Geomorphic Constraints on the Structural Evolution of an Obliquely Extending Region: The Fault-Bounded Ranges of the Plio-Quaternary Premygdonia-Mygdonia Basin Complex, Northern Greece.

Abstract:

Landscape evolution studies have a lot to reveal about the evolutionary pathways that faulted terrains undergo. The transient response of river long profiles can be a powerful aid in unraveling sequences of tectonic perturbations associated with the inception and establishment of normal fault arrays. The Premygdonia-Mygdonia basin complex in continental northern Greece is an obliquely extending region of horst and graben topography that was established in the Pliocene and evolved in a complex manner to this day. It is the product of the setting of new tectonic boundary conditions in the north Aegean associated with the interaction of slab rollback-induced back-arc extension and the transtensional influence of the westward propagation of the North Anatolian fault zone. This study attempts to constrain the stages of development of the basin complex's fault bounded ranges by utilizing drainage network analysis, footwall relief distribution, and river long profiles that drain across the main faults of this significant area. The ubiquitous presence of two sets of knickpoints on all the major range fronts points to two significant tectonic perturbations associated with the inception of the basin complex area and its later modification. Footwall drainage patterns and the spatial scaling of the upper set of knickpoints point to discrete fault segments that accommodated the initial phase of deformation. The lower set of knickpoints is taken to signify either a phase of uplift and reworking of the initial hangingwall by basinward migration of faulting or fault linkage and establishment of a continuous fault array, depending on the orientation of the initial fault structures to the evolving stress regime. The relation of these tectonic perturbations to the regional geodynamic evolution of the broader north Aegean realm during the Plio-Quaternary is discussed.