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Adam Maloof - Research

The Shuram-Wonoka Transition

The Wonoka Formation is a 300-1000 meter thick limestone rich unit found within a sedimentary basin otherwise dominated by siliclastic rocks. The Wonoka sits directly beneath sandstones that contain the first macro-scale animal fossils (know as the Ediacaran Biota). The Wonoka also contains the most extreme negative carbon isotope excursion recorded in Earth history (also found in Oman, China, and possibly Namibia and Siberia).  Some workers have linked the deep carbon isotope excursion to the rise of oxygen that allowed large animals to evolve.

At some localities, the base of the Wonoka is marked by deep paleo-canyons that cut into the underlying strata.  In the Google Earth image below, the Wonoka is a buff/tan colored unit in the west edge of the syncline, while the underlying Brachina formation is dark brown and forms the canyon walls to three segments of a sinuous submarine canyon. The beds are shallowly dipping (~15-20 degrees) to the east/southeast.


These canyons suggest that large changes in local sea-level were coincident with the carbon isotope excursion.  What is the cause and effect relationship between profound sea level change, animal evolution, and complete reorganization of the carbon cycle?  Jon Husson and I are in the midst of a concerted field effort (see amazing outcrop below) coupled to geochemical and paleomagnetic lab work to try to shed light on this question.