Evidence for the reactivation of a pre-existing zone of weakness and its contributions to the evolution of the Küçük Menderes Graben: a study on the Ephesus Fault, Western Anatolia, Turkey
{"title":"Evidence for the reactivation of a pre-existing zone of weakness and its contributions to the evolution of the Küçük Menderes Graben: a study on the Ephesus Fault, Western Anatolia, Turkey","authors":"Ökmen Sümer","doi":"10.1080/09853111.2014.986874","DOIUrl":null,"url":null,"abstract":"Detailed geological mapping at the western end of the Küçük Menderes Graben (KMG) in western Turkey reveals two main sedimentary packages separated by a regional unconformity: (1) Miocene units and (2) KMG basin-fill deposits of Quaternary age. The older basin-fill is represented by colluvial/alluvial fan facies association, which was controlled by a NW–SE-trending and SW-facing dip-slip normal fault (the Ortaburun Fault) and the conformably overlying fluvial and lacustrine deposits. The younger basin-fill, besides being characterised by lateral colluvial fan and axial river sediments deposited under the control of the Ephesus Fault, a southern basin-margin fault character, is also responsible for the evolution of the modern KMG. The analysis of structural, stratigraphic and sedimentological data indicates that three different deformation phases dominated during the Miocene to Recent time in the region: (i) during Early–Middle Miocene Phase 1 deformation (D1), the NW–SE-trending Ephesus Fault moved as a left-lateral strike-slip fault and occurred within the NE–SW-trending dextral shear zone of the İzmir-Balıkesir Transfer Zone (İBTZ) time; (ii) Middle Miocene Phase 2 deformation (D2) was associated with Ortaburun Fault, the northern basin-margin fault of the ancient basin. During this phase, the sinistral Ephesus Fault was reactivated as a dip-slip normal fault; and (iii) Phase 3 deformation (D3) was related with the formation of the KMG during the Quaternary and the Ephesus Fault forms the southern margin of the modern KMG. Structural evidence and computed palaeostress results show that the main extension direction during phase 1 and phase 3 has changed from north-west to north-east direction. This further suggests an approximately 60° rotation around the vertical axes and is attributed to the fact the region lies within the strike-slip dominated İBTZ.","PeriodicalId":50420,"journal":{"name":"Geodinamica Acta","volume":"27 1","pages":"130 - 154"},"PeriodicalIF":1.5000,"publicationDate":"2015-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09853111.2014.986874","citationCount":"13","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geodinamica Acta","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1080/09853111.2014.986874","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Earth and Planetary Sciences","Score":null,"Total":0}
引用次数: 13
Abstract
Detailed geological mapping at the western end of the Küçük Menderes Graben (KMG) in western Turkey reveals two main sedimentary packages separated by a regional unconformity: (1) Miocene units and (2) KMG basin-fill deposits of Quaternary age. The older basin-fill is represented by colluvial/alluvial fan facies association, which was controlled by a NW–SE-trending and SW-facing dip-slip normal fault (the Ortaburun Fault) and the conformably overlying fluvial and lacustrine deposits. The younger basin-fill, besides being characterised by lateral colluvial fan and axial river sediments deposited under the control of the Ephesus Fault, a southern basin-margin fault character, is also responsible for the evolution of the modern KMG. The analysis of structural, stratigraphic and sedimentological data indicates that three different deformation phases dominated during the Miocene to Recent time in the region: (i) during Early–Middle Miocene Phase 1 deformation (D1), the NW–SE-trending Ephesus Fault moved as a left-lateral strike-slip fault and occurred within the NE–SW-trending dextral shear zone of the İzmir-Balıkesir Transfer Zone (İBTZ) time; (ii) Middle Miocene Phase 2 deformation (D2) was associated with Ortaburun Fault, the northern basin-margin fault of the ancient basin. During this phase, the sinistral Ephesus Fault was reactivated as a dip-slip normal fault; and (iii) Phase 3 deformation (D3) was related with the formation of the KMG during the Quaternary and the Ephesus Fault forms the southern margin of the modern KMG. Structural evidence and computed palaeostress results show that the main extension direction during phase 1 and phase 3 has changed from north-west to north-east direction. This further suggests an approximately 60° rotation around the vertical axes and is attributed to the fact the region lies within the strike-slip dominated İBTZ.
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Geodinamica Acta provides an international and interdisciplinary forum for the publication of results of recent research dealing with both internal and external geodynamics. Its aims to promote discussion between the various disciplines that work on the dynamics of the lithosphere and hydrosphere. There are no constraints over themes, provided the main thrust of the paper relates to Earth''s internal and external geodynamics. The Journal encourages the submission of papers in all fields of earth sciences, such as biostratigraphy, geochemistry, geochronology and thermochronology, geohazards and their societal impacts, geomorphology, geophysics, glaciology, igneous and metamorphic petrology, magmatism, marine geology, metamorphism, mineral-deposits and energy resources, mineralogy, orogeny, palaeoclimatology, palaeoecology, paleoceanograpgy, palaeontology, petroleum geology, sedimentology, seismology and earthquakes, stratigraphy, structural geology, surface processes, tectonics (neoteoctonic, plate tectonics, seismo-tectonics, Active tectonics) and volcanism.
Geodinamica Acta publishes high quality, peer-reviewed original and timely scientific papers, comprehensive review articles on hot topics of current interest, rapid communications relating to a significant advance in the earth sciences with broad interest, and discussions of papers that have already appeared in recent issues of the journal. Book reviews are also included. Submitted papers must have international appeal and regional implications; they should present work that would be of interest to many different specialists. Geographic coverage is global and work on any part of the world is considered. The Journal also publishes thematic sets of papers on topical aspects of earth sciences or special issues of selected papers from conferences.
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