摘要：We present a study of pressure and temperature evolution in the passivecontinental margin under the Oman Ophiolite using numerical basin modelscalibrated with thermal maturity data, fluid-inclusion thermometry, andlow-temperature thermochronometry and building on the results of recent workon the tectonic evolution. Because the Oman mountains experienced only weakpost-obduction overprint, they offer a unique natural laboratory for thisstudy. Thermal maturity data from the Adam Foothills constrain burial in the basinin front of the advancing nappes to at least 4km. Peak temperatureevolution in the carbonate platform under the ophiolite depends on theburial depth and only weakly on the temperature of the overriding nappes,which have cooled during transport from the oceanic subduction zone toemplacement. Fluid-inclusion thermometry yields pressure-correctedhomogenization temperatures of 225 to 266∘C for veins formedduring progressive burial, 296–364∘C for veins related to peakburial, and 184 to 213∘C for veins associated with late-stagestrike-slip faulting. In contrast, the overlying Hawasina nappes have notbeen heated above 130–170∘C, as witnessed by only partialresetting of the zircon (U-Th)/He thermochronometer. In combination with independently determined temperatures from solid bitumenreflectance, we infer that the fluid inclusions of peak-burial-related veinsformed at minimum pressures of 225–285MPa. This implies that the rocks ofthe future Jebel Akhdar Dome were buried under 8–10km of ophiolite on topof 2km of sedimentary nappes, in agreement with thermal maturity datafromsolid bitumen reflectance and Raman spectroscopy. Rapid burial of the passive margin under the ophiolite results insub-lithostatic pore pressures, as indicated by veins formed in dilatantfractures in the carbonates. We infer that overpressure is induced by rapidburial under the ophiolite. Tilting of the carbonate platform in combinationwith overpressure in the passive margin caused fluid migration towards thesouth in front of the advancing nappes. Exhumation of the Jebel Akhdar, as indicated by our zircon (U-Th)/He data andin agreement with existing work on the tectonic evolution, started as earlyas the Late Cretaceous to early Cenozoic, linked with extension above amajor listric shear zone with top-to-NNE shear sense. In a second exhumationphase the carbonate platform and obducted nappes of the Jebel Akhdar Domecooled together below ca. 170∘C between 50 and 40Ma before thefinal stage of anticline formation.
