Seismic stratigraphy and structural evolution of the Adana Basin, eastern Mediterranean

Abstract

Detailed interpretation and mapping of multi-channel seismic reflection profiles from the Adana Basin show that a south-verging linked imbricate thrust stack existed across the northern portion of the Adana Basin prior to the deposition of early Miocene sedimentary successions. Following the development of the basement-cored fold–thrust belt the region was irregularly denuded. Paleohighs and lows delineate the axis of hanging wall culminations and intervening structural depressions between forelimbs and backlimbs of the stacked sheets, with residual topographic relief locally reaching 1500 m. The stratigraphic and structural architecture of the early to middle Miocene successions in the Adana Basin records a significant phase of tectonic subsidence that initiated in the early Miocene, followed by deposition of a thick deep water succession in an underfilled basin. Then, relatively rapid uplift gave rise to basin inversion and erosion prior to or during the early Tortonian. The upper Miocene global eustatic sea-level fall initiated in the Tortonian. The transition from deep water to fluvio-deltaic sedimentation in the early Tortonian recorded the combined effects of a global eustatic sea-level fall and regional tectonic uplift, presumably related to renewed activity in the Tauride orogen to the north. It led to widespread erosion giving rise to a smooth unconformity surface in most of the Adana Basin. The stratigraphic and structural relationships suggest that the onset of east-directed thrusting in the trailing portion of the Misis fold–thrust belt occurred sometime during the lower Tortonian, coinciding with the switch from marine to terrestrial sedimentation. The truncation by this unconformity of the folded–thrusted successions of both Miocene successions across the trailing thrust sheets marks the effect of progressive erosion as the thrust sheets are uplifted above base level. A prominent progressive syntectonic unconformity is developed extending from the region of main thrust culminations westward into the depocentre situated on the backlimb of the leading thrust of the Misis fold–thrust belt. Much of the Tortonian deposition took place within this trailing piggy-back basin and the easterly onlap and the westerly tilt of this succession mark the progressive uplift of the fold–thrust belt during the remainder of the Tortonian. Terrestrial and fluvio-deltaic deposition in the Tortonian was succeeded in the Messinian by the deposition of mixed evaporite–carbonate–clastic succession in the Adana Basin. The base of this succession is a local unconformity across the Tortonian succession that marks the cessation of the fold–thrust activity in the east and ensuing erosion across the fill of the Tortonian piggy-back basin. The subcrop of the Messinian succession marks the edge of deposition in a paleotopographic depression situated between the Tortonian Misis fold–thrust belt in the east and the paleoslope over the front of the reactivated Tauride fold–thrust belt in the north. The western margin of deposition of the Messinian succession was probably controlled by the development of the Kozan Fault zone. Plio-Quaternary subsidence created the accommodation space that allowed rapid delta progradation.