A Reference Section Through Fast‐Spread Lower Oceanic Crust, Wadi Gideah, Samail Ophiolite (Sultanate of Oman): Insights From Crystallographic Preferred Orientations

We established a 5,000 m thick profile through the paleo lower oceanic crust of Samail ophiolite (Sultanate Oman, Wadi Gideah), in order to investigate accretion processes beneath fast-spreading mid-ocean ridges. The is regarded as best on-land analog for fast-spread crust, and Gideah allows sampling entire along bed. Here, we provide microstructural constraints crustal ridges, which reveal changing microstructures fabrics with depth. Grain size coarsening occurs from foliated layered gabbro section. A ∼350 zone gabbroic rocks top, interpreted frozen fillings axial melt lens defined varitextured gabbros, shows intergranular textures without crystallographic preferred orientations. Rocks varitextured/foliated transition (∼500 thick) upper gabbros (∼600 m) are lineated. lineation absent or very weak underlying ∼800 gabbros. In fabric gradually strengthens becomes more lineated down section local scattering at small spatial scales. This implies distinct mechanisms deep shallow plutonic crust. For our data suggest in-situ crystallizing individual magma reservoirs. Dominant suggests vertically transported crystal-laden melts mushes being consistent subsiding crystal lens, and/or upward migrating expelled mush beneath.