Constraints on the timing and regional conditions at the start of the present phase of crustal extension in western Turkey, from observations in and around the Denizli region


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Westaway R., Guillou H., Yurtmen S., Demir T., Scaillet S., Rowbotham G.

GEODINAMICA ACTA, cilt.18, ss.209-238, 2005 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 18
  • Basım Tarihi: 2005
  • Doi Numarası: 10.3166/ga.18.209-238
  • Dergi Adı: GEODINAMICA ACTA
  • Sayfa Sayıları: ss.209-238

Özet

The chronology of extension of the continental crust in western Turkey has been the subject of major controversies. We suggest that these difficulties have arisen in part because of past misuse of dating evidence; and in part because the assumption often made, that deposition of major terrestrial sedimentary sequences implies crustal extension to create the necessary accommodation space, is incorrect. We report evidence that the present phase of extension began in the Denizli region at similar to 7 Ma, around the start of the Messinian stage of the Late Miocene. This timing matches the estimated start of right-lateral slip on the North Anatolian Fault Zone, and corresponds to a substantial increase in the dimensions of the Aegean extensional province to roughly its present size: beforehand, between similar to 12 Ma and similar to 7 Ma, extension seems to have only occurred in the central part of this modem province. In some localities, terrestrial sedimentation that began before this stan of extension continued into this extensional phase, both within and outside normal fault zones. However, in other localities within the hanging-walls of normal faults, the start of extension marked the end of sedimentation. Relationships between sedimentation and crustal extension in this region are thus not straightforward, and a simple correlation should therefore not be assumed in structural interpretations. During the time-scale of this phase of extension, the Denizli region has also experienced major vertical crustal motions that are unrelated to this extension. The northern part of this region, in the relatively and interior of western Turkey, has uplifted by similar to 400 m since the Middle Pliocene, whereas its southern pan, closer to the Mediterranean Sea and with a much wetter climate, has uplifted by similar to 1,200 m since the Early Miocene, by up to similar to 900 m since the Middle Pliocene, and by an estimated similar to 300 m since the Early Pleistocene. This regional uplift, superimposed on the local effects of active normal faulting, is interpreted as a consequence of lateral variations in rates of erosion. A reliable chronology for this phase of extension in western Turkey, in relation to changes in the geometry of motions of adjoining plates and Late Cenozoic environmental change, is now in place. (c) 2005 Lavoisier SAS. All rights reserved.