Plates, Plumes and Planetary Processes
Crustal geotherm in southern Deccan basalt province, India: The Moho is as cold as adjoining cratons
Published:January 01, 2007
P. Senthil Kumar, Rajeev Menon, G. Koti Reddy, 2007. "Crustal geotherm in southern Deccan basalt province, India: The Moho is as cold as adjoining cratons", Plates, Plumes and Planetary Processes, Gillian R. Foulger, Donna M. Jurdy
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Deccan basalts have long been considered to be a product of Réunion plume–Indian lithosphere interaction, ca. 65 Ma. However, recent studies call into question their plume origin. In this study, we investigate whether there is a thermal signature of the plume in the present-day thermal regime of the Deccan crust. Our study is limited to the southeastern Deccan province, where surface heatflow values are abundant and the radiogenic heat contribution of the underlying crust (ca. 2.7- to 2.5-Ga eastern Dharwar craton) can be well constrained from its exposed crustal cross-section. Surface heatflow varies from 33 to 73 mW m−2, with a mean of 45 mW m−2. Heat production of the Deccan basalts (tholeiite) is 0.39 µW m−3, and heat production of the basement rocks is assigned on the basis of the data from the Dharwar craton. The basement Dharwar crust is composed of middle-to-late Archaean greenstone belts, gneisses, granites, and granulites, whose heat production has been determined from >1500 sites, which belong to various crustal depth layers (greenschist, amphibolite, and granulite facies) of the exposed crustal section. The data suggest a radiogenic heat contribution of Deccan crust of ∼38 mW m−2, implying a Moho heatflow of ∼7 mW m−2 and Moho temperature of ∼280 °C, which are similar to those in the adjoining Archaean Dharwar craton. Therefore, it appears that there is no thermal trace of the supposed plume in the present-day crustal thermal regime of the southeastern Deccan basalt province.