292-9 Insights into a Persististrombus-dominated assemblage from the lower Miocene of Kutch, India: Contrasting Shell Bed Dynamics in Western India

Session: Life and Environments Through Time and Space: Multi-Record Approaches to Stratigraphic Paleobiology, Part II

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Abstract:

Turritella-dominated gastropod assemblages were reported from the Aquitanian of Kutch, Gujarat. The present study documents the presence of a Persististrombus-dominated shell bed along with multiple turritelline-dominated assemblages (TDAs) from the Khari Nadi Formation (Aquitanian) of the Kutch Basin, western India. The Persististrombus assemblage is overwhelmingly dominated by Persististrombus deperditus (92% of the total assemblage), with associated gastropod species including Xenophora gajensis, Natica obscura, Phasianella variegata, and Cerithium rude. 

The genus Persististrombus first appeared in the Western Tethys during the early Oligocene, mainly recorded from the localities of Italy, Greece, France, and Bulgaria. Whereas, in the east, it was reported from the Oligocene of Iran, Arabian Peninsula and the Kutch Basin of India. By the early Miocene, the genus had existed in the eastern Tethyan realm, including Iran and western India. During this time, Persististrombus became a prominent component of western Indian gastropod faunas, particularly in the Dwarka and Kutch basins, and also in the southern Indian Quilon basins.

The presence of these strombid gastropods typically indicates tropical, warm, shallow marine environments characterized by sandy bottom substrates, coral rubble, and abundant seagrass vegetations – conditions associated with high nutrient availability. These environmental factors align with the thermal range (16°C-20°C) preferred by extant strombid species.

A comparative analysis of the Kutch and Dwarka basins reveals regional variation in gastropod assemblage patterns. The Kutch Basin features multiple TDAs and also a Persististrombus-dominated bed. In contrast, the adjacent Dwarka Basin displays frequent shell beds rich in strombids (which may even dominate the fauna) alongside a single time-condensed TDA bed. These differences likely reflect localized ecological dynamics operating within a broadly similar paleoenvironmental framework during the early–middle Miocene.

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

doi: 10.1130/abs/2025AM-6750

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