Middle-Late Triassic radiolarian cherts from the Arkotdağ mélange in northern Turkey: implications for the life span of the northern Neotethyan branch

Abstract

Moderately to well-preserved, relatively diverse Middle and Late Triassic radiolarian assemblages have been obtained from the chert slide-blocks within the Late Cretaceous mélange of the IntraPontide Suture Zone at the Pelitören village to the NE of Kastamonu-Araç in northern Central Anatolia. In this locality, chert slide-blocks are tectonically overlain by metamorphic sole of the serpentinized peridotites belonging to the IntraPontide ophiolites. The oldest radiolarian assemblages, with the middle Late Anisian and late Early Ladinian ages, were found in green cherts in a pebbly mudstone. They are underlain by a larger slide-block composed of an alternation of radiolarian cherts and mudstones with late Early and early Late Carnian radiolarians. Another slide-block with cherts and mudstones between the sub-ophiolitic amphibolite and the Carnian cherts includes the late Early to early Middle Norian radiolarian assemblages. These new data reveal that the IntraPontide basin was already open during the Middle to Late Triassic time and deep enough for radiolarian cherts to deposit. Moreover, it suggests that the IntraPontide Ocean is contemporaneous with a number of inferred Paleo-and Neotethyan oceanic basins in SE Europe and NW Anatolia, which were proposed in copious tectonic models.

Geochemistry of the metavolcanic rocks from the Çangaldağ Complex in the Central Pontides: implications for the Middle Jurassic arc-back-arc system in the Neotethyan Intra-Pontide Ocean

“…This interpretation is supported by the presence of the Late Jurassic MORBtype volcanism in the eastern Bolu area . Additional evidence gives Late Jurassic to early Late Cretaceous radiolarian ages from numerous outcrops within the CC (Göncüoğlu et al, 2012(Göncüoğlu et al, , 2014Tekin et al, 2012). Considering that the CC tectonically overlies the Late Jurassic-Cretaceous mélanges with an emplacement direction from N to S, we speculate that they (the Elekdağ, Domuz Dağ, Arkot Dağ, and Aylı Dağ mélanges) were originally located to the S of the Çangaldağ subduction.…”

“…The turbiditic sediments of the complex include Carnian-Norian fossils (Kozur et al, 2000;, indicating that this basin was still open. On the other hand, recent data (Göncüoğlu et al, 2012;Tekin et al, 2012) show that contemporaneously with the closure of the Küre Basin another oceanic branch, the Intra-Pontide Ocean, existed to the south of it. The remains of this ocean cover a vast area in the Central Pontides and are included in the CPSC (Tekin et al, 2012).…”

“…On the other hand, recent data (Göncüoğlu et al, 2012;Tekin et al, 2012) show that contemporaneously with the closure of the Küre Basin another oceanic branch, the Intra-Pontide Ocean, existed to the south of it. The remains of this ocean cover a vast area in the Central Pontides and are included in the CPSC (Tekin et al, 2012). In general terms, the CPSC is an imbricated stack (e.g., Marroni et al, 2015;Aygül et al, 2016) of accretionary mélanges, dominated by variably deformed and metamorphosed volcanic rocks.…”

“…The IPO basin was obviously larger and older than the intraoceanic subduction event producing the CC volcanism during the Middle Jurassic time (Okay et al, 2014;Çimen et al, 2016b). That it existed prior to the Middle Jurassic is proven by the Middle to Late Triassic oceanic volcanics found in the Arkot Dağ Mélange (Tekin et al, 2012). Moreover, it has not been completely eliminated by the Çangaldağ Mid-Jurassic subduction.…”

First evidence of Middle to Late Triassic radiolarians in the Garba mountains, South Sumatra, Indonesia

“…Spongotortilispinus tortilis (Kozur and Mostler), Bragin, , Plate 1(19). Tekin, Göncüoglu, Pandolfi, & Marroni, , Figure a. Carter & Orchard, , Figure (5).…”