Seismically derived Gondwana and Proterozoic sediments east of Cuddapah basin, south Indian shield and its possible geotectonic implications
Pure and Applied Geophysics, 2017•Springer
The study area situated east of the intracratonic Proterozoic Cuddapah basin, that covers
Nellore Schist belt, Ongole domain of the Eastern Ghats Belt and adjacent East Coast
Terrain, forms a geodynamically important segment of the Dharwar craton. This region came
into focus due to proposition that during Paleoproterozoic to Mesoproterozoic era, it
underwent persistent oceanic subduction, continent–continent collision and multi-stage
accretional growth. In view of this, we have reprocessed in detail the deep seismic sounding …
Nellore Schist belt, Ongole domain of the Eastern Ghats Belt and adjacent East Coast
Terrain, forms a geodynamically important segment of the Dharwar craton. This region came
into focus due to proposition that during Paleoproterozoic to Mesoproterozoic era, it
underwent persistent oceanic subduction, continent–continent collision and multi-stage
accretional growth. In view of this, we have reprocessed in detail the deep seismic sounding …
Abstract
The study area situated east of the intracratonic Proterozoic Cuddapah basin, that covers Nellore Schist belt, Ongole domain of the Eastern Ghats Belt and adjacent East Coast Terrain, forms a geodynamically important segment of the Dharwar craton. This region came into focus due to proposition that during Paleoproterozoic to Mesoproterozoic era, it underwent persistent oceanic subduction, continent–continent collision and multi-stage accretional growth. In view of this, we have reprocessed in detail the deep seismic sounding data over this region and integrated the obtained results with other geophysical studies to decipher the deep subsurface crustal structure underneath. The derived shallow seismic section across this region showed the presence of a thin layer (~250 m) of Gondwana sediments with a distinct velocity of 4.20 km/s and a lateral dimension of about 40 km around Vinjamuru region of the Nellore Schist Belt. Another important finding has been the depiction of 5.3 and 5.5 km/s velocity sediments (comparable to upper and lower Cuddapah sediments) between Nellore Schist Belt and the east coast, indicating the possible presence of an additional Proterozoic sedimentary terrain (named here as East Coast Sedimentary Basin), overlying the concealed Archean crystalline basement. The presence of this sedimentary terrain, which is separated from the Cuddapah basin by an exhumed horst-like feature, situated below Nellore Schist Belt, would indicate Proterozoic sedimentation in a much larger area during Columbia and Rodinia supercontinental assembly periods than hitherto known. Importantly, no seismic trace of the Eastern Ghats Belt has been found between Nellore Schist Belt and the east coast. It appears that during the Gondwana period, entire eastern segment of the east Dharwar craton has been persistently rifting, uplifting and eroding together with other Gondwana grabens in India, thereby leaving behind only a thin veneer of Gondwana sediments at many places. In view of the presence of number of Gondwana occurrences all along the east coast, it is felt that the rifting during the Gondwana period may have been a prelude to India–Antarctica breakup, with final separation between the two taking place much later during early Cretaceous.
Springer
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