Evidence for shock provides insight into the formation of the central elevated area in the Dhala impact structure, India

Amar Agarwal, Satyendra Kumar, Gaurav Joshi, K. K. Agarwal

Meteoritics & Planetary Science
Version of Record online: 14 December 2020


“The central elevated area is a postimpact morphological landmark in the otherwise flat eroded remnant of the Dhala impact structure, India. Its base is the Bundelkhand granitic complex followed by beds of Dhala and Kaimur Formations. The beds of the Dhala and Kaimur Formation present typical sedimentary textures and structures such as cross‐bedding. The grains are angular, sorting is moderate to poor, and brittle–ductile deformation of the protolith is still preserved in some grains. This reveals a short distance of transport. Detailed microscopy and U‐stage measurements confirm planar deformational features (PDFs) oriented (0001) and {10–13} in few quartz grains. Based on these facts, it is suggested that the quartz with PDFs was shocked, ejected out of the crater, and deposited near the crater cavity. Reworking of the ejecta blanket redeposited these quartz grains to their present location. Relatively few shocked grains in the rocks favor a postimpact fluvial process over impact resurge.”