Proterozoic basin evolution and tectonic geography of Madagascar during
the Nuna/Columbia Supercontinent
Abstract
Madagascar hosts several Paleoproterozoic sedimentary sequences that are
key to unravelling 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 against the Tanzania Craton of East Africa.