A Review of Stratigraphic, Geochemical, and Paleontologic Data of the Terrestrial End-Permian Record in the Karoo Basin,
The Karoo Basin has long been considered to contain the type stratigraphic succession for the terrestrial expression of the end-Permian mass extinction. A detailed extinction model, based on biostratigraphic and geologic data, has proposed rapid environme
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Johann Neveling, Robert A. Gastaldo, Sandra L. Kamo, John W. Geissman, Cindy V. Looy, and Marion K. Bamford
Abstract
The Karoo Basin has long been considered to contain the type stratigraphic succession for the terrestrial expression of the end-Permian mass extinction. A detailed extinction model, based on biostratigraphic and geologic data, has proposed rapid environmental change that coincides with a vertebrate biozone boundary, which was postulated to have been caused by increased aridity. Our sedimentologic, geochronologic, palaeomagnetic, and geochemical data collected from reported boundary sections, show that the link between the floral and faunal turnover and marine end-Permian event is tenuous. A review of existing, as well as our own palaeontological data, interpreted within a robust stratigraphic and sedimentologic framework, further indicate that ecological change was more subtle and protracted than currently modeled, and reflects the complex way in which the ancient Karoo landscape responded to changes in several extrinsic factors.
15.1
Introduction
The continental stratigraphic record in the Karoo Basin, South Africa, plays a central role in our understanding of the terrestrial ecosystem response to the end-Permian mass extinction. The basin formed in southern Gondwana during the Late Paleozoic and contains a sedimentary succession
J. Neveling (&) Council for Geosciences, Pretoria, South Africa e-mail: [email protected] R.A. Gastaldo Colby College, Waterville, ME, USA S.L. Kamo Jack Satterly Geochronology Laboratory, University of Toronto, Toronto, Canada J.W. Geissman University of Texas at Dallas, Richardson, TX, USA C.V. Looy University of California at Berkeley, Berkeley, CA, USA M.K. Bamford Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
that records deposition from the Late Carboniferous to Middle Jurassic. Research on the events reported to be associated with the end-Permian crisis focused on an interval encompassing the two uppermost lithologic members recognized in the Balfour Formation, a part of the fully continental Beaufort Group. The Elandsberg Member consists predominantly of greenish gray mudstone and is overlain by the Palingkloof Member, characterized by greenish gray and grayish red mudstone which is, in turn succeeded by the largely arenaceous Katberg Formation (SACS 1980).
15.2
Background
The rich fossil record of tetrapods preserved in the Beaufort Group allowed for the establishment of an eightfold (Fig. 15.1) biozone subdivision (Rubidge 1995; see also Chap. 14 in this book). The origin of this scheme can be traced to that of Broom (1906), who proposed a sixfold subdivision and presumed the Lystrosaurus beds (i.e., the Lystrosaurus AZ in the modern scheme) to be Early Triassic in age; all preceding units were considered Permian. The
© Springer International Publishing Switzerland 2016 B. Linol and M.J. de Wit (eds.), Origin and Evolution of the Cape Mountains and Karoo Basin, Regional Geology Reviews, DOI 10.
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