Middle Jurassic radiolarians from the Akgol Formation, central Pontids, northern Turkey

Bragin, N. Yu.; Tekin, U. Kagan; Ozcelik, Y.

doi:10.1127/njgpm/2002/2002/609

Cited by 12 publications

(4 citation statements)

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“…The age of the radiolarites from the locality Abeško Brdo is compatible with the age of the siliceous sediments in the locality Komarani (Callovian;GAWLICK et al 2009). The radiolarian associations from the locality Komarani are correlatable with the radiolarian associations identified from sediments of the central Pontides in northern Turkey (BRAGIN et al 2002), in the West Carpathians (RAKUŠ & OŽVOLDOVA 1999), as well as with the Upper Bajocian to Oxfordian associations from the sedimentary cover of ophiolites in Albania (MARCUCCI et al 1994). Similar radiolarian associations are known from a locality on the Mangart Mt.…”

Section: Final Remarkssupporting

confidence: 61%

Middle Jurassic radiolarian assemblages from Zlatar Mt. (SW Serbia)

Djerić¹,

Gerzina²,

Simic³

2010

Geol An Balk Poluos

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Section: Final Remarkssupporting

confidence: 61%

Middle Jurassic radiolarian assemblages from Zlatar Mt. (SW Serbia)

Djerić¹,

Gerzina²,

Simic³

2010

Geol An Balk Poluos

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“…). Radiolaria from the intercalated mudstones indicate a Callovian to Oxfordian age (Bragin et al ., ).…”

Section: Middle Jurassic Magmatism In the Central Pontidesmentioning

confidence: 97%

Low‐pressure–high‐temperature metamorphism during extension in a Jurassic magmatic arc, Central Pontides, Turkey

Okay

Sunal

Tüysüz

et al. 2013

Journal Metamorphic Geology

102

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Magmatic arcs are zones of high heat flow; however, examples of metamorphic belts formed under magmatic arcs are rare. In the Pontides in northern Turkey, along the southern active margin of Eurasia, high temperature-low pressure metamorphic rocks and associated magmatic rocks are interpreted to have formed under a Jurassic continental magmatic arc, which extends for 2800 km through the Crimea and Caucasus to Iran. The metamorphism and magmatism occurred in an extensional tectonic environment as shown by the absence of a regional Jurassic contractional deformation, and the presence of Jurassic extensional volcaniclastic marine basin in the Pontides, over 2 km in thickness, where deposition was coeval with the high-T metamorphism at depth. The heat flow was focused during the metamorphism, and unmetamorphosed Triassic sequences crop out within a few kilometres of the Jurassic metamorphic rocks. The heat for the high-T metamorphism was brought up to crustal levels by mantle melts, relicts of which are found as ultramafic, gabbroic and dioritic enclaves in the Jurassic granitoids. The metamorphic rocks are predominantly gneiss and migmatite with the characteristic mineral assemblage quartz + K-feldspar + plagioclase + biotite + cordierite AE sillimanite AE garnet. Mineral equilibria give peak metamorphic conditions of 4 AE 1 kbar and 720 AE 40°C. Zircon U-Pb and biotite Ar-Ar ages show that the peak metamorphism took place during the Middle Jurassic at c. 172 Ma, and the rocks cooled to 300°C at c. 162 Ma, when they were intruded by shallow-level dacitic and andesitic porphyries and granitoids. The geochemistry of the Jurassic porphyries and volcanic rocks has a distinct arc signature with a crustal melt component. A crustal melt component is also suggested by cordierite and garnet in the magmatic assemblage and the abundance of inherited zircons in the porphyries.

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“…b) The fact that Triassic deposits with Permo-Carboniferous limestone blocks are found only in the Sakarya Zone in the area from Biga peninsula at west to Tokat at the east and they are contiguous to the ‹zmir-Ankara Suture, c) The presence of pelagic deposits (Önder et al, 1987;Bragin et al, 2002) associated with middle Jurassic ophiolites in the Küre ophiolites that are considered as Paleotethys (Y›lmaz and Tüysüz, 1984), and Late Triassic fossil ages in the ‹zmir-Ankara-Erzincan Zone (‹AEZ) which is accepted as northern branch of Neotethys and thought to be opened in Liassic (U¤uz et al, 1999;Tekin et al, 2002), the presence of middle-late Triassic volcanic seamounts of OIB character, late Permian metamorphism age in basic rocks of oceanic crust within the Ankara mélange (Sar›fak›o¤lu et al, 2011(Sar›fak›o¤lu et al, , 2014 and the presence of Devonian aged radiolarian-bearing chert slices (Okay et al, 2011) within the Triassic Orhanlar greywacke that is adjacent to the suture. Okay ( 2004) also previously stated that Tauride-Anatolide block and Sakarya Zone that comprises the southern margin of Pontides did not amalgamate until Tertiary.…”

Section: Discussionmentioning

confidence: 99%

Late Permian Unconformity Around Ankara and New Age Data on the Basement Rocks, Ankara, Turkey

Sevin¹,

Dönmez²,

Atıcı³

et al. 2015

Bulletin of the Mineral Research and Exploration

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At southwest of Gölbafl› (Ankara) there are two different sequences in tectonic contact. The one at the bottom with low-degree metamorphism is represented by phyllite, metabasite, crystallized limestone, schist and quartz porphyry veins. Above them are early Carboniferous-late Permian neritic and pelagic carbonates which are unconformably overlain by late Permian clastics and carbonates. Samples collected from neritic carbonates yielded early Carboniferous (Visian-Serpuhovian) to middle Carboniferous (Bashkirian-Moskovian) ages. These carbonates of shallow facies character are overlain by radiolaritebearing pelagic deposits of middle Carboniferous-Permian age. Fossils from the upper most neritic carbonates gave Kubergandian-Murgabian age. This Permo-Carboniferous sequence is unconformably overlain by a sequence consisting of clastics and carbonates. Basal conglomerates and sandstones contain abundant quartz and fewer amounts of carbonated-cemented metamorphic rock fragments and they change to medium-thick bedded dolomitic limestone and limestones to the top. The age of these carbonates of shallow marine character is found Murgabian-Dorashamian. It is suggested that late Paleozoic carbonate basement was deposited in a neritic environment during early-middle Carboniferous, in a pelagic environment during middle Carboniferous-Permian and again in a neritic environment during Kubergandian-Murgabian. Following a deformation stage, it was accreted onto the Variscan basement at north and carbonate deposition took place as a result of late Permian transgression and finally some of exotic blocks within the upper Karakaya Complex were derived from this basement.

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Middle Jurassic radiolarians from the Akgol Formation, central Pontids, northern Turkey

Cited by 12 publications

References 0 publications

Middle Jurassic radiolarian assemblages from Zlatar Mt. (SW Serbia)

Middle Jurassic radiolarian assemblages from Zlatar Mt. (SW Serbia)

Low‐pressure–high‐temperature metamorphism during extension in a Jurassic magmatic arc, Central Pontides, Turkey

Late Permian Unconformity Around Ankara and New Age Data on the Basement Rocks, Ankara, Turkey

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