Conditions and timing of incorporation of ophiolite into orogenic crust during oblique convergence, Central Anatolia

Molly Radwany, Leah E. Morgan, Donna L. Whitney

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Ophiolitic fragments scattered over a wide area of Central Anatolia exhibit varying degrees of metamorphism, from unmetamorphosed to upper amphibolite facies, although geochemical similarities suggest they are all part of the Central Anatolian Ophiolite (CAO). Magmatic crystallization of oceanic crust in the CAO at ~ 91 Ma coincided with high-grade metamorphism of rocks that underlie the southern, highest grade part of the CAO, raising questions about the tectonic relationship of the ophiolite to underlying metasedimentary and plutonic rocks. New geochronology results show that the 40Ar/39Ar hornblende age of amphibolite-facies metagabbro in the high-grade metamorphic part of the CAO is ~ 87 Ma, similar to hornblende ages from amphibolite in the underlying Niğde metamorphic/plutonic massif. Biotite in a deformed quartzofeldspathic rock associated with high-grade meta-ophiolitic rocks yielded an 40Ar–39Ar age of ~ 78 Ma, similar to biotite ages from the Niğde Massif. Hornblende in gabbro from unmetamorphosed CAO yielded an older 40Ar/39Ar age of ~ 90 Ma, similar to the previously determined crystallization age of the ophiolite. These data indicate that the southern part of the ophiolite was incorporated into and therefore metamorphosed and deformed with the orogenic mid-crust now exposed in the Niğde metamorphic–plutonic complex, whereas the northern, unmetamorphosed part of the ophiolite was obducted onto the continent. This distinct difference in different parts of the ophiolite may indicate oblique collision or irregularities in the continental margin, resulting in part of the ophiolite being incorporated into the orogenic crust and subsequently exhumed and cooled with it, and another part being obducted.

Original languageEnglish (US)
Pages (from-to)2393-2406
Number of pages14
JournalInternational Journal of Earth Sciences
Volume109
Issue number7
DOIs
StatePublished - Oct 1 2020

Bibliographical note

Funding Information:
This research was funded by NSF Grant EAR-1109762, “Continental Dynamics: Central Anatolian Tectonics” (CD-CAT) to Donna Whitney. This project represents the M.S. thesis work of Molly Radwany (née Ray) at the University of Minnesota. We thank Bülent Tokay and Ekrem Tosun for assistance with field work, and Başar Özşafak for hospitality in the Çamardı area. We also thank Mike Cosca and Mary Reid for advice and insights. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Funding Information:
This research was funded by NSF Grant EAR-1109762, ?Continental Dynamics: Central Anatolian Tectonics? (CD-CAT) to Donna Whitney. This project represents the M.S. thesis work of Molly Radwany (n?e Ray) at the University of Minnesota. We thank B?lent Tokay and Ekrem Tosun for assistance with field work, and Ba?ar ?z?afak for hospitality in the ?amard? area. We also thank Mike Cosca and Mary Reid for advice and insights. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Keywords

  • Central Anatolia
  • Metaophiolite
  • Nigde Massif

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