Abstract
The Triassic sedimentary pattern of the north Arabian margin represents a transition from continental to deep-marine; we here present a transect part of this suite from southern to northern Israel. Cuttings from the Ramalla (S) and Devora (N) boreholes were studied by petrographic and cathodoluminescence microscopy. Biotic and sedimentological components were grouped into microfacies, upon which a carbonate-evaporitic depositional facies model was based. Mid-to-inner ramp conditions persisted along the transect, essentially following a S–N depositional strike, with outer-ramp to basinal facies to the west. Five low-order (LO) cycles were identified and integrated into a sequence-stratigraphic model with eustatic, tectonic, and differential subsidence components: LO cycle 1 is Late Anisian (Pelsonian), cycle 2 is Late Anisian to Longobardian, cycle 3 is Early Carnian, cycle 4 is Late Carnian, and cycle 5 is at the Carnian/Norian transition. Facies range from supratidal via lagoonal facies in late HST or LST, to calcarenitic shoals and short-term deepening to offshore at maximum flooding. Cycles 1 and 2 are non-evaporitic, with a clastic influx event in cycle 2. Cycles 3 and 4 contain sabkha or salina evaporites in the lagoonal facies that end in the lower part of cycle 5. These facies group into a higher-order cyclicity with discrete events that can be correlated between the boreholes. Depositional and burial history were correlated to Alpine and Arabian Plate stratigraphy over 20 Myr, from the Anisian (Pelsonian) to the Norian. Siliciclastic, carbonate and evaporite-dominated environments indicate climates ranging from relatively humid to extremely arid. Rapid subsidence in the Late Anisian is attributed to Neotethyan rifting of northeastern Gondwana. From latest Anisian to Early Carnian, reduced subsidence took place in the face of eustatic sea level rise. Renewed subsidence in the Carnian is attributed to further Neotethyan rifting. Subsidence terminated in the Norian with uplift to the north, attributed to pre-volcanic doming.
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