Sediments from Purana basins, India: Where were they derived from?

Abstract

The present exposures of the (Mesoproterozoic to Neoproterozoic) Purana basins of Peninsular India occupy nearly 1.5 × 105 km2 area in the Indian subcontinent, with an equal area being concealed under younger cover or lost to ensuing erosion. These extensional basins evolved on the margins (& with basement) of the existing cratonic blocks during the ‘boring billion years’ of Earth history. They host nearly 0.8 million km3 of epicratonic compacted and lithified sediments derived by weathering and erosion of the adjoining cratonic blocks and deposited on their fringes. The volumetric contents of these basins and their temporal distribution are compiled. The relative distribution and secular variations of sediment contents from these basins appear to synchronise with global Proterozoic supercontinental assembly and dispersal cycles. A comparison of mass-transfer by the erosion of the provenance area and sedimentation in continent margin basins shows that the volumes preserved in the Purana basins are at least 2 magnitudes larger than what can be derived from adjoining cratonic areas within the Indian Subcontinent. Much wider continental masses as well as exhumation (aided by uplift) of km-scale magnitudes of the provenance areas are required to reconcile their volume. Possible linkages with other cratonic blocks within the contemporary supercontinental assemblies are required to resolve this discrepancy.