Wet magmatic processes during the accretion of the deep crust of the Oman Ophiolite paleoridge: Phase diagrams and petrological records

The Oman Ophiolite is regarded as an analogue to modern fast-spreading ocean ridge systems in environment of subduction zone initiation. In contrast recent mid-ocean basalts from the East Pacific Rise, parental melts at paleoridge are assumed be hydrous nature. order constrain role water during magmatic accretion processes deep crust paleoridge, we evaluated several experimental studies tholeiitic performed shallow pressures. We concluded that wehrlitic phase assemblage (olivine coexisting with clinopyroxene but without plagioclase) most significant feature indicative high prevailing activities. stability decreases decreasing pressure (not stable upper plutonic crust) and depends on chemical system (only primitive MORB systems). applied these results rocks cores drilled part Drilling Project (OmanDP). A key observation presence coherent layers within layered gabbro series, which frequent lowermost gabbros (20%), relative sparse mid-crust (6%), absent top dike/gabbro transition. Based combined relations for MORB-type pressures, interpret this a direct consequence activity not local phenomenon related variations temperature or bulk chemistry. These findings have implications mechanism lower supporting model parts were produced by in-situ crystallization melt sills. • Magmatic was wet. Water enables formation crustal wehrlites. Phase diagrams initiation Construction axial lens 50 MPa wet Importance paleocrust