Tethyan suture zones commonly undergo a change from compression to extension shortly after suturing. The mechanics and timing of this change in tectonic regime are poorly understood, and the extensional sedimentary basins of west Turkey, and , in particular, the northern Menderes massif, provide an excellent natural laboratory for the study of the crustal response to these different processes. During this study, field observations of sedimentary, structural and lithological features of the Alasehir Graben, Gördes and Selendi Basins, and their surroundings were combined with new radiometric age data to investigate the onset of N/S crustal extension in west Turkey. This timing of initiation has major implications for the driving mechanism of extension, since alternative models are time dependant. Extension driven by tectonic escape of west Anatolia requires extension to have begun in the Late Miocene, whilst extension driven by orogenic collapse of thickened crust in the region, and extension related to subduction roll-back both are postulated to have commenced in the Early Miocene. Extension in the northern Menderes massif took place on large-scale, presently low-angle (<20°), north-dipping normal (detachment) faults. Two separate detachment basin systems are recognised in the study area. The Gördes and Selendi Basins both trend NE/SW and formed by extension on the same northerly detachment system. This detachment has a strongly corrugated morphology when viewed parallel to extension, with a wavelength of ~30 km and an amplitude of ~1.5 km. The corrugations form the eastern and western margins of the Gördes and Selendi Basins and have produced 'scoop-shaped' depocentres and their characteristic NE/SW basin trend. No upper plate metamorphic lithologies are exposed within the basins and the total extension on the detachment fault system is in excess of 60 km. Syn-extensional sedimentation in the form of coarse alluvial fan conglomerates were deposited from south to north, and subsequently back rotated and tectonically emplaced against the detachment as a result of continuing extension. The initial sediments were followed by northward transported, braided-fluvial to alluvial-plain sandstones and conglomerates. These sediments unconformably overlie the syn-extensional deposits and passively onlap the basin margins.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:660817 |
| Date | January 1999 |
| Creators | Purvis, Martin |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12815 |
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