Nielsen, Sune G. et al. (2011): New age for ferromanganese crust 109D-C and implications for isotopic records of lead, neodymium, hafnium, and thallium in the Pliocene Indian Ocean

Leg/Site/Hole:
ODP 121
ODP 121 756
Identifier:
2013-035826
georefid

10.1029/2010PA002003
doi

Creator:
Nielsen, Sune G.
University of Oxford, Department of Earth Sciences, Oxford, United Kingdom
author

Gannoun, Abdelmouhcine
U. S. Geological Survey, United States
author

Marnham, Charles
author

Burton, Kevin W.
author

Halliday, Alex N.
author

Hein, James R.
author

Identification:
New age for ferromanganese crust 109D-C and implications for isotopic records of lead, neodymium, hafnium, and thallium in the Pliocene Indian Ocean
2011
Paleoceanography
American Geophysical Union, Washington, DC, United States
26
2
This study presents a high-resolution record of osmium and thallium isotopes in a ferro-manganese (Fe-Mn) crust from the Indian Ocean, Antipode 109D-C. These results, when combined with additional new Os isotope data from ODP Hole 756B in the southeast Indian Ocean, define a new best estimate for the age at the base of this crust of approximately 6.5 Ma, which is significantly different from a previous estimate of approximately 15 Ma based on Co-flux modeling. The Tl isotope record obtained for the Indian Ocean resembles that for the Pacific Ocean with a small but well-defined increase occurring over the last approximately 5 Myr. This contrasts with two records from the Atlantic Ocean which do not have resolvable variations. Ocean basin-scale Tl isotope variation may be inconsistent with the inferred modern marine residence time for Tl of approximately 20 kyr but could be explained by an increase in ocean crust production rates in the Pacific and Indian oceans since approximately 10 Ma. The improved age model for 109D-C reveals that the Hf isotope composition of Indian Ocean bottom waters has remained homogenous over the last approximately 6 Myr. Thus, this isotope system does not bear any evidence that the influence of North Atlantic Deep Water in the formation of Indian Ocean bottom waters has changed during that time. However, because of the lack of knowledge about Hf isotopes as a tracer of ocean circulation, we cannot conclude that export of NADW decreased over the last 6 Myr.
English
Serial
Coverage:Geographic coordinates:
North:-27.2115
West:60.4800East: 87.3554
South:-27.5800

Isotope geochemistry; Stratigraphy; age; Cenozoic; ferromanganese crusts; geochemistry; hafnium; Hf-177/Hf-176; Indian Ocean; isotope ratios; isotopes; lead; Leg 121; metals; Miocene; Nd-144/Nd-143; neodymium; Neogene; Ninetyeast Ridge; Ocean Drilling Program; ODP Site 756; Os-188/Os-187; osmium; paleo-oceanography; Pb-206/Pb-204; Pb-208/Pb-206; platinum group; Pliocene; radioactive isotopes; rare earths; southwestern Indian Ocean; stable isotopes; Tertiary; thallium; Tl-205/Tl-203; upper Miocene;

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