Relationship between the anisotropy of magnetic susceptibility and development of the Haymana Anticline, Central Anatolia (Turkey)

Abstract

Integrated structural and anisotropy of magnetic susceptibility (AMS) analyses were carried out on the CampanianMaastrichtian shale-mudstone dominated sedimentary sequences (Haymana Formation) cropping out within the doubly plungingHaymana Anticline in Central Anatolia (Turkey). In order to understand the relationship between the development of magnetofabricsand the tectonic processes, six sites from different parts of the anticline were sampled and analyzed. AMS lineations from 634 cylindricalsamples and structural data were collected in the field. The results show very high correlation with the structural trend of the region andindicate that the maximum susceptibility vector (k1) is almost parallel to the Haymana Anticline fold axis (~E-W) and the trace of theDereköy Thrust Fault, which is the basin-bounding fault at the northern margin of the Haymana Basin. In order to assess the relationshipbetween shortening ratios and obtained AMS vectors, a number of balanced cross-sections are constructed along five traverses almostperpendicular to the axis of the anticline. Results from both the AMS and the balanced cross-sections yielded similar shortening ratios(~18%–32%) that decrease towards the eastern closure of the anticline from its culmination. In a regional sense, we related these resultsto compressional/transpressional deformation that formed during the Eocene to Early Miocene period. Differential shortening ratioscalculated from AMS and restored balanced cross-sections indicate that the shortening is associated with the transcurrent tectonics,possibly in relation with rotational convergence of the Pontides and the Taurides and/or the oblique indentation of the Kırşehir Blockinto the Pontides during or subsequent to the collision.