Jean A., Beauvais Anicet, Chardon Dominique, Arnaud N. , Jayananda M., Mathe P.E. (2020). Weathering history and landscape evolution of Western Ghats (India) from 40Ar/39Ar dating of supergene K-Mn oxides. Journal of the Geological Society, 177 (3), p. 523-536.
Titre du document
Weathering history and landscape evolution of Western Ghats (India) from 40Ar/39Ar dating of supergene K-Mn oxides
Jean A., Beauvais Anicet, Chardon Dominique, Arnaud N. , Jayananda M., Mathe P.E.
Source
Journal of the Geological Society, 2020,
177 (3), p. 523-536
Laterites preserved on both sides of the Western Ghats Escarpment of Peninsular India have formed by long-term lateritic weathering essentially after India-Seychelles continental break-up following Deccan Traps emplacement (c.63 myrago). Supergene manganese ores of the Western Ghats were formed on Late Archean manganese protores. Among Mn oxides composing the ores, cryptomelane (K-rich Mn oxide) was characterized and dated by 40Ar/39Ar geochronology. Measured ages complement those previously obtained in other South Indian manganese ores from the hinterland plateau and further documentthree major weathering periods,c.53-44,c.39-22 andc.14-10 Ma, the last being documented for the first time in India. These periods coincide with global palaeoclimatic proxies and date the lateritic weathering of three successive palaeolandscapes of the Western Ghats that evolved under slow denudation (c.8mMa-1) over the last 44 myr and were mostly incised during the Neogene (<22 Ma). This indicates that the Western Ghats are a relict of a South Indian plateau preserved at the headwaters ofvery long east-flowing river systems and above the Western Ghats Escarpment. Topography and denudation history of thislandscape do not require Neogene tilt of the Peninsula as recently proposed.
