Geochemistry, geochronology, and cathodoluminescence imagery of the Salihli and Turgutlu granites (central Menderes Massif, western Turkey): Implications for Aegean tectonics

The Menderes Massif (western Turkey) is an important metamorphic core complex located in the Aegean region; geochemical and geochronological data from this extensional domain facilitates our understanding of large-scale extension of the Earth's lithosphere. S-type, peraluminous granites (Salihli and Turgutlu) that intrude the Alasehir detachment which bounds the northern edge of the central Menderes Massif may have been generated due to subduction of the Eastern Mediterranean floor along the Hellenic trench. In situ Th-Pb ion microprobe monazite ages from the granites range from 21.7 ± 4.5 Ma to 9.6 ± 1.6 Ma (± 1 σ). Higher uncertainty in the ages is attributed to monazite common Pb, but the range is consistent with cathodoluminescence (CL) imagery that document complex textures within the samples. Salihli and Turgutlu granites share many similar characteristics, including multiple generations of plagioclase (some with shocked cores), plagioclase replacing K-feldspar and the development of myrmekite, evidence for fluid interaction, and multiple generations of microcracks and microfaults. The granites may have evolved from compositionally distinct magma sources, as Salihli samples in general contain allanite as the major accessory mineral, whereas Turgutlu granites contain monazite. However, the CL imagery document similar alteration textures. The youngest Turgutlu monazite grain (11.5 ± 0.8 Ma) is located in the rim of a K-feldspar grain close to myrmekite, and the youngest Salihli monazite grain (9.6 ± 1.6 Ma) is located in the outer edge of an altered plagioclase crystal. These ages likely time episodes of deformation as the granites were subjected to exhumation along the Alasehir detachment. Ages reported here are similar to dates constraining extension reported elsewhere in the Aegean, but indicate a level of complexity when linking movement within the Menderes Massif to the large-scale geodynamic processes that created other metamorphic core complexes in the region. Difficulties exist in linking the ages obtained from the granites to specific tectonic events due to the presence of secondary alteration textures, generations of mineral growth, and multiple episodes of deformation. © 2009 Elsevier B.V

Quantifying rates of detachment faulting and erosion in the central Menderes Massif (western Turkey) by thermochronology and cosmogenic 10

Exhumation of rocks in extensional tectonic settings results from a combination of normal faulting and erosion but the relative contribution of these processes has rarely been quantified. Here we present new low-temperature thermochronological data and the first Be-10-based catchment-wide erosion rates from the Boz Dag region in the central Menderes Massif, which has experienced NNE-SSW extension since the Miocene. The slip rate of the shallow-dipping Gediz detachment fault, which defines the northern flank of the Boz Dag block, is 4.3 (+3.0/-1.2) mm a(-1), as constrained by zircon (U-Th)/He ages of c. 4-2 Ma in the footwall. Apatite and zircon (U-Th)/He and fission-track ages from the northern flank of the Boz Dag block yield exhumation rates of 0.6-2 km Ma(-1) beneath the Gediz detachment, whereas those on the southern flank are only 0.2-0.6 km Ma(-1). Erosion of catchments on the northern and southern flanks proceeds at rates of 80-180 and 330-460 mm ka(-1), respectively. This marked contrast is a combined effect of the topographic asymmetry of the Boz Dag block and differences in rock erodibility. If these erosion rates persisted in the past, rock exhumation on the northern flank occurred predominantly by tectonic denudation, whereas rocks on the southern flank were mainly exhumed by erosion

The Role Of Oroclinal Bending In The Structural Evolution Of The Central Anatolian Plateau: Evidence Of A Regional Changeover From Shortening To Extension

The NW-SE striking extensional Inonu-Eskisehir Fault System is one of the most important active shear zones in Central Anatolia. This shear zone is comprised of semi-independent fault segments that constitute an integral array of crustal-scale faults that transverse the interior of the Anatolian plateau region. The WNW striking Eskisehir Fault Zone constitutes the western to central part of the system. Toward the southeast, this system splays into three fault zones. The NW striking Ilica Fault Zone defines the northern branch of this splay. The middle and southern branches are the Yeniceoba and Cihanbeyli Fault Zones, which also constitute the western boundary of the tectonically active extensional Tuzgolu Basin. The Sultanhani Fault Zone is the southeastern part of the system and also controls the southewestern margin of the Tuzgolu Basin. Structural observations and kinematic analysis of mesoscale faults in the Yeniceoba and Cihanbeyli Fault Zones clearly indicate a two-stage deformation history and kinematic changeover from contraction to extension. N-S compression was responsible for the development of the dextral Yeniceoba Fault Zone. Activity along this structure was superseded by normal faulting driven by NNE-SSW oriented tension that was accompanied by the reactivation of the Yeniceoba Fault Zone and the formation of the Cihanbeyli Fault Zone. The branching of the Inonu-Eskisehir Fault System into three fault zones (aligned with the apex of the Isparta Angle) and the formation of graben and halfgraben in the southeastern part of this system suggest ongoing asymmetric extension in the Anatolian Plateau. This extension is compatible with a clockwise rotation of the area, which may be associated with the eastern sector of the Isparta Angle, an oroclinal structure in the western central part of the plateau. As the initiation of extension in the central to southeastern part of the Inonu-Eskisehir Fault System has similarities with structures associated with the Isparta Angle, there may be a possible relationship between the active deformation and bending of the orocline and adjacent areas.WoSScopu