Large massive sulfide deposits in a newly discovered active hydrothermal system, The High‐Rise Field, Endeavour Segment, Juan De Fuca Ridge

Abstract

Submersible observations and side‐scan sonar imagery delineate ten large venting sulfide‐sulfate‐silica structures located on an uplifted block of the axial valley floor on the central portion of the Endeavour Segment, Juan de Fuca Ridge. This newly discovered vent field lies 1.8 km north of the main Endeavour vent field. The axial valley, a horst, and faults controlling sulfide deposition trend parallel to the ridge axis. The horst rises 10 to 15 m above the valley floor and offsets a lava lake which extended 500 m in width across the valley. The largest sulfide structures are perched along the major horst‐bounding faults. One structure is the tallest single edifice (45 m) reported in the Pacific Ocean. Smaller, less‐active and inactive sulfide edifices are associated with faulted remnants of the lava lake surface, fissured pressure ridges, and at the edge of collapse pits. Based on the relationship between faults and sulfide structures, the morphology of sulfide edifices, and their venting characteristics, we infer that sulfide structures grow vertically by chimney accumulation and laterally by flange development. Late stage deposition of amorphous silica toughens the large deposits and may be responsible for the unusual size and aspect ratio of Endeavour edifices.

Spatial variation in the reproductive biology of Paralvinella palmiformis (Polychaeta: Alvinellidae) from a vent field on the Juan de Fuca Ridge

“…The High Rise vent field (47°58.00' N, 129°05.50' W) was discovered during reconnaissance dives to the north of the Main Endeavour field in 1988 and mapped in 1991 (Robigou et al 1993). The vent field is situated on a central horst within the narrow axial valley of the Endeavour Segment.…”

“…2). Robigou et al 1993) McHugh (1989) examined the reproductive development of Paralvinella palmiformis in 3 samples collected from the Endeavour segment in July, August and September 1984. Very few or no oocytes were found in females from the samples collected in August and September, but oocytes were present in females from the July sample.…”

Precipitation and growth of barite within hydrothermal vent deposits from the Endeavour Segment, Juan de Fuca Ridge

“…The sulfide edifices at Endeavour are typically steepsided, often reaching heights of greater than 20 metres above the seafloor, with fluid venting temperatures that range from <10°C up to $375°C (Delaney et al, 1992;Robigou et al, 1993;Butterfield et al, 1994;Glickson et al, 2006;Kelley et al, 2012). The edifices are rich in barite relative to typical mid-ocean ridge deposits.…”

Biological characteristics of a hydrothermal edifice mosaic community

“…S&M has been the focus of an extensive biological and geological study, where the distnbution of fluid flow, geological features and 6 identified faunal assemblages (I to VI) were mapped and followed over a 4 yr penod (1991, 1994 & 1995) (Sarrazin et al 1997). Salut is a smaller, highly active edifice with abundant horizontal flanges that are typical of sulfide structures on Endeavour Segment (Delaney et al 1992, Robigou et al 1993, Hannington et al 1995. Sample collection.…”