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Data report: 87Sr/86Sr in pore fluids
from NanTroSEIZE Expeditions 322 and 3331

Craig Joseph,2 Marta E. Torres,2 and Brian Haley2


We report on the Sr isotopic composition of pore fluids recovered during Integrated Ocean Drilling Program Expeditions 322 and 333 at Sites C0011 and C0012, drilled on the Philippine Sea plate before subduction along the Nankai Trough. Acidified pore fluids were directly loaded into EICHROM Sr-specific columns, and isotopic analysis was performed using a Nu multicollector inductively coupled mass spectrometer. At both Sites C0011 and C0012, 87Sr/86Sr decreases with depth from the seawater value to ~0.7069 at a depth that corresponds to the bottom of lithologic Unit I, which consists of ash-bearing hemipelagic sediments. This decrease is consistent with the reported observation of increasing ash alteration with depth within Subunit IB. Pore fluids recovered from lithologic Units II–IV show a relatively constant 87Sr/86Sr ratio, which ranges between 0.7069 and 0.7065 at both sites. The volcaniclastic turbidites of Unit V and the red clay (Unit IV) directly overlying the basement were only recovered at Site C0012. The 87Sr/86Sr ratio below Unit IV shows a marked decrease, reaching the lowest value of 0.704367 in the deepest pore fluids recovered (529 m below seafloor), suggesting a diffusional communication with an 87Sr-depleted fluid in the igneous upper crust.

1 Joseph, C., Torres, M.E., and Haley, B., 2013. Data report: 87Sr/86Sr in pore fluids from NanTroSEIZE Expeditions 322 and 333. In Saito, S., Underwood, M.B., Kubo, Y., and the Expedition 322 Scientists, Proc. IODP, 322: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.322.207.2013

2College of Earth, Ocean and Atmospheric Science, 104 CEOAS Administration Building, Oregon State University, Corvallis OR 97331, USA. Correspondence author:

Initial receipt: 29 June 2012
Acceptance: 4 February 2013
Publication: 21 May 2013
MS 322-207