Denudation history of Eastern Indian peninsula from apatite fission track analysis: Linking possible plume-related uplift and the sedimentary record

摘要

The Late Archaean-Early Proterozoic (~. 2.5. Ga) Eastern Dharwar Craton (EDC), eastern India, which underlies much of the drainage basins of the Krishna and Godavari rivers, has undergone an erosionally controlled evolution since the Pan African event (~. 500-550. Ma). This evolution has been responsible for the sedimentation and overall development of the Krishna-Godavari (KG) sedimentary basin. In order to reconstruct the denudation history of the EDC, which forms the hinterland to the petroliferous KG basin, we report apatite fission track (AFT) data from 41 samples. Thermal history modelling suggests that little denudation occurred before Mid-Cretaceous time. However, during the Late Cretaceous, accelerated cooling commenced from a temperature range of 60-75. °C. Assuming a low palaeogeothermal gradient of 10. °C/km, similar to that of the present day, cooling of the EDC translates to ~. 0.5-2. km of denudation during the Late Cretaceous and a total of ~. 4. km since that time. The denudation history is closely related to the sedimentary record in the KG basin. The episode of accelerated cooling in the Late Cretaceous is interpreted as a geomorphic response to uplift of the Indian peninsula possibly resulting from an ascending mantle plume, which produced the voluminous Deccan Traps at the K-T boundary. The denudation history coupled with previous palaeocurrent studies in the KG basin suggest that the Krishna-Godavari drainage system was established in Late Cretaceous time.