100 Snowballs, Unconformities, BIFs and Beyond: Navigating the Neoproterozoic Rock and Climate Records Using Geochronology

The Neoproterozoic comprised periods of upheaval in Earth’s climate which changed the course of life and resulted in unique geologic features and formations. We welcome contributions applying geochronometers to investigate the timing of events and processes which shaped the Neoproterozoic.

Monday, 20 October 2025
8:00 AM - 12:00 PM
HBGCC, 304C

Stable Sedimentary Dynamics of the Zerrissene Deep-Sea Fan Across the Marinoan Snowball Earth

Paper number: 100-2
Program: Technical Sessions
Time: 8:35 AM – 8:50 AM

Authors

Abstract

The Zerrissene deep-sea fan in Namibia is a Cryogenian-Ediacaran turbidite succession that formed between the Congo paleocontinent and an arc terrane to the west. Dropstones in the upper Brak River Formation of the Zerrissene Group evidence glacigenic sedimentation correlated with the Marinoan Snowball Earth, providing a rare deep sea record of Snowball sedimentation. We identify a traceable horizon of the lowest stratigraphic dropstones, which we interpret to record Marinoan onset in the deep water setting. The youngest zircon grain in a preglacial detrital sample 155 m below this horizon yields a concordant CA-ID-TIMS date of ca. 642 Ma, which is consistent with recent work suggesting Marinoan onset ca. 639 Ma. The stratigraphic architecture and sediment provenance of the Brak River Formation persists unmodified by the Marinoan glaciation, changing only at the contact with the overlying Gemsbok River Formation, which marks an influx of carbonate and the disappearance of dropstones. The insensitivity of deep-sea sediment provenance to Snowball Earth glaciation conflicts with the hypothesis of expansive syn-Snowball continental denudation. Instead, the continuity of deep-sea sediment routing is consistent with a stable Snowball ice sheet volumes.

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

doi: 10.1130/abs/2025AM-412317

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