HR: 1330h
AN: B12A-0727 INVITED     [PDF]
TI: The Eastern Lau Basin Integrated Studies Site (ISS)
AU: * Wiens, D
EM: doug@seismo.wustl.edu
AF: Dept Earth and Planetary Sci., Washington University, St. Louis, MO 63130
AB: A new venue for Ridge 2000 (R2K) Integrated Studies, the Eastern Lau Spreading Center (ELSC) adds the element of a spreading center in a back-arc basin to the R2K program. The ELSC, located in the western Pacific near Tonga, is a 390 km-long first-order ridge segment that displays a broad range of effects of the back-arc environment. At its southern end it is only 40 km from the Tonga arc volcanic front and is propagating southward into a back-arc rift. At its northern end it is 100 km from the volcanic front and terminates at a large, non-transform offset. The ELSC displays substantial and systematic changes in multiple parameters: spreading rate, magma source and lava chemistry, axial depth and morphology, melt lens characteristics, and crustal thickness and structure. A main focus of the work at the ELSC is to determine how changes in these forcing functions affect key parameters such as magma source composition, crustal structure, and characteristics of hydrothermal venting such as temperature, chemistry, and faunal composition and abundance. Prior reconnaissance investigation shows that these hydrothermal field characteristics also vary within the southernmost segments, and show distinct differences compared with well-studied mid-ocean ridge sites. Four R2K cruises are planned for the ELSC in 2004. The first cruise (PI: Martinez) will investigate interrelationships among crustal structure, volcanism, and hydrothermal activity using deep tow, CTD's, and Tow-Yo. A second cruise (PI: Langmuir) will focus on petrological and water column properties using dredging, CTD's and ABE. The next cruise (PI: Tivey) will provide an initial characterization of vent fields, fluid chemistry, mineralogy, and biodiversity using Jason II and net tows, and a final cruise (PI: Childress) will investigate community ecology using Jason II. An additional study (PI: Thurnherr) will deploy autonomous floats to investigate hydrothermal plume circulation and dispersal . An overview of the site is presented here.
DE: 3035 Midocean ridge processes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting