of 8
Late
Miocene
Uplift
and
Exhumation
of
the
Lesser
Himalaya
Recorded
by
Clumped
Isotope
Compositions
of
Detrital
Carbonate
U.
Ryb
1
,
C.
Ponton
2
,
C.
France‐Lanord
3
,
K.
Yoshida
4
,
and
J.
M.
Eiler
5
1
The
Freddy
and
Nadine
Hermann
Institute
of
Earth
Sciences,
The
Hebrew
University
of
Jerusalem,
Jerusalem,
Israel,
2
Western
Washington
University,
Bellingham,
WA,
USA,
3
Centre
de
Recherche
Pétrographiques
et
Géochimiques,
Nancy,
Vandoeuvre,
France,
4
Institute
of
Mountain
Science,
Shinshu
University,
Matsumoto,
Japan,
5
California
Institute
of
Technology,
Pasadena,
CA,
USA
Abstract
The
Himalaya
orogen
evolved
since
the
Eocene
as
the
Tethyan‐,
Greater‐,
Lesser‐
and
Sub‐
Himalaya
thrust
sheets
were
uplifted
and
exhumed
in
sequence.
Reconstructing
the
provenance
of
sediment
in
Himalayan
River
systems
can
inform
on
stages
in
the
tectonic
history
of
the
orogen.
Here,
we
analyze
the
oxygen,
carbon
and
“clumped”
isotope
compositions
of
carbonate
minerals
from
Himalayan
bedrock,
Ganga
River
sediments
and
Bengal
Fan
turbidite
deposits.
We
demonstrate
that
river
sediments
consist
of
a
mixture
of
Himalayan‐derived
and
authigenic
calcite
precipitated
in
the
river
system.
The
relative
abundance
and
clumped
isotope
apparent
temperatures
of
detrital
calcite
in
turbidite
deposits
decreased
between
the
Late
Miocene
and
Pliocene,
while
chemical
weathering
intensity
did
not
increase
during
this
interval.
Considered
together,
these
results
reflect
the
establishment
of
the
Lesser
Himalaya
as
an
important
carbonate
sediment
source
for
Himalayan
rivers,
driven
by
the
uplift
and
exhumation
of
this
thrust
sheet.
Plain
Language
Summary
The
Himalaya
Range
consists
of
a
series
of
tectonic
units
that
accreted
during
the
last
50
million
years
as
the
Indian
and
Asian
continents
collided.
Sediment
provenance
analyses
are
commonly
used
to
reconstruct
stages
in
tectonic
evolution
of
mountain‐belts,
but
often
capture
local
conditions
and/or
are
altered
by
various
sediment‐transport
processes.
We
overcome
these
complexities
by
measuring
oxygen,
carbon
and
“clumped”
isotope
compositions
of
carbonate
minerals
in
turbidite
deposits
cored
from
the
Bengal
Fan,
to
constrain
sediment
provenance
at
a
Himalaya‐wide
scale
since
the
Early
Miocene.
Considered
together
with
records
describing
weathering
intensity,
our
data
suggests
that
the
Lesser
Himalaya
became
the
dominant
source
for
detrital
carbonate
as
this
tectonic‐unit
was
uplifted
and
exhumed
between
the
Late
Miocene
and
Pliocene.
1.
Introduction
The
Himalaya
orogen
has
been
evolving
since
the
Eocene
along
the
convergence
boundary
between
the
Indian
and
Asian
plates,
as
the
Tethyan‐,
Great‐,
Lesser‐,
and
Sub‐Himalaya
thrust
sheets
were
uplifted
and
exhumed
in
sequence
(Yin
&
Harrison,
2000
)
(Figure
1
).
These
tectonic
units
are
characterized
by
different
mineral,
element
and
isotope
compositions
(e.g.,
Derry
&
France‐Lanord,
1997
).
Reconstructions
of
sediment
provenance,
mostly
based
on
Sr,
Nd
and
U‐Pb
isotope
systems,
have
been
used
to
reveal
stages
in
Himalayan
tectonic
history
(e.g.,
DeCelles
et
al.,
1998
;
Najman
et
al.,
2009
).
In
turn,
these
reconstructions
can
reveal
how
the
compositions
of
solid
and
dissolved
loads
of
Himalayan
river
systems
have
changed
through
time,
and
therefore
improve
estimations
of
the
fluxes
of
silicate
mineral
weathering
generated
by
the
Himalaya
and
their
relative
role
in
the
Cenozoic
cooling
of
Earth.
Nevertheless,
the
interpretation
of
Himalayan
detrital
records
is
complicated
by
the
combined
effects
of
provenance,
mineral‐fertility
biases,
weathering
intensity,
addition
of
secondary
authigenic
minerals,
and
hy-
drological
sorting
and
routing
of
the
sediments
during
river
and
turbidite
transport
(France‐Lanord
et
al.,
2016
;
Garçon
et
al.,
2014
;
Garzanti
et
al.,
2010
;
Lupker
et
al.,
2012
).
Often,
sediments
are
sampled
from
the
relatively
accessible
Himalayan
foreland
basin,
and
therefore
reflect
local
rather
than
Himalayan‐wide
variation
in
sediment
properties
and
environmental
forcing.
Sediments
eroded
from
the
Himalaya
are
transported
to
the
Bay
of
Bengal
by
the
Ganga
and
Brahmaputra
(G‐B)
rivers
that
together
make
the
largest
sediment
transport
system
on
Earth
(Milliman
&
Meade,
1983
)
(Figure
1
).
Since
the
initiation
of
significant
crustal
shortening
during
the
Eocene,
the
Bengal
Fan
has
accumulated
80%
of
RESEARCH
LETTER
10.1029/2024GL109643
Key
Points:
Detrital
calcite
in
Himalayan
river
systems
derives
from
Himalayan‐
bedrock
and
authigenic
sources
47
values
of
detrital
calcite
in
the
Bengal
Fan
drop
between
the
Late
Miocene
and
Pliocene
while
weathering
intensity
remains
invariant
On
a
Himalayan‐wide
scale,
the
Lesser
Himalaya
became
an
important
source
of
detrital
carbonate
between
the
Late
Miocene
and
Pliocene
Supporting
Information:
Supporting
Information
may
be
found
in
the
online
version
of
this
article.
Correspondence
to:
U.
Ryb,
uri.ryb@mail.huji.ac.il
Citation:
Ryb,
U.,
Ponton,
C.,
France‐Lanord,
C.,
Yoshida,
K.,
&
Eiler,
J.
M.
(2024).
Late
Miocene
uplift
and
exhumation
of
the
lesser
Himalaya
recorded
by
clumped
isotope
compositions
of
detrital
carbonate.
Geophysical
Research
Letters
,
51
,
e2024GL109643.
https://doi.org/10.1029/
2024GL109643
Received
7
APR
2024
Accepted
6
OCT
2024
Author
Contributions:
Conceptualization:
U.
Ryb,
C.
Ponton
Formal
analysis:
U.
Ryb,
C.
Ponton
Funding
acquisition:
U.
Ryb
Investigation:
U.
Ryb,
C.
Ponton,
C.
France‐Lanord
Methodology:
J.
M.
Eiler
Resources:
C.
France‐Lanord,
K.
Yoshida
Writing
original
draft:
U.
Ryb
Writing
review
&
editing:
C.
Ponton,
C.
France‐Lanord,
K.
Yoshida,
J.
M.
Eiler
©
2024.
The
Author(s).
This
is
an
open
access
article
under
the
terms
of
the
Creative
Commons
Attribution‐NonCommercial‐NoDerivs
License,
which
permits
use
and
distribution
in
any
medium,
provided
the
original
work
is
properly
cited,
the
use
is
non‐commercial
and
no
modifications
or
adaptations
are
made.
RYB
ET
AL.
1
of
8
Himalayan
sediments
(France‐Lanord
et
al.,
2016
).
Cores
drilled
in
the
Bengal
Fan
during
the
International
Ocean
Discovery
Program
Expedition
354
(IODP
354),
have
recovered
a
series
of
Early
Miocene
to
Holocene
turbidite
deposits,
consisting
primarily
of
Himalayan
rivers
sediments
(Blum
et
al.,
2018
;
Lenard
et
al.,
2020
).
Geochemical
signals
recorded
in
samples
collected
from
these
cores
are
considered
to
reflect
most
of
the
Himalaya
range
(France‐Lanord
et
al.,
2016
).
Here,
we
combine
mineral
and
isotope
(oxygen,
carbon
and
“clumped”)
measurements
of
calcite
and
dolomite
in
bedrock,
modern
river
sediments,
and
Bay
of
Bengal
turbidite
deposits,
and
compare
these
to
independent
reconstructions
of
weathering
intensity,
to
interpret
a
Late
Miocene
to
Pliocene
shift
in
Himalayan
provenance—spe-
cifically,
the
rise
of
the
Lesser
Himalaya.
This
approach
constraints
sediment
sources
independently
from
more
commonly
applied
tracers.
Since
it
is
based
single
carbonate
mineral
phases
(calcite
or
dolomite),
we
expect
it
to
be
less
susceptible
to
the
effects
of
hydrological
sorting.
Detrital
carbonate
in
the
G‐B
rivers
sediments
derives
from
two
main
sources
(Lupker
et
al.,
2012
):
(a)
Tethyan,
Greater
and
Lesser
Himalayan
carbonate
formations,
which
have
been
altered
in
metamorphic
or
deep‐diagenetic
en-
vironments
(Liu
&
Einsele,
1994
;
Najman
et
al.,
2017
;
Quade
et
al.,
2003
;
Sciunnach
&
Garzanti,
2012
);
and
(b)
authigenic
calcite
precipitated
in
the
river
system
from
pedogenic
or
biogenic
sources
(Gajurel
et
al.,
2006
;
A.
Galy
et
al.,
1999
;
Quade
et
al.,
1989
;
Vögeli
et
al.,
2017
).
During
river
transport,
detrital
carbonate
dissolution
and
authigenic
calcite
precipitation
increase
the
relative
abundance
of
authigenic
calcite
and
decrease
that
of
Himalayan
carbonate
(Lupker
et
al.,
2012
).
Currently,
only
the
Ganga
River
waters
are
sufficiently
saturated
with
respect
to
carbonate
minerals
to
transport
detrital
carbonates,
whereas
the
Brahmaputra
River
waters
dissolve
all
its
carbonate
load
(S.
K.
Singh
&
France‐Lanord,
2002
).
Carbonate
sourcing
and
dissolution
are
recorded
in
the
oxygen
18
O)
and
carbon
13
C)
isotope
compositions
of
modern
river
sediments
(Lupker
et
al.,
2012
).
However,
using
these
relatively
widely
applied
isotope
measurements
to
estimate
the
proportional
contribution
from
Himalayan
and
authigenic
sources
in
modern
and
ancient
river
systems
is
complicated
by
the
overlapping
isotopic
values
of
the
sources
and
their
potential
compositional
changes
over
geologic
time
(Figure
S1
in
Supporting
Information
S1
).
Clumped
isotope
thermometry
provides
an
independent
constraint,
as
it
is
sensitive
to
the
temperature
at
which
carbonate
minerals
form
or
equilibrate
(Eiler,
2007
).
Clumped
isotope
apparent
temperatures
(TΔ
47
)
of
carbonate
minerals
can
potentially
discriminate
between
higher
temperature
crustal
versus
lower
temperature
Earth‐surface
origins,
and
therefore
can
be
used
to
distinguish
between
Himalayan
and
authigenic
origins
of
detrital
carbonates.
2.
Materials
and
Methods
We
collected
13
carbonate
bedrock
samples
from
Tethyan
Himalaya
outcrops
in
the
Annapurna
Range.
Ganga
River
sediments
from
Himalayan
tributaries,
floodplain
rivers,
and
subaerial
delta
locations
have
been
collected
by
previous
workers
including
A.
Galy
et
al.
(
1999
),
S.
K.
Singh
and
France‐Lanord
(
2002
)
and
Lupker
et
al.
(
2012
).
Here,
we
analyze
13
of
these
samples
including
suspended
load
filtered
from
river
water,
as
well
as
bedload
samples
dredged
from
the
active
river
bed
or
(for
one
sample)
collected
directly
from
a
river
bank.
Sediment
samples
from
the
Bengal
Fan
have
been
collected
from
cores
drilled
during
IODP
expedition
354
and
R/
V
SONNE
expedition
SO93.
Bengal
Fan
samples
consists
mostly
of
turbidite
deposits
(
n
=
15),
and
minor
slowly
accumulating
hemipelagic
sequences
(
n
=
3).
Rock
samples
have
been
powdered
using
a
ball‐mill.
All
samples
have
been
analyzed
for
their
relative
calcite
and
dolomite
content
using
a
Bruker
2D
Phaser
X‐ray
diffractometer
housed
at
Caltech.
Carbonate
bulk
18
O,
δ
13
C)
and
clumped
47
)
isotope
analyses
followed
procedures
described
in
Huntington
et
al.
(
2009
)
and
Passey
et
al.
(
2010
).
Briefly,
samples
consisting
of
single
carbonate
mineral
(i.e.,
95%
calcite
or
dolomite)
have
been
dissolved
in
phosphoric
acid
(103%)
at
90°C.
Calcite
and
dolomite
from
mineral‐mixed
samples
containing
>
5%
of
calcite
or
dolomite
from
the
total
carbonate
mineral
content,
have
been
dissolved
using
a
stepwise
digestion
protocol
designed
to
separate
CO
2
derived
from
each
mineral‐phase
(Lloyd
et
al.,
2017
).
In
some
sediment
samples
CO
2
yield
was
sufficiently
high
for
isotope
analysis
in
one
of
the
steps
but
Figure
1.
Location
map
of
the
Ganga
and
Brahmaputra
rivers
and
the
extents
of
Tethyan‐,
Greater‐,
and
Lesser‐Himalayan
thrust
sheets.
Dots
mark
the
location
of
sampled
bedrock
(black),
river
sediments
(white)
and
Bengal
Fan
cores
(orange)
retrieved
during
IODP
expedition
354
(France‐Lanord
et
al.,
2016
),
and
R/V
SONNE
expedition
SO93
(Hübscher
et
al.,
1997
).
Numbers
are
47
(°C)
values
of
detrital
calcite
in
river
sediment
samples.
Geophysical
Research
Letters
10.1029/2024GL109643
RYB
ET
AL.
2
of
8
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not
the
other.
Evolved
CO
2
has
been
separated
cryogenically
and
purified
on
a
gas‐chromatograph
before
measurement.
We
measured
masses
44–49
using
a
Thermo
MAT253
isotope
ratio
mass
spectrometer
housed
at
Caltech.
We
calculate
Δ
47
values
and
errors
in
the
absolute
reference
frame
(Dennis
et
al.,
2011
)
as
defined
by
25°C
and
1,000°C
equilibrated
gases,
using
the
“clumpy‐crunch”
calculator
(Daëron
et
al.,
2016
).
In
the
calculation
we
assumed
the
“Brand”
parameters
for
18
O/
16
O,
17
O/
16
O
and
13
C/
12
C
in
VPDB
standard,
and
the
slope
of
the
triple‐isotope
line
(
λ
)
(Daëron
et
al.,
2016
;
Schauer
et
al.,
2016
).
Samples‐replicates
have
been
analyzed
on
several
different
sessions
and
/or
different
mass‐spectrometers.
We
corrected
measured
clumped
and
bulk
isotope
compositions
to
acid
fractionation
(Henkes
et
al.,
2013
)
and
solid
standards
(CIT
Carrara
0.405
±
0.02
and
TV04
0.655
±
0.02).
Corrected
error‐weighted
average
of
replicated
Δ
47
mea-
surements
span
a
wide
range
of
values
(0.313–0.777‰)
which
is
not
entirely
captured
by
a
single
temperature‐calibration
trend.
Therefore,
we
use
Boni-
facie
et
al.
(
2017
)
temperature
calibration
to
calculate
47
values
from
Δ
47
values
lower
than
0.7‰,
and
Hines
et
al.
(
2019
)
to
calculate
47
values
from
Δ
47
values
higher
than
0.7‰.
3.
Results
and
Discussion
Measured
clumped,
oxygen,
and
carbon
isotope
compositions
of
calcite
and
dolomite
in
bedrock
and
sediment
samples
are
summarized
in
Table
S1
and
Figure
S2
in
Supporting
Information
S1
.
Tethyan‐Himalaya
carbonate
bedrock
samples
(11
calcite
and
2
dolomite)
have
low
δ
18
O
values
(
12
±
3‰
calcite
and
14
±
0.5‰
dolomite,
all
values
are
reported
as
average
and
1SD
relative
to
the
VPDB
standard),
δ
13
C
values
typical
to
marine
carbonates
(0.2
±
1.5‰
calcite
and
1.1
±
1.2‰
dolomite),
and
high
47
(140
+
82
51
°C,
calcite
and
278
+
30
25
°C,
dolomite).
These
isotope
values
are
consistent
with
alteration
in
metamorphic
or
deep
burial
environments
(Taylor,
1974
).
The
upper
range
of
47
is
a
typical
“blocking
temperature”
observed
in
exhumed
calcite
and
dolomite
marbles
(Lloyd
et
al.,
2018
;
Ryb
et
al.,
2017
).
47
values
measured
in
detrital
calcite
in
river
sediments
generally
decrease
with
transport
distance.
In
the
upper
reaches
of
Himalayan
rivers,
47
values
of
detrital
calcite
average
128
+
47
34
°C
(uncertainty
is
1SD)—consistent
with
the
range
of
calcite
bedrock
samples
reported
here.
In
contrast,
47
values
of
detrital
calcite
in
sediment
samples
collected
from
the
Gangetic
floodplain
and
Lower
Meghna
in
the
Bangladesh
delta
average
38
+
21
17
°C
(Figure
1
).
Detrital
calcite
in
modern
river
sediments
forms
trends
in
both
δ
18
O
and
δ
13
C
versus
47
composition
spaces
(Figure
2
).
We
interpret
these
trends
to
reflect
the
binary
mixing
of
“hot”
Himalayan
bedrock
and
“cold”
authigenic
calcite
endmember
components.
The
“hot”
calcite
endmember
δ
18
O,
δ
13
C
and
47
values
are
within
the
range
of
Tethyan
Himalaya
bedrock
samples
(Figure
2
),
and
we
suggest
indicates
the
integration
of
material
eroded
from
Tethyan‐,
Greater‐
and
Lesser‐Himalaya
during
river
transport.
The
“cold”
calcite
endmember
plausibly
reflects
some
combination
of
pedogenic
and
biogenic
Ca‐carbonate
derived
from
the
floodplain
(Figure
S1
in
Supporting
Information
S1
).
Unlike
calcite,
47
values
of
detrital
dolomite
are
not
significantly
different
between
the
upper
reaches
of
Himalayan
rivers
and
the
lower
Gangetic
floodplain
and
delta
(153
+
162
47
°C
and
99
+
75
47
°C,
respectively)
neither
do
they
correlate
with
δ
18
O
or
δ
13
C.
This
is
expected
as
dolomite
generally
does
not
precipitate
in
terrestrial
/fluvial
environments.
Dolomite
bedrock
samples
have
lower
δ
18
O
and
hotter
47
values
than
detrital
samples.
This
difference
likely
results
from
the
limited
and
local
representation
of
dolomite
bedrock
samples
(
n
=
2)
compared
with
the
basin
average
value
represented
in
the
sediment
samples.
47
of
calcite
and
dolomite
fractions
in
Bay
of
Bengal
turbidites
reach
values
as
high
as
127
±
12
and
203
±
12°C,
respectively
(Table
S1
).
These
high
temperatures
require
the
transport
of
detrital
carbonates
across
a
distance
of
2,500–3,500
km
as
solids,
from
the
Himalaya
to
the
Bengal
Fan.
The
fact
that
we
find
measurable
quantities
of
highly
soluble
mineral
phases
in
the
G‐B
rivers
system
and
the
Bengal
Fan
likely
reflects
river
water
saturation
with
respect
to
calcite
and
short
residence
time
of
sediments
during
river
transport.
δ
18
O,
δ
13
C
and
Figure
2.
Stable
isotope
measurements
of
calcite
minerals
in
Himalayan
bedrock
(gray
background),
Ganga
River
sediments
(green
background)
and
Bengal
Fan
turbidite
(red
background)
or
hemiplegic
/shelf
deposits
(blue
background).
Black
line
is
a
mixing
model
prediction
between
an
integrated
Himalayan‐bedrock
endmember
and
a
river‐authigenic
endmember;
assuming
end‐member
values
of
δ
18
O
=
14‰,
δ
13
C
=
0‰
and
47
=
184°C
for
Himalayan‐bedrock
and
δ
18
O
=
10‰
δ
13
C
=
2‰
and
47
=
19°C
for
authigenic
calcite.
Numbers
are
the
percent
of
the
latter
component.
(a)
47
versus
δ
18
O;
and
(b)
47
versus
δ
13
C.
Geophysical
Research
Letters
10.1029/2024GL109643
RYB
ET
AL.
3
of
8
19448007, 2024, 21, Downloaded from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL109643 by California Inst of Technology, Wiley Online Library on [20/11/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License