ABR: Continued Geochronologic, Paleomagnetic, and Rock-Magnetic Studies of Continental Flood Volcanism

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RenneEAR-9909517This project is a continuation of ongoing research into the origins and consequences of continental flood volcanism. Previous work has documented that the peak of volcanic activity during these events occurs over geologically brief intervals of 1-3 million years, but the details of magma production history are not well known in most cases. This study will provide more detailed Ar/Ar and U/Pb geochronologic data aimed at improved magma production histories in the Parana-Etendeka, Central Atlantic, and Deccan Traps provinces. Comparison between detailed magma production histories and improved biostratigraphic time-scales will further clarify the relations between flood volcanism and mass extinctions. Additional emphasis will be placed on dating igneous rocks in these provinces that are clearly associated with extensional tectonism, such as dikes swarms, to better constrain the relationship between rifting, magmatism, and the eventual formation of ocean basins. A further goal of the project is to better delineate the spatial extent of these flood volcanic provinces, some of which overlap aerially with others and can be confidently distinguished only on the basis of age. Delineating the extent of the Central AtlanticMagmatic Province, only recently defined despite its widespread occurrence in North and South America, Africa, and Europe, is a top priority.