Deglacial Neodymium Isotopic Ratios in the Florida Straits and the Response of Intermediate Waters to Reduced Meridional Overturning Circulation
Abstract
The
relationship
between
intermediate
watermass
response
to
Atlantic
Meridonial
Overturning
Circulation
(AMOC)
during
two
abrupt
cooling
events
of
the
last
deglacial,
the
Younger
Dryas
(YD)
and
Heinrich
Event
1
(H1)
is
controversial
and
has
been
studied
using
conventional
paleo-circulation
tracers.
In
this
study
we
measure
Nd
isotopes
in
sediments
of
the
Florida
Straits
to
investigate
this
discrepancy.
Nd
isotope
ratios
in
the
authigenic
component
of
marine
sediments
are
thought
to
be
a
reliable
tracer
of
past
changes
in
ocean
circulation.
We
will
use
the
Nd
isotopic
ratios
of
Fe-Mn
oxide
leachate
of
deep-sea
sediments
(representative
of
the
seawater
fraction
of
Nd)
to
understand
the
behavior
of
AAIW
during
the
YD
and
H1
climate
events.
Two
cores
within
the
Florida
Straits
are
selected
because
this
site
has
been
exposed
to
a
combination
of
re-circulated
North
Atlantic
subtropical
gyre
waters
and
AAIW.
Our
preliminary
data
suggest
that
the
northward
incursion
of
AAIW
was
weaker
during
the
YD
and
H1
events.
Specifically,
?Nd
values
are
significantly
lower
during
cold
periods
(i.e.,
YD
and
H1),
than
during
the
warmer
Holocene
epoch.
This
is
consistent
with
interpretation
of
S 18 O
analyses
on
sediments
from
the
same
cores.
Such a trend supports the idea that during the Younger Dryas, there was a reduction
within the Florida Current of the flow of intermediate, southern-sourced waters.
Subject
PaleoceanographyNeodymium
Antarctic Intermediate Water
North Atlantic Deep Water
Atlantic Meridonial Overturning Circulation
Younger Dryas
Heinrich Event 1
Citation
Franklin, Alyssa L. (2010). Deglacial Neodymium Isotopic Ratios in the Florida Straits and the Response of Intermediate Waters to Reduced Meridional Overturning Circulation. Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2010 -05 -8073.