Formation of the Moho transition zone in the Oman ophiolite, and comparison with sub-Moho melt lenses at fast spreading ridges

Our knowledge of melt distribution in the lower crust and upper mantle at oceanic fast spreading centers is very limited. Evidence accumulation, sometimes away from axis, has been imaged interpreted Moho East Pacific Rise; but detailed structures these deep magma lenses remains much more difficult to unveil than that shallow axial lens top plutonic crust. Ophiolites offer on-land sections lithosphere can complement marine geological geophysical observations. We present results a survey transition zone paleospreading center Oman ophiolite. find thickness this dunite-rich horizontal layer increases few meters axis hundreds 6 km reduced 2–3 further away. The base contains dunite depleted harzburgite with isotropic plagioclase clinopyroxene impregnations, stockwork-like magmatic breccia, indicative episodic high fractions. conclude melt-free may stop progression ascending melt; lead accumulation within uppermost beneath forms impregnations. As dissolves orhtopyroxene, flushed MTZ though it leaves new zone. Repetition process renders thicker as moves ridge until main area delivery. Then, tectonic thinning intrusion parts into reduce thickness. These processes seem coherent several