The tectonic domains of southern and western Madagascar

Boger, Steven D.; Maas, Roland; Pastuhov, M.; Macey, P.H.; Hirdes, W.; Schulte, B.; Fanning, C. Mark; Ferreira, Carlos; Jenett, T.; Dallwig, R.

doi:10.1016/j.precamres.2019.03.005

Cited by 19 publications

(20 citation statements)

References 78 publications

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“…Based on the maximum depositional ages, and lack of any younger detrital zircons, the simplest interpretation is that the Greater Itremo Basin was actively accumulating sediments in the Paleoproterozoic. An alternative interpretation to this, is that the Greater Itremo Basin was accumulating sediments in the Mesoproterozoic and possibly even through to the early Neoproterozoic (e.g., Boger et al, 2014Boger et al, , 2019. However, if the second interpretation is correct, the zircons within the basin sediments must have been exclusively eroded from relatively ancient source rocks with no near-contemporaneous zircon sources eroded and preserved in the process.…”

Section: (A) (B)mentioning

confidence: 99%

“…Boger et al. (2014, 2019) linked the Anosyen Domain of southern Madagascar to the Itremo Group. The validity of these correlations, and likelihood that these represent contiguous Paleoproterozoic–Mesoproterozoic depositional systems, governs the paleogeographic reconstruction of this extensive part of Nuna and its tectono‐geographic interpretation.…”

Section: Introductionmentioning

confidence: 99%

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Proterozoic Basin Evolution and Tectonic Geography of Madagascar: Implications for an East Africa Connection During the Paleoproterozoic

et al. 2021

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Reconstructing the geometry of the terranes of eastern Africa, Madagascar and India prior to the Neoproterozoic is challenging due to a scarcity of Mesoproterozoic magmatic rocks in some of these regions, limiting the use of zircon U-Pb dates in the correlation assessments. The Neoproterozoic to Cambrian amalgamation of central Gondwana, which formed the East African Orogen, has been extensively studied in recent years and provides important constraints on global plate reconstruction models (Merdith, Collins,

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Section: (A) (B)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proterozoic Basin Evolution and Tectonic Geography of Madagascar: Implications for an East Africa Connection During the Paleoproterozoic

et al. 2021

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“…The southwestern part of Madagascar there are four distinct tectonic domains (Boger et al, 2014(Boger et al, , 2019: the Anosyen, the Androyen, the Graphite and the Vohibory (Fig. 1b).…”

Section: The Sw Terranesmentioning

confidence: 99%

“…The narrow and elongate Graphite Terrane (Boger et al, 2019) have gneisses that hosts the Ankiliabo Suite, therefore predating by several hundreds of millions of years the formation of the intermediate to felsic protoliths of the Vohibory Domain, to the west (Fig. 1b).…”

Section: The Sw Terranesmentioning

confidence: 99%

Tectonic evolution of an Early Cryogenian late-magmatic basin in central Madagascar

Costa¹,

Schmitt²,

Collins³

et al. 2021

Preprint

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 Early Cryogenian basin with volcanoclastic contribution in Central Madagascar  Three distinct tectonic models for Late Tonian-Early Cryogenian  Extensional intracontinental magmatic setting related to an outboard subduction  A transform continental setting resolves the tectonic Cryogenian paucity  Continental collision dated with 550 Ma metamorphic rims on zircons ABSTRACT Central and southern Madagascar comprise a number of distinctive Archaean crustal blocks (the Antongil-Masora and Antananarivo domains) overlain by Proterozoic supracrustal sequences, preserved in the East African Orogen. Here, we present U-Pb and Lu-Hf isotopic data for two supracrustal units from detrital and metamorphic zircon grains. The lower sequence is comprised of quartzite and calcsilicate units with a major Palaeoproterozoic detrital zircon source and a minor Archaean contribution with a maximum depositional age of ca. 1780 Ma. This sequence reflects a stable shelf sedimentation within the Antananarivo Domain and is correlated with the Itremo Group. U-Pb and Hf data are equivocal in determining the direct sources for the Archaean and early Palaeoproterozoic detrital zircon grains. However, the abundant ca. 2.3-1.8 Ga detrital grains are correlative with the Congo-Tanzania-Bangweulu Block and as these are close to the inferred age of the Itremo Basin, these are interpreted to be single cycle detritus. This implies that the Congo-Tanzania-Bangweulu craton was close to central Madagascar at ca. 1.8-1.6 Ga and the lower sequence would correspond to an originally contiguous late Palaeoproterozoic to early Mesoproterozoic sedimentary basin across central

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“…Thick black line delimits the boundary between the Phanerozoic-Cenozoic sedimentary basins and the Proterozoic-Archean basement domains. Insets show larger scale context of the study region and Gondwana reconstruction after amalgamation at the end of the Neoproterozoic/Cambrian (modified after Boger et al 2019). Main map: Cn: Cenozoic sediments, Cr: Cretaceous sediments, Cb-Jr: Carboniferous-Jurassic sediments, Vl:volcanis, Ad-Vl: Volcan de l' Androy; Tectonic domains Vb: Vohibory, Ad: Androyen, An: Anosyen, Ik: Ikalamavony, It: Itremo, At: Antananarivo, Ms: Masoara.…”

Section: G E O L O G I C a L S E T T I N G A N D P R E V I O U S S E mentioning

confidence: 99%

Velocity structure and radial anisotropy of the lithosphere in southern Madagascar from surface wave dispersion

Rindraharisaona

Tilmann

Yuan

et al. 2020

Geophysical Journal International

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Summary We investigate the upper mantle seismic structure beneath southern Madagascar and infer the imprint of geodynamic events since Madagascar’s break-up from Africa and India and earlier rifting episodes. Rayleigh and Love wave phase velocities along a profile across southern Madagascar were determined by application of the two-station method to teleseismic earthquake data. For shorter periods (<20 s), these data were supplemented by previously published dispersion curves determined from ambient noise correlation. First, tomographic models of the phase velocities were determined. In a second step, 1D models of SV and SH wave velocities were inverted based on the dispersion curves extracted from the tomographic models. As the lithospheric mantle is represented by high velocities we identify the lithosphere-asthenosphere boundary by the strongest negative velocity gradient. Finally, the radial anisotropy (RA) is derived from the difference between the SV and SH velocity models. An additional constraint on the lithospheric thickness is provided by the presence of a negative conversion seen in S receiver functions, which results in comparable estimates under most of Madagascar. We infer a lithospheric thickness of 110−150 km beneath southern Madagascar, significantly thinner than beneath the mobile belts in East Africa (150−200 km), where the crust is of comparable age and which were located close to Madagascar in Gondwanaland. The lithospheric thickness is correlated with the geological domains. The thinnest lithosphere (∼110 km) is found beneath the Morondava basin. The pre-breakup Karoo failed rifting, the rifting and breakup of Gondwanaland have likely thinned the lithosphere there. The thickness of the lithosphere in the Proterozoic terranes (Androyen and Anosyen domains) ranges from 125 to 140 km, which is still ∼30 km thinner than in the Mozambique belt in Tanzania. The lithosphere is the thickest beneath Ikalamavony domain (Proterozoic) and the west part of the Antananarivo domain (Archean) with a thickness of ∼150 km. Below the eastern part of Archean domain the lithosphere thickness reduces to ∼130 km. The lithosphere below the entire profile is characterized by positive RA. The strongest RA is observed in the uppermost mantle beneath the Morondava basin (maximum value of ∼9%), which is understandable from the strong stretching that the basin was exposed to during the Karoo and subsequent rifting episode. Anisotropy is still significantly positive below the Proterozoic (maximum value of ∼5%) and Archean (maximum value of ∼6%) domains, which may from result of lithospheric extension during the Mesozoic and/or thereafter. In the asthenosphere, a positive RA is observed beneath the eastern part Morondava sedimentary basin and the Proterozoic domain, indicating a horizontal asthenospheric flow pattern. Negative RA is found beneath the Archean in the east, suggesting a small-scale asthenospheric upwelling, consistent with previous studies. Alternatively, the relatively high shear wave velocity in the asthenosphere in this region indicate that the negative RA could be associated to the Réunion mantle plume, at least beneath the volcanic formation, along the eastern coast.

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The tectonic domains of southern and western Madagascar

Cited by 19 publications

References 78 publications

Proterozoic Basin Evolution and Tectonic Geography of Madagascar: Implications for an East Africa Connection During the Paleoproterozoic

Proterozoic Basin Evolution and Tectonic Geography of Madagascar: Implications for an East Africa Connection During the Paleoproterozoic

Tectonic evolution of an Early Cryogenian late-magmatic basin in central Madagascar

Velocity structure and radial anisotropy of the lithosphere in southern Madagascar from surface wave dispersion

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