Flood Basalts and Stratigraphic Boundaries

Flood Basalts and Stratigraphic Boundaries The great continental flood-basalt lava flows exceeded 2000 cubic kilometres and comprise one form of large igneous province (LIP map). [image Columbia River Basalt Flows] Large igneous provinces are believed to have been caused by mantle plumes in the lithosphere, which injected magma into the lithosphere and erupted as huge basalt lava flows, probably within a million years or less. The Deccan, Newark, and Siberian flood basalts (each with lava volumes greater than 2 x 10^6 km^3 over periods of 1 million years or less) have been correlated with major extinction events. Extinctions could have been caused by environmental impacts of released gases – climatic cooling due to sulphuric acid aerosols, greenhouse warming caused by CO2 and SO2 gases, and acid rain. Mantle plume activity and flood basalts may also have been associated with other deleterious global geological factors, such as changes in sea-floor spreading rates, rifting events, increased tectonism and volcanism, or sea-level variations. The end-Cretaceous (Cretaceous/Tertiary or K/T boundary) mass extinction that wiped out the dinosaurs has been correlated with the impact of a 10-km diameter asteroid about 65 million years ago. Several other extinction events correlate with evidence of similar impacts.
Flood Basalt	Age Ma	Stratigraphic Boundary	Age Ma
Columbia River 0.25 x 10^6 km^3	16 ± 1 duration ~ 1 Myr	Early/Mid-Miocene [image]	16.4
Ethiopia ~1 x 10^6 km^3	31 ± 1 duration ~ 1 Myr	Early/Late Oligocene	30
North Atlantic >1 x 10^6 km^3	57 ± 1 duration ~ 1 Myr	Paleocene/Eocene(Thanetian/Selandian)	54.8 (57.9)
Deccan >2 x 10^6 km^3	66 ± 1 duration ~ 1 Myr	Cretaceous/Tertiary [image]	65.0 ± 0.1
Madagascar ? volume	88 ± 1 duration ~ 6? Myr	Cenomanian/Turonian(Turonian/Coniacian)	93.5 ± 0.2 (89 ± 0.5)
Rajmahal ? volume	116 ± 1 duration ~ 2 Myr	Aptian/Albian	112.2 ± 1.1
Serra Geral/Etendeka >1 x 10^6 km^3	132 ± 1 duration ~ 1 or 5 Myr	Jurassic/Cretaceous(Hauterivian/Valanginian) [image 1]	142 ± 2.6 (132 ± 1.9)
Antarctica >0.5 x 10^6 km^3	176 ± 1 or 183 ± 1 duration ~ 1? Myr	(Aalenian/Bajocian)	(176.5 ± 4)
Karoo > 2 x 10^6 km^3 td>	183 ± 1 duration ~ 0.5 -1 Myr	Early/Middle Jurassic [image 1, image 2]	180.1 ± 4
Newark >2? x 10^6 km^3	201 ± 1 duration ~ 0.6 Myr	Triassic/Jurassic [images]	205.7 ± 4
Siberian > 2 x 10^6 km^3	249 ± 1 duration ~ 1 Myr	Permian/Triassic [image, image 2]	248.2 ± 4.8

adapted from here.

Other flood basalts Paraña,