[Geophysical Research Letters]
Supporting Information for
[Abrupt Intensification of North Atlantic Deep Water formation at the late Pliocene climate
transition]
[Masahiko Sato1,2*, Masato Makio2, Tatsuya Hayashi3, Masao Ohno2]
[1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8567,
Japan, 2Department of Environmental Changes, Faculty of Social and Cultural Studies, Kyushu University, Fukuoka
819-0395, Japan, 3Mifune Dinosaur Museum, Kumamoto 861-3207, Japan]
Contents of this file
Figures S1 to S4
Additional Supporting Information (Files uploaded separately)
Captions for Table S1
Figures S1 and S2
To convert the depth of core into ages, we used the method of Hayashi et al. [2010].
They constructed a hybrid environmental proxy of the U1314 sediments by combining
magnetic susceptibility (χ) and natural gamma radiation (NGR), in which glacial–
interglacial variations are extracted and the small-scale variations (attributed to icerafted debris) are eliminated. They tuned the hybrid environmental proxy record
between 188.0 and 262.5 mcd to the global-standard oxygen isotope curve (LR04 δ18O
stack record) [Lisiecki and Raymo, 2005], and established the age model during the
period 2.1–2.75 Ma. This paper applied the same method as used in Hayashi et al. [2010]
to 188.0–299.2 mcd data, and extend the age model up to 2.91 Ma (Figure S1).
We constructed an age model of IODP Site U1314 sediments by tuning the χ + NGR
index record between 188.0 and 299.2 mcd to the LR04 δ18O stack record between the
marine oxygen isotope stage (MIS) 80 and the MIS G13 with the use of an automated
graphic correlation software, Match 2.0 [Lisiecki and Lisiecki, 2002]. We ran the Match
2.0 software with the same parameter values as used in Hayashi et al. [2010], other
than the tie points. In our age model, the additional tie point was given at 299.15 mcd
1
with 2.875 Ma (at the bottom of the core) and the tie point given at 262.45 mcd with
2.755 Ma (at the bottom of the age model in Hayashi et al. [2010]) was removed. As the
result, the age model in this study clearly differs before 2.69 Ma from the age model of
Hayashi et al. [2010], although a very subtle difference between them exists from
around 2.62 Ma to 2.69 Ma.
There was no hiatus reported throughout the study interval [Expedition 306 Scientists,
2006], and the obtained age-depth curve shows smooth change in sedimentation rate
throughout the study interval. Therefore, it seems unlikely that about 40 kyr (an
obliquity cycle) are add to or subtracted from the age of the sediments. Although there
is a negative (downward in the figure) excursion in the normalized χ + NGR index at
around MIS G8 in our age model, which is not seen in the LR04 stack, the negative
excursion is clearly seen at around MIS G8 in the benthic δ18O data from the North
Atlantic (Figure 2 in Bartoli et al., [2005]). The age model for the Site U1314 will be
improved by future δ18O analyses.
Reference
Lisiecki, L. E., and P. A. Lisiecki, (2002), Application of dynamic programming to the
correlation
of
paleoclimate
records,
Paleoceanography,
17(4),
1049,
doi:10.1029/2001PA000733.
2
Figure S1. (a) Normalized x + NGR index vs. sediment depth of spiced section. (b) LR04 global
benthic δ18O stack [Lisiecki and Raymo, 2005]. Numbers indicate marine oxygen isotope stage.
Tie points are show as TP1–TP4. (c) Normalized χ + NGR index (green curve) is tuned to
normalized LR04 global benthic δ18O stack (red curve).
3
Figure S2. Age-depth plot of the automated tuning result (solid curve). The dashed line
indicates the age-depth model of Hayashi et al. [2010]. Tie points (TP1–TP4) are show as grey
circles.
Figure S3
Grützner and Higgins [2010] measured the X-ray fluorescence of Gardar Drift sediments
(IODP Site U1314) and reported changes in the terrigenous province during the last 1.1
Ma. During the interglacial periods, vigorous Iceland–Scotland Overflow Water (ISOW)
flowed south over the Iceland–Faroe Ridge and delivered high amounts of basaltic
material (low K/Ti) to the Gardar Drift. Conversely, during the glacial periods, the core
of the ISOW shoaled and sedimentation at depth of site U1314 became influenced by
the acidic sediment (high K/Ti) transported by the Northeast Atlantic Deep Water
(NEADW) and/or Lower Deep Water (LDW) flow.
For 39 samples of the U1314 sediment, we measured Ti and K contents using an EDX800 Energy Dispersive X-ray Fluorescence Spectrometer (SHIMADZU) at Kyushu
University. The relationship between the fraction of component 1 and the Ti/K ratio
showed a clear positive correlation (Figure S3), while data at around the marine oxygen
isotope stage (MIS) G9 slightly deflected from this trend, thus indicating that the
fraction of component 1 represents the fraction of basaltic components.
4
1.5
Ti/K
1
0.5
0
0
0.2
0.4
0.6
0.8
Component 1 fraction (%)
1
Figure S3. Relationship between the fraction of component 1 and the Ti/K ratio. Data from
interval 2.33–2.73 Ma are shown in red color. Data at around the MIS G9 (2.77–2.80 Ma) are
shown in black color.
Figure S4
Fraction of component 1 calculated from isothermal remanent magnetization (IRM)
gradient curves, the LR04 global benthic δ18O stack [Lisiecki and Raymo, 2005], and IRM
intensity normalized by mass are plotted as a function of age in Figure S3a, S3b, and
S3c. Mode, median, and mean of IRM gradient curves are also plotted as a function of
age in Figure S3d, S3e, and S3f. The component fraction data show the clear periodic
variations, which are not apparent in the raw coercivity data such as the mode, median,
mean of IRM gradient curves.
5
Figure S4. (a) The fraction of component 1. (b) The LR04 global benthic δ18O stack [Lisiecki
and Raymo, 2005]. Numbers indicate the marine oxygen isotope stage. Shaded areas mark
warmer climate intervals. (c) The IRM intensity. (d) Mode, (e) median, and (f) mean of IRM
gradient curves.
Table S1
Fraction of component 1 (C1) and component 2 (C2), integral of residual curve (R), IRM
intensity (Mr), and mode, median, and mean of IRM gradient curves are summarized in
Table S1.
6