Strain pattern and late Precambrian deformation history in southern Madagascar

Martelat, Jean-Emmanuel; Lardeaux, Jean‐Marc; Nicollet, Christian; Rakotondrazafy, Raymond

doi:10.1016/s0301-9268(99)00083-2

Cited by 131 publications

(146 citation statements)

References 34 publications

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“…They concluded that the Archean crust is also slightly thicker (38-43 km) compared to the Proterozoic crust (33-38 km). They attributed the difference to the absence of a mafic lower crustal underplate in the Proterozoic terranes, and suggested that the underplated layer may have delaminated due to the high-temperature metamorphism that affected the areas, a process described by Martelat et al (2000); Schenk (2011), andHorton et al (2016).…”

Section: Discussionmentioning

confidence: 99%

The structure of the crust and uppermost mantle beneath Madagascar

Andriampenomanana

Nyblade

Wysession

et al. 2017

Geophysical Journal International

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S U M M A R YThe lithosphere of Madagascar was initially amalgamated during the Pan-African events in the Neoproterozoic. It has subsequently been reshaped by extensional processes associated with the separation from Africa and India in the Jurassic and Cretaceous, respectively, and been subjected to several magmatic events in the late Cretaceous and the Cenozoic. In this study, the crust and uppermost mantle have been investigated to gain insights into the present-day structure and tectonic evolution of Madagascar. We analysed receiver functions, computed from data recorded on 37 broad-band seismic stations, using the H-κ stacking method and a joint inversion with Rayleigh-wave phase-velocity measurements. The thickness of the Malagasy crust ranges between 18 and 46 km. It is generally thick beneath the spine of mountains in the centre part (up to 46 km thick) and decreases in thickness towards the edges of the island. The shallowest Moho is found beneath the western sedimentary basins (18 km thick), which formed during both the Permo-Triassic Karro rifting in Gondwana and the Jurassic rifting of Madagascar from eastern Africa. The crust below the sedimentary basin thickens towards the north and east, reflecting the progressive development of the basins. In contrast, in the east there was no major rifting episode. Instead, the slight thinning of the crust along the east coast (31-36 km thick) may have been caused by crustal uplift and erosion when Madagascar moved over the Marion hotspot and India broke away from it. The parameters describing the crustal structure of Archean and Proterozoic terranes, including average thickness (40 km versus 35 km), Poisson's ratio (0.25 versus 0.26), average shear-wave velocity (both 3.7 km s -1 ), and thickness of mafic lower crust (7 km versus 4 km), show weak evidence of secular variation. The uppermost mantle beneath Madagascar is generally characterized by shear-wave velocities typical of stable lithosphere (∼4.5 km s -1 ). However, markedly slow shear-wave velocities (4.2-4.3 km s -1 ) are observed beneath the northern tip, central part and southwestern region of the island where the major Cenozoic volcanic provinces are located, implying the lithosphere has been significantly modified in these places.

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Section: Discussionmentioning

confidence: 99%

The structure of the crust and uppermost mantle beneath Madagascar

Andriampenomanana

Nyblade

Wysession

et al. 2017

Geophysical Journal International

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“…Peak metamorphism along the BongolavaRanotsara shear zone, interpreted to be coincident with movement, is dated at Ma, and move-547 ‫ע‬ 6 ment had ceased by about 530 Ma, based on the age of stitching intrusions (Mü ller 2000). Regional metamorphism is estimated at about 520 Ma in northern and eastern Madagascar (Buchwaldt and Tucker 2001;Buchwaldt et al 2003) and in southern Madagascar at 500-590 Ma (Martelat et al 2000) and 520-605 Ma (de Wit et al 2001). The broad range of metamorphic estimates probably reflects both the complexity of the orogenic episode and the reconnaissance nature of most of the geochronology.…”

Section: A Model For Madagascar Assembly Based On Sediment Provenancementioning

confidence: 99%

Proterozoic Tectonostratigraphy and Paleogeography of Central Madagascar Derived from Detrital Zircon U‐Pb Age Populations

Cox

Coleman²,

Chokel

et al. 2004

The Journal of Geology

104

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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%