A lithostratigraphic and magnetostratigraphic framework in a geochronologic context for a purported Permian–Triassic boundary section at Old (West) Lootsberg Pass, Karoo Basin, South Africa

Field: Earth and Planetary Sciences (Physical Sciences)

Research Article| April 03, 2018 A lithostratigraphic and magnetostratigraphic framework in a geochronologic context for a purported Permian–Triassic boundary section at Old (West) Lootsberg Pass, Karoo Basin, South Africa Robert A. Gastaldo; Robert A. Gastaldo † 1Department of Geology, Colby College, Waterville, Maine 04901, USA †ragastal@colby.edu, jneveling@geoscience.org.za, geissman@utdallas.edu, skamo@es.utoronto.ca. Search for other works by this author on: GSW Google Scholar Johann Neveling; Johann Neveling † 2Council for Geosciences, Private Bag x112, Silverton, Pretoria, 0001, South Africa †ragastal@colby.edu, jneveling@geoscience.org.za, geissman@utdallas.edu, skamo@es.utoronto.ca. Search for other works by this author on: GSW Google Scholar John W. Geissman; John W. Geissman † 3Department of Geosciences, ROC21, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA †ragastal@colby.edu, jneveling@geoscience.org.za, geissman@utdallas.edu, skamo@es.utoronto.ca. Search for other works by this author on: GSW Google Scholar Sandra L. Kamo Sandra L. Kamo † 4Jack Satterly Geochronology Laboratory, University of Toronto, Toronto, Ontario, M5S 3B1, Canada †ragastal@colby.edu, jneveling@geoscience.org.za, geissman@utdallas.edu, skamo@es.utoronto.ca. Search for other works by this author on: GSW Google Scholar Author and Article Information Robert A. Gastaldo † 1Department of Geology, Colby College, Waterville, Maine 04901, USA Johann Neveling † 2Council for Geosciences, Private Bag x112, Silverton, Pretoria, 0001, South Africa John W. Geissman † 3Department of Geosciences, ROC21, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA Sandra L. Kamo † 4Jack Satterly Geochronology Laboratory, University of Toronto, Toronto, Ontario, M5S 3B1, Canada †ragastal@colby.edu, jneveling@geoscience.org.za, geissman@utdallas.edu, skamo@es.utoronto.ca. Publisher: Geological Society of America Received: 07 Jul 2017 Revision Received: 30 Jan 2018 Accepted: 19 Feb 2018 First Online: 03 Apr 2018 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2018 Geological Society of America GSA Bulletin (2018) 130 (9-10): 1411–1438. https://doi.org/10.1130/B31881.1 Article history Received: 07 Jul 2017 Revision Received: 30 Jan 2018 Accepted: 19 Feb 2018 First Online: 03 Apr 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Robert A. Gastaldo, Johann Neveling, John W. Geissman, Sandra L. Kamo; A lithostratigraphic and magnetostratigraphic framework in a geochronologic context for a purported Permian–Triassic boundary section at Old (West) Lootsberg Pass, Karoo Basin, South Africa. GSA Bulletin 2018;; 130 (9-10): 1411–1438. doi: https://doi.org/10.1130/B31881.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Current models of the terrestrial biosphere's response to the end-Permian crisis are based largely on lithostratigraphic, magnetostratigraphic, and biostratigraphic records obtained from sedimentary successions in the Karoo Basin, South Africa. These successions have been interpreted to represent continuous sedimentation across the upper Daptocephalus and lower Lystrosaurus vertebrate-assemblage zones, assigned to the Elandsberg Member and lower Palingkloof Member, and upper Palingkloof Member and overlying Katberg Formation, respectively. The stratigraphic section at Old (West) Lootsberg Pass, Eastern Cape Province, is used as a cornerstone for the currently accepted model correlated with the marine extinction event, in part, based on a magnetic polarity stratigraphy of limited documentation. Our current multidisciplinary effort provides a refined stratigraphic framework, encompassing over 740 m of measured section, compiled from 12 closely spaced and physically correlated localities across a northwest-to-southeast distance of less than 2 km. This framework is placed into magnetostratigraphic context and constrained by U-Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) results for two horizons.The Old Lootsberg Pass succession does not record continuous sedimentation, as previously argued. Rather, the presence of several intraformational pedogenic-nodule conglomerate-lag deposits, a character used by other workers as diagnostic of the Katberg Formation, occurs in the Elandsberg Member ∼100 m stratigraphically below the Katberg Formation. An interlaminated lithofacies, previously used as a diagnostic feature of the terrestrial extinction event, occurs isolated at several stratigraphic positions, indicating that it is neither unique nor mappable. A dominant signature of normal-polarity magnetozones in the section is interrupted by two, short, reverse-polarity intervals that are restricted to siltstone beneath erosional contacts with fluvial sandstones, indicating their cryptic nature in the succession. In addition, we report a Wuchiapingian maximum-age estimate for a detrital zircon population from a bed stratigraphically above a previously reported Early Changhsingian age estimate for these rocks. A comparison of the sedimentologic features of these deposits reveals that the bed from which the Changhsingian age is derived supports an ashfall interpretation rather than a reworked deposit from which the Wuchiapingian depositional age is derived. A synthesis of our observations from Old (West) Lootsberg Pass with global patterns reported from the marine realm leads to the conclusion that the turnover from the Daptocephalus to Lystrosaurus Assemblage Zones is not coincident with the end-Permian marine event. Hence, our results demonstrate that geochronometric constraints, where available, and a high-resolution sampling strategy for paleomagnetic context are essential to any research program when attempting to interpret patterns of biological turnover, replacement, and extinction in continental successions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.