The geological setting of the ultramafic-hosted Logatchev hydrothermal field (14°45′N, Mid-Atlantic Ridge) and its influence on massive sulfide formation

Zn-, Mn- and Co-rich chromian spinels from the Bou-Azzer mining district (Morocco): Constraints on their relationship with the mineralizing process

“…The temperature of these vent fluids reaches 400°C , with the highest concentrations of Fe, Mn, Cu, Zn, Co and Ni ever reported for MAR and is considered a modern analogue for the formation of ancient mafic-hosted VMS deposits (e.g. Douville et al, 2002;Von Damm et al, 2003;Marques et al, 2007;Petersen et al, 2009). In addition, reported mineral assemblages in serpentinites and sediments collected close to vents from hydrothermal fields occurring along the MAR and other hydrothermal systems worldwide Bougault et al, 1998;Dias and Barriga, 2006;Usui et al, 2007) have very high proportions of Mn oxyhydroxides.…”

Sulfur and lead isotopic compositions of massive sulfides from deep-sea hydrothermal systems: Implications for ore genesis and fluid circulation

“…The KHF is situated on basaltic rocks, but the hydrothermal fluids also interact with and circulate through ultramafic rocks (Nakamura et al, 2009). In the LHF, the hydrothermal sulfide deposit is associated with ultramafic rocks located in a debris flow consisting of heterogeneous ultramafic and mafic intrusive rocks, including serpentinized harzburgite, serpentinized dunite, gabbronorite, and olivine-bearing basalt (e.g., Petersen et al, 2009;Zeng et al, 2014Zeng et al, , 2015a. In addition, in the North Fiji Basin, the S99HF is located immediately south of the triple junction point at 16°50´S and is hosted by basaltic rocks, the trace element composition of which indicates that magma generation was influenced by two different sources: normal mid-ocean ridge basalt (N-MORB) and ocean island basalt (OIB)-related to enriched mid-ocean ridge basalt (E-MORB) Nohara et al, 1994;Koschinsky et al, 2002;Kim et al, 2006).…”

The Trans-Atlantic Geotraverse hydrothermal field: A hydrothermal system on an active detachment fault

“…Furthermore, it should be noted that not all sulfide deposits spatially associated with detachment faults and oceanic core complexes are located on the hanging wall; some are perched high above the axial valley on the exposed fault surface (e.g., the Logatchev (14°45'N, MidAtlantic Ridge) and Ashadze (13°N, Mid-Atlantic Ridge) hydrothermal fields (Petersen et al, 2010;Ondréas et al, 2012). Given the importance of detachment faulting for crustal extension at slow spreading ridges, the fundamental question that needs to be addressed is: How do detachment fault systems, and the structure at depth associated with these systems (e.g., presence of plutons and/or high permeability zones), influence the pattern of hydrothermal circulation, mineral deposition, and fluid chemistry, both in space and time, within slowly accreted ocean crust?…”