In extensional provinces with low-angle normal faulting (such as the Aegean region), both tectonic processes and erosion induce landscape change, but their interaction during the evolution of topography and relief accompanying continental extension has rarely been addressed. Here we present local and catchment-wide 10Be erosion rates that document the spatial pattern of erosion in the central Menderes Massif, a metamorphic core complex consisting of two asymmetric mountain ranges (Bozdağ and Aydın) bound by detachment faults and active grabens. Catchment-wide erosion rates on the northern flank of the Bozdağ Range are rather low (40–110 mm/k.y.) but reach values of >300 mm/k.y. on the steep southern escarpment—a pattern that reflects both topography and bedrock lithology. In the Aydın Range, erosion rates are generally higher, with mean erosion rates of ∼190 and ∼260 mm/k.y. on the northern and southern flank, respectively, and more variable along strike. In both ranges, erosion rates of ridge crests derived from amalgamated clasts are 30–90 mm/k.y. The difference between local and catchment-wide erosion rates indicates that topographic relief increases in most parts of the massif in response to ongoing fault-related uplift and concomitant river incision. Our findings document that tectonic processes exert a significant control on landscape evolution during active continental extension and are reflected in both the topographic signature and the spatial pattern of erosion. In the Menderes Massif, rock susceptibility to weathering and erosion is a dominant factor that controls the erosional contribution to rock exhumation, which varies spatially between ∼10% and ∼50%.

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The central Menderes Massif (western Turkey) is a prominent example of symmetrical exhumation of a core complex. It comprises the Bozdaǧ and Aydın ranges, which represent the footwalls of the north-dipping Gediz detachment and the south-dipping Büyük Menderes detachment, respectively. In contrast to the Gediz detachment, the role of the Büyük Menderes detachment during Late Cenozoic extension and exhumation of the central Menderes Massif is less well resolved. Here, we present results from structural and geological mapping as well as new fission-track and (U–Th)/He data to show that two low-angle normal faults contributed to the exhumation of the Aydın range. Our data indicate that the sustained activity of the Büyük Menderes detachment since the early Miocene is followed by the onset of faulting along the previously unrecognized Demirhan detachment, which is situated in the hanging wall of the Büyük Menderes detachment, in the latest Miocene/Pliocene. Thermokinematic modelling of cooling ages from the footwalls of the Büyük Menderes and Demirhan detachments yielded exhumation rates of c. 0.5 and c. 0.4 km Ma -1 , respectively. Apatite fission track ages from the Demirhan detachment indicate a slip rate of c. 2 km Ma -1 during the Pliocene. High-angle normal faulting along the modern Büyük Menderes graben commenced in the Quaternary. Supplementary material: Further results of thermal history modelling are available at https://doi.org/10.6084/m9.figshare.c.4392905

Abstract:The Alpine nappe stack in the Penninic-Austroalpine boundary zone in the Rätikon (Austria) contains a 4×1 km tectonic sliver of meta-diorite, known as the Schwarzhorn Amphibolite. It was deformed and metamorphosed in the amphibolite facies and is unconformably overlain by unmetamorphic Lower Triassic sandstone, indicating pre-Triassic metamorphism. Cataclastic deformation and brecciation of the amphibolite is related to normal faulting and block tilting during Jurassic rifting. Zircon dating of the Schwarzhorn Amphibolite using LA-ICP-MS gave a U-Pb age of 529+9/-8 Ma, interpreted as the crystallization age of the protolith. Geochemical characteristics indicate formation of the magmatic protolith in a supra-subduction zone setting. The Cambrian protolith age identifies the Schwarzhorn Amphibolite as a pre-Variscan element within the Austroalpine basement. Similar calc-alkaline igneous rocks of Late Neoproterozoic to Early Cambrian age are found in the Upper Austroalpine Silvretta Nappe nearby and in several other Variscan basement units of the Alps, interpreted to have formed in a peri-Gondwanan active-margin or island-arc setting.