The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin

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doi: 10.1016/j.chemgeo.2011.10.010
Author(s): Kim, Ji-Hoon; Torres, Marta E.; Haley, Brain A.; Kastner, Miriam; Pohlman, John W.; Riedel, Michael; Lee, Young-Joo
Author Affiliation(s): Primary:
Korean Institute of Geoscience and Mineral Resources, Petroleum and Marine Resources Division, Daejeon, South Korea
Oregon State University, United States
Scripps Institution of Oceanography, United States
U. S. Geological Survey, United States
Geological Survey of Canada, Canada
Volume Title: Chemical Geology
Source: Chemical Geology, Vol.291, p.152-165. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541 CODEN: CHGEAD
Note: In English. 95 refs.; illus., incl. 2 tables, sketch map
Summary: Analytical challenges in obtaining high quality measurements of rare earth elements (REEs) from small pore fluid volumes have limited the application of REEs as deep fluid geochemical tracers. Using a recently developed analytical technique, we analyzed REEs from pore fluids collected from Sites U1325 and U1329, drilled on the northern Cascadia margin during the Integrated Ocean Drilling Program (IODP) Expedition 311, to investigate the REE behavior during diagenesis and their utility as tracers of deep fluid migration. These sites were selected because they represent contrasting settings on an accretionary margin: a ponded basin at the toe of the margin, and the landward Tofino Basin near the shelf's edge. REE concentrations of pore fluid in the methanogenic zone at Sites U1325 and U1329 correlate positively with concentrations of dissolved organic carbon (DOC) and alkalinity. Fractionations across the REE series are driven by preferential complexation of the heavy REEs. Simultaneous enrichment of diagenetic indicators (DOC and alkalinity) and of REEs (in particular the heavy elements Ho to Lu), suggests that the heavy REEs are released during particulate organic carbon (POC) degradation and are subsequently chelated by DOC. REE concentrations are greater at Site U1325, a site where shorter residence times of POC in sulfate-bearing redox zones may enhance REE burial efficiency within sulfidic and methanogenic sediment zones where REE release ensues. Cross-plots of La concentrations versus Cl, Li and Sr delineate a distinct field for the deep fluids (z>75mbsf) at Site U1329, and indicate the presence of a fluid not observed at the other sites drilled on the Cascadia margin. Changes in REE patterns, the presence of a positive Eu anomaly, and other available geochemical data for this site suggest a complex hydrology and possible interaction with the igneous Crescent Terrane, located east of the drilled transect. Abstract Copyright (2012) Elsevier, B.V.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Accretionary wedges; Aliphatic hydrocarbons; Alkaline earth metals; Alkalinity; Alkanes; Bransfield Strait; British Columbia; Canada; Carbon; Cascadia subduction zone; Cerium; Chemical composition; Chemical ratios; Continental margin; Crescent Terrane; Diagenesis; East Pacific; Europium; Expedition 311; Fluid phase; Geochemical anomalies; Geochemistry; Hydrocarbons; Hydrochemistry; ICP mass spectra; IODP Site U1325; IODP Site U1329; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Marine sediments; Mass spectra; Metals; Methane; Movement; North Pacific; Northeast Pacific; Organic carbon; Organic compounds; PH; Pacific Ocean; Pore water; Rare earths; Sea water; Sediments; Solutes; Southern Ocean; Spectra; Sr-87/Sr-86; Stable isotopes; Strontium; Tofino Basin; Tracers; Vancouver Island; Western Canada
Coordinates: N483700 N484800 W1264000 W1270400
Record ID: 2012026185
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands