Oceanic Core Complex - History, Distribution and Exploration

History, Distribution and Exploration

The first oceanic core complexes described were identified in the Atlantic Ocean (Cann et al., 1998; Tucholke et al., 1998). Since then numerous such structures have been identified primarily in oceanic lithosphere formed at intermediate, slow- and ultra-slow spreading mid-ocean ridges, as well as back-arc basins (Fujimoto et al., 1999; O'Hara et al., 2001). Examples include large expanses of ocean floor and therefore of the oceanic lithosphere, particularly along the Mid-Atlantic Ridge (Smith et al., 2006; Escartin et al., 2008) and the Southwest Indian Ridge (Cannat et al., 2006). Some of these structures have been drilled and sampled, showing that the footwall can be composed of both mafic plutonic and ultramafic rocks (gabbro and peridotite primarily, in addition to diabase), and a thin shear zone that includes hydrous phyllosilicates. Oceanic core complexes are often associated with active hydrothermal fields.