198 publications

References 29 publications

Crustal assembly of the Antananarivo and Masora domains, central–eastern Madagascar: constraints from U–Pb zircon geochronology and whole–rock geochemistry of meta–granitoids

Crustal assembly of the Antananarivo and Masora domains, central–eastern Madagascar: constraints from U–Pb zircon geochronology and whole–rock geochemistry of meta–granitoids

A new perspective on the significance of the Ranotsara shear zone in Madagascar

Focused radiogenic heating of middle crust caused ultrahigh temperatures in southern Madagascar

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