Process Sedimentology, Stratigraphic Architecture, and Provenance of the Deep-Water Neoproterozoic Zerrissene Group, Damara Orogen, Namibia
Nora M. Nieminski
Stanford University, Department of Geological and Environmental Sciences, Stanford, CA 94305 USA
The study of the Late Proterozoic Zerrissene Group, exposed in westcentral Namibia, investigates the nature of deep-water systems. In particular, the work documents the spatial variability of distal deep-water deposits, defining lateral extent and facies distribution as they relate to the system’s morphology. The study of over 2000 sq. km of Late Proterozoic strata is facilitated by lack of vegetation in the Namib Desert and by regular east-west repetition of stratigraphy. The rocks that compose the Zerrissene Group have undergone lowgrade metamorphism and three significant stages of deformation, which have resulted in complex stratigraphy and metamorphic structures. Still, primary sedimentary structures are observed and serve in characterizing the depositing flows. The laterally extensive nature and relatively uniform thickness of the Late Proterozoic Zerrissene turbidites suggest that these sediments were primarily deposited in a distal lobe, basin floor depositional environment. Changes in thickness and lithofacies are documented over hundreds of meters and record the evolution and/or morphology of this large, unconfined system.
This study also aims to better constrain the provenance and depositional age of the Zerrissene Group. The Zerrissene turbidite system was deposited in a basin between the Congo and Kalahari Cratons. However, neither the source nor the orientation of the basin relative to the source is known. Detrital, geochemical, and petrological work on the siliciclastics, in addition to isotopic analysis on the carbonates incorporated into the deposits, help constrain the system’s provenance and offer insight to the overall tectonic setting and timing of this poorly studied Precambrian system.
AAPG Search and Discovery Article #90183©2013 AAPG Foundation 2013 Grants-in-Aid Projects