The effects of linear coarse-grained slope channel bodies on the orientations of fold developments: a case study from the Middle Eocene-Lower Oligocene Kırkgeçit Formation, Elazığ, eastern Turkey

A significant magnitude of tectonic feature deflection away from the principal stress direction was investigated. This was caused by oblique spatial orientation of coarse-grained sediment bodies, principally large conglomerate and sand-filled deep-water slope channels, in an otherwise mud-rich sedimentary section. After detailed mapping and field work to find the cause of this localised fold axis deflection, superbly exposed conglomerate and sand filled deep-water slope channel bodies were found both in and/or next to the core of the folds with the same spatial orientation as the folds. It was concluded that the channel bodies are effectively dictating the orientations of the tectonic structures such as bedding attitude, fold axis orientation, and both trend and location of shearing fractures are related to the folds. It was interpreted that fold growth and propagation have been controlled by the channel orientation within the stratigraphy in this study. The implications of this study urge inclusion of sedimentary body mapping as part of all structural geology work. Conversely, mapping of fold orientation in detail in three-dimensions on seismic data, from subsurface deep-water slopes with hydrocarbon potential, may reveal a direct association between fold axes and the location of coarse-grained reservoir bodies within otherwise low net: gross (muddy) deep water sections. This is a case study in this subject which may also possibly lead to examination of other currently unpublished outcrops and subsurface examples such as the Alikayasi Canyon Member of the Tekir Formation in Maras, eastern Turkey and the Rehy Hill Channel in the Ross Sandstone Formation, Loop Head Peninsula (County Clare), western Ireland, given in the discussion section.