South Chamorro Seamount
South Chamorro Seamount is a large serpentinite mud volcano and seamount located in the Izu-Bonin-Mariana Arc, one of 16 such volcanoes in the arc. These seamounts are at their largest 50 km (31 mi) in diameter and 2.4 km (1 mi) in height. Studies of the seamount include dives by the submersible dives (DSV Shinkai, 1993 and 1997), drilling (Ocean Drilling Program, 2001), and ROV dives (2003, 2009).[1]
Geology
Origin and geochemistry
South Chamorro Seamount and the other mud volcanoes formed as a result of the subduction of the Pacific Plate below the Mariana Plate; fualt lines in the Mariana Plate provide a gateway for churned up rock and fluid from the grinding process up to the ocean surface. Reactions with the overlying mantle produce serpentinite, hydrogen gas, and other alkaline substances.[1]
South Chamorro Seamount was first recognized as a mud volcano is 1977, on the basis of sonar data, and confirmed as such in 1981 by the collection of serpentine and schist. is one of the furthest volcanoes from the trench, 85 km (53 mi) away, where the plate rides approximatly 25 km (16 mi) underneath. Because of its distance from the trench, its eruptive fluids are hotter (> 350 °C (662 °F)), less alkalic, and with more calcium. Its flows have a pH of 12.2 (highly basic) and are sulfate and methane rich.[1]
Structure
Side-scan surveys of South Chamorro Seamount show a major southeastern sector edifice collapse, with debris flows of serpentine material (dredged in 1981 and observed by submersibles in 1995) that blankets the slope of the trench from summit to axis. The true summit of the volcano sits above this collapse; its formation was likely tied to the collapse. Submarine observation of the summit show that the summit knoll is broken up into slabs of serpentine mud, with meter-deep fissures arranged in a crosscutting orientation.[2]
References
- ^ a b c d e "Spotlight 9: South Chamerro Seamount" (PDF). Oceanography. Seamounts Special Issue. 23 (1). Oceanography Society. Retrieved 28 July 2010.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ "Site 1200: Serpentine Mud Volcano Geochemical Observatory: Geological Setting". Ocean Drilling Program. Retrieved 28 July 2010.