Continued Geochronologic, Paleomagnetic, and Rock-Magnetic Studies of the Parana-Etendeka Flood Volcanic Province

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9628065 Renne The proposed research will provide fundamental data toward clarifying the spatial-temporal evolution of flood volcanism in the Parana-Etendeka province (PEP) of southwestern Africa and eastern South America. The PEP is one of the largest continental flood volcanic provinces known, and data acquired herein will be relevant to broader questions about the origin of flood volcanism. Relations between volcanism, the Tristan da Cunha hotspot, and Early Cretaceous rifting of the South Atlantic will be elucidated by high-precision geochronologic and paleomagnetic and rock magnetic work that will be done in connection with ongoing stratigraphic and petrologic studies. New and detailed magnetostratigraphy will be established for volcanic sections in the Etendeka Province of Namibia as well as the Parana Province of Uruguay. Refined and well-dated apparent polar wander paths (APWP's) will be derived for both South America and southern Africa over the interval of 135-120 Ma; the APWP's will quantify rotation due to asymmetric opening of the South Atlantic and will be used to refine the trace of the Tristan hotspot. 40Ar/39Ar and U/Pb dating will be used to constrain with greater certainty any migratory trends in volcanism. Correlations between individual flows across the Atlantic will be tested paleomagnetically and rock-magnetically; a corollary of such correlation will be a high-precision basis for pre-drift reconstruction of western Gondwanaland. Determination of volcanic flow directions (constraining locations of sources) will be attempted using anisotropy of magnetic susceptibility (AMS) from widely separated flow sequences, particularly units being tested for Transatlantic correlation.