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

• Published in: Tectonics (Washington, D.C.) Vol. 40; no. 3
• Main Authors: Armistead, Sheree E., Collins, Alan S., Schmitt, Renata S., Costa, Raisa L., De Waele, Bert, Razakamanana, Théodore, Payne, Justin L., Foden, John D.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-03-2021
• Subjects: Cratons; detrital zircon; Evolution; geochronology; Geography; Isotopes; Itremo; Nuna; Precambrian; provenance; Sedimentary basins; supercontinent; Zircon; Madagascar; East Africa; Africa; Tanzania; India
• ISSN: 0278-7407; 1944-9194
• DOI: 10.1029/2020TC006498

Madagascar hosts several Paleoproterozoic sedimentary sequences that are key to unraveling the geodynamic evolution of past supercontinents on Earth. New detrital zircon U–Pb and Hf data, and a substantial new database of ∼15,000 analyses are used here to compare and contrast sedimentary sequences in Madagascar, Africa, and India. The Itremo Group in central Madagascar, the Sahantaha Group in northern Madagascar, the Maha Group in eastern Madagascar, and the Ambatolampy Group in central Madagascar have indistinguishable age and isotopic characteristics. These samples have maximum depositional ages >1700 Ma, with major zircon age peaks at c. 2500 Ma, c. 2000 Ma, and c. 1850 Ma. We name this the Greater Itremo Basin, which covered a vast area of Madagascar in the late Paleoproterozoic. These samples are also compared with those from the Tanzania and the Congo cratons of Africa, and the Dharwar Craton and Southern Granulite Terrane of India. We show that the Greater Itremo Basin and sedimentary sequences in the Tanzania Craton of Africa are correlatives. These also tentatively correlate with sedimentary protoliths in the Southern Granulite Terrane of India, which together formed a major intra‐Nuna/Columbia sedimentary basin that we name the Itremo‐Muva‐Pandyan Basin. A new Paleoproterozoic plate tectonic configuration is proposed where central Madagascar is contiguous with the Tanzania Craton to the west and the Southern Granulite Terrane to the east. This model strongly supports an ancient Proterozoic origin for central Madagascar and a position adjacent to the Tanzania Craton of East Africa.
Key Points
Detrital zircon U‐Pb and Hf isotope data from Madagascar indicate an extensive Paleoproterozoic basin defined as the Greater Itremo Basin
Database of ∼15,000 zircon analyses from East Africa, Madagascar, and southern India support a Paleoproterozoic basin across these regions
Plate tectonic configuration at c. 1700 Ma show Madagascar, the Tanzania Craton, and the Southern Granulite Terrane of India are contiguous