Geochemistry and geochronology of meta-igneous rocks from the Tokat Massif, north-central Turkey: implications for Tethyan reconstructions

Petrology, Geochronology and Tectonic Setting of Early Triassic Alkaline Metagabbros From the Eastern Pontide Orogenic Belt (NE Turkey): Implications for the Geodynamic Evolution of Gondwana's Early Mesozoic Northern Margin

“…We prefer the amphibole ages, measured on igneous kaersutite, as the best estimate of the age of gabbro intrusion. The 200–220 Ma average ages in Catlos et al () are consistent with other estimates of the age of metamorphism in the Karakaya Complex (Okay et al, ; Okay & Monie, ). It is difficult to separate the age of igneous activity from the age of metamorphism, and to get robust ages for these rocks.…”

“…All of these age estimates are closure ages for temperatures of ~ 500° (K‐Ar in amphibole; Harrison, ) to 600 °C (U/Pb in titanite; Heaman & Parrish, ; Cherniak, ). There are poorly constrained U/Pb zircon ages, ranging from 137 to 258 Ma, on potentially correlative units in the Tokat Massif (Catlos et al, ). The images in Catlos et al () show that none of the zircons are euhedral, and we interpret these zircons as metamorphic.…”

“…There are poorly constrained U/Pb zircon ages, ranging from 137 to 258 Ma, on potentially correlative units in the Tokat Massif (Catlos et al, ). The images in Catlos et al () show that none of the zircons are euhedral, and we interpret these zircons as metamorphic. Nevertheless, the oldest ages are 258 ± 28 and 254 ± 16 Ma (Catlos et al, , uncertainty as 2 σ), comparable to the titanite age of our sample SY‐2 (256 ± 23 Ma), and this age range may be an upper limit for the intrusion age of the gabbros.…”

“…Interpreting the igneous petrogenesis of the Tokat samples is difficult because they have few analogs. We have compared our data with other rocks of the Karakaya Complex (analyses from Catlos et al, ; Eyuboglu, Santosh, Bektaş, & Chung, ; Genç, ; Sayit & Göncüoğlu, ; Sayit et al, ). It is clear from Figure that the clinopyroxene gabbros, with low SiO 2 , Al 2 O 3 , and Na 2 O, and high Fe 2 O 3 (t) and TiO 2 are unique among the Karakaya Complex rocks.…”

“…The Triassic geographic position of the Pontides Belt, which corresponds to the northern part of Turkey and is divided tectonically into three subbelts, the western, central, and eastern Pontides, is still controversial. The Pontides Belt most commonly is assigned to Laurasia and its Triassic geodynamic evolution is ascribed to northward subduction of oceanic lithosphere from the south of the belt (e.g., Adamia et al, ; Catlos et al, ; Dilek et al, ; Okay & Sahintürk, ; Rice et al, ). In contrast, some researchers emphasize that the Pontides Belt belonged to Gondwana and, beginning in the Triassic, was shaped by southward subduction of Paleo‐Tethyan lithosphere from Paleozoic to Cenozoic (Bektaş et al, ; Dewey et al, ; Eyuboglu et al, , , ; Eyuboglu, Chung, et al, ; Eyuboglu, Dudas, Santosh, Xiao, et al, ; Eyuboglu, Santosh, Bektaş, & Chung, ; Eyuboglu, Santosh, Dudas, et al, ; Şengör & Yılmaz, ).…”