"Timing of
global regression
and microbial bloom
linked with the
Permian-Triassic
boundary mass extinction:
implications for
driving mechanisms"
Björn Baresel, Hugo Bucher,
Borhan Bagherpour, Morgane Brosse,
Kuang Guodun & Urs Schaltegger
Scientific Reports volume 7,
Article number: 43630
(2017)
global regression
and microbial bloom
linked with the
Permian-Triassic
boundary mass extinction:
implications for
driving mechanisms"
Björn Baresel, Hugo Bucher,
Borhan Bagherpour, Morgane Brosse,
Kuang Guodun & Urs Schaltegger
Scientific Reports volume 7,
Article number: 43630
(2017)
95% of marine species
became extinct during
the Permian-Triassic
mass extinction event.
Baresel et al 2017 say
the cause was an ice age,
not global warming,
as previously claimed.
Science is never settled !
Baresel et al 2017
say the extinction
was caused by
a combination of:
1)
Abrupt cooling causing
falling sea levels and
marine regression from
a shrinking habitat
on shelves, and
2)
Intense acidification
of the oceans due to
release of sulphur rich
volatiles during the
Siberian Traps volcanism.
Terrestrial plants were also
impacted by the drier
and cooler climate,
during the abrupt ice age.
I don't know how to
summarize the
following details,
without changing
meanings, so I'll
present direct quotes
from the study:
(I added some commas)
“The mainstream claim
that the mass extinction
occurred “during the
transgressive pulse
when anoxic
bottom waters
often became extensive”,
is untenable in the view
of our timing from the
South Chinese record,
with its locally restricted
occurrences of Griesbachian
anoxic marine deposits."
"The duration
of 89 ± 38 kyr
for the hiatus in the
Luolou Platform
can only be
explained by
a short term
marine regression
of glacio-eustatic origin,
possibly combined with
submarine dissolution
of carbonate, through
acidification of
surface waters. …”
“All these observations
from the Nanpanjiang Basin,
as well as from other
relevant sections world-wide,
must be integrated into
a coherent causes and
effects model."
"In this endeavor,
the volcanogenic sulfur
aerosol-driven model
proposed by refs 37 and 38
provides the most parsimonious
working frame, with the
greatest explanatory power."
"Stratospheric
injection
of volcanogenic
sulfur volatiles
and subsequent
condensation
into aerosols
are seen as
the proximal cause
for brief
climate cooling,
and ensuing
global regression,
provided that
the cooling
was profound enough
to store water
as terrestrial ice."
"Sulfur volatiles also provide
a direct mechanism
for ocean acidification."
"Abrupt cooling likely resulted
from the atmospheric injection
of both volcanogenic and
remobilized SO2 and H2S
from early Paleozoic evaporites,
by the initial emplacement
of dykes and sills of the
Siberian Traps"
"This scenario simultaneously
accounts for acidification
of ocean surface waters,
and for the global regression."
"The synergistic effects
of shrunken marine habitats
on continental shelves,
through a global eustatic
regression, of fast
temperature drop down,
and of substantial acidification,
are all compatible with the
new timing proposed here."
Moreover,
paleontological evidence
facies interpretations
and sediment accumulation
rates are all compatible
with the volcanogenic sulfur
aerosol-driven model
for the PTBME.”
[ Permian Triassic Boundary
Mass Extinction Event ]
“The “lethally” hot temperatures
“The “lethally” hot temperatures
that were subsequently proposed
as second kill mechanism,
are also irreconcilable
with our model that involves
a glacio-eustatic low-stand
at the PTB".
( Permian Triassic Boundary )
“Abrupt drop down
“Abrupt drop down
of sea surface temperature,
shrunken habitats on shelves,
resulting from a global low stand,
and short-term acidification,
may all have synergistically
triggered the PTBME.”