Synchrony of continental flood basalts (CFB) and
significant Phanerozoic mass extinction events may suggest a
trigger effect of large scale basaltic eruptions on the global
climate and environment,mainly due to intense emissions of
volcanic gases such as SO2 and CO2 [1]. However,this
interpretation is based on poorly constrained gas contents of
the basalts and on even less well known gas emission rates.
Here we investigate the S content of basalts of two of the
largest CFB provinces: the Central Atlantic magmatic
province (CAMP) and the Paranà-Etendeka (PE). Notably,while the CAMP is synchronous with and possibly triggered
the end-Triassic extinction [2],PE basalts had a very minor
effect on the early Cretaceous biosphere [3].
Melt inclusions in CAMP basalt olivines yield S contents
(electron microprobe analyses) comparable to those found in
Deccan basalts [1],whereas S in matrix glass is close to
detection limit,suggesting that degassing during the eruption
was almost complete.
As an alternative approach,we measure S (and Cl)
contents (synchrotrone analyses) also in phenocrysts from
CAMP and PE basalts and extrapolate the magmatic S content
through newly established crystal/melt partition coefficients.
These results illuminate the difference which seem to exist
between the two CFB provinces and contribute to our
understanding of their different environmental impacts.
[1] Self S. et al. (2008),Science 319,1654-1657. [2] Cirilli S.
et al. (2009),EPSL 286,514-525. [3] Wignall P. (2001),Earth. S. Rev 53,1-33.
