LIP eruptions seems to have dramatically altered the atmosphere and oceans for hundreds of thousands of years 94 million years ago and again 56 million years ago. A serious problem with such theories has often been an exact timing of the eruption events.
In a new study - “Paleocene-Eocene Thermal Maximum and the Opening of the Northeast Atlantic” - published in SCIENCE of 27 April 2007 precise rock dating were used to tie the outpourings of 5 to 10 million km2 basalt in a LIP, whose remains now span the North Atlantic from Greenland to Great Britain to the sudden 5°C warming 56 million years ago known as the Paleocene-Eocene thermal maximum, or PETM (See my post Global warming 55 million years ago). PETM included ocean acidification and extinction of 30 to 50% of deep-sea benthic formaminiferal species. Combined with previously published data, the dating places one of the largest surges of magma of the past quarter-billion years at 56.1 ± 0.5 million years ago.
Another study has strengthened the linkage between massive volcanism in the Caribbean and an abrupt transformation of the oceans 94 million years ago, known as oceanic anoxic event 2 (OAE2). OAEs were a half-dozen episodes in the warm mid-Cretaceous period 120 million to 80 million years ago when ocean sediments accumulated with so much organic matter that the sediments turned black. Something shifted ocean conditions to produce these "black shale" sediments, perhaps by eliminating oxygen from the deep sea.