Record of glacial overriding driven soft-sediment deformation structures (SSDS) from Late Paleozoic glaciomarine Talchir Formation, Son Valley Basin: Implications on ice-sheet dynamics and Lower Gondwana paleogeography.

Soft-sediment deformation structures (SSDS) associated with glacial overriding are crucial as they significantly reflect glacier dynamics during glaciation–deglaciation cycles. The stress produced by overriding ice sheets on unconsolidated sediments can form mesoscale folds and shear structures. The Permo-Carboniferous Talchir Formation in the Son Valley Basin, India, is characterised by glacigenic sedimentation and signatures of post-glacial marine transgressions. Larger-scale (several metre-long) deformation structures, such as mesoscale open folds, pushover folds, drag folds, recumbent folds, and listric faults recorded within sandstone–mudstone heteroliths are interpreted as having formed by the overriding glacier and/or the bulldozing effect of advancing glaciers. Moreover, the load induced by bulldozing glaciers and associated shaking effects led to liquefaction and fluidization related SSDS in cm-thin bedset scale, producing smaller load and flame structures, complexly deformed laminations, and water-escape structures. Based on morphology, stratigraphic distribution, and mechanism of formation, identified SSDS are divided into two categories, i.e., glacigenic SSDS are interpreted to be of glaciotectonic origin related to the frontal pushing and ice-marginal deformation, whereas non-glacigenic SSDS are caused by loading, localized shaking, and/or rapid sedimentation under complex ice-marginal fluctuations in a glaciomarine setting. These SSDS are associated with glacial advancements followed by a deglaciation sequence in relation to climatic amelioration in a proglacial–periglacial basin-margin setting, which demonstrates important clues for reconstructing the paleogeography of the Son Valley Basin in the frame of the Late Paleozoic ice age (LPIA). Research highlights: The present study identifies soft-sediment deformation structures (SSDS) resulting from glacial overriding processes in the Permo-Carboniferous Talchir Formation, Gondwana Supergroup. Based on the morphology, stratigraphic distribution, mechanism of formation, driving forces and the responsible trigger agents of their origin, identified SSDS are interpreted as glacigenic and non-glacigenic in origin. The structural heterogeneity of the deformed sedimentary lithounits indicates glacitectonic deformation at different stages of glacier advancements and overriding. In-depth examination of deformation structures has provided insight into the ice-sheet dynamics, which has contributed in reconstructing the paleogeography of the basin during the Late Paleozoic Ice Age (LPIA). [ABSTRACT FROM AUTHOR]