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This study provided insight into the origin, age, and formation conditions of the Late Oligocene sulfate lithofacies that were deposited in the SW Erzincan Basin throughout a broad region. Primary, secondary gypsum, and anhydrite make up the majority of sulfates, which are interbedded with clastic, volcanic, volcaniclastic and carbonated rocks. During the early-late diagenetic processes, primary gypsum changes into secondary gypsum along with primary anhydrite that is growing within the host-sediment. In the lithofacies, sedimentary structures created by tectonism and diagenesis are commonly found. The distribution of element concentrations shows that continental detrital input has a significant impact. Fe- and Mg-rich clays imply alkaline and hot-humid environmental conditions in the basin. The negative trend relationship of CaO with MgO refers to carbonation in the environment, while Sr, Ba, U, Mo, Ni, Cu and Zn values and Co, Ni/Co (0.98), Co/Zn (11.3), Cu/Zn (1.39) ratios and the high positive correlation of Cu with Al2O3 (r = +0.72) indicate the dominance of biologic factor, high salinity and reducing conditions in sulfates. The presence and values of Fe–Mn-rich alteration zones detected by field, mineralogical and geochemical studies within the gypsum revealed the hydrothermal solution activity in the region. 87Sr/86Sr, 18O/16O, 34S/32S and δ13C isotope data are consistent with Late Oligocene marine sulfates and suggest occasional mixing of freshwater. In addition, the origin and age data revealed by this study; It contributed to the paleogeographic evolution of the northern branch of Neotethys (Inner Tauride Ocean), which extends along the Central and northern-central Anatolia and Eastern Anatolia basins line, which includes Paleogene evaporitic deposits in Turkey, where the study area is located. Accordingly, it is obvious that the Neotethys, which extends along the basins from west to east, is quite shallow (lagoonal and coastal sabkha, etc.) and started to close further east during the Middle-Late Miocene (Erzurum-Pasinler- Horasan, Erzurum-Hınıs-Tekman, Iğdır-Tuzluca lacustrine basins, etc.). [ABSTRACT FROM AUTHOR]

The Beyşehir-Hoyran Nappes, one of the tectonostratigraphic units of the Taurides, are thought to be originated from the Izmir-Ankara Ocean (northern branch of Neotethys). In this study, Late Paleozoic rock units from the blocks of Beyşehir-Hoyran Nappes were studied in detail using foraminiferal assemblages in two different locations from the southwest of Karaman City (southern Turkey). In both places, blocks/slices and pebbles of various origins are embedded within a highly sheared matrix of Late Cretaceous Age, and the whole unit can be regarded as a sedimentary mélange. The ages of the blocks from the southwest of Karaman City range from the Late Serpukhovian (Late Mississippian) to Late Capitanian (Middle Permian) with some depositional breaks (e.g., Bashkirian, Kasimovian). Combined with the previous data from the Mersin Mélange, which also include the remnants of the Beyşehir-Hoyran Nappes, our new findings suggest that a shallowing-upward sequence, characterized by a shallow water environment with foraminifera-bearing limestones, was deposited over the Tournaisian pelagic sequence in the Beyşehir-Hoyran Nappes till the Early Moscovian (Early Middle Pennsylvanian). This shallowing-upward sequence in the Beyşehir-Hoyran Nappes could be related to the Late Paleozoic Glaciation on the Gondwana supercontinent (Glacial II), which resulted in a sea-level drop and deposition of platform carbonates during the Viséan–Early Moscovian (Middle Mississippian to Early Middle Pennsylvanian) time interval. The absence of the main part of the Middle-Upper Pennsylvanian deposits (continental phase during the Middle Moscovian–Middle Gzhelian) in the Beyşehir-Hoyran Nappes can be mainly attributed to the occurrence of a mantle plume and partially to the effect of Late Paleozoic Gondwanan Glaciation (Glacial III). Progressive uplifting by the buoyant mantle plume material has resulted in rifting at the center of the basin where the Beyşehir-Hoyran Nappes have deposited. The rifting process led to tectonic destabilization of the platform in the basin, causing accumulation of the Upper Gzhelian (uppermost Pennsylvanian) detrital limestone with broken and abraded foraminiferal shells. Following this, deep basinal conditions prevailed during the Late Asselian–Kungurian (Early Permian), as revealed in the Mersin Mélange, where radiolarian cherts are associated with continental within-plate lavas of extreme incompatible trace element enrichment. Similar processes were responsible for the continual deposition of detrital limestones in the same basin until the end of Late Capitanian (Middle Permian). Based on all these, the uplifting process followed by rift-related volcanic rocks and detrital limestones can be interpreted as the opening of the Izmir-Ankara Ocean (northern Neotethys). [ABSTRACT FROM AUTHOR]

The Hercynian Orogeny was caused by the collision of Gondwana and Laurussia in the Mid‐/Late Carboniferous–Early Permian. This orogeny strongly influenced the pattern and evolution of basins and hydrocarbon accumulation on the southern margin of the Tethyan region (i.e., North Africa and the Middle East). Research on the Carboniferous–Early Permian Hercynian Orogeny is of great value in both plate tectonic reconstructions and hydrocarbon exploration. For its influence on basin evolution, some previous studies have considered the modification of the early Palaeozoic basins, but there has been less work on the evolution of the post‐Hercynian Mesozoic basins. We review the available data and re‐analyse the spatiotemporal impacts of this key tectonic event on the evolution of the basins in this region. The Carboniferous–Early Permian Hercynian Orogeny was an important turning point in basin evolution in North Africa and the Middle East. It interrupted the stability of the Gondwana platform and heralded a huge change in the pattern of basins from the uniform pre‐Hercynian Palaeozoic basins to the post‐Hercynian Mesozoic basins characterized by strong segmentation. The Carboniferous–Early Permian Hercynian Orogeny not only modified the pre‐Hercynian Palaeozoic basins but also controlled the distribution and evolution of the post‐Hercynian Mesozoic basins. Large‐scale uplifts were generated among the basins through modification of the inherited palaeohighs and five large NE‐trending arches were newly formed. These uplifts divided the early unified basin into multiple separate basins. Five large‐scale, almost equidistant, NE‐trending arches were generated on the northern margin of Gondwana (the Allala, Sirte, Levant, Al‐Batin and Oman arches), forming the present‐day Palaeozoic Basin pattern with an alternating distribution of uplifts and depressions. The northern part of the large, NE‐trending Hercynian arches collapsed as a result of the extensional stress caused by the opening of the Neotethys Ocean in the Late Permian–Triassic and formed Mesozoic basin depocenters (the Oued Mya–Pelagian basins, the Sirte Basin, the Eastern Mediterranean Basin and the Central Arabian Basin). These depocenters are important oil and gas enrichment zones. The NE‐trending Hercynian arches, the Mesozoic basin depocenters, the opening of the Neotethys Ocean and the segmentation of the basins by the Alpine Orogeny all show relatively consistent east–west‐directed segmentation on the northern margin of Gondwana. This shows that they may have a unified dynamic genetic background. The zone of structural weakness formed by the collision of multiple terranes during the Pan‐African Orogeny may have controlled this segmentation. The inheritance between reformation of the pre‐Hercynian Palaeozoic basins and influence on the post‐Hercynian Mesozoic basins by Carboniferous–Early Permian Hercynian Orogeny, is the result of the tectonics repetitively focused in pre‐existing weaker domains, under the lithospheric mantle modification in the polyphase assembly and break‐up of the supercontinent. [ABSTRACT FROM AUTHOR]

A new family of Cyphophthalmi with disjunct Mediterranean distribution, Parasironidae fam. nov., is proposed. The new family comprises four genera and seven species. Cimmerosiro gen. nov., Tirrenosiro gen. nov. and Ebrosiro gen. nov. are described as new genera, and Tirrenosiro axeli gen. et sp. nov., Cimmerosiro krivolutskyi gen. et sp. nov., C. juberthiei gen. et sp. nov. and C. rhodiensis gen. et sp. nov. as new species. Parasironidae stands out by a set of characteristics that we recognize as predominantly plesiomorphic. These characteristics and the present distribution indicate the great age of the family, probably early Mesosoic. We attribute its origin to the western part of the Cimmerian terrane, and its current distribution and diversification of the major clades to geotectonic events during the Mesozoic. Additionally, a new sensory organ (sensilla) has been discovered in Cyphophthalmi. This organ is located on the pedipalp coxae and is believed to have a potential hygroreceptive function.

The Neotethyan Ankara Melange is a global reference for oceanic accretionary processes preserved in a collisional orogen. Here we show, based on eight representative outcrops around Ankara, that the melange encompasses stratigraphically coherent volcanic-sedimentary successions of mainly Late Jurassic-Early Cretaceous age. Our results indicate that the melange has a relatively organised tectonostratigraphy, in contrast to previous interpretations that emphasised its chaotic nature. Coherent volcanic-sedimentary successions of Late Jurassic-Early Cretaceous age are interpreted as flank facies of a large oceanic seamount (probably plume related) and its capping carbonate platform (atoll), including reef-and back-reef facies. Remnants of other seamounts are dated as Late Triassic-Early Jurassic and Late Cretaceous. Variably dismembered supra-subduction zone ophiolites of latest Early Jurassic-Middle Jurassic age, including boninites, formed in an oceanic fore-arc setting, similar to that of the Cenozoic Izu-Bonin fore arc, NW Pacific. The melange in the Ankara region partly accreted during the Early Cretaceous (pre-Albian) in response to collision of the inferred large seamount with the oceanic (ophiolitic) fore arc. During the collision which involved subduction-erosion slices of proximal–distal seamount flank lithologies accreted sequentially, whereas the seamount core subducted. Also during the collision, the distal outer edge of the ophiolitic fore arc, mainly mantle harzburgite, detached from the over-riding lithosphere and was incorporated into the melange. Structural evidence emphasises the importance of tectonic processes (rather than olistostromes) in the melange accretion. The accretionary prism in the outcrops studied was covered by arc-related sediments and volcanics during the Late Cretaceous and deformed by collision-related processes during latest Cretaceous-Paleogene.

In the southeastern part of Chios Island, Greece, exotic blocks of amphibolites and serpentinized peridotite can be found within a narrow, approximately N–S elongated area adjacent to non-metamorphosed sedimentary strata of Triassic age to its west and of Cenozoic age to its east. In this work, we present for the first time petrological and mineral chemical data for the amphibolites and ultramafic rock fragments from SE Chios Island, describe their possible origin and estimate the metamorphic pressure–temperature conditions and the age of metamorphic overprint. The protoliths of the amphibolites were mafic rocks of enriched (Type I amphibolite) and normal (Type II amphibolite) mid-ocean ridge character metamorphosed under upper amphibolite-facies conditions at 640–780 °C and 5–7 kbar. U–Pb isotopic data from titanite from three amphibolites yielded early Middle to early Late Jurassic lower intercept ages, which we interpret as the age of metamorphism during oceanic lithosphere emplacement. The peridotite is strongly serpentinized, mainly containing lizardite, which implies low-grade metamorphic conditions. With the exception of alteration rims, Cr- and Mg-numbers of the chrome spinel from the serpentinized peridotite range from 10–26 and 69–79, respectively, a range similar to abyssal peridotites of the subcontinental lithospheric mantle. We suggest that the amphibolites and ultramafic rocks represent separate fragments within a mélange, most likely of tectonic rather than accretionary origin. Metamorphism of the amphibolites took place prior to their presumed emplacement in the mélange. The mafic and ultramafic rock fragments of Chios preserve a different sort of subcontinental signature than that largely reported elsewhere within the Eastern Mediterranean ophiolite belts. A correlation with rocks of mélange units in western Turkey or in the northern and/or southern Aegean region is discussed. [ABSTRACT FROM AUTHOR]

A key but challenging task for biostratigraphers is to provide a biozonal/bioevent framework for geological correlation. Species of Larger Benthic Foraminifera (LBF) are important biostratigraphic markers in depositional environments where classical biostratigraphic fossils such as planktonic micro- and macrofossils are rare or absent - e.g., tropical-subtropical shallow water platforms. However, a lack of taxonomic rigour in identifying some LBF species, together with a lack of good age-calibration of their occurrences, has given rise to artificially extended biostratigraphic and paleogeographic ranges for many taxa, diluting their usefulness. In this study, the occurrences of Cenomanian LBF belonging to a "planispiral morphogroup", both agglutinated and calcareous, have been critically evaluated to determine (i) identity; (ii) stratigraphic range; and (iii) palaeogeographic distribution. Since the last major review of the group in 1985, a voluminous literature has appeared reporting occurrences and adding new taxa. An extensive review of some 600+ published items on Cenomanian planispiral LBF - mostly published after 1985 - and a critical review of the confidence in species identification and age-calibrations therein, has led us to identify 39 taxa (three in "open" status) which appear to have distinct identity. The vast majority of these records are from Neotethys although some also occur in (or are endemic to) the Caribbean/West Atlantic and the Eastern Pacific. The quality of the published taxonomic data is variable and many published records based on identity can be discounted or termed "unconfirmed". Likewise, many records (confirmed or otherwise) are poorly age-calibrated due to lack of corroborating biostratigraphy or chemostratigraphy, or by using circular reasoning. We summarise and illustrate the main defining characteristics of each taxon and their possible confusion species, including new taxa described since the mid-1980s. We publish new, more confident, age-ranges for these taxa - confirmed by identity and/or age-calibration - and identify where published range data may be unreliable. Paleogeographic distribution maps for each taxon are also provided. Particular stratigraphic issues around the Cenomanian-Turonian boundary are observed due to the difficulty of identifying that boundary, or its preservation, in shallow marine carbonate settings. Although most Cenomanian planispiral LBF are somewhat long-ranging, an increase in diversity throughout the middle - late Cenomanian has shown potential for biostratigraphic resolution to at least substage level using this group. Integration of the planispiral taxa with other LBF morphogroups, after similar treatment, will yield even higher biostratigraphic resolution of Cenomanian LBF and provide a sound basis for biozonation (both local and global), correlation, and age calibration. [ABSTRACT FROM AUTHOR]

In the Cenomanian, the southern passive margin of the Neotethys Ocean was dominated by a giant carbonate factory. This succession is known as Sarvak Formation, a significant reservoir in Iran. This study focuses on a detailed analysis of facies variations and paleoenvironmental reconstruction, including the interpretation of the platform types, during this time interval. Based on field observations and petrographical studies, 12 facies have been recognized and ascribed to six facies belts on a carbonate ramp. Sub-environments include the outer ramp and basin (distal open marine), talus and channel (mid-ramp) and lagoon and shoal (inner-ramp). The frequency of the facies and isochore maps indicate the paleoenvironmental conditions and their spatial variations in the study area. Based on all data and analyses, the suggested conceptual model for the Sarvak Formation in the Lurestan Zone is an isolated platform surrounded by two ramps. The upwind and downwind parts of these ramps were located in the central and northern sub-zones of the Lurestan Zone. This model can be used as a template for isolated platforms worldwide. [ABSTRACT FROM AUTHOR]

The questions of how and when the Neotethys Ocean opened are crucial for understanding the evolution of the Tethys Realm and the break-up of Gondwana. However, the evolution of the Neotethys remains controversial. Herein, we report the zircon U–Pb ages, whole-rock major as well as trace elements, and Sr–Nd isotopic data for the basaltic volcanic rocks from the Zhongba Terrane in the western Yalung–Zangbo Suture Zone. The results demonstrate that the Saga basalts were extruded during the Late Permian (257–258 Ma). All samples are characterized based on the low SiO2 content (44.03–50.33 wt%) and belong to the high-K calc-alkaline series. Furthermore, they exhibit light rare earth element enrichment ((La/Yb)N = 12.7–26.7); slightly positive Eu anomaly(Eu/Eu* = 1.01–1.14); prominent Nb and Ta positive anomalies; slightly negative Zr, Hf, and Ti anomalies and exhibit high ratios of Ta/Hf (0.93–1.21), Zr/Y (8.68–10.63), and Nb/Zr (0.39–0.45). The (87Sr/86Sr)i ratio varied from 0.7050 to 0.7063, with relatively constant and depleted εNd(t) values ranging from 0.52 to 1.08. The rocks were probably sourced from a low-degree partial melting of the asthenospheric mantle in a rift environment and had undergone the process of fractional crystallization. These characteristics indicate that the Saga basalts differ from the rift-related magmatic rocks produced by the Panjal Traps. Consequently, combined with the recently reported detailed fieldwork, the Zhongba Terrane disintegrated from the northern margin of Gondwana during the Late Permian, promoting the opening of the Neotethys Ocean, which is most likely caused by the northward subduction of the Paleotethys Ocean. [ABSTRACT FROM AUTHOR]

In 1953 Wolf Maync introduced the lituolid (now regarded as loftusiid) foraminiferal genus Hemicyclammina, with its type species Hemicyclammina sigali from the Cenomanian of Algeria. Since then, this distinctive microfossil has been frequently reported from mainly Neotethyan mid-Cretaceous (mostly Albian and Cenomanian) sedimentary rocks in locations as far apart as Brazil and Oman. However, Maync was seemingly unaware of the 1948 publication of Francis R.S. Henson in which a new species of foraminifera, Cyclammina whitei, was described from the mid-Cretaceous of the Middle East. During the course of the last 70 years, C. whitei has been placed in the genus Hemicyclammina, tenuously regarded as distinct from H. sigali. We demonstrate that H. whitei and H. sigali are synonyms, with H. whitei the senior synonym, and hence the type species of Hemicyclammina. This argument is supported by the re-illustration of the type material of H. whitei and H. sigali. It is also argued that a number of poorly known taxa (e.g., Hemicyclammina evoluta Hamaoui, Ismailia neumannae El-Dakkak, Sinainella aegyptiaca El-Dakkak) are most likely the junior synonyms of H. whitei and that thus, for the Albian - Cenomanian at least, there is only one species of Hemicyclammina. Limited Barremian/Aptian records of Hemicyclammina are probably best assigned to a potentially ancestral form herein termed "Hemicyclammina? sp." pending access to further material and a full assessment of the evolution of Hemicyclammina. A critical review of the many published records demonstrates that H. whitei ranges throughout the Albian and Cenomanian, although locally it may have a more restricted range because of facies control on its inception, extinction, and abundance. It is confidently known to occur from southern and central America, North Africa, the Mediterranean, the Arabian Plate and Somalia. [ABSTRACT FROM AUTHOR]

The Sanandaj-Sirjan Zone of western Iran is characterized by significant Mesozoic magmatic activity (from the early Jurassic to the late Cretaceous), with Cenozoic rocks being less common. Granitoids are prevalent in this zone, displaying A-, I-, and S-type geochemical characteristics. Despite several studies on these granitoids, there are still some questions regarding their sources– especially the S- and A-type granitoids – and the crustal growth and recycling in this zone, which require further studies using isotopes. This study focuses on the Aligoodarz, Kolah-Ghazi, and Golpayegan granitoids from the central SaSZ to better understand crustal growth and recycling in the Sanandaj-Sirjan Zone. The Aligoodarz and Kolah-Ghazi granitoids are identified as S-type granites, showing strong peraluminous signatures. Geochemical evidence suggests a mixture of melts from sub-crustal metasedimentary and meta-igneous sources, with factors such as source diversity and disequilibrium melting contributing to their formation. in contrast, the Golpayegan granitoids exhibit high total alkali (Na 2 O + K 2 O) contents and high field strength elements, indicating alkaline magmatic affinity. Their geochemical signatures suggest derivation from an enriched portion of an Indian MORB-like protolith. Golpayegan syenites share similarities with within-plate A1 granites, suggesting they are related to anorogenic silica-oversaturated granitoids. Golpayegan A-type granites probably originated from high-degree fractionation of alkali basic magmas. Golpayegan gabbros may be derived from a MORB or OIB-like mantle source, with characteristics indicating the presence of garnet in the mantle source and potentially deep melting from a mantle plume. Newly compiled zircon U Pb data from the Sanandaj-Sirjan Zone show a complex magmatic chronology spanning from approximately 180 million years ago to the Eocene epoch, revealing peaks of magmatic activity at various intervals. Distinct phases of A-, I-, and S-type magmatism are identified, and synthesis of zircon U Pb ages and Hf O isotope data reveals the simultaneous occurrence of S-type and I-type magmas during specific periods. Furthermore, our study explores the tectonic settings underlying these magmatic processes and proposes scenarios involving subduction, continental rifting, and asthenospheric upwelling to elucidate the geological dynamics of the SaSZ. • Abundant Jurassic-Cretaceous A-, S-, and I-type granitoids are found in the Sanandaj-Sirjan Zone of Iran. • The granitoids exhibit evidence of mantle and crustal components, defining crustal growth and recycling processes. • The SaSZ rocks are believed to have originated from Jurassic subduction and late Cretaceous asthenospheric upwelling. [ABSTRACT FROM AUTHOR]

The Late Cretaceous-Early Paleogene (K-Pg) was a critical period of transition in geological time. This period encompassed short-term climatic fluctuations on a global scale, changes in ocean circulation, and sudden and large extinctions of marine and terrestrial organisms. In the study area, located in the mid to low latitudes, the Late Cretaceous and Early Paleogene were very tectonically active due to the positioning of the site close to the collision zone of two large continents. The impacts of the global K-Pg crisis can be observed in the study area. In this study, the calcareous nannofossil contents of late Maastrichtian-Danian sediments were studied, and the nannofossil biostratigraphy determined, from samples from the Samanlık and Dizilitaşlar Formations, deposited in the Kırıkkale Basin. From three stratigraphic sections, 26 nannofossil genera and 36 nannofossil species were identified from the Late Maastrichtian UC20aTP and UC20bTP biozones and the NP1 and NP2 biozones of the Danian. Additionally, it was determined that the K-Pg boundary was not continuous in the study area. In the Kırıkkale Basin, relatively low abundances of Micula decussate Vekshina, 1959 signals a diagenetic effect and stressful environment in the Late Maastrichtian, whereas the relatively low abundances of Thoracosphaera operculata Bramlette & Martini, 1964, Braarudosphaera bigelowii (Gran & Braarud, 1935) Deflandre, 1947 and Futyania petalosa (Ellis & Lohmann, 1973) Varol, 1989 in the Danian assemblages indicate unstable environmental conditions and major environmental perturbations that reflect tectonic activity in the region. No nannofossils were encountered in those samples taken from turbiditic levels, which contained high proportions of sand. [ABSTRACT FROM AUTHOR]

The Oligo-Miocene Daralu gabbro–dioritic rocks, structurally located in the southern part of Urumieh-Dokhtar magmatic arc (UDMA), are exposed as isolated outcrops in the Eocene volcanoclastic-sedimentary rocks. The gabbro–dioritic rocks are mainly consisting of plagioclase, clinopyroxene, amphibole, and biotite phenocrysts in a microlithic groundmass. Clinopyroxenes compositionally belong to Ca-Mg-Fe type and classified as diopside-augite (En39.0-47.3Fs9.3-17.5Wo38.1-47.0). Their various thermobarometric calculations suggest that the clinopyroxenes were formed at 1.9–7 kbar, 930–1114 °C, and high oxygen fugacity. These thermodynamic parameters reveal a polybaric crystallization which is inline with their formation in a multi-level magmatic storage system. Moreover, composition of clinopyroxenes indicates that the Daralu gabbro-dioritic rocks have a calc-alkaline nature and formed in a volcanic arc tectonic environment. It seems that northward subduction of Neotethys oceanic lithosphere beneath the Central Iranian microcontinent during Tertiary triggered magmatism. This happened as a result of partial melting of subcontinental lithospheric mantle at depth over 23 Km that produced mafic magma and its crystallization during ascent in the magmatic reservoirs at different levels. The role of crustal contamination in the development of these rocks is relatively insignificant. [ABSTRACT FROM AUTHOR]

We carried out a comprehensive facies/microfacies, micropalaeontological and biostratigraphical analysis of several carbonate olistoliths incorporated within a widely developed Albian conglomeratic sequence from the Eastern Carpathians of Romania. The majority of the sampled olistoliths contain a rich assemblage of benthic foraminifera and calcareous green algae. All of the described microfossils represent common lowermost Cretaceous taxa not previously reported from these carbonate elements or from this region. Based on benthic foraminifera assemblages the age of the studied olistoliths is upper Berriasian–lower Valanginian, contrary to the general belief that they are Barremian–Aptian in age. The dominant microfacies types mainly reflect deposition in shallow-water environments and show similarities with synchronous platform carbonates of the central-western Neotethys Ocean. The micropalaeontological and sedimentological data support new interpretations concerning the source area of these carbonate elements and provide new information concerning the evolution of the lowermost Cretaceous carbonate platforms of the Carpathians. [ABSTRACT FROM AUTHOR]

The middle‐upper Jurassic successions (Sargelu, Najmah, and Gotnia formations) of the NW sector of the Zagros Mountain belt are studied to generate a sequence stratigraphic model that helps to understand the Jurassic tectono‐depositional processes and palaeogeographic reconstructions of the northeastern passive margin of the Arabian Plate. The major geological structures observed in northwestern Iran indicate the predominance of an extensional deformation during the Toarcian to Aalenian owing to the eastern Mediterranean rifting. This extensional regime reached its maximum from the Early to Middle Jurassic, causing the fragmentation/drowning of the long‐lived Triassic to Early Jurassic carbonate platform and the development of the Hawraman intrashelf basin (HIB). Associated changes in marine current dynamics, trophic conditions, and degree of substrate oxygenation led to the bloom of oligotypical biota (Bositra limestones) creating unfavourable conditions for the development of other benthic communities (Sargelu Formation). Later, from the Callovian to Oxfordian, changes in carbonate production types (switch from the Bositra filament facies to the stromatolitic‐thrombolitic boundstones) remarkably decreased the dip angle of the depositional profile (Najmah Formation). A second‐order tectono‐eustatic cycle (a major long‐term transgressive/regressive [T/R] cycle) including six minor short‐term T/R facies cycles (TR1–TR6) is identified in the study area. The development of the T/R facies cycles during the Middle Jurassic (TR1–TR3; give‐up sequences; Sargelu Formation) as a result of combined global eustatic transgression and linear subsidence resulted in drowning and backstepping of the platform. In contrast, the short‐term cycles that developed in the upper Jurassic (TR4–TR6; keep‐up sequences; Najmah and Gotnia formations), following a sea‐level fall, resulted in progressive shallowing of the carbonate platform. This study suggests that extensional deformation of the area reached its peak in the transition of the Early to Middle Jurassic, leading to the creation of HIB, but either decreased or played a subordinate role to eustatic sea‐level variations during the deposition of the TR1–TR3 facies cycles (Bajocian‐Callovian). Changes in tectonic regime from an extensional deformation (Early Jurassic) to cooling subsidence (Middle Jurassic), accompanied by a long‐term transgressive sea‐level trend during the Middle Jurassic, were important factors in the development of anoxic trough environments with the deposition of organic‐rich intervals, represented by the TR1–TR3 facies cycles. Tectonic instability (tectonic uplift plus considerable differential subsidence due to the reactivation of faults) in the eastern margin of the Arabian platform during the Late Jurassic led to the development of the TR4–TR6 facies cycles. [ABSTRACT FROM AUTHOR]

Events in the tectono-magmatic framework of the Eocene Bulfat Igneous Complex in the Kurdistan region of northeastern Iraq are revealed through the integrated field, petrographic, geochemical and zircon petrography and U–Pb geochronology of the Qaladeza trondhjemite sheets that cut gabbros of the complex. The trondhjemite sheets are variably deformed, with the cataclasis of large plagioclase feldspars. The trondhjemites are albitic, and geochemical features such as strong enrichment of the light REE relative to the heavy REE and low Ti and REE content show that they did not form as late differentiates of a MORB-like source, but instead by hydrous partial melting of mafic rocks, possibly also involving some more evolved crustal source as well. Qaladeza trondhjemite oscillatory-zoned magmatic zircon has an age of 48.0 ± 0.6 Ma (95% confidence). These domains have been etched to form voids in the zircons, the walls of which have thin coatings of Th- and Ca-bearing species. Subsequent partial recrystallization of the zircons obliterated the voids and increased the Th/U of the recrystallized zircon, which mostly formed at 38.74 ± 0.74 Ma. The 48 Ma domains relate to recycling of mafic crust in a proto-arc tectonic setting and are congruent with Eocene proto-arc magmatic activity within the Neotethyan oceanic basin. The 39 Ma domains relate to later tectonic-induced recrystallisation events coeval with the closure of Neotethys resulting from the late Eocene collision between the Arabian plate and Eurasia in Kurdistan. [ABSTRACT FROM AUTHOR]

Collision between the Pontides and Anatolide‐Tauride Block along the İzmir‐Ankara‐Erzincan suture in Anatolia has been variously estimated from the Late Cretaceous to Eocene. It remains unclear whether this age range results from a protracted, multi‐phase collision or differences between proxies of collision age and/or along strike diachroneity. Here, we leverage the Cretaceous‐Eocene evolution of the forearc‐to‐foreland Central Sakarya Basin system in western Anatolia to determine when and how collision progressed. New detrital zircon (DZ) and sandstone petrography results indicate that the volcanic arc was the main source of sediment to the forearc basin in the Late Cretaceous. The first appearance of Pontide basement‐aged DZs, in concert with exhumation of the accretionary prism and a decrease in regional convergence rates, indicates intercontinental collision initiated no later than 76 Ma. However, this first contractional phase does not produce advanced thick‐skinned deformation and basin partitioning until ca. 54 Ma. We propose three non‐exclusive and widely applicable mechanisms to reconcile the observed ∼20 Myr delay between initial intercontinental collision and thick‐skinned upper plate deformation: slab breakoff, relict basin closure north and south of the İAES, and underthrusting of progressively thicker passive margin lithosphere. These mechanisms highlight the links between upper plate deformation and plate coupling during continental collision. Plain Language Summary: Key to understanding the interconnectedness of Earth's systems is unraveling feedbacks between climate, biology, and tectonic plate movements. This can only be resolved within a robust timeframe of tectonic events, including the collision of continents. Yet, the timing of collisions is difficult to determine. We present results from western Turkey where the history of oceanic basin closure and collision from 110 to 40 million years ago (Ma) is preserved in the sedimentary rock record. We identify three phases of oceanic closure (subduction) and continental collision. Subduction was active from at least 110 Ma through 76 Ma when sediment was derived from active volcanoes. At 76 Ma, continental deformation uplifted and eroded older rocks; this is the initial contact between colliding continents. The next phase of collision began at 54 Ma when continental deformation separated the zone of sediment deposition into two basins. The 20‐million‐year collision duration can be explained by three changes to tectonic plate coupling. Together, we conclude that collision age discrepancies are representative of collision mechanics not a function of ill‐fit comparisons between proxies. This long history of collision illuminates how the movement and amalgamation of small continents aided the migration and evolution of species in the Mediterranean. Key Points: Multi‐phase intercontinental collision is identified in western Anatolia by sedimentary basin changesSedimentary provenance change indicate collision was at 76 Ma, but significant thick‐skinned deformation was delayed until 54 MaThe 20 Myr duration of initial collision can be explained by three multi‐stage mechanisms involving changes in plate coupling [ABSTRACT FROM AUTHOR]

Abstract Collision between the Pontides and Anatolide‐Tauride Block along the İzmir‐Ankara‐Erzincan suture in Anatolia has been variously estimated from the Late Cretaceous to Eocene. It remains unclear whether this age range results from a protracted, multi‐phase collision or differences between proxies of collision age and/or along strike diachroneity. Here, we leverage the Cretaceous‐Eocene evolution of the forearc‐to‐foreland Central Sakarya Basin system in western Anatolia to determine when and how collision progressed. New detrital zircon (DZ) and sandstone petrography results indicate that the volcanic arc was the main source of sediment to the forearc basin in the Late Cretaceous. The first appearance of Pontide basement‐aged DZs, in concert with exhumation of the accretionary prism and a decrease in regional convergence rates, indicates intercontinental collision initiated no later than 76 Ma. However, this first contractional phase does not produce advanced thick‐skinned deformation and basin partitioning until ca. 54 Ma. We propose three non‐exclusive and widely applicable mechanisms to reconcile the observed ∼20 Myr delay between initial intercontinental collision and thick‐skinned upper plate deformation: slab breakoff, relict basin closure north and south of the İAES, and underthrusting of progressively thicker passive margin lithosphere. These mechanisms highlight the links between upper plate deformation and plate coupling during continental collision.

Biostromes and low‐relief bioherms, some of which are characterized by exceptionally large, flat specimens of larger benthic foraminifera, are common in Palaeogene and Miocene carbonates, most notably those deposited along the Neotethys Seaway and tropical Pacific islands. By incorporating insights from palaeoceanographic research and the biology of living larger benthic foraminifera, a scenario is proposed that can account for palaeontological and sedimentological features while augmenting previous interpretations. Sexual reproduction by gamete broadcasting is common in foraminiferal taxa, including extant Nummulitidae and Amphisteginidae. Resultant zygotes can develop into tiny, resistant, easily dispersed propagules that recruit in suitable benthic‐environmental conditions. The role of algal symbiosis in the biology of larger benthic foraminifera is well‐documented. Palaeoceanographically, such taxa proliferated during times of reduced thermal stratification of the oceans. In regions with exceptionally clear, nutrient‐depleted waters, 'twilight‐zone' light penetration was sufficient, at least intermittently, to support some photosynthesis. On outer‐shelf or promontory sites at depths of ca 100 to 200 m, the tiny propagules of larger benthic foraminiferal species, incorporating algal symbionts with the lowest light requirements, could have settled and recruited, growing very slowly, nourished by feeding on bacteria and the limited photosynthate produced by their algal symbionts. Under such conditions, thin microspheric individuals of one or two larger benthic foraminiferal taxa could have survived and grown slowly over several years to very large shell diameters, seldom reproducing asexually. Resulting carbonate accumulation rates would have been very slow, such that even rare disturbances by currents, major storms or internal waves could have produced evidence of winnowing and sedimentary structures. The fossil evidence of such habitats should include biostromes or possibly low‐relief bioherms of low diversity assemblages characterized by abundant, exceptionally large, flat, microspheric larger benthic foraminifera. [ABSTRACT FROM AUTHOR]

The East Anatolian Accretionary Complex formed as a result of the natural process of collision between the Arabian and Eurasian plates and the subduction of the Neotethys oceanic lithosphere located between them, covers a broad area, largely east of Lake Van. This study presents new information about the formation environment of mantle peridotites located within the East Anatolian Accretionary Complex and its rock-melt interactions. According to petrographic and geochemical investigations, peridotites comprise olivine, orthopyroxene, and chromite with low modal content in clinopyroxene (<1 vol%) while whole rock geochemical data indicates that they contain a high MgO (40.56–43.31 wt%) and low Al2O3 (0.16–0.48 wt%) and CaO (0.02–0.38 wt%) content. These values show that these rocks have a high degree of depletion, revealing typical arc peridotite features. Studies on olivine and pyroxene minerals, which are commonly observed in peridotites, show that these rocks are related to the arc. When peridotites are normalized to chondrite, partial enrichment takes place in light and heavy rare earth elements, while partial depletion occurs in medium rare earth elements. The enrichment of the rare earth elements is considered sufficient proof that the mantle peridotites underwent a boninitic mantle-induced enrichment during subduction. Analysis of chromites in the main melt, and its contents (Al2O3, TiO2 and FeO/MgO) suggest boninitic effects in peridotites. All data obtained from peridotites reveal formation of a subduction zone within the Neotethys oceanic lithosphere with an advanced degree of melting leading to re-enrichment of forearc peridotites in advancing periods. These features compare with southern Neotethys and Iran ophiolites. [ABSTRACT FROM AUTHOR]

The peculiar Jadar block has an intervening position separating the main Neotethyan West Vardar Zone (including ophiolites of Late Jurassic age) and a passive margin lithospheric segment of the Apulia/Adria microplate referred to as the Drina-Ivanjica block. The review aimed to reassess the peri- Neotethyan paleogeography affecting the evolution of the Neotethyan oceanic crust (‘single’ vs. ‘multiple oceans’ or single- vs. two ophiolite belts) by juxta - posing the key differences of the late Variscan temporal evolution (controlling early Alpine paleogeography) between the Jadar block and Drina–Ivanjica crystalline segment. The study goal is the questionable paleogeographic affinity of the Jadar block. Contrary to the recent inferences attributing the Jadar block as a segment of the Apulia/Adria microplate, the study examine whether and how the Jadar Late Paleozoic succession may allow for an alter - native paleogeographic solution of the Neotethyan relevance. According to this comparison survey of these late Paleozoic successions, it appears that the Jadar block may carry a (tentative) evidence of the proximity of the western Paleotethys. The comparison yields a putative paleogeographic position as - sociating the Jadar block with the post-Variscan European margin (not Аpulia/Adria microplate). The proposed shift of the Permian-Triassic paleo - geographic position of the Jadar block inevitably affects the obduction length i.e. questions a favourable protracted along strike-width of the overriding Neotethyan West Vardar ophiolites (‘single ocean model’).

During the Late Cretaceous in the Eastern Mediterranean, the northern branch of the southern Neotethys was closed by multiple northward subductions. Of these, the most northerly located subduction created the Baskil continental arc at around 82–84 Ma. The more southerly and intra‐oceanic subduction, on the other hand, produced an arc‐basin system, the Yüksekova Complex, as early as the late Cenomanian–early Turonian. The abundant and relatively well‐studied basaltic rocks of this complex were intruded by dykes, sills and small stocks of felsic–intermediate rocks, not previously studied in detail. The intrusives collected from five different localities in the Elazığ region of eastern Turkey are all subalkaline, with low Nb/Y values. Most of them have been chemically classified as rhyodacites/dacites, whereas a small number appear to be andesites. In normal mid‐ocean‐ridge basalt (N‐MORB)‐normalised plots, the intrusives are characterised by relative enrichments in Th and La over Nb, Zr, Hf, Ti and high field strength elements (HREEs), indicating their derivation from a subduction‐modified source. While their relatively high, positive εNd(i) values (+6.4 and +7.2) might suggest a depleted mantle source for their ultimate origin, somewhat radiogenic Pb values indicate a sedimentary contribution to the source of the rocks. The overall geochemical characteristics indicate their generation in an oceanic arc setting. The zircon U‐Pb Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) data obtained from five felsic‐intermediate rock samples yielded intrusion dates of 80–88 Ma. This suggests that the Elazığ oceanic arc‐related intrusives are slightly younger than those of the Yüksekova arc‐basin system, but coeval with the Baskil continental arc. However, the felsic–intermediate intrusives show different geochemical characteristics (oceanic arc‐type, with a lack of crustal contamination) to those of the Baskil continental arc. This indicates that these two igneous systems are unrelated and likely developed in different tectonic settings. This, in turn, supports a geodynamic model in which the northern strand of the southern Neotethys was consumed by multiple northward subductions. [ABSTRACT FROM AUTHOR]

Back‐arc regions are usually punctuated by pulses of tectonic deformation, lasting for few tens of millions of years. Yet, the origin of those short‐lived deformation episodes is disputed. Here, we compile structural, stratigraphic, geochemical, and geochronological data from Iran and we combine them with a kinematic reconstruction to show that the back‐arc region of the Central Neotethys subduction zone was affected by alternating pulses of extension and compression, linked to episodes of trench retreat and advance, respectively. To back‐up these observations and investigate the causes of such a trench behavior, we run 2D numerical models exploring (i) the dynamics of subduction into a viscously stratified mantle, and (ii) the deep slab deformation induced by mineral phase changes at the mantle transition zone. Our results indicate that episodes of trench retreat and trench advance, like those observed in the Central Neotethys domain, emerge spontaneously by slab folding, and penetration into the mantle transition zone. We propose a coupled mantle‐surface tectonic evolution model of the Central Neotethys slab that reconciles back‐arc deformation and short‐lived pulses of upper‐plate vertical motion in a unique, dynamically self‐consistent model of deep mantle subduction. Key Points: The upper plate of the Neotethys subduction system has been deformed by alternating episodes of compression and extension since the CretaceousThe alternating episodes of deformation are due to the episodes of advancing and retreating trenchNumerical models simulate the episode of trench migration and upper‐plate deformation by slab folding in the mantle transition zone [ABSTRACT FROM AUTHOR]

Amanoslar’da, Yarpuz-Kaypak (Osmaniye) yöresindeki ofiyolitik kayaçlar harzburjitik tektonitler ve mafik kümülat kayaçlarından oluşmaktadır. Tektonitler serpantinize harzburjitler ile temsil edilirken kümülat kayaçları gabronorit ve gabro ile temsil edilmektedir. Kümülat kayaçlardaki minerallerin kristallenme sırası klinopiroksen, ortopiroksen, plajiyoklaz ve amfibol şeklindedir. Tektonit ve kümülatların ana element içerikleri yay ile ilişkili tektonik ortamlar ile uyumludur. Bu kayaçlar, iz element konsantrasyonları bakımından, büyük iyon yarıçaplı elementlerce zenginleşme göstermektedir. Elde edilen jeokimyasal ve petrografik veriler, Yarpuz-Kaypak (Osmaniye) yöresindeki tektonit ve kümülat kayaçların Güney Neotetis okyanusunun Geç Kretase’de kapanması sırasında okyanus içi yitim zonu dalma-batma zonu üzerinde oluşan ve Arap platformunun kuzey kenarına yerleşen okyanusal litosfer kalıntıları olduğuna işaret etmektedir.

In northwestern Iran, magmatic activity occurred during three main intervals: The Cretaceous, Eocene, and Miocene-Quaternary. The first two phases of magmatic activity are more consistent with arc-type magmatism on an active continental margin; whereas the last phase, which has calc-alkaline and alkaline affinities, shows more similarity to postcollisional magmatism. Magmatic belts are mostly situated in the northern and eastern parts of the Oshnavieh–Salmas–Khoy ophiolite belt (OSK-Ophiolite) in northwestern Iran. The OSK-Ophiolite is known as the Neotethys, an ocean remnant in northwestern Iran, and extends to eastern Turkey and surrounds the Van area. This configuration shows that the Van microplate and surrounding ocean have played an important role in the evolution of magmatic activity in northwestern Iran, eastern Turkey, and the Caucasus since the Cretaceous. The Van microplate is situated among the Arabian plate to the south, northwestern Iran to the east, and Armenia to the north. The subduction of the northern branch of the Neotethys oceanic lithosphere beneath southern Eurasia has been critical in flare-up magmatism in the southern Caucasus since the Late Cretaceous. Considering the Van area as a new microplate makes understanding the geodynamic evolution of this area easier than in the many tectonic models that have been suggested before. When regarding the Van microplate, the main suture zone, which is known as the Bitlis–Zagros zone, should be changed to the Zagros–Khoy–Sevan–Akera suture zone, which extends to the eastern and northern Van microplate and western Iran.

Mélanges are formed by sedimentary, tectonic and diapiric processes and are generally found in collisional belts. The Zagros Orogeny provides an intriguing geological laboratory for the study of mélange‐forming processes during the progressive tectonic evolution of the Neotethys Ocean. Different types of tectonic and sedimentary mélanges occur in specific structural positions within the Zagros orogenic belt in the Neyriz Region (Iran). Based on their block‐in‐matrix fabrics, and tectonostratigraphic positions, we differentiated 14 different mélange types, which mark different episodes of the tectonic evolution of the Neyriz Region from the Cretaceous subduction to the Miocene collision. The Cretaceous subduction stage is recorded by volcanic‐sedimentary mélanges (Mv). Sedimentary mélanges characterized by megabreccia from the Cretaceous limestone (Ms1) and Eocene polymictic megabreccia (Ms2) represent epi‐nappe mélanges formed during the Palaeocene–Eocene in wedge‐top basins. The ophiolite emplacement in the Oligocene resulted in local extensional tectonics in the upper part of the ophiolitic nappe, and deposition of a polymictic megabreccia (Ms3, Ms4). As the final production of the Neotethys Ocean closure and the Eurasian‐Arabian collision, the sedimentary mélanges characterized by different types of chaotic rock units (Ms5, Ms6, Ms7 and Ms8 facies) were developed in front of the Cretaceous–Eocene nappes due to growth of the orogenic wedge in the Miocene. Our findings indicate that the recognition and distinction of different types of mélange may provide additional constraints for a better understanding of the tectono‐sedimentary evolution of the Neotethyan region. [ABSTRACT FROM AUTHOR]

Zircon U-Pb age, mineral compositional, elemental and Sr-Nd isotopic data are documented for intermediate to felsic rocks in the Takht batholith, a Late Oligocene igneous complex in the southeastern segment of the Urumieh-Dokhtar belt, Iran, to investigate magma genesis in the context of regional tectonics. A large part of the magmatic belt formed by northward subduction of the Neotethys before the Arabia–Eurasia continental collision. Zircon U-Pb age data indicate the batholith crystallized at ∼25 Ma, an age consistent with previous results. Geochemical data indicate that the rocks share features typical of calc-alkaline magmas and I-type granitoids. The least evolved magma inferred from the data has basaltic andesite composition, consistent with either of the following origins: (i) a partial melt of the mantle followed by differentiation, or (ii) a partial melt of the lower crust. With increasing SiO2, (87Sr/86Sr)25Ma increases from 0.7053 to 0.7073, and εNd25Ma decreases from −0.3 to −2.9, consistent with increasing effects of assimilation–fractional crystallization, although processes such as magma mixing and melting of heterogeneous source rocks cannot be entirely ruled out. Aluminum-in-hornblende thermometry indicates that the batholith might have emplaced at ∼6.5 km or shallower paleo-depths. Moho depth proxies Sr/Y and (La/Yb)N yield crustal thickness of ∼20–30 km, showing no evidence for magma processing within thick crust. Overall, our results indicate that the Takht batholith is a Cordilleran-type batholith formed beneath a continental or transitional arc of normal crustal thickness. This is consistent with the notion that Arabia and Eurasia have collided in a diachronous manner, propagating from the northwest to the southeast since the Late Eocene–Early Oligocene.

We report paleomagnetic data showing that an intraoceanic Trans- Tethyan subduction zone existed south of the Eurasian continent and north of the Indian subcontinent until at least Paleocene time. This system was active between 66 and 62 Ma at a paleolatitude of 8.1 ± 5.6 °N, placing it 600-2,300 km south of the contemporaneous Eurasian margin. The first ophiolite obductions onto the northern Indian margin also occurred at this time, demonstrating that collision was a multistage process involving at least two subduction systems. Collisional events began with collision of India and the Trans-Tethyan subduction zone in Late Cretaceous to Early Paleocene time, followed by the collision of India (plus Trans-Tethyan ophiolites) with Eurasia in mid-Eocene time. These data constrain the total postcollisional convergence across the India-Eurasia convergent zone to 1,350-2,150 km and limit the north-south extent of northwestern Greater India to <900 km. These results have broad implications for how collisional processes may affect plate reconfigurations, global climate, and biodiversity. [ABSTRACT FROM AUTHOR]

The nature and geodynamic setting of Inner Makran ophiolites (SE Iran) are controversial and are the focus of a growing debate. The Fannuj-Maskutan ophiolite complex (central Inner Makran) is made up of lherzolites, harzburgites, layered and isotropic gabbros and diabase dikes and basaltic lavas. Here we present new textural description, mineral and whole-rock chemistry of peridotites together with bulk geochemistry of magmatic mafic rocks and U-Pb geochronology and Lu-Hf isotopes of inherited zircons in gabbros, with the aim to reconstruct the petrogenesis of the Fannuj-Maskutan ophiolite. The results indicate to a subduction-metasomatized depleted mantle source experienced 10–20% of partial melting. A transition from IAT-gabbros to E-MORB-basalts is also outlined. We interpret the obtained results as evidence for the Fannuj-Maskutan genesis in a supra-subduction zone (SSZ) basin developed in the Iranian cadomian crust as indicated by the presence of inherited Cadomian zircons (ca. 515 Ma, εHf(t): −13.6 – +11.2). Comparing the Fannuj-Maskutan ophiolites to well-known SSZ-systems such as the South Sandwich SSZ, and integrating with the existing literature on Inner Makran ophiolite belt we interpret the Fannuj-Maskutan ophiolite as a part of a major SSZ-basin opened in the Iranian cadomian crust and evolved during the Neotethys subduction under Central Iran. [ABSTRACT FROM AUTHOR]

The Antalya Complex in southern Turkey comprises a number of autochthonous and allochthonous units that originated from the Southern Neotethys. Late Triassic volcanic rocks are widespread in the Antalya Complex and are important for the onset of the rifting stage of the southern Neotethys. The studied Late Triassic volcanic rocks within the Antalya Complex are exposed in the southern part of Saklıkent (Antalya) region. They are represented by pillow, massive, and columnar-jointed lava flows with volcaniclastic breccias and pelagic limestone intercalations. Spilitic basalts exhibit intersertal, microlithic porphyritic, and ophitic textures and are represented by plagioclase, pyroxene, and olivine. Secondary phases are characterized by serpentine, calcite, chlorite, epidote, zeolite, and quartz. Based on Zr/Ti vs. Nb/Y ratios, the volcanic rocks are represented by alkaline basalts (Nb/Y = 1.54-2.82). A chondrite normalized REE diagram for the volcanic rocks displays significant LREE enrichment with respect to HREE ([La/Yb]N = 15.14-19.77). Trace element geochemistry of the studied rocks suggests that these rocks are more akin to ocean island basalt (OIB) and were formed by small degrees (~2-4%) of partial melting of an enriched mantle source (spinel + garnet-bearing lherzolite). The volcanic rocks of the Saklıkent region exhibit similarities to the Late Triassic volcanics of the Koçali Complex in SE Anatolia and the Mamonia Complex (Cyprus) in terms of their geochemical features. All evidence suggests that the Late Triassic alkaline volcanics in Antalya, Mamonia (Cyprus), and the Koçali (Adıyaman) Complexes were formed in an extensional environment at the continent-ocean transition zone during the rifting of the southern Neotethyan Ocean. [ABSTRACT FROM AUTHOR]

Detailed fieldwork was carried out in the SW Bükk Mts. at six locations in order to understand the Jurassic pre-orogenic deformation. All localities expose Middle Jurassic oolitic limestones with grains probably derived from the Adriatic Carbonate Platform and therefore from the Dinaridic passive margin of the Neotethys Ocean. Results of the structural analysis revealed early, soft-sedimentary deformation structures. The observed small-scale normal faults are characterized by rounded, curved shapes without any discrete fault planes (sealed faults) and the displaced beds often thicken towards the faults. These faults were interpreted as syn-sedimentary/syn-diagenetic faults, meaning that the deformation took place in unconsolidated or semi-consolidated sediments. During the early diagenetic silica mobilization, the already-present early faults may have served as conduits of silica-rich fluids, which led to the formation of planar silica injection dykes. Sedimentary slump folds were also identified based on the presence of underlying detachment slip surfaces and the observed thickness changes and onlap surfaces within the folded layers. The significance of these early normal faults and slump folds is that they are the first direct evidence for pre-orogenic deformation in the Bükk Mts. The overall structural data suggest NE--SW or NNE--SSW striking early faults and SE to S verging slump folds in the present-day coordinates. By reconstructing the Cenozoic rotations of the Bükk Mts. this means a roughly NW--SE striking original margin and a south-westward facing paleoslope for the Middle Jurassic. Considering the paleogeographic setting of the Adriatic Platform, this paleoslope direction is possible if the deposition area was located above a deeply submerged tilted normal fault block or alternatively, along the landward side of a larger intraoceanic high. The extensional structures may indicate that the Bükk Mts. were closer to the passive margin than the already ongoing intra-oceanic subduction and related trench, all governed by compression. [ABSTRACT FROM AUTHOR]

Gabbros, sheeted dikes and volcanic rocks of the Meydan ophiolite in the South-east Anatolian orogenic belt were examined to determine their U–Pb zircon ages, whole-rock, mineral chemistry and Nd‒Sr–Pb isotope compositions. The new U–Pb dating of zircon separates yielded a 88.3 ± 1.3 Ma crystallization age for gabbroic rocks of Meydan ophiolite. The ophiolite includes tectonites, ultramafic-mafic cumulates, isotropic gabbros, isolated mafic dikes, sheeted dikes, plagiogranites and rare basalts. The sheeted dikes and volcanics of the Meydan ophiolite exhibit near-flat rare earth element (REE) patterns, flat high field strength element trends and negative Nb anomalies that are similar to other SSZ–type eastern Mediterranean ophiolites. The whole-rock and mineral chemistry of the Meydan ophiolite/volcanic rocks suggests that they formed a supra-subduction zone and the dismembered ophiolite metamorphic sole formed beneath the ophiolite in a subduction trench setting. Isotopic ratios, i.e., 87Sr/86Sr versus 206Pb/204Pb and 143Nd/144Nd versus 87Sr/86Sr, show only limited variations, whereas 143Nd/144Nd versus 206Pb/204Pb, 87Sr/86Sr ratios are much more variable. The isotopic ratios are indicative of mixed magmatic contributions from DMM/MORB and EMII reservoirs that probably reflect the overall recycling of mantle wedge, pelagic sediment, oceanic crust and continentally derived sediment. The Meydan ophiolite, inferred arc volcanics and accretionary mélange are all intruded by Late Cretaceous (87.7 ± 0.47 to 80.1 ± 0.46 Ma; zircon U–Pb) granitic rocks which are evaluated as the product of continental margin arc magmatism. The available regional comparisons suggest that the rocks studied were derived from the Berit Ocean to the north of the Bitlis Pütürge continent, in which the Kömürhan, İspendere and Göksun ophiolites also formed during the Late Cretaceous. [ABSTRACT FROM AUTHOR]

While the Neogene history of the Eastern Mediterranean region is now fairly well understood, our knowledge of older regional palaeogeographies is less accurate, especially the positions of blocks and nappes constituting the Aegean Islands prior to the Cenozoic. Our study focuses on the ophiolite exposed on the island of Karpathos (Dodecanese), which is located in the Aegean fore-arc at a pivotal position between the 'western' and 'eastern' ophiolites of the Mediterranean region and where conflicting Late Jurassic and Late Cretaceous ages have led to diverging tectonic and palaeogeographic interpretations. To test these ages, we targeted the radiolarian cherts that depositionally overlie the ophiolite and extracted diagnostic radiolarian assemblages of Aptian (∼125−113 Ma), early–middle Albian (∼113−105 Ma) and Turonian (∼93.9−89.8 Ma) ages. These results suggest that previous Late Cretaceous K–Ar isotopic ages (from 95.3 ± 4.2 Ma to 81.2 ± 1.6 Ma) may have been reset by Late Cretaceous metamorphism or affected by argon loss. Overall, the new Early Cretaceous ages show that the Karpathos ophiolite should not be correlated with the Pindos Nappes of Greece or the ophiolites of Cyprus or Syria but rather with the Lycian Nappes of Turkey and their root located in the Izmir–Ankara–Erzincan Suture Zone. Therefore, the Karpathos ophiolite represents a remnant of the Northern Neotethys, not the Pindos Ocean or the proto-Eastern Mediterranean Basin. [ABSTRACT FROM AUTHOR]

We present new, geological, metamorphic, geochemical and geochronological data on the East Anatolian–Lesser Caucasus ophiolites. These data are used in combination with a synthesis of previous data and numerical modelling to unravel the tectonic emplacement of ophiolites in this region. All these data allow the reconstruction of a large obducted ophiolite nappe, thrusted for >100 km and up to 250 km on the Anatolian-Armenian block. The ophiolite petrology shows three distinct magmatic series, highlighted by new isotopic and trace element data: (1) The main Early Jurassic Tholeiites (ophiolite s.s.) bear LILE-enriched, subduction-modified, MORB chemical composition. Geology and petrology of the Tholeiite series substantiates a slow-spreading oceanic environment in a time spanning from the Late Triassic to the Middle‒Late Jurassic. Serpentinites, gabbros and plagiogranites were exhumed by normal faults, and covered by radiolarites, while minor volumes of pillow-lava flows infilled the rift grabens. Tendency towards a subduction-modified geochemical signature suggests emplacement in a marginal basin above a subduction zone. (2) Late Early Cretaceous alkaline lavas conformably emplaced on top of the ophiolite. They have an OIB affinity. These lavas are featured by large pillow lavas interbedded a carbonate matrix. They show evidence for a large-scale OIB plume activity, which occurred prior to ophiolite obduction. (3) Early‒Late Cretaceous calc-alkaline lavas and dykes. These magmatic rocks are found on top of the obducted nappe, above the post-obduction erosion level. This series shows similar Sr-Nd isotopic features as the Alkaline series, though having a clear supra-subduction affinity. They are thus interpreted to be the remelting product of a mantle previously contaminated by the OIB plume. Correlation of data from the Lesser Caucasus to western Anatolia shows a progression from back-arc to arc and fore-arc, which highlight a dissymmetry in the obducted oceanic lithosphere from East to West. The metamorphic P - T - t paths of the obduction sole lithologies define a southward propagation of the ophiolite: (1) P - T - t data from the northern Sevan-Akera suture zone (Armenia) highlight the presence and exhumation of eclogites (1.85 ± 0.02 GPa and 590 ± 5 °C) and blueschists below the ophiolite, which are dated at ca. 94 Ma by Ar-Ar on phengite. (2) Neighbouring Amasia (Armenia) garnet amphibolites indicate metamorphic peak conditions of 0.65 ± 0.05 GPa and 600 ± 20 °C with a U-Pb on rutile age of 90.2 ± 5.2 Ma and Ar-Ar on amphibole and phengite ages of 90.8 ± 3.0 Ma and 90.8 ± 1.2 Ma, respectively. These data are consistent with palaeontological dating of sediment deposits directly under (Cenomanian, i.e. ≥ 93.9 Ma) or sealing (Coniacian‒Santonian, i.e., ≤89.8 Ma), the obduction. (3) At Hınıs (NE Turkey) P-T-t conditions on amphibolites (0.66 ± 0.06 GPa and 660 ± 20 °C, with a U-Pb titanite age of 80.0 ± 3.2 Ma) agree with previous P-T-t data on granulites, and highlight a rapid exhumation below a top-to-the-North detachment sealed by the Early Maastrichtian unconformity (ca. 70.6 Ma). Amphibolites are cross-cut by monzonites dated by U-Pb on titanite at 78.3 ± 3.7 Ma. We propose that the HT-MP metamorphism was coeval with the monzonites, about 10 Ma after the obduction, and was triggered by the onset of subduction South of the Anatolides and by reactivation or acceleration of the subduction below the Pontides-Eurasian margin. Numerical modelling accounts for the obduction of an "old" ∼80 Myr oceanic lithosphere due to a significant heating of oceanic lithosphere through mantle upwelling, which increased the oceanic lithosphere buoyancy. The long-distance transport of a currently thin section of ophiolites (<1 km) onto the Anatolian continental margin is ascribed to a combination of northward mantle extensional thinning of the obducted oceanic lithosphere by the Hınıs detachment at ca. 80 Ma, and southward gravitational propagation of the ophiolite nappe onto its foreland basin. Image 1 • A large obducted ophiolite nappe was thrusted for > 100 km on Anatolia. • HP-LT sole metamorphics (blueschists/eclogites) evidence 94 Ma obduction initiation. • MT-HT sole metamorphics (garnet amphibolites) evidence 90 Ma propagation on the continent. • Hınıs core-complex shows 80 Ma extension and gravitational collapse of the obducted nappe. • Numerical modelling agrees for obduction following OIB magmatism and heating of Neotethys. [ABSTRACT FROM AUTHOR]

The Göksun (Kahramanmaraş) ophiolite (GKO), cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south, is located in the EW-trending lower nappe zone of the southeast Anatolian orogenic belt (Turkey). It exhibits a complete oceanic lithospheric section and overlies the Middle Eocene Maden Group/Complex with a tectonic contact at its base. The ophiolitic rocks and the tectonically overlying Malatya metamorphic (continental) unit were intruded by I-type calc-alkaline Late Cretaceous granitoid (∼81–84 Ma). The ultramafic to cumulates in the GKO are represented by wehrlite, plagioclase wehrlite, olivine gabbro and gabbro. The crystallization order for the cumulate rocks is as follows: olivine ± chromian spinel→clinopyroxene→plagioclase. The major and trace element geochemistry as well as the mineral chemistry of the ultramafic to mafic cumulate rocks suggest that the primary magma generating the GKO is compositionally similar to that observed in the modern island-arc tholeiitic sequences. The mineral chemistry of the ultramafic to mafic cumulates indicates that they were derived from a mantle source that was previously depleted by earlier partial melting events. The highly magnesian olivine (Fo 77–83), clinopyroxene (Mg# of 82–90) and the highly Ca-plagioclase (An 81–89) exhibit a close similarity to those, which formed in a supra-subduction zone (SSZ) setting. The field and the geochemical evidence suggest that the GKO formed as part of a much larger sheet of oceanic lithosphere, which accreted to the base of the Tauride active continental margin, including the İspendere, Kömürhan and the Guleman ophiolites. The latter were contemporaneous and genetically/tectonically related within the same SSZ setting during the closure of the Neotethyan oceanic basin (Berit Ocean) between the Taurides to the north and the Bitlis-Pütürge massif to the south during the Late Cretaceous. Image 1 • Petrology of cumulate rocks is constrained by whole rock and mineral chemistry. • The arc-related volcanics and the cumulates were genetically linked during intraoceanic subduction. • Within Southern Neotethys, two different oceanic basins existed. [ABSTRACT FROM AUTHOR]

Two sites in the Villány Hills, Hungary, have yielded rich fish assemblages from Middle to Late Triassic shallow marine deposits. The collected material comes from the Ladinian Templomhegy Dolomite Member and from the Carnian Mészhegy Sandstone Formation. The ichthyofauna is composed of both chondrichthyans (Hybodontidae indet., Palaeobates angustissimus , ' Polyacrodus ' sp., ? Lissodus sp.) and osteichthyans (Gyrolepis sp., Birgeria sp., and further indeterminate actinopterygians). Despite the large sample size, no remains of neoselachians have been found. The Ladinian Templomhegy Dolomite is dominated by durophagous hybodontiforms (Palaeobates angustissimus , ? Lissodus sp.), but the piscivorous hybodontid and the generalist ' Polyacrodus ' sp. are missing, while in the fish fauna collected from the Carnian Mészhegy Formation indeterminate piscivorous hybodontids are the most common elements and durophagous forms are much less abundant. The dominance of piscivorous hybodontids in the Carnian Mészhegy Sandstone could be related to the global decrease of diversity of marine fish-eating reptiles (e.g., nothosaurs) or to a change of paleoenvironmental conditions. The present study improves our knowledge on the poorly known Triassic vertebrate faunas of the Tisza Mega-unit, which formed a segment of the passive Neotethys margin of the European Plate and shows an important example of a potential vertebrate faunal shift during the Middle to Late Triassic. [ABSTRACT FROM AUTHOR]

Ancient evaporite deposits are geological archives of depositional environments characterized by a long‐term negative precipitation balance and bear evidence for global ocean element mass balance calculations. Here, Cretaceous selenite pseudomorphs from western Anatolia ('Rosetta Marble') — characterized by their exceptional morphological preservation — and their 'marine' geochemical signatures are described and interpreted in a process‐oriented context. These rocks recorded Late Cretaceous high‐pressure/low‐temperature, subduction‐related metamorphism with peak conditions of 1·0 to 1·2 GPa and 300 to 400°C. Metre‐scale, rock‐forming radiating rods, now present as fibrous calcite marble, clearly point to selenitic gypsum as the precursor mineral. Stratigraphic successions are recorded along a reconstructed proximal to distal transect. The cyclical alternation of selenite beds and radiolarian ribbon‐bedded cherts in the distal portions are interpreted as a two type of seawater system. During arid intervals, shallow marine brines cascaded downward into basinal settings and induced precipitation. During more humid times, upwelling‐induced radiolarian blooms caused the deposition of radiolarite facies. Interestingly, there is no comparable depositional setting known from the Cenozoic world. Meta‐selenite geochemical data (δ13C, δ18O and 87Sr/86Sr) plot within the range of reconstructed middle Cretaceous seawater signatures. Possible sources for the 13C‐enriched (mean 2·2‰) values include methanogenesis, gas hydrates and cold seep fluid exhalation. Spatially resolved component‐specific analysis of a rock slab displays isotopic variances between meta‐selenite crystals (mean δ13C 2·2‰) and host matrix (mean δ13C 1·3‰). The Cretaceous evaporite‐pseudomorphs of Anatolia represent a basin wide event coeval with the Aptian evaporites of the Proto‐Atlantic and the pseudomorphs share many attributes, including lateral distribution of 600 km and stratigraphic thickness of 1·5 to 2·0 km, with the evaporites formed during the younger Messinian salinity crisis. The Rosetta Marble of Anatolia may represent the best‐preserved selenite pseudomorphs worldwide and have a clear potential to act as a template for the study of meta‐selenite in deep time. [ABSTRACT FROM AUTHOR]

We have carried out a several-year-long study of the Amanos Mountains, on the basis of which we present new sedimentary and structural evidence, which we combine with existing data, to produce the first comprehensive synthesis in the regional geological setting. The ca. N-S-trending Amanos Mountains are located at the northwesternmost edge of the Arabian plate, near the intersection of the African and Eurasian plates. Mixed siliciclastic-carbonate sediments accumulated on the north-Gondwana margin during the Palaeozoic. Triassic rift-related sedimentation was followed by platform carbonate deposition during Jurassic-Cretaceous. Late Cretaceous was characterised by platform collapse and southward emplacement of melanges and a supra-subduction zone ophiolite. Latest Cretaceous transgressive shallow-water carbonates gave way to deeper-water deposits during Palaeocene-Eocene. Eocene southward compression, reflecting initial collision, resulted in open folding, reverse faulting and duplexing. Fluvial, lagoonal and shallow-marine carbonates accumulated during Late Oligocene(?)-Early Miocene, associated with basaltic magmatism. Intensifying collision during Mid-Miocene initiated a foreland basin that then infilled with deep-water siliciclastic gravity flows. Late Miocene-Early Pliocene compression created mountain-sized folds and thrusts, verging E in the north but SE in the south. The resulting surface uplift triggered deposition of huge alluvial outwash fans in the west. Smaller alluvial fans formed along both mountain flanks during the Pleistocene after major surface uplift ended. Pliocene-Pleistocene alluvium was tilted towards the mountain front in the west. Strike-slip/transtension along the East Anatolian Transform Fault and localised sub-horizontal Quaternary basaltic volcanism in the region reflect regional transtension during Late Pliocene-Pleistocene (

Quaternary alkali basalts and related rocks are located in the northern portion of the Sanandaj–Sirjan zone in Iran (SaSZ). These rocks, also known as the Salmas Quaternary volcanic rocks (SQVR), consist primarily of basalts and trachy basalts (mafic parts) and basaltic trachy andesites and trachy andesites (intermediate parts), which are highly sodic alkaline and high-K calc-alkaline in character, respectively. These mafic to intermediate samples contain variable proportions of pyroxene, olivine and plagioclase, alongside ubiquitous accessory levels of biotite, amphibolte and oxides. Based on the negative Nb, Ta, Zr, and Hf, and also positive Th and U anomalies in some samples, the SQVR formed in a widely-recognized syn -collision environment following the termination of oblique Neotethys subduction beneath the Central Iranian microplate. Following slab break-off of the remnants of the oceanic lithosphere under the Arabia-Eurasia collision zone, a combination of asthenospheric upwelling, small-scale mantle convection, and localized crustal extension promoted magmatism. We model that decompression melting occurred on the boundary of the lithosphere and asthenosphere at around 65–70 km. The magma of the SQVR resulted from relatively small degrees of partial melting (<5%) of a metasomatized amphibole-bearing garnet-spinel lherzolite. Fractional crystallization, combined with a small amount of assimilation and fractional crystallization occurred during transfer to the surface and resulted in the evolution of basaltic parent magmas towards intermediate compositions. Unlabelled Image • The Salmas volcanic rocks are composed of alkaline and high-K calc-alkaline basalt and andesite. • The rocks are related with a syn-collision tectonic environment. • Magma were generated by slab break-off of the remnants of Neotethys in a subduction zone. • Formation of the rocks may have involved in assimilation and fractional crystallization process. [ABSTRACT FROM AUTHOR]

The world's largest ongoing collisional orogeny is the Europe Alps–Himalayan–SE Asian belt and is a natural laboratory to understand many processes that have shaped the continents. Due to political instability and conflict throughout this millennium, the Iraq (Kurdish) sector of the Zagros mountain chain is the least studied part of this orogenic system. In Iraq, the Zagros contains the suture between the Arabian subcontinent to the south and west and the Iranian edge of the Eurasian continent to the north and east. The suture zone is marked by several allochthons of Neotethyan ophiolitic and volcanic arc assemblages that were obducted onto the Arabian margin. New geochronological data, including SHRIMP U-Pb zircon, integrated with whole rock geochemistry, indicates that both Cretaceous (˜96 Ma) and Cenozoic (˜40 Ma) assemblages are present. The relationships between these units are complicated, thus some Cretaceous arc rocks were intruded by Cenozoic arc rocks, and out-of-sequence thrusting has interleaved and juxtaposed assemblages of different ages. Ongoing wrench faulting since continental collision at ˜14 Ma has further complicated the pattern of lithotectonic units, particularly those that were obducted out of the Neotethyan realm. The new data indicate that the Iraqi sector of Neotethys was not 'quiet' in the Cretaceous, but contains fragments of arcs of that age, contiguous with those along strike in Turkey, Iran and the Himalayas. [ABSTRACT FROM AUTHOR]

• The Semail ophiolite formed along a NNE–SSW striking ridge above a parallel, incipient subduction zone. • The nascent Semail subduction zone formed orthogonal and close to the Arabian passive margin. • Subduction initiation likely occurred along an ancient, Permian Neotethyan fracture zone. The archetypal Semail ophiolite of Oman has inspired much thought on the dynamics of initiation of intra-oceanic subduction zones. Current models invoke subduction initiation at a mid-oceanic ridge located sufficiently close to the Arabian passive margin to allow initiation of continental subduction below the ophiolite within ∼10–15 Myr after the 96–95 Ma age of formation of supra-subduction zone crust. Here, we perform an extensive paleomagnetic analysis of sheeted dyke sections across the Semail ophiolite to restore the orientation of the supra-subduction zone ridge during spreading. Our results consistently indicate that the ridge was oriented NNE–SSW, and we infer that the associated trench, close to the modern obduction front, had the same orientation. Our data are consistent with a previously documented ∼150° clockwise rotation of the ophiolite, and we reconstruct that the original subduction zone was WNW-ward dipping and NNE–SSW striking. Initial subduction likely occurred in the ocean adjacent and parallel to a transform margin of the part of the Arabian continent now underthrust below Iran that originally underpinned the nappes of the Zagros fold-thrust belt. Subduction thus likely initiated along an ancient, continental margin-parallel fracture zone, as also recently inferred from near-coeval ophiolites from the eastern Mediterranean and NW Arabian regions. Subduction initiation was therefore likely induced by (WN)W–(ES)E contraction and this constraint may help the future identification of the dynamic triggers of Neotethyan subduction initiation in the Late Cretaceous. [ABSTRACT FROM AUTHOR]

Continent-continent collision drives crustal deformation, topographic rise and geodynamic change. Africa-Eurasia convergence accommodated in the Eastern Mediterranean involved subduction of the Neotethyan oceanic lithosphere in Anatolia. Subduction was followed by collision of continental crust of Greater Adria with Eurasia to form the Izmir-Ankara-Erzincan suture zone. Discerning the effects of this collision from pre-collisional ophiolite obduction-related orogeny of Greater Adria is notoriously difficult. Estimates on the timing of collision in Central Anatolia are based on a forearc-to-foreland basin transition along the Eurasian margin and suggest a ~60 Ma age of initial collision. Here, we assess whether this age is also representative for collision in Eastern Anatolia and across the Cenozoic Sivas Basin that straddles the Greater Adria-Europe suture. To this end we retro-deform regional block rotations in the Pontides, the Kırşehir Block and the Taurides, building a first-order regional 'block circuit' around the Sivas Basin. We show that up to ~700 km of convergence must have been accommodated across the Sivas Basin after Central Anatolian Kırşehir-Pontide collision at ~60 Ma – an order of magnitude more than estimated crustal shortening, and that wholesale lithospheric subduction must have occurred throughout much of the Cenozoic. Paleocene collision would require that this subduction consumed continental lithosphere, which is unlikely. We consequently infer that oceanic subduction continued much longer in Eastern Anatolia, perhaps well into the Miocene. We postulate that prolonged oceanic subduction and slab pull drew the Eastern Taurides north relative to the Central Taurides, leading to shortening and oroclinal bending in Central Anatolia. The diachronous demise of the Neotethys Ocean in Anatolia, as a function of its paleogeography, is thus a likely driver for the strong non-cylindricity of the Cenozoic Anatolian collisional orogen. • Continent-continent collision in Anatolia was diachronous. • After ~60 Ma, ~700 km of convergence was yet to be accommodated in Eastern Anatolia. • Convergence accommodated is an order of magnitude more than crustal shortening. • Prolonged subduction resulted from a kinked passive margin paleogeography. • Oceanic subduction in Eastern Anatolia continued longer than previously thought. [ABSTRACT FROM AUTHOR]