Environmental Engineering Reference
In-Depth Information
attempted to model the climate response to CAMP pulsed volcanism, using a
geochemical model coupled with a three-dimensional climate model. Eruptive
history is modelled as a series of ten identical volcanic pulses, each lasting
100 yr and equally spaced in time over 500 kyr. The total amount of CO
2
released
is 77,700 Gt. The model simulates a decrease by 30% of carbonate production
and reproduces the negative carbon isotopic excursions (but only by assuming a
-
20
isotopic composition for CO
2
released by CAMP or by adding a source
of highly depleted
13
C).
SO
2
emissions during continental
‰
flood basalt emplacement have also been
proposed as a major agent of environmental perturbations (Wignall,
2001
;
Courtillot
et al
., 2006b; Self
et al
.,
2006
). SO
2
is rapidly oxidized in the atmos-
phere, leading to the formation of sulfate aerosols (Robock,
2000
). In the case of
stratospheric injection, the lifetime of sulfate aerosols is about 1
2 yr, with global
cooling at the surface as a response. The amount of SO
2
released in a LIP eruption
is estimated using the relationship between the TiO
2
/FeO ratio and S established
for recent and historical tholeiitic lava
-
flows (Self
et al
.,
2006
,
2008
). The amount
6.5 Tg/km
3
of erupted magma. Chenet
et al
.(
2009
) proposed
that volcanic pulses had emitted up to 1 Gt/yr of SO
2
over 100 yr and between
impact of the joint release of SO
2
and CO
2
using an approach similar to Paris
et al
.
(
2012
). A series of 280 volcanic pulses lasting 10 yr each and equally spaced in
time (1,500 yr) over 400 kyr was considered. The release of 28,000 Gt of CO
2
(alone) increases the pCO
2
by 150 ppmv and sea surface temperature by 1.5
Cat
mid-to-low latitudes after 400 kyr. When CO
2
(28,000 Gt) and SO
2
(6,500 Gt)
are released simultaneously, the simulated pCO
2
variation is larger, reaching
200 ppmv, and sea surface temperatures warm by 2.5
C, due to SO
2
(which
of SO
2
is 3.6
-
rst
leads to abrupt cooling events, decreasing the ef
ciency of silicate weathering
and amplifying the rise of pCO
2
). The injection of SO
2
during trap emplacement
and its conversion to sulfate aerosols lead to climate changes on a short timescale,
shorter than the temporal resolution of most records.
Ganino and Arndt (
2009
) proposed that
the amount of gas released by a
continental
flood basalt is the sum of direct magma degassing and degassing
of sediments intruded by the lava. Contact metamorphism driven by intrusions
feeding LIPs may have released large amounts of volatiles (Svensen
et al
.,
2007
;
Ganino and Arndt,
2009
; Retallack and Jahren,
2008
; Black
et al
.,
2012
). The
nature of these volatiles depends on the type of sediment intruded. Svensen
et al
.
(
2004
) estimate that the intrusion of basaltic sills belonging to the NAIP in organic-
rich layers in the Vøring and Møre basins would have injected 300 to 3,000 Gt
of methane with a highly depleted carbon isotope signature. Such massive
release would have occurred at the start of the Initial Eocene Thermal Maximum
