Late Cretaceous to Paleocene oroclinal bending in the central Pontides (Turkey)

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Tethyan evolution of the Black Sea region since the Paleozoic: a paleomagnetic approach. Geologica Ultraiectina (319)

In the early Jurassic, Africa plus Arabia and Eurasia were separated by a ~2000 km wide domain containing oceanic lithosphere – including continental fragments that rifted off Africa - known as the Tethys ocean(s). In the northern part, the Paleo-Tethys ocean was subducting, while in the south, the Neo-Tethys ocean was spreading between the continental fragments and the African plate. The subsequent break-up of the supercontinent Pangea led to convergence between Africa and Eurasia, resulting in the disappearance of the Tethyan oceanic domains, and collision of the Tethyan continental fragments with Eurasia. Paleolatitude analysis and the timing of the collision of these continental terranes help to constrain this history. Here, the results of a paleomagnetic study of the circum-Black Sea region since the Paleozoic are presented, focusing on the geological history of Ukraine and Turkey. New paleomagnetic results from Carboniferous and lower Permian sediments exposed in the Donbas Foldbelt of Ukraine - corrected for inclination error and hence paleolatitude error - improved the Eurasian apparent polar wander (APW) path. This APW path was earlier not well constrained for the Carboniferous, and the new results were discussed in the light of the Pangea A versus B controversy. The upper Jurassic results from the European plate (Pontides, Turkey and Crimea, Ukraine) show much lower paleolatitudes than predicted by the APW paths. Similar results from an earlier study on Adria, as part of the African plate, have been interpreted as fast southward motion to low latitudes in the late Jurassic, followed by a northward motion. However, in the late Jurassic, the African and Eurasian plates were separated by subduction zones. For the Black Sea region we could prove northward subduction in the middle Jurassic to earliest Cretaceous by conducting isotopic 40Ar/39Ar dating and geochemical analysis on Crimean volcanics. Because subducting slabs function as an anchor in the mantle, we find it unlikely that the low paleolatitudes were the result of rapid motion of entire plates. We therefore argue that this cusp in the APW paths represents motion of the entire mantle and crust with respect to the Earth’s spin axis, a process known as True Polar Wander. We also studied Cretaceous to Eocene rocks from the central and eastern Pontides in north-central Turkey and were able to prove that this peculiar northward arc-shaped orogen is the result of latest Cretaceous to early Paleocene oroclinal bending. We suggest that this orocline resulted from the collision and indentation of the Anatolide-Tauride Block and its promontory, the metamorphic Central Anatolian Crystalline Complex. Our paleomagnetic data from Carboniferous to Eocene rocks from the central Taurides in south-central Turkey were aimed at reconstructing the paleolatitude history. It appeared, however, that a remagnetization event affected all sampled sections. We provide evidence for remagnetization by a novel end-member modeling approach of rock magnetic properties (IRM acquisition curves). Our new data and previously published results bracket the remagnetization event between ~85 and 20 Ma (late Cretaceous to early Miocene). We discuss the implications of our findings for the dimensions, timing and amount of vertical axis rotations in this region

Tethyan evolution of the Black Sea region since the Paleozoic: a paleomagnetic approach. Geologica Ultraiectina (319)

In the early Jurassic, Africa plus Arabia and Eurasia were separated by a ~2000 km wide domain containing oceanic lithosphere – including continental fragments that rifted off Africa - known as the Tethys ocean(s). In the northern part, the Paleo-Tethys ocean was subducting, while in the south, the Neo-Tethys ocean was spreading between the continental fragments and the African plate. The subsequent break-up of the supercontinent Pangea led to convergence between Africa and Eurasia, resulting in the disappearance of the Tethyan oceanic domains, and collision of the Tethyan continental fragments with Eurasia. Paleolatitude analysis and the timing of the collision of these continental terranes help to constrain this history. Here, the results of a paleomagnetic study of the circum-Black Sea region since the Paleozoic are presented, focusing on the geological history of Ukraine and Turkey. New paleomagnetic results from Carboniferous and lower Permian sediments exposed in the Donbas Foldbelt of Ukraine - corrected for inclination error and hence paleolatitude error - improved the Eurasian apparent polar wander (APW) path. This APW path was earlier not well constrained for the Carboniferous, and the new results were discussed in the light of the Pangea A versus B controversy. The upper Jurassic results from the European plate (Pontides, Turkey and Crimea, Ukraine) show much lower paleolatitudes than predicted by the APW paths. Similar results from an earlier study on Adria, as part of the African plate, have been interpreted as fast southward motion to low latitudes in the late Jurassic, followed by a northward motion. However, in the late Jurassic, the African and Eurasian plates were separated by subduction zones. For the Black Sea region we could prove northward subduction in the middle Jurassic to earliest Cretaceous by conducting isotopic 40Ar/39Ar dating and geochemical analysis on Crimean volcanics. Because subducting slabs function as an anchor in the mantle, we find it unlikely that the low paleolatitudes were the result of rapid motion of entire plates. We therefore argue that this cusp in the APW paths represents motion of the entire mantle and crust with respect to the Earth’s spin axis, a process known as True Polar Wander. We also studied Cretaceous to Eocene rocks from the central and eastern Pontides in north-central Turkey and were able to prove that this peculiar northward arc-shaped orogen is the result of latest Cretaceous to early Paleocene oroclinal bending. We suggest that this orocline resulted from the collision and indentation of the Anatolide-Tauride Block and its promontory, the metamorphic Central Anatolian Crystalline Complex. Our paleomagnetic data from Carboniferous to Eocene rocks from the central Taurides in south-central Turkey were aimed at reconstructing the paleolatitude history. It appeared, however, that a remagnetization event affected all sampled sections. We provide evidence for remagnetization by a novel end-member modeling approach of rock magnetic properties (IRM acquisition curves). Our new data and previously published results bracket the remagnetization event between ~85 and 20 Ma (late Cretaceous to early Miocene). We discuss the implications of our findings for the dimensions, timing and amount of vertical axis rotations in this region

[Polygenic risk prediction of common diseases: from epidemiology to clinical application]

Since the first map of the human genome was published in 2001 our knowledge about our genetic code has increased exponentially. In addition to high-risk genes for monogenic diseases, such as Huntington's disease and cystic fibrosis, for a number of common diseases, such as breast cancer and cardiovascular disease, many genetic variants that each have a slight increased-risk effect, have been identified via genome-wide association studies (GWAS). A polygenic risk score (PRS) can be calculated on the basis of these single-nucleotide polymorphisms (SNPs), by which an increasingly accurate prediction can be made of an individual's risk for diseases. The results of epidemiological studies in which a PRS is used to predict an individual's total genetic risk for particular diseases are promising. In the future, the PRS could be a valuable addition to traditional monogenic tests. It is, however, important that the predictive value of a genetic risk profile increases further and that it becomes more clear how a clinician must interpret this type of genetic profile - in combination with traditional risk factors

[Polygenic risk prediction of common diseases: from epidemiology to clinical application]

Item does not contain fulltextSince the first map of the human genome was published in 2001 our knowledge about our genetic code has increased exponentially. In addition to high-risk genes for monogenic diseases, such as Huntington's disease and cystic fibrosis, for a number of common diseases, such as breast cancer and cardiovascular disease, many genetic variants that each have a slight increased-risk effect, have been identified via genome-wide association studies (GWAS). A polygenic risk score (PRS) can be calculated on the basis of these single-nucleotide polymorphisms (SNPs), by which an increasingly accurate prediction can be made of an individual's risk for diseases. The results of epidemiological studies in which a PRS is used to predict an individual's total genetic risk for particular diseases are promising. In the future, the PRS could be a valuable addition to traditional monogenic tests. It is, however, important that the predictive value of a genetic risk profile increases further and that it becomes more clear how a clinician must interpret this type of genetic profile - in combination with traditional risk factors

New palaeomagnetic results from the Oslo Graben, a Permian Superchron lava province

International audienceWe have performed an extended palaeomagnetic study of the Oslo Graben volcanics, compared to the study of half a century ago by van Everdingen, using modern techniques and a four times larger amount of sites, plus additional rock magnetic experiments. We conclude that the average direction (D = 204.0, I = −37.9, k = 46.9, α95 = 2.0) and associated palaeomagnetic pole (λ = 48.3, ϕ = 155.5, K = 52.2, A95 = 1.9) of the Krokskogen and Vestfold volcanics together are statistically identical to those of the earlier study. This gives confidence in the fact that older palaeomagnetic studies can be reliable and robust, even though methods have improved. Our larger number of samples, and better age constraints, enable us to separate the data into two major intervals: the younger, on average, Krokskogen area and the older Vestfold area. The results show firstly that palaeolatitudes are slightly higher than predicted by the latest apparent polar wander path (APWP) for Eurasia by Torsvik et al. These data support an early Permian Pangaea A configuration and do not necessitate a Pangaea B configuration.The larger data set also allows us to assess the distribution of the characteristic remanent magnetization directions of the Oslo Graben in terms of geomagnetic field behaviour, which were acquired during a long period of dominantly single polarity the Permo-Carboniferous Reversed Superchron (PCRS). The distributions show a significantly lower virtual geomagnetic pole (VGP) scatter at the observed (low) latitudes than expected from a compilation from lavas of the last 5 Myr. The data do however show excellent agreement with the scatter observed both during the Cretaceous Normal Superchron and the PCRS. A comparison of the directional distributions in terms of elongation is less discriminating, since the large errors in all cases allow a fit to the predicted elongation/inclination behaviour of the TK03.GAD model