Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
GSA Bulletin Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
GSA Bulletin; July 2008; v. 120; no. 7-8; p. 893-911; DOI: 10.1130/B26229.1
© 2008 Geological Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Web of Science (1)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Okay, A.I.
Right arrow Articles by Topuz, G.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

An Oligocene ductile strike-slip shear zone: The Uludag Massif, northwest Turkey—Implications for the westward translation of Anatolia

A.I. Okay1,{dagger}, M. Satir2, M. Zattin3, W. Cavazza3 and G. Topuz4

1 Avrasya Yerbilimleri Enstitüsü ve Jeoloji Mühendisligi Bölümü, Maden Fakültesi, Istanbul Teknik Üniversitesi, Maslak, 34469 Istanbul, Turkey
2 Institut für Geowissenschaften, Universität Tübingen, Wilhelmstrasse 56, D-72074 Tübingen, Germany
3 Dipartimento di Scienze della Terra e Geologico-ambientali, Università di Bologna, 40126 Bologna, Italy
4 Avrasya Yerbilimleri Enstitüsü, Istanbul Teknik Üniversitesi, Maslak, 34469 Istanbul, Turkey

Correspondence: {dagger}E-mail: okay{at}itu.edu.tr.

The Uludag Massif in northwest Turkey represents an exhumed segment of an Oligocene ductile strike-slip shear zone that is over 225 km long and has ~100 km of right-lateral strike-slip displacement. It forms a fault-bounded mountain of amphibolite-facies gneiss and intrusive Oligocene granites. A shear-zone origin for the Uludag Massif is indicated by: (1) its location at the tip of the active Eskisehir oblique-slip fault, (2) pervasive subhorizontal mineral lineation in the gneisses with a right-lateral sense of slip, (3) foliation with a consistent strike, (4) the presence of a subvertical synkinematic intrusion, and (5) the alignment of the Eskisehir fault, synkinematic metagranite, and the strike of the foliation and mineral lineation. The shear zone nucleated in amphibolite-facies gneisses at peak pressure-temperature (P-T) conditions of 7.0 kbar and 670 °C, and it preserves Eocene (49 Ma) and Oligocene (36–30 Ma) Rb/Sr muscovite and biotite cooling ages. The shear zone was active during the latest Eocene and Oligocene (38–27 Ma), as shown by the crystallization and cooling ages from synkinematic granite. A 27 Ma postkinematic granite marks the termination of shear-zone activity. The 20–21 Ma apatite fission-track (AFT) ages indicate rapid exhumation during the early Miocene. A 14 Ma AFT age from an Uludag gneiss clast deposited in a neighboring Neogene basin shows that the shear zone was on the surface by the late Miocene. Results of this study indicate that during the Oligocene, crustal-scale right-lateral strike-slip faults were transporting crustal fragments from Anatolia into the north-south–extending Aegean; this implies that the westward translation of Turkey, related to the Hellenic slab suction, started earlier than the Miocene Arabia-Eurasia collision.

Key Words: ductile shear zone • strike-slip faulting • Rb/Sr ages • apatite fission tracks • amphibolite-facies metamorphism • Turkey • Aegean Sea






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Geological Society of America