Ando, Atsushi; Nakano, Takanori; Kawahata, Hodaka; Yokoyama, Yusuke; Khim, Boo-Keun (2010): Testing seawater Sr isotopic variability on a glacial-interglacial timescale; an application of latest high-precision thermal ionization mass spectrometry. Geochemical Society of Japan, Nagoya, Japan, Geochemical Journal, 44 (5), 347-357, georefid:2011-047941

Abstract:
Stability in seawater (super 87) Sr/ (super 86) Sr ratios over a glacial-interglacial timescale has gained the consensus, yet inter-site inconsistency exists in the previous data employed for validation of this issue. This study tests if the use of state-of-the-art Thermo Finnigan (super TM) TRITON multi-collector thermal ionization mass spectrometer (TIMS) can place more rigorous constraints on the seawater (super 87) Sr/ (super 86) Sr evolution at such a narrow timescale, by utilizing modern seawater, benthic foraminifera (150 ka-present) and corals (30 ka-present) (all sampled from the western Pacific realm). Application of a high-intensity setting (mass (super 88) Sr beam at 20 V) with internal and external precisions of + or -0.000005 (2 SE) and + or -0.000006 (2 SD), respectively, generates remarkably consistent 150 ka record of seawater Sr isotopes, such that 94.4% of foraminiferal (super 87) Sr/ (super 86) Sr data fall within a + or -0.000006 envelope relative to a regression function. Undoubtedly the 150 ka (super 87) Sr/ (super 86) Sr trend exhibits no short-term, orbitally-paced variation. Meanwhile, unlike previous inference, our (super 87) Sr/ (super 86) Sr record cannot be attributed to a simple linear function, implying that higher-order, minor (amplitude < or =0.000010) (super 87) Sr/ (super 86) Sr oscillation might have been present on the timescale greater than glacial-interglacial cycle. Our observations are demonstrative data-based verification and improvement upon previous knowledge of the glacial-interglacial seawater (super 87) Sr/ (super 86) Sr ratios. We emphasize that high-precision (super 87) Sr/ (super 86) Sr analysis with the TRITON TIMS certainly enables us to discriminate minute Sr isotopic details of (paleo-)oceanographic significance.
Coverage:
West: 157.5100 East: 174.4004 North: 32.1950 South: 21.2101
Relations:
Expedition: 62
Site: 62-463
Data access:
Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=2011-047941 (c.f. for more detailed metadata)
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