Subaqueous Flood Basalt Volcanism, Volcanosedimentary Associations, and Lava-Sediment Interaction

Abstract

Subaqueous counterparts of the subaerial flood basalts, whether formed under the sea in an oceanic plateau or along a rifted volcanic margin, or in inland lakes and rivers, are exposed in many places due to erosion or tectonic uplift (e.g. Kerr et al. 2000). Icelandic subglacial eruptions also create lakes of meltwater with deposits of pillow lavas, hyaloclastites and tuffs. Pillow lavas are analogous to small-scale compound pāhoehoe lava flows that form subaerially, and form in the same effusive manner as the latter. Flood basalt lava flows can be interstratified with sedimentary strata (called intertrappeans in the Deccan literature). Sills and even lava flows (called invasive flows) may invade such strata. Mingling between lava and soft, unconsolidated, typically wet sediment produces heterogeneous rocks called peperites.