HR: 0800h
AN: OS21A-1195    [Abstracts]
TI: Barium Geochemistry of a Marginal Cold-seep Basin: Abundance and Provenance of Total Barium and Barite in the San Clemente Basin.
AU: * McQuay, E L
EM: emcquay@coas.oregonstate.edu
AF: COAS, Oregon State University, Corvallis, OR 97331
AU: Torres, M E
EM: mtorres@coas.oregonstate.edu
AF: COAS, Oregon State University, Corvallis, OR 97331
AU: Collier, R
EM: rcollier@coas.oregonstate.edu
AF: COAS, Oregon State University, Corvallis, OR 97331
AU: Huh, C
EM: huh@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, Taipei, 11529 Taiwan
AU: Newell, S
EM: sonya@exchangenet.net
AF: COAS, Oregon State University, Corvallis, OR 97331
AB: Barium in marine sediments is found in various solid phases including barite, aluminosilicates, carbonates, organic material and oxyhydroxides. Barite, the dominant Ba-bearing solid phase in pelagic settings, is of particular interest as it has the potential for use as a tracer for paleoproductivity and past isotopic and rare earth element composition of seawater. Barite crystals form by abiotic precipitation in supersaturated microenvironments of decaying organic material in the water column and then settle as aggregates to the sediments. In areas of cold seep activity, discharge of barium-rich seep fluid also results in large in situ barite deposits at the seafloor. Transport of particles from these deposits leads to significantly increased barium concentrations in surrounding sediments. The San Clemente basin located about 100km off the coast of San Diego, is one such location where massive barite deposits have been observed in association with cold seep activity along the San Clemente fault that transects the basin. Analysis of surface sediments from the San Clemente basin has shown total barium enrichment of up to 140% higher than surface sediments from the neighboring Santa Catalina basin. Cold seeps are not present in the latter location, where the major source of barite is likely to be that associated with biogenic material. The significant input of barium from authigenic barite deposits to surrounding sediments affects global barium geochemistry and could possibly be used to provide a paleorecord for cold seep activity.
DE: 4825 Geochemistry
DE: 1050 Marine geochemistry (4835, 4850)
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting