Xunmei hydrothermal site, 26°S hydrothermal field, Southern Mid-Atlantic Ridge complex, Atlantic Oceani

Regional Level Types
Xunmei hydrothermal site	Hydrothermal Vent
26°S hydrothermal field	Group of Hydrothermal Vents
Southern Mid-Atlantic Ridge complex	Mid-Ocean Ridge
Atlantic Ocean	Ocean

Oxidized vent chimneys.
Xunmei is located in the 2 N ridge segment between 25°40′ and 26°35′. It is approximately 100 km long and represents an asymmetric slow-spreading ridge, with a westward spreading rate of approximately 19.3 mm/yr and an eastward spreading rate of approximately 16.3 mm/yr.
Xunmei is located in a depression between two volcanoes. At a water depth of approximately 2600 m, a flat plateau has formed along a 7–9 km wide axial valley. The bedrock mainly consists of N-MORB and lesser microcrystalline basalt, vesicular basalt, porous basalt, and basaltic glass. The high-elevation fields are completely composed of pillow basalt, with a flat top and limited sedimentation. In the low-elevation fields, fresh basalt is partially covered by loose sediments, whereas no ultramafic rocks are exposed. Abundant metallic sulfide fragments, vent biota, chimney fragments, and inactive chimneys on slopes and low-lying fields were observed by camera tow surveys. The detected temperature anomalies, presence of methane (CH4), and widespread turbidity anomalies highlight the existence of hydrothermal vents in the Xunmei HF. An underwater video survey conducted in the Xunmei HF revealed the presence of three different types of sulfide chimneys. The iron-rich sulfide chimneys were predominantly composed of pyrite and marcasite; the iron-copper-rich sulfide chimneys were mainly composed of pyrite and chalcopyrite; the copper-rich sulfide chimneys were primarily composed of chalcopyrite and pyrite.

Other Regions, Features and Areas containing this locality

References