From Ophiolites to Oceanic Crust: Sheeted Dike Complexes and Seafloor Spreading

Geologic evolution of the Lost City Hydrothermal Field

“…[ Cannat et al ., ; Karson et al ., ; Smith et al ., ]. These structures share similarities with terrestrial metamorphic core complexes [ Howard et al ., ; Dick , ; Karson , ; Mutter and Karson , ; Tucholke et al ., ; Blackman et al ., ; Reston et al ., ; John and Cheadle , ].…”

Tectonic Controls on Block Rotation and Sheeted Sill Emplacement in the Xigaze Ophiolite (Tibet): The Construction Mode of Slow‐Spreading and Ultraslow‐Spreading Oceanic Crusts

“…The geometry of sheeted dike complexes at modern slow‐spreading and ultraslow‐spreading ridges are still poorly studied, due to the lack of in situ drill cores into the upper crusts (see the review in Karson, 2018). However, detailed field observations for those in ophiolites could provide key insight into the geometry of internal oceanic crustal architectures.…”

“…However, it is symmetrical accretion that dominates in the regions where detachment faults are rarely generated. In these regions, sheeted dike complexes are expected to be dominant, which are geometrically similar to those at fast-spreading ridges (Karson, 2018). Therefore, considering the complex crustal architectures at modern slow-spreading and ultraslow-spreading ridges, it is a perfect balance between block exhumation, rotation, and foundering that constructs the sheeted and non-sheeted pseudosills in the Xigaze ophiolite, which are almost unique in the world (Hopson, 2007;Nicolas et al, 1981).…”

“…The construction of oceanic crusts, transferring vast energy and mass from the Earth's interior to the seafloor, is one of the most important geological processes on planet Earth. Oceanic crustal architectures can be directly investigated at modern mid‐ocean ridges via deep drilling, and can also be precisely mapped in ophiolites (e.g., Dick et al., 2006; Karson, 2018; Snow & Edmonds, 2007). Ophiolites have been genetically linked to oceanic lithospheres since the recognition of sheeted dike complex, whose formation needs continuous spreading and magma injection (e.g., Gass, 1968; Moores & Vine, 1971).…”

“…Thus, formation mechanism of sheeted dike complexes is key to understanding the construction of oceanic crusts. Sheeted dike complexes have been well studied and precisely mapped in several ophiolites, such as the Troodos ophiolite in Cyprus and Semail ophiolite in Oman (e.g., France et al., 2009; MacLeod & Rothery, 1992; Moores & Vine, 1971; Nicolas et al., 2008), of which internal structures match well crustal architectures at the East Pacific Rise (EPR) (e.g., France et al., 2009; Karson, 2018). These observations collectively improved the recognition of vertical sheeted dikes within the horizontally layered oceanic crusts (Figure 1a) (e.g., Karson, 2018; Sinton & Detrick, 1992).…”