No surface breaking on the Ecemiş Fault, central Turkey, since Late Pleistocene (~64.5ka); new geomorphic and geochronologic data from cosmogenic dating of offset alluvial fans

M. A. Sarikaya*, C. Yildirim, A. Çiner

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33 Atıf (Scopus)

Özet

The Ecemiş Fault Zone (EF) has been recognized as a major left lateral strike-slip fault in the Central Anatolian Fault Zone (CAFZ) of Turkey. However, its Quaternary slip-rate has been challenging to determine due to the difficulty of dating offset markers. Using high-precision offset measurements and 36Cl cosmogenic nuclide dating, we present the first geochronologically determined Late Quaternary slip-rate for the EF. Our study focuses on the excellent exposures of offset alluvial fan surfaces, originating from the Aladağlar, a Late Quaternary glaciated mountain. Analysis of airborne orthophotogrametry and GNSS (Global Navigation Satellite System) surveys indicates 168±2m left lateral and 31±1m vertical displacements. In-situ terrestrial cosmogenic 36Cl geochronology obtained from eleven surface boulders provides a minimum abandonment/incision age of 104.2±16.5ka for the oldest offset alluvial fan surface. Our geomorphic observations together with Self-potential geophysical surveys revealed the presence of an unfaulted alluvial fan terrace, which allows us to constrain the timing of deformation. The abandonment/incision age of this fan is 64.5±5.6ka based on thirteen 36Cl depth profile samples. Accordingly, we obtained a geologic fault slip-rate of 4.2±1.9mma-1 horizontally and 0.8±0.3mma-1 vertically for the time frame between 104.2±16.5ka and 64.5±5.6ka. Our analysis indicates that the EF has not been producing a major surface breaking earthquake on the main strand at least since 64.5±5.6ka (mid-Late Pleistocene). This could be the result of abandonment of the main strand and accommodation of deformation by other faults within the EF. Nevertheless, a recently occurred (30 September 2011) low magnitude (ML: 4.3) left lateral strike-slip earthquake indicates recent seismic activity of the EF. Comparison of the recent GPS velocity field with the longer slip history along the CAFZ indicates a constant but low strain release without surface breaking and very long large earthquake recurrence intervals.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)33-46
Sayfa sayısı14
DergiTectonophysics
Hacim649
DOI'lar
Yayın durumuYayınlandı - 9 May 2015

Bibliyografik not

Publisher Copyright:
© 2015 Elsevier B.V.

Finansman

This work was supported by the TÜBİTAK grant # 112Y087 . We are grateful to Birlik Harita Inc. from Ankara for the aerial photography. We are thankful to Lucilla Benedetti for her help on the 36 Cl measurements, to Fırat Yiğit and Sefa Şahin for the geophysical surveys and to Kevin McClain for the proof readings. Editor Rob Govers (Utrecht University), A.M. Celâl Şengör (Istanbul Technical University) and an anonymous reviewer provided helpful comments that improved the manuscript.

FinansörlerFinansör numarası
TÜBİTAK112Y087

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