"Flood basalts" refers to large volcanic eruptions that occur over a vast area, creating layers of solidified lava. It is like a huge flood of lava flowing out from the ground, covering the surface and forming flat plains of rock. Full definition
The Siberian flood basalt eruption, the biggest volcanic effect on Earth, lasted for millions of years. (news.mongabay.com)
Continental flood basalt provinces (LIPs) are enriched in mafic / ultramafic igneous rocks and have a relatively high concentration of Cu, Co, Cr, etc. (Brügmann et al. 1987). (sp.lyellcollection.org)
There is a strong association between flood basalt volcanism and perturbations of the Earth's carbon cycle (as indicated by oceanic anoxic events, mass extinctions, and hyperthermals). (royalsociety.org)