Subsurface
shallow
gas,
primarily
composed
of
biogenic
methane
(>95%),
is
commonly
found
in
nearshore
sediments
worldwide.
The
redox
conditions
pore
fluid
play
a
crucial
role
shaping
the
geochemical
signatures
associated
with
anaerobic
oxidation
(AOM)
and
vertical
displacement
sulfate-methane
transition
zones
(SMTZs)
within
deep
sedimentary
records.
However,
complete
understanding
these
archives
limited
by
depth
collected
sediment
samples.
In
this
study,
we
employed
combination
mineralogical
methods
to
investigate
dynamics
Zhoushan
offshore
area.
profiles
water
provided
evidence
for
occurrence
AOM
presence
multiple
SMTZs,
which
were
attributed
flow
methane-rich
fluid.
Analysis
sulfur
content
characteristics
authigenic
pyrite
different
facies
revealed
four
intervals
impacted
core
JC-1.
Notably,
marine
(<40
meters
below
seafloor)
exhibited
positive
peaks
δ34S-CRS
values,
reaching
up
27‰.
These
overflow
resulting
from
unstable
conditions,
such
as
changes
sedimentation
rate,
intense
physical
reworking,
and/or
biological
activity
influencing
mud.
Interestingly,
covariation
molybdenum
(Mo)
uranium
(U),
indicated
(Mo/U)EF
ratios,
proved
be
valuable
tool
providing
insights
into
intensity
past
seepages,
thereby
constraining
conditions.
AOM-derived
H2S
led
suboxic
sulfidic
occurring
narrow
zone
close
seafloor
proximity
seawater.
Consequently,
enrichments
Mo
U.
This
Mo-U
proxy
particularly
recommended
use
methane-impacted
seabed
sediments,
where
diagenetic
processes
make
sulfide
minerals’
δ34S
values
tracers
SMTZ
fluctuations
challenging.
Solid Earth Sciences,
Journal Year:
2022,
Volume and Issue:
7(3), P. 237 - 246
Published: Aug. 6, 2022
The
shales
of
the
Mamfe
basin
were
geochemically
analyzed
to
determine
their
paleosalinity
and
hydrothermal
characteristics
which
existed
at
time
deposition.
Elemental
ratios
such
as
boron/gallium
(B/Ga),
strontium/barium
(Sr/Ba),
total
sulphur/total
organic
carbon
(S/TOC)
TOC/S
applied
for
reconstruction.
show
B/Ga
is
<3,
Sr/Ba
<0.2,
S/TOC
<0.1
>6
values
elemental
ratio
that
deposited
in
a
freshwater
environment.
For
activities
ratio,
Sc/Cr
was
used
Binary
diagrams
TOC
vs
P
Co/Zn
constructed
discriminate
between
normal
water,
mixed
influence.
greater
than
0.14
indicating
water
environment
with
no
influence
from
processes.
binary
discriminant
diagram
shows
all
not
influenced
by
any
processes
during
•
study
area
have
same
similar
geochemical
characteristics.
fresh
affected
activity
Frontiers in Earth Science,
Journal Year:
2023,
Volume and Issue:
11
Published: May 9, 2023
Offshore
Zhoushan
sediments
are
a
potential
area
for
shallow
gas
resources
in
China,
where
authigenic
pyrite
is
widely
distributed.
Pyrite
content,
size
distribution,
and
morphology
influenced
by
depositional
conditions
sensitive
to
environmental
changes.
This
study
investigated
the
pyrites
or
gypsums
of
core
JC-1
offshore
Zhoushan.
Scanning
electron
microscopy
was
used
observe
identify
various
aggregations.
Changes
lithology,
chlorine
stable
isotope
values
organic
matter
were
analyzed
indicate
evolution
ancient
marine,
floodplain
estuary,
tidal
flat
environments,
marine
sedimentary
facies.
The
microcrystalline
structure
these
types
can
be
divided
into
spherical
framboid
aggregates,
sub-euhedral
euhedral
with
different
Gypsum
minerals
coexistence
gypsum
found
enriched
at
SMTZs.
sources
sulfate
formed
may
originate
from
overlying
seawater
oxidation,
whereas
calcium
ions
come
dissolution
carbonate
calcareous
shells
caused
local
acidification.
aggregations
observed
related
SO
4
-AOM
environments.
findings
suggest
that
form
due
acidification
oxidation.
provides
new
perspective
understanding
responses
environments
sea
level
rise
climate
change.
Frontiers in Marine Science,
Journal Year:
2022,
Volume and Issue:
9
Published: Sept. 8, 2022
The
content
and
isotopic
composition
of
pyrite
sulfur
are
significantly
affected
by
local
depositional
conditions
sensitive
to
environmental
evolution.
Here,
we
use
core
QK11,
collected
from
Xiapu
Bay,
southeast
coast
China,
reveal
how
constrained
formation
since
MIS5.
Our
results
show
that
the
is
mainly
controlled
TOC
during
interglacial
intervals
limited
supplement
sulfate
in
glacial
intervals.
Therefore,
C/S
ratios
can
effectively
identify
three
transgressions
ranges
-36.7
18.4‰
whole
core.
occurrence
isotopically
“heavy”
observed
at
depth
2.2~9.2,
27.2~33.8,
43.5~62.5
mbsf,
which
attributed
influence
reservoir
effect,
event,
unsteady
diagenetic
environment,
other
factors,
highlighting
processes
on
sulfur.
Pyrite
layers
generally
depleted
34
S,
as
low
-36.7‰,
indicating
early-stage
organiclastic
reduction
(OSR)
plays
an
important
role
fractionation.
also
suggest
organic
carbon
indicators
(TOC/TN
ratio
δ
13
C)
combined
with
distinguish
between
freshwater
marine
environments,
great
significance
evolution
deep
time.
Palaeogeography Palaeoclimatology Palaeoecology,
Journal Year:
2024,
Volume and Issue:
639, P. 112087 - 112087
Published: Feb. 13, 2024
We
present
an
integrated
sedimentological,
paleontological
and
oxygen
isotope
stratigraphic
study
of
a
Pleistocene
marine
to
coastal
section
at
the
Enza
river,
allowing
highlight
role
tectonics
mountain
front
Northern
Apennines
that
climate
onset
Mid
Transition.
Two
main
evolutive
steps,
separated
by
pronounced
angular
unconformity,
characterize
deposition
studied
sedimentary
succession
ranging
between
1.73
1.071
Ma.
The
lower
part
shows
continuous
outer
shelf
sedimentation,
whereas
post
unconformity
sedimentation
cyclothemes,
documenting
progressive
shallowing
bathymetry.
These
are
linked
enhanced
eustatic
oscillations
leading
increasing
amplitude
transgressive-regressive
cycles.
new
δ18O
data
allowed
correlating
last
14
m
underneath
MIS
49
45,
improving
our
understanding
time
duration
gap,
estimated
around
140
ka.
This
is
primarily
associated
with
growth
Quattro
Castella
thrust
ramp
anticline,
when
deeper
mid-crustal
co-occurred,
causing
increased
deformation
tilting
rate.
consequent
change
in
morphotectonic
setting
strongly
impacted
environment
ecosystem
this
Early
shelf.
Starting
about
1.25
Ma,
records
riverine
detritus,
competing
shore-parallel
shelfal
sediment
dynamics.
In
frame
slope
topography,
fluvial
activity
might
correlate
during
Transition,
as
recognized
other
Mediterranean
settings.
recorded
cyclothemic
deposition,
oscillations.
Frontiers in Marine Science,
Journal Year:
2024,
Volume and Issue:
11
Published: March 11, 2024
The
correlation
between
the
amount
of
organic
carbon
(OC)
and
sulfur
(S)
in
sediments
has
been
widely
used
as
a
paleosalinity
indicator
to
distinguish
marine
freshwater
environments.
However,
whether
ratio
total
OC
S
(TOC/TS)
can
be
identify
unsteady
or
dynamic
environments
across
sedimentary
strata
is
still
contended.
An
HZW1907
sediment
core
80
m
length
was
successfully
collected
middle
Hangzhou
Bay
(HZB),
serving
one
few
boreholes
that
are
crucial
for
study
geologic
geo-environment
changes
coastal
regions
eastern
China
since
Last
Glacial
Maximum
(LGM).
Total
(TOC),
stable
isotope,
TS
82
subsamples
from
were
analyzed
reconstruct
history
shallow
water
biological
pump
preservation
record
bay
Late
Pleistocene.
Our
results
indicate
samples
had
low
concentrations
TOC
(0.21%)
nitrogen
(TN)
(0.02%),
high
mass
TOC/TN
(10.8),
δ
13
C
(−24.9‰),
content
(0.06%),
TOC/TS
(9.1)
33.6
ka
BP
12.3
BP,
implying
matter
(OM),
algae,
C3
plant
fragments
main
sources
OM
relatively
cold
environment.
abundances
TOC,
TN,
increased
0.56%,
0.07%,
0.4%,
respectively,
while
(−23.9‰)
(2.7)
decreased
Holocene
sediments,
suggesting
seawater
began
influence
composition
HZB.
Climate
warming,
which
likely
have
impacted
results,
experienced
BP.
isotope
mixing
model
indicated
Mid-late
Holocene,
more
than
70%
riverine
accounted
OM.
identified
an
effective
intrusion,
with
C/S
ratios
1–6
being
considered
“sea–land
transitional
zone”
environment,
>6
indicating
freshwater,
C/S<1
normal
facies.
These
findings
provide
evidence
using
enhance
our
understanding
past
climate
changes.
Therefore,
these
geochemical
indicators
conjunction
other
records
obtain
accurate
about
evolution.
