Geochronology and paleomagnetism of Large Igneous Provinces: testing the dynamic relationships between plate motions and mantle plumes

The often cited links between LIPs and continental break up and mass extinctions have been proposed primarily on the basis of detailed studies of the massive volumes of flood basalts that are characteristic features of all LIPs, and which are documented t o have erupted within very short geologic time periods (on the order of <1-2 m.y.). Because LIPs have erupted through continental crust, ocean crust, or both, they are also excellent markers with which to study large-scale plate motion and deformation, st retching and rupture of the crust, and mantle thermal and chemical evolution. The tendency to emphasize collection of data that can quantify the rates and volumes of production of the short-lived flood basalt eruptions has left a paucity of data for mos t of the rest of LIPs' histories that may last >10 to >100 m.y. Several LIPs of renown are located in the Atlantic-S. Africa region and include the North Atlantic Igneous Province (NAIP), the Central Atlantic Margin Province (CAMP), the Paraná-Etendeka P rovince (P-E), and the Karoo Igneous Province (KIP). These provinces were erupted at different times during the evolution of the Atlantic margin and southern Indian Ocean. Temporal and paleolatitudinal information for the LIPs provided by 40Ar/39Ar geoc hronology and paleomagnetism will yield rates and velocities for magma emplacement and plate motions. This study would address the complete history of the LIPs, of which the flood basalt phase is only one part, to gain regional understanding about: ·chan ge in rates of plate motion over time; ·timing of rapid plate motion relative to flood basalt volcanism; ·temporal relationship of volcanism to continental break up (if any); ·causal mechanisms for continental rifting and break up in presence/absence of L IPs. Laboratory experiments will also be designed to resolve a long-standing issue related to the low-temperature aspects of argon diffusion and remanent magnetism in igneous minerals and rocks.