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The Southeast Anatolian Orogenic Belt (SAOB) is characterized by a tectonic assemblage consisting of dismembered ophiolites, subduction-related assemblages, and continental fragments. Whether the subduction-related volcanic assemblages formed in a Southern Neotethys oceanic arc-basin system (the Yüksekova Complex) or in a back-arc basin (the Maden Complex) originated after the closure of Southern Neotethys is still debated. To shed light on this matter, we focus on the Maden area, known as the type locality for the Maden Complex. The dating of radiolarian cherts associated with the volcanics from the Maden area yields Late Cretaceous (Santonian-Campanian) ages, indicating that these extrusives belong to the Yüksekova Complex. The Yüksekova volcanics are all subalkaline and mainly characterized by basalts, with subordinate andesitic varieties. The Zr-Nb-Y systematics of the Yüksekova lavas suggest that they have tapped a heterogeneous mantle source region with variable contribution from the depleted mantle. The positive εNd values of the volcanics also support the involvement of the depleted mantle. A common feature of the Yüksekova lavas is the marked depletion in Nb relative to Th and La, indicating a subduction-modified mantle source for their petrogenesis. The Pb isotope systematics, particularly the high 207Pb/206Pb, further implies a variable slab-derived sediment input in the source of these volcanics. Overall, trace element and isotopic characteristics of the Yüksekova lavas are consistent with their generation in an oceanic back-arc basin during the Santonian-Campanian interval in the Southern Neotethys. The Yüksekova back-arc basin characterizes the westward continuum of an extensive Late Cretaceous intra-oceanic subduction system, whose remnants can be traced further to the east, toward Iran. [ABSTRACT FROM AUTHOR]

Abundant and well-preserved radiolarians are reported from a limestone sample taken from near the town of Fojnica, southern Bosnia and Herzegovina. A late late Ladinian age is assigned to this sample based on the index species Spongoserrulafluegeli and Muelleritortis cochleata and associated radiolarian fauna. As a result of taxonomic studies on the entactinarian and nassellarian fauna of this sample, three species (Pseudostylosphaera multispinata, P. oblonga, and P. procera) from the suborder Entactinaria, and 18 species (Bulbocyrtium cordeyi, B.? longobardicum, Goestlingella goricanae, G. pseudoillyrica, Monicasterix ornata, M. parvisegmentata, M. pulchra, Nabolella brevispinosa, N. crenulata, N. trispinata, Ladinocampe dinarica, Spinotriassocampe praecarnica, Pseudosaturniforma ladinica, Pararuesticyrtium coniformis, P.? sanfihippoae, Conospongocyrtis bragini, Castrum blomei, and Triassocyrtium longum) from the suborder Nassellaria are described as new. Moreover, the genus Pseudosaturniforma is emended based on the new materials. [ABSTRACT FROM AUTHOR]

Blocks and tectonic slices within the Mersin Mélange (southern Turkey), which are of Northern Neotethyan origin (Izmir–Ankara–Erzincan Ocean (IAE)), were studied in detail by using radiolarian, conodont, and foraminiferal assemblages on six different stratigraphic sections with well‐preserved Permian succesions. The basal part of the Permian sequence, composed of alternating chert and mudstone with basic volcanics, is assigned to the late Asselian (Early Permian) based on radiolarians. The next basaltic interval in the sequence is dated as Kungurian. The highly alkaline basic volcanics in the sequence are extremely enriched, similar to kimberlitic/lamprophyric magmas generated at continental intraplate settings. Trace element systematics suggest that these lavas were generated in a continental margin involving a metasomatized subcontinental lithospheric mantle source (SCLM). The middle part of the Permian sequences, dated by benthic foraminifera and conodont assemblages, includes detrital limestones with chert interlayers and neptunian dykes of middle Wordian to earliest Wuchiapingian age. Higher in the sequence, detrital limestones are overlain by alternating chert and mudstone with intermittent microbrecciated beds of early Wuchiapingian to middle Changhsingian (Late Permian) age based on the radiolarians. A large negative shift at the base of the Lopingian at the upper part of section is correlated to negative shifts at the Guadalupian/Lopingian boundary associated with the end‐Guadalupian mass extinction event. All these findings indicate that a continental rift system associated with a possible mantle plume existed during the late Early to Late Permian period. This event was responsible for the rupturing of the northern Gondwanan margin related to the opening of the IAE Ocean. When the deep basinal features of the Early Permian volcano‐sedimentary sequence are considered, the proto IAE oceanic crust formed possibly before the end of the Permian. This, in turn, suggests that the opening of the IAE Ocean dates back to as early as the Permian. Blocks and tectonic slices within the Mersin Mélange (southern Turkey), which are of Northern Neotethyan origin (Izmir–Ankara–Erzincan Ocean), were studied in detail by using Radiolaria, Conodont, and Foraminiferal assemblages on six different stratigraphic sections with well‐preserved Permian succesions. The findings indicate that a continental rift system associated with a possible mantle plume existed during late Early to Late Permian period. This event was responsible for the rupturing of northern Gondwanan margin related to the opening of the Izmir–Ankara–Erzincan Ocean. [ABSTRACT FROM AUTHOR]