New insights into the relationship between the Central Atlantic Magmatic Province (CAMP) and the End-Triassic extinction from CAMP U-Pb zircon and baddeleyite dates.
Joshua Davies, University of Geneva, Geneva, Switzerland, Herve Bertand, Ecole Normale Supérieure de Lyon UMR-CNRS, Laboratoire de Géologie, Lyon, France, Nasrrddine Youbi, Cadi Ayyad University, Faculty of Sciences-Semlalia, Department of Geology, Marrakech, Morocco and Urs Schaltegger, University of Geneva, Earth Sciences, Geneva, Switzerland
Contact First Author: Joshua Davies; joshua.davies@unige.ch
English Abstract:
The Central Atlantic Magmatic Province (CAMP) is a sequence of flood basalts, dyke swarms and sill complexes , emplaced predominantly into the Triassic and Jurassic basins of Pangea. The exact extent of the flood basalts is unknown, but it is thought to be one of the largest outpourings of basalt magma onto the continental crust during the Phanerozoic Eon. Consequently, the basaltic eruptions has been linked with the End-Triassic extinction, the initiation of Pangea breakup and the opening of the Central Atlantic Ocean. However, the link between the CAMP basalts and the End-Triassic extinction is still unclear, which is in part, due the basalts being stratigraphically above the extinction horizon in all of the basins where they have been discovered. A negative carbon isotope excursion and a spike in fern spore abundance mark the extinction horizon and these are below the lowest basalts in North America, and also just below the basalts in Morocco, where the oldest CAMP basalts are thought to outcrop.
Here we present high precision U-Pb TIMS dates for zircons from the Moroccan and North American CAMP successions that suggest that there was CAMP magmatic activity before the eruption of the first basalts. Antecrystic zircons from a basalt flow in North America suggest a long pre-eruption history of magmatism associated with the CAMP. Baddeleyite and zircon from a dyke in the Moroccan CAMP also suggest a similar pre-eruptive history. Both the zircon and baddeleyite were extracted from coarse gained sections of the flow and dyke in an attempt to avoid zircons crystalizing in late melt segregations which are usually the target for basalt U-Pb dating. We also present hafnium isotope data from the zircons and baddeleyites to support our conclusions. The identification of zircon and baddeleyite antecrysts provide an insight to the pre-eruptive history of the CAMP and have significant implications for the relationship between the CAMP and the End-Triassic extinction.
