137-14 Catastrophic Signals in the Stratigraphic Silence: Geochemical and Mineralogical Insights from the Gandhwani Intertrappean Beds, Central India

Session: Joint SGD-SEPM-IAS Focus on the Sedimentary Record of Climate Change

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The newly discovered intertrappean sequences at Gandhwani, Madhya Pradesh, represent a rare and significant sedimentary archive within the Deccan Volcanic Province, capturing the complex interplay between lacustrine environments, and rapid geochemical perturbations during the terminal Cretaceous. This study employs a multiproxy approach—integrating major oxide geochemistry, trace and rare earth element (REE) systematics, XRD-based mineralogy, and SEM-EDS microtextural analysis—to reconstruct depositional conditions and assess the influence of volcanic activity on basin evolution.

Two distinct stratigraphic exposures, GWL2 and GWL4, record contrasting paleoenvironmental settings. The GWL2 interval is characterized by calcite-dominated mineralogy, fossiliferous textures, and geochemical signatures consistent with freshwater lacustrine deposition under sub-humid conditions. In contrast, GWL4 exhibits elevated salinity indices, strong redox fluctuations, REE anomalies (positive Eu, Ce depletion), and microstructural evidence of hydrothermal overprinting—collectively reflecting episodic volcanic ash influx and diagenetic alteration.

These data challenge the traditional interpretation of intertrappean periods as volcanic quiescence and instead support a model of active volcanic-sedimentary coupling. The geochemical excursions observed in both exposures, particularly within GWL4, suggest repeated short-lived but intense environmental disturbances linked to Deccan eruptive pulses. This study contributes to a growing body of evidence positioning Deccan volcanism as a key driver of Late Cretaceous paleoenvironmental change.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10953

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