Environmental Engineering Reference
In-Depth Information
End-Frasnian ?
350
300
End-Guadalupian
250
End-Permian
End-Triassic
200
End-Pliensbachian
End-Jurassic ?
150
End-Valanginian ?
End-Early Aptian?
100
End-Cenomanian?
End-Turonian?
End-Cretaceous
End-Paleocene
50
End-Early Oligocene ?
End-Early Miocene ?
0
50
100
150
200
250
300
350
Ages of continental flood basalts or oceanic plateaus (Ma)
Figure 15.2 Correlation between the ages of LIPs and those of mass extinctions
and oceanic anoxia events (from Courtillot and Renne,
2003
). The larger symbols
are the major mass extinctions.
earliest volcanic activity of many major hot spots, which are thought to result
from deep mantle plumes.
...
and hot spots
represent continuing magmatism associated with the remaining plume conduit or
'
flood basalts represent plume
'
heads
'
This started another debate on the reality and depth of origin of plumes,
as intense as the impact vs. volcanism debate. The main
tail
'
.
”
flood basalt provinces
that correlate with the main mass extinctions originate from the deepest mantle
(Courtillot
et al
.,
2003
) and there is often a close connection between
ood
basalts and continental breakup (Courtillot
et al
.,
1999
). A link between magnetic
superchrons and
has been proposed (Courtillot and Olson,
2007
).
As foreseen by Morgan (
1981
), hotspots are major geodynamical players: they
link core and mantle convection,
“
killer plumes
”
flood basalt eruption and major changes in
the
fluid envelopes and biosphere. There are a dozen such punctuated events in
the Phanerozoic, with a random distribution in time (Courtillot
et al
.,
2004
): the
Earth
'
s heat engine, trying to get rid of its excess heat.
