2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 155-2
Presentation Time: 1:45 PM

PALEOMAGNETISM OF MESOPROTEROZOIC LAVAS IN THE BARBY FORMATION OF THE SINCLAIR REGION, SOUTHERN NAMIBIA


XU, XinXin1, EVANS, David A.D.2, PANZIK, Joseph E.3, LINNEMANN, Ulf4, HOFMANN, Mandy4, HESSERT, Jenna5 and HANSON, R.6, (1)Geology & Geophysics, Yale University, 210 Whitney Ave., New Haven, CT 06511, (2)Department of Geology and Geophysics, Yale University, New Haven, CT 06520, (3)Department of Geology and Geophysics, Yale University, New Haven, CT 06511, (4)Senckenberg Naturhistorische Sammlungen Dresden, Museum für Mineralogie und Geologie, Königsbrücker Landstraße 159, Dresden, 01109, Germany, (5)Dept of Geosciences, Texas Tech University, Lubbock, TX 79409, (6)Geology Dept, Texas Christian University, Fort Worth, TX 76129, xinxin.xu@yale.edu

Southern Namibia is part of the Kalahari Craton, which is speculated to have occupied a central location the Rodinia supercontinent. The Sinclair region, along the western margin of the Kalahari Craton, comprises several low-grade volcano-sedimentary sequences that are amenable to paleomagnetic study. With a stratigraphic thickness of between 3000m and 5000m, low metamorphic grade, and gentle deformation, the Barby lavas provide ample opportunity for generating a robust paleomagnetic pole. The goal of this project is to combine newly collected field data of the Barby formation with previously published paleomagnetic results from the Sinclair region, to obtain a fuller understanding of the motion of the Kalahari craton as global paleogeography transitioned between the Nuna and Rodinia supercontinents. Paleomagnetic results from previous sampling campaigns demonstrate a North to Northeast shallow characteristic remanent magnetization, bolstered by positive inverse baked-contact tests on ca. 1100-Ma dikes that intrude the Barby lavas. Here we present initial results from the latest field season, sampling five different structural panels of different bedding attitudes (younging directions as follows): Vergenoeg (NE), Klein Haremub (SE), Naus (N), Aruab (SW), and Osis (W; the Osis panel is isolated and is only tenuously correlated with the other Barby sections). Our sampling includes regional fold tests, more inverse baked-contact tests, and intraformational conglomerate tests on the age of magnetization. New zircon U-Pb geochronology via laser-ablation ICP-MS dates the nonconformably underlying Haremub granite at ca. 1335 Ma, providing a maximum age for the Barby succession. The combination of geochronologic and paleomagnetic results will help to constrain the location of the Kalahari Craton in mid-Mesoproterozoic time.