Strike-slip metamorphic core complexes: Gneiss domes emplaced in releasing bends

We investigate the development of a Neoproterozoic metamorphic core complex (MCC) in the Marbat area (southern Arabian Peninsula). The MCC is a gneiss dome emplaced in a releasing bend along a dextral strike-slip fault system. Dome emplacement-related extension was at a high angle to the long axis of the dome and 65 degrees from the strike-slip fault system. Shortening is recorded in the upper plate of the MCC in a direction normal to the extension direction. Extensional emplacement of the gneiss dome accommodated lower crust exhumation and contributed to the formation of a ductile strike-slip releasing bend from an initial fault step. The Marbat example allows defining transversal stretching-dominated strike-slip MCCs, which would represent the early development stages of longitudinal stretching-dominated strike-slip MCCs. Conversely, longitudinal stretching-dominated strike-slip MCCs produced at low finite extension would result from strike-slip-dominated transtension. This study bears important implications for lower crust exhumation under pulla-part basin systems in obliquely convergent or divergent settings.