1999 Projects: Benthic processes
Geochemistry of oceanic fracture zones and spreading centers
This project completes a major developmental effort that also accomplished important regional scientific goals. During this transition phase, the project will lay the groundwork for further development of MBARI technology for research on the formation of oceanic crust. During 1997 our research team completed a multi-year development and demonstration effort to optimize and use the MBARI rock-coring system for detailed geological sampling and mapping of rock layers in the Monterey Bay area. In 1998 we completed our analyses of the Monterey Canyon cores. In 1999 we plan to expand our research to mid-ocean ridges and fracture zones within range of the R/V Western Flyer. This will allow us to conduct studies on newly formed crust on the Juan de Fuca Ridge and older crust on adjacent fracture zones.
The 35 rock cores recovered from 1994 to 1997 from the walls of Monterey and Carmel canyons yielded significant geochemical, petrological, and age data. Studies on these high-quality samples have provided evidence on the formation of the Monterey Canyon and its relationship to the mid-Oligocene reorganization of the (now) Central California margin. In the coming year we will analyze samples previously collected from the Blanco Fracture Zone, the Mendocino Ridge, and the Atlantis II Fracture Zone to address questions of seafloor metamorphism, seawater-rock interactions, and high-temperature deformation in these areas of the seafloor. Studies of the mineralogy, stable-isotope chemistry, and textures of these lower crustal rocks will link rock characteristics to inferred subsurface processes, such as fluid flow along shear zones.
For a series of dives planned for 1999 in the Mendocino Fracture Zone, we will piece together detailed base maps from existing SeaBeam and EM300 data. We will also integrate EM300 and DS120 sidescan and bathymetric data to assess major features of the southern Juan de Fuca Ridge at its intersection with the Blanco Fracture Zone. Studies of sulfides from three major vent areas will complement this geological mapping effort. The integration of the sulfide and basalt geochemistry with the mapping results will provide a detailed geological overview of mid-ocean ridge processes in this area. This will enhance our ability to wisely exploit the improved sampling capability for future field programs
Last updated: 23 November 2005