Hydrothermal activity on the Gorda Ridge



Were port our discovery of the first hydrothermal field on the northern Gorda Ridge located only 200 km off southern Oregon within the proclaimed U.S. Exclusive Economic Zone (Figure 1). The discovery was made with the U.S. Navy Deep Submergence Vehicle Sea Cliff and her support ship the DSVSS Laney Chouest on a dive series between September 15 and 30, 1988.

The northern Gorda Ridge is characterized by an intermediate spreading rate (2.8 cm/yr half-rate), although the high relief of the sediment-free rift valley a n d distribution of volcanic rock types resemble the slow-spreading Mid-Atlantic Ridge more than other intermediate- to fast-spreading centers in the Pacific. The hydrotheral field extends several hundred meters along the east wall at water depths between 2700 and 2800 m, about 300 m above the floor of the rift valley.