Conodonts of Middle Moscovian Age from the Kongul Formation (Bolkardag Unit), Northwest of Hadim, Central Taurus, Turkey

A rich shallow water conodont fauna with Idiognathodus incurvus DUNN, I. cf. suberectus (DUNN), Idioprioniodus sp., and Neognathodus columbiensis STIBANE was found in the lower part of the Kongul Formation of the Bolkardag Unit, about 12 km NW of Hadim town, central Taurus, Turkey. The conodonts indicate a middle to late Atokan age (on the American scale) for this part of the formation. On the Russian scale, the fauna corresponds to the middle Moscovian. According to previous correlations between the Russian and North American scales, a (middle) late Atokan (middle Moscovian age) is assumed for this fauna. Variscan deep-water sequences are not present in the study area

Problems for Evaluation of the Scenario of the Permian-Triassic Boundary Biotic Crisis and of Its Causes

Determination of the causes of the Permian-Triassic boundary (PTB) biotic crisis is hindered primarily by the diachronous nature of the used PTB, poor stratigraphic control of compared Upper Permian and Lower Triassic faunas, especially in continental biotopes, poor knowledge of the lower and middle Scythian faunas from many environments, and by interpolation of the unknown (lower and middle) Scythian diversity from the known Upper Permian and Middle Triassic diversity data in many major fossil groups. Most of these problems can be resolved by using the first appearance datum (FAD) of Hindeodus parvus as either an isochronous PTB, or as an isochronous marker level very close to the base of the Triassic; careful studies of fossil-rich, complete continental boundary sections (e.g., Dalongkou in Sinkiang), and utilisation of uninterpolated diversity data, which are based on known Scythian data, for the reconstruction of the extinction and recovery patterns in all fossil groups. The most important features of the PTB biotic crisis are: (1) Among the marine biota, only the plankton and the warm-water benthos, nektobenthos and nekton are strongly affected by the PTB biotic crisis. (2) The recovery of the warm-water nekton and nektobenthos was very fast (after one conodont zone). The recovery of the warm-water benthos, some of the plankton (radiolarians) and the terrestrial plant productivity was strongly delayed for several million years, and occurred only in the upper Olenekian (upper Scythian) and in the Middle Triassic. (3) The number of the Lazarus taxa that re-appeared in the upper Olenekian and above all in the Middle Triassic, is very high (about 50%) and in some fossil groups 90-100% at generic level. The reconstruction of the scenario for the PTB biotic crisis requires not only the consideration of the uninterpolated extinction and recovery patterns of all fossil groups across all environments, but must also account for the main features of geological evolution from the Middle Permian to the Lower Triassic. The most important causal factors in the PTB biotic crisis are the extinction event at the Guadalupian-Lopingian boundary that restricted the diverse Upper Permian warm-water benthos to the Tethyan shelves, the long-lasting, widespread Siberian Trap volcanism (Dzhulfian-lower Scythian) which was the greatest volcanic event during the Phanerozoic, and the very strong explosive felsic to intermediate volcanism around the PTB, close to the margin between eastern Tethys and Panthalassa. These volcanic activities resulted in those climatic changes that were directly and indirectly (as cause of the oceanic superanoxia) responsible for the PTB biotic crisis, such as periodic cooling of the climate by volcanic dust and sulphate aerosols (mainly caused by the Siberian Trap volcanism), acid rain, a 3-6 month “volcanic winter” at low latitudes and the strongly reduced input of sunlight during the uppermost Dorashamian (both caused by the very strong explosive volcanism at the Tethys/Panthalassa margin), followed by global warming in the lower Scythian, and uppermost Dorashamian to lower Scythian superanoxia

New Stratigraphic and Palaeogeographic Results from the Palaeozoic and Early Mesozoic of the Middle Pontides (Northern Turkey) in the Azdavay, Devrekani, Küre and Inebolu Areas: Implications for the Carboniferous-Early Cretaceous Geodynamic Evolution and Some Related Remarks to the Karakaya Oceanic Rift Basin

The Küre Complex of the Middle Pontides, northern Turkey, is not a remnant of the Palaeotethys but consists of three different units with differing geological history, the Küre Ridge Unit, the Küre Ocean Unit and the Çalça Unit. The Küre Ridge Unit consists of the Serveçay Group, a pre-Permian, low-grade metamorphic Variscan oceanic sequence, and the Sirçalik Group, a Lower and Middle Triassic shallow-water sequence of North Alpine facies and event succession which disconformably overlies the Serveçay Group. Following a hiatus, the Sirçalik Group is overlain by marginal parts of the Akgöl Group with olistoliths of local origin which were derived mainly from the Sirçalik Group. The Küre Ocean Unit consists mostly of the Akgöl Group (siliciclastic turbidites and olistostromes of the Karadagtepe Formation, which is a middle Carnian to Middle Jurassic accretionary complex from the southern, active margin of the Küre Ocean, and mainly Middle Jurassic molasse type shallow-water sandstones, siltstones and shales of an unnamed formation) and of thick oceanic basalts (Ipsinler Basalt). Tectonic slices of Middle Triassic to lower Carnian ophiolites and basalts are also present. The Karadagtepe Formation contains numerous Middle Triassic exotic olistoliths and blocks of shallow-water and predominantly slope and basinal limestones, ocean-floor deep-sea sediments (shales and radiolarites), basalts and small clasts of ophiolites or ophiolitic detritus. The Çalça Unit consists of deposits from the northern, passive margin of the Küre ocean with many Pelsonian to upper Norian Hallstatt Limestones and Rhaetian-Lower Jurassic (?Middle Jurassic) deep-water shales and marls. All three units are overlain following a period of non deposition by the Upper Jurassic Bürnük Formation (red conglomerate, sandstone) and Inalti Formation (shallow-water platform carbonates). The Küre Ridge Unit was split away from the Variscan Sakarya Continent by the opening of the Karakaya oceanic rift basin during latest Permian (Dorashamian) and became a continental splinter between the Karakaya oceanic rift basin and the Küre Ocean (opened during the late Scythian). Southward subduction began in the Küre Ocean during the middle Carnian (beginning of the Karadagtepe siliciclastic turbidites), whereas at the northern passive margin the deposition of Hallstatt Limestones continued until the latest Norian. The deposition of siliciclastic turbidites and olistostromes (Diskaya Unit) began in the entire Karakaya oceanic rift basin during the middle Carnian, and ocean basin deposits (radiolarites, pelagic limestones) and slope deposits form the passive margin (e.g., Hallstatt Limestones) are no more present in the Karakaya oceanic rift basin indicating that this basin was very narrow (only a few hundreds of kilometres). During the late Norian, the Karakaya oceanic rift basin closed, whereas subduction at the southern (active margin) of the Küre ocean continued. At the northern margin of the (Upper Triassic?) Jurassic-Lower Cretaceous Beykoz-Çaglayan turbidite basin (north of the Küre Complex) the accretionary complex of an older ocean, the Late Palaeozoic Paphlagonian Ocean, was exposed that yielded clasts in the Beykoz-Çaglayan turbidite basin. Among these clasts Carboniferous to Middle Permian (Capitanian) pelagic rocks (pelagic limestones, radiolarites) could be dated. A Middle to Late Permian southward-directed subduction is assumed for the Paphlagonian Ocean. Its closure occurred either at the end of the Permian or during the Scythian

New Stratigraphic and Palaeogeographic Results from the Palaeozoic and Early Mesozoic of the Middle Pontides (Northern Turkey) in the Azdavay, Devrekani, Küre and Inebolu Areas: Implications for the Carboniferous-Early Cretaceous Geodynamic Evolution and Some Related Remarks to the Karakaya Oceanic Rift Basin

The Küre Complex of the Middle Pontides, northern Turkey, is not a remnant of the Palaeotethys but consists of three different units with differing geological history, the Küre Ridge Unit, the Küre Ocean Unit and the Çalça Unit. The Küre Ridge Unit consists of the Serveçay Group, a pre-Permian, low-grade metamorphic Variscan oceanic sequence, and the Sirçalik Group, a Lower and Middle Triassic shallow-water sequence of North Alpine facies and event succession which disconformably overlies the Serveçay Group. Following a hiatus, the Sirçalik Group is overlain by marginal parts of the Akgöl Group with olistoliths of local origin which were derived mainly from the Sirçalik Group. The Küre Ocean Unit consists mostly of the Akgöl Group (siliciclastic turbidites and olistostromes of the Karadagtepe Formation, which is a middle Carnian to Middle Jurassic accretionary complex from the southern, active margin of the Küre Ocean, and mainly Middle Jurassic molasse type shallow-water sandstones, siltstones and shales of an unnamed formation) and of thick oceanic basalts (Ipsinler Basalt). Tectonic slices of Middle Triassic to lower Carnian ophiolites and basalts are also present. The Karadagtepe Formation contains numerous Middle Triassic exotic olistoliths and blocks of shallow-water and predominantly slope and basinal limestones, ocean-floor deep-sea sediments (shales and radiolarites), basalts and small clasts of ophiolites or ophiolitic detritus. The Çalça Unit consists of deposits from the northern, passive margin of the Küre ocean with many Pelsonian to upper Norian Hallstatt Limestones and Rhaetian-Lower Jurassic (?Middle Jurassic) deep-water shales and marls. All three units are overlain following a period of non deposition by the Upper Jurassic Bürnük Formation (red conglomerate, sandstone) and Inalti Formation (shallow-water platform carbonates). The Küre Ridge Unit was split away from the Variscan Sakarya Continent by the opening of the Karakaya oceanic rift basin during latest Permian (Dorashamian) and became a continental splinter between the Karakaya oceanic rift basin and the Küre Ocean (opened during the late Scythian). Southward subduction began in the Küre Ocean during the middle Carnian (beginning of the Karadagtepe siliciclastic turbidites), whereas at the northern passive margin the deposition of Hallstatt Limestones continued until the latest Norian. The deposition of siliciclastic turbidites and olistostromes (Diskaya Unit) began in the entire Karakaya oceanic rift basin during the middle Carnian, and ocean basin deposits (radiolarites, pelagic limestones) and slope deposits form the passive margin (e.g., Hallstatt Limestones) are no more present in the Karakaya oceanic rift basin indicating that this basin was very narrow (only a few hundreds of kilometres). During the late Norian, the Karakaya oceanic rift basin closed, whereas subduction at the southern (active margin) of the Küre ocean continued. At the northern margin of the (Upper Triassic?) Jurassic-Lower Cretaceous Beykoz-Çaglayan turbidite basin (north of the Küre Complex) the accretionary complex of an older ocean, the Late Palaeozoic Paphlagonian Ocean, was exposed that yielded clasts in the Beykoz-Çaglayan turbidite basin. Among these clasts Carboniferous to Middle Permian (Capitanian) pelagic rocks (pelagic limestones, radiolarites) could be dated. A Middle to Late Permian southward-directed subduction is assumed for the Paphlagonian Ocean. Its closure occurred either at the end of the Permian or during the Scythian

Sweetospathodus n.gen. and Triassospathodus n.gen., Two Important Lower Triassic Conodont Genera

Two new Lower Triassic conodont genera, Sweetospathodus n.gen. and Triassospathodus KOZUR n.gen., are described. Sweetospathodus is a transitional form between the platform-bearing gondolellid Clarkina and the platformless Neospathodus. Triassospathodus was formerly included into Neospathodus, but is clearly distinguished by the outline of the lower side (lower side of the basal cavity not upward curved as in all Neospathodus species)

Sweetospathodus n.gen. and Triassospathodus n.gen., Two Important Lower Triassic Conodont Genera

Two new Lower Triassic conodont genera, Sweetospathodus n.gen. and Triassospathodus KOZUR n.gen., are described. Sweetospathodus is a transitional form between the platform-bearing gondolellid Clarkina and the platformless Neospathodus. Triassospathodus was formerly included into Neospathodus, but is clearly distinguished by the outline of the lower side (lower side of the basal cavity not upward curved as in all Neospathodus species)