Reactivation history of the North Anatolian fault zone based on calcite age-strain analyses


Nuriel P., Craddock J., Kylander-Clark A. R. C. , Uysal I. T. S. , KARABACAK V. , Dirik R. K. , ...More

GEOLOGY, vol.47, no.5, pp.465-469, 2019 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 47 Issue: 5
  • Publication Date: 2019
  • Doi Number: 10.1130/g45727.1
  • Title of Journal : GEOLOGY
  • Page Numbers: pp.465-469

Abstract

New ages and strain analysis of syntectonic calcite from the west-central part of the North Anatolian fault zone (NAFZ; northern Turkey) shed light on the debate over the origin and reactivation behavior of this major active fault system. Contrasting views suggest that the west-central part of the NAFZ was already active during the mid-Eocene, mid-Miocene, or early Pliocene. The deformation style is also controversial: early stages of activity are associated with strike-slip, thrust, or normal faulting. Strike-slip deformation of the NAFZ marks the onset of tectonic escape of the Anatolian block westwards and is therefore a key player in tectonic reconstructions. We sampled syntectonic calcite from polished fault surfaces with horizontal slickenlines at four key sites along a 190-km-long sector of the NAFZ. All sites still show active faulting during the Holocene. Combined U-Pb ages (laser ablation-multicollector-inductively coupled plasma-mass spectrometry) and strain analyses of mechanically twinned calcite indicate that the west-central part of the NAFZ was associated with an extensional normal fault system at 42 Ma and reactivated as a dextral strike-slip fault at least 11 m.y. ago. The results indicate that the NAFZ evolved through the reactivation of major preexisting fault structures rather than by a gradual east (13 Ma) to west (5 Ma) propagation. The onset of westward translation of the Anatolian block occurred at least 11 m.y. ago, possibly as a result of the Miocene collision between the Arabian plate and Anatolian block.