Synsedimentary metre-scale normal faults within turbiditesof Miocene submarine fans in the Adana Basin, southern Turkey – implications for their origin

This study investigates the origin, geometry, and deformation of faults in turbidite deposits that form submarine fans of the upper Burdigalian–lower Serravallian Cingöz Formation, in the Adana Basin, southern Turkey, as revealed in newly exposed road cuts. Field observations indicate their synsedimentary origin based on two principal criteria: (i) undeformed younger units of the same formation overlie the faults, (ii) younger beds in a local area are flexurally deformed into a hanging-wall depression, forming a monoclinal, step-like fold, with the remaining part of the depression above the fold subsequently infilled by locally reworked intraformational sediments. The faults predominantly occur within sandstone-dominated middle-fan deposits. They are high-angle normal faults with preferred orientations in two principal directions and generally occur as single structures; however, some appear as parallel synthetic faults or as paired faults forming small-scale horst and graben geometries. The displacement of the faults is often uncertain due to the absence of marker horizons. Nevertheless, a displacement of 10–15 cm was measured on one fault pair, and an estimated displacement of 4.8 m was identified on another fault. The faults exhibit zones of variable width, some of which contain breccia and cataclastic infill. Deformation features associated with faulting include drag folds, secondary faulting within shear zones, and monoclinal flexural collapse. Within a broader tectono-sedimentary framework, we propose that deeper-seated faults at the base of the foreland basin indirectly controlled the development of these synsedimentary structures. The faults probably occur due to tectonic subsidence of the basin, which is facilitated when the sediment achieves sufficient consolidation by the weight of the overlying deposits.