By: magic-gigapans
Image: Robin Rohrback, Mid-Atlantic Geo-Image Collection
License: Creative Commons Non Commercial ⧉

Uploaded: 13 May 2020
Last Updated: 7 Jul 2020

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Roll up structures in a dolomitic microbialaminite from the ca. 740 Ma Rasthof Formation cap carbonate in the Otavi Group of northwestern Namibia. This thick cap carbonate lithofacies, which sits immediately atop the Chuos diamictite, starts with allodapic layers of transported carbonate (both limestone and dolomite) that grade into these microbial fabrics. The transported layers have strongly negative carbon isotope compositions that grade to positive values within the microbialaminite. This sample was provided by Dr. Jay Kaufman of the University of Maryland.