UNDERSTANDING THE ONSET OF FLOOD VOLCANISM; VOLCANIC FACIES AND THE SEDIMENTARY ENVIRONMENTS PRESERVED

The lowermost stratigraphy of flood basalt provinces provides valuable information to understand the onset of flood volcanism and the environments that these vast volcanic outpourings erupted into. Detailed investigation of the volcanic facies and facies associations found at the transition from sediments into flood volcanics is used to help characterize the environments of deposition of the volcanic units. Additionally the preservation of key sedimentary units within the volcanics can be used to constrain how these environments develop during the early stages of volcanism and into the main ‘acme’ of the flood volcanic event. From lava flows, pillow basalts and hyaloclastites to deserts, fluvial and marine settings, the environments preserved by flood basalts are wide and varied. Using examples from the Paranã-Etendeka, North Atlantic, Emeishan, and the Deccan, we look at a number of examples of these facies variations to help fuel the discussion on what happens at the onset of flood volcanism and how does the sedimentary and volcanic environment respond.