Deep high-temperature hydrothermal circulation in a detachment faulting system on the ultra-slow spreading ridge

Abstract

Coupled magmatic and tectonic activity plays an important role in high-temperature hydrothermal circulation at mid-ocean ridges. The circulation patterns for such systems have been elucidated by microearthquakes and geochemical data over a broad spectrum of spreading rates, but such data have not been generally available for ultra-slow spreading ridges. Here we report new geophysical and fluid geochemical data for high-temperature active hydrothermal venting at Dragon Horn area (49.7°E) on the Southwest Indian Ridge. Twin detachment faults penetrating to the depth of 13 ± 2 km below the seafloor were identified based on the microearthquakes. The geochemical composition of the hydrothermal fluids suggests a long reaction path involving both mafic and ultramafic lithologies. Combined with numerical simulations, our results demonstrate that these hydrothermal fluids could circulate~6 km deeper than the Moho boundary and to much greater depths than those at TransAtlantic Geotraverse and Logachev-1 hydrothermal fields on the Mid-Atlantic Ridge.

Progressive Dissolution of Titanomagnetite in High‐Temperature Hydrothermal Vents Dramatically Reduces Magnetization of Basaltic Ocean Crust

“…Correspondence to: L. Chang, and C. Tao,liao.chang@pku.edu.cn;taochunhuimail@163.com Citation: Wang, S., Chang, L., Wu, T., & Tao, C. (2020). Progressive dissolution of titanomagnetite in high-temperature hydrothermal vents dramatically reduces magnetization of Basaltic Ocean crust.…”

“…It has been found that most hydrothermal vents along slow-spreading Atlantic are hosted on detachment faults, whose interfaces and related fissures provide important fluid paths for hydrothermal circulation (deMartin et al, 2007;Humphris et al, 2015;McCaig et al, 2007). The same scenario may exist at SWIR, and there is evidence for multistage detachment faulting at the Longqi site (Tao et al, 2020). As up-flow fluids penetrate the fissures in the hanging wall, heat and fluid pressure further hydrofracture country rocks, producing hydrothermal breccias.…”

Dual symbiosis in the deep-sea hydrothermal vent snailGigantopelta aegisrevealed by its hologenome

“…Previous reports showed that the concentrations of reduced components (i.e., CH 4 , sulphur substances, and hydrogen) in the endmember fluid from the Longqi field are comparable or higher than those in the vents along the Central Indian Ridge 25,26,27 . Although methane is enriched in Longqi compared to other vents on the Central Indian Ridge 26 , further biogenic methane input from microbes living below and around the community may be sufficient to sustain the MOB.…”

<i>HydrothermalFoam</i> v1.0: a 3-D hydro-thermo-transport model for natural submarine hydrothermal systems

“…At slow spreading ridges, fluid circulation may extend much deeper (up to 35 km) into the ultramafic mantle (Schlindwein and Schmid, 2016), although the maximum extent of the brittle layer remains debated and may be confined to the upper 15 km (Grevemeyer et al, 2019). Such deep-reaching fluid flow can sometimes be channelized along deep detachments at fault-controlled systems such as TAG and Lonqi (Tao et al, 2020;deMartin et al, 2007) and/or may propagate to greater depths via thermal cracking (Olive and Crone, 2018;Lister, 1974). Temperatures can also vary over large ranges with high-temperature systems typically being driven by a magmatic heat source of 1000 • C or more and 1 https://doi.org/10.5194/gmd-2020-140 Preprint.…”

“…to solve a wide range of problems. Examples include Schultz (2000, 2004), who showed that hydrothermal systems operate close to optimal efficiency with their maximum vent temperatures set by the thermodynamic properties of water, studies that revealed the complex 3-D structure of recharge and discharge flow in mid-ocean ridge hydrothermal systems (Hasenclever et al, 2014;Coumou et al, 2008;Fontaine et al, 2014), dedicated case studies for individual vent systems (Tao et al, 2020;Andersen et al, 2015;Lowell et al, 2012), and models exploring tidal forcing of hydrothermal circulation (Crone and Wilcock, 2005; Barreyre et al, 2018). This list is nowhere near complete and there are many more examples.…”