Palomagnetism of Mesoproterozoic Lavas in the Barby Formation of the Sinclair Region, Southern Namibia

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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.

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Geological Society of America Abstracts with Programs, v. 47, issue 7, p. 401