TY - JOUR
T1 - Blueschist facies overprint of late triassic tethyan oceanic crust in a subduction–accretion complex in north-central anatolia, Turkey
AU - Çelik, Ömer Faruk
AU - Özkan, Mutlu
AU - Chelle-Michou, Cyril
AU - Sherlock, Sarah
AU - Marzoli, Andrea
AU - Ulianov, Alexey
AU - Altıntaş, Iṡmail Emir
AU - Topuz, Gültekin
N1 - Publisher Copyright:
© 2018 The Author(s). Published by The Geological Society of London. All rights reserved.
PY - 2018
Y1 - 2018
N2 - The late Cretaceous accretionary complex along the Iżmir–Ankara–Erzincan suture zone, northern Turkey, includes various types of metamorphic rock together with radiolarite, sandstone, mudstone, serpentinite, basalt and limestone. Metaplagiogranite blocks (up to 5 m in diameter) and a meta-gabbro slice (800 × 500 m) cross-cut by meta-plagiogranite are observed in a matrix of serpentinite, mudstone and radiolarian chert. These meta-gabbros and meta-plagiogranites show subduction-related geochemical characteristics. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of zircons from two metaplagiogranites yielded 222.3 ± 1.5 and 227.2 ± 1.6 Ma crystallization ages. This study shows that the meta-gabbro and metaplagiogranite from the accretionary complex are remnants of the metamorphosed equivalents of the late Triassic lower crustal rocks of the subducted Tethyan oceanic crust. They are the oldest lower crustal rocks observed in the Iżmir–Ankara–Erzincan suture zone. Both the meta-gabbros and meta-plagiogranites have Na–Ca amphiboles, indicating blueschist facies metamorphism. However, phengites from a blueschist facies rock yielded an40Ar/39Ar age of 104.3 ± 0.7 Ma, indicating that blueschist metamorphism occurred during the Albian. All these data suggest that the oceanic crust formed during the Norian, metamorphosed during the Jurassic to early Cretaceous and then dismembered during accretionary complex formation in the late Cretaceous.
AB - The late Cretaceous accretionary complex along the Iżmir–Ankara–Erzincan suture zone, northern Turkey, includes various types of metamorphic rock together with radiolarite, sandstone, mudstone, serpentinite, basalt and limestone. Metaplagiogranite blocks (up to 5 m in diameter) and a meta-gabbro slice (800 × 500 m) cross-cut by meta-plagiogranite are observed in a matrix of serpentinite, mudstone and radiolarian chert. These meta-gabbros and meta-plagiogranites show subduction-related geochemical characteristics. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of zircons from two metaplagiogranites yielded 222.3 ± 1.5 and 227.2 ± 1.6 Ma crystallization ages. This study shows that the meta-gabbro and metaplagiogranite from the accretionary complex are remnants of the metamorphosed equivalents of the late Triassic lower crustal rocks of the subducted Tethyan oceanic crust. They are the oldest lower crustal rocks observed in the Iżmir–Ankara–Erzincan suture zone. Both the meta-gabbros and meta-plagiogranites have Na–Ca amphiboles, indicating blueschist facies metamorphism. However, phengites from a blueschist facies rock yielded an40Ar/39Ar age of 104.3 ± 0.7 Ma, indicating that blueschist metamorphism occurred during the Albian. All these data suggest that the oceanic crust formed during the Norian, metamorphosed during the Jurassic to early Cretaceous and then dismembered during accretionary complex formation in the late Cretaceous.
UR - http://www.scopus.com/inward/record.url?scp=85071877148&partnerID=8YFLogxK
U2 - 10.1144/jgs2018-045
DO - 10.1144/jgs2018-045
M3 - Article
AN - SCOPUS:85071877148
SN - 0016-7649
VL - 176
SP - 945
EP - 957
JO - Journal of the Geological Society
JF - Journal of the Geological Society
IS - 5
ER -