Project Manager: Alicé Davis
Lead Scientist: Dave Clague
Submarine eruptions, besides producing lava flows, also inject heat and chemical constituents into the oceans on two time scales. Hydrothermal inputs (chronic plumes) occur over decades, and inputs directly linked to eruptions (event plumes) occur over periods as short as months or hours. Eruptions along the mid-ocean ridge system occur infrequently and their direct chemical and thermal inputs to the deep ocean are poorly understood. Analysis of fine-grained pyroclastic deposits, collected along the Gorda Ridge and East Pacific Rise, revealed distinctive curved glass shards which indicate that mildly explosive eruptions are common in the area. We will combine similar particle-distribution studies and volume estimates of known, distinctive mid-ocean ridge eruptions with laboratory measurements of particle settling rates to distinguish between two different models of dispersal. Five historic and two pre-historic eruption sites along the Gorda and Juan de Fuca Ridges have been identified as suitable targets for study. The historic sites are: Co-axial, Axial, North Cleft, South Cleft, and northern Gorda. The two prehistoric sites are: Northern Escanaba Trough (NESCA) and a large lava pond on the Juan de Fuca Ridge.
A major focus in the early part of the year will be completing work on the coral reefs. We will continue to work on and publish results from previous dives around Hawaii, on Gorda Ridge, on the East Pacific Rise, and on seamounts offshore California. We will also continue our analytical work, particularly isotopic analyses and Ar-Ar age dating, on seamount samples recovered in 2003 and 2004 offshore California.