The characteristics of carbonate system recovery during a relatively dry event in a mixed carbonate/siliciclastic environment in the Pelsonian (Middle Triassic) proximal marginal marine basins: A case study from the tropical Tethyan northwest Gondwana margins

Abstract

Eight early-mid Pelsonian (Middle Triassic) marine sedimentary successions, an outcrop and subsurface sections of the Ra'af Formation from the northwest Gondwana margins facing the southeast corner of the tropical western Tethyan seaway assigned to the southern Intertropical Convergence Zone (ITCZ) (south Israel, Levant Basin, north Arabian plate) are the focus of this work. The successions, especially with the exclusive outcrop at Har 'Arief, are a golden opportunity to observe the still connected transitional zone between the huge siliciclastic domains derived from Gondwana hinterland parts (north Arabian plate) and the open, tropical Tethyan marine carbonate domain and their mutual relationships.This multidiscipline research tracks a carbonate recovery attempt in a dominant siliciclastic system. The recovery effort was characterized by starved sedimentary conditions, basin-constrained oxygen-stressed environments, and low-diverse, autochthonous burrowed sediments barren of other faunal remains. Low-diverse fossiliferous allochthonous beds, transported from higher sites on the slopes, revealed differential distributions of echinoids, mollusks and especially foraminifera (large Pilammina-Pilamminella versus small glomospirids); these variances were attributed to different environmental conditions on the slopes of each basin-type and illuminate some constraints on their distribution pattern and climate affinity in the Triassic, southern ITCZ mixed carbonate/siliciclastic, sedimentary system. The carbonate recovery phase is ascribed to a relatively dry period in the hinterland rather than to sea-level rise; this dry period, which interrupted the relatively humid climate in the northern tropical Gondwana during the Pelsonian, is represented by the constant, although with some perturbations, siliciclastic sedimentary system that prevailed in the southeastern corner of the Tethys seaway during the Anisian. Insights from the symmetric and asymmetric correlation of climate fluctuations in the hinterlands of the southeastern European basins (northern hemisphere) and this work (from the southern hemisphere), both embracing basins ascribed to the western tropical Tethyan seaway, illuminate the possible effects of the ICTZ behavior pattern and possible extra-tropical forces on the climate variations.