Some Like It Cold: The “Conundrum of Samail” Revisited

Most tectonic models consider that the “Samail subduction zone” was only zone at mid-Cretaceous convergent Arabian margin. We report four new Rb-Sr multimineral isochron ages from high-pressure (HP) rocks and a major shear of uppermost Ruwi-Yiti Unit Saih Hatat window in Oman Mountains NE Arabia. These demand reassessment intraoceanic suprasubduction-zone evolution formed Samail Ophiolite its metamorphic sole zone. Our constrain waning HP metamorphism Ruwi subunit ∼99-96 Ma associated deformation Yenkit between ∼104 93 Ma. for late stages (thermal gradients ∼8–10°C km−1) overlap with published ∼105-102 Samail-subduction-zone prograde-to-peak ∼20–25°C km−1), subsequent decompressional partial melting crystallization ∼30°C ∼100 Thermal considerations two zones existed High-pressure occurred mature, thermally equilibrated “Ruwi ∼110 Initiation infant, unequilibrated and, thus, immature, outboard ∼105 The were then thrust over exhuming onto margin after ∼92 Ma, while bulk below started to be underthrust