Vortex states in 2D superconductor at high magnetic field in a periodic pinning potential

The effect of a periodic pinning array on the vortex state in a 2D superconductor at low temperatures is studied within the framework of the Ginzburg-Landau approach. It is shown that attractive interaction of vortex cores to a commensurate pin lattice stabilizes vortex solid phases with long range positional order against violent shear fluctuations. Exploiting a simple analytical method, based on the Landau orbitals description, we derive a rather detailed picture of the low temperatures vortex state phase diagram. It is predicted that for sufficiently clean samples application of an artificial periodic pinning array would enable one to directly detect the intrinsic shear stiffness anisotropy characterizing the ideal vortex lattice.Comment: 8 pages, 5 figure

Этапы каменноугольно-триасового магматизма в Причерноморье по результатам изотопно-геохронологического изучения зерен детритового циркона из юрских грубообломочных толщ Горного Крыма

The article presents the results of U-Pb isotope dating of detrital zircons from the Jurassic coarse rocks in the apex and the western slope of Mnt. Biyuk-Sinor (the southern wall of the Baidar basin, near the village of Orlinoe). These dates are compared with the detrital zircon dates obtained for sandy rocks from the Upper Jurassic coarse clastic strata composing the slopes of Mnt. Spilia near Balaklava Harbor and Mnt. Southern Demerdzhi near Alushta city, as well as the Middle Jurassic Bitak conglomerates near the village of Strogonovka (suburb of Simferopol city). The comparison shows a high degree of similarity of the averaged age characteristics of the main detrital zircon populations. Sandy rocks of Jurassic coarse clastic strata for zircon dating were sampled in four locations of the Mountaineous Crimea. Based on their dates and a summary set of ages of detrital zircon grains from sandstones of the Southern Coast of Crimea, spanning the stratigraphic interval from the Middle Jurassic to Neogene, we can provide a statistically reliable specification of the Carboniferous-Triassic time interval (360–200 Ma) of magmatic activity within the Black Sea region. This period was bounded in time by the Late Devonian and Early Jurassic relative magmatic lulls. None of the zircon grains of the Carboniferous-Triassic age has revealed Hf-isotopic characteristics indicating any significant contribution of crustal material older than the Mesoproterozoic into the protolith of the parent zircon rocks. Within the Carboniferous-Triassic interval of magmatic activity, three stages are distinguished: (I) 360–315 Ma, (II) 315–270 Ma, and (III) 270–200 Ma. Magmatic stage I (360–315 Ma) is related to the closure of the Reik ocean, which completed after the subducted slab ‘broke off’ into the mantle and was accompanied by the ubiquitously manifested HT-LP metamorphism. Zircon grains of stage I are characterized by peak ages of about 325–340 Ma and the dominance of negative εHf. Magmatic stages II (315–270 Ma) and III (270–200 Ma) correlate with functioning of the Scythian-Pontian volcanic suprasubduction belt. In these magmatic stages, zircon εHf values scatter from weakly negative to substantially positive (referred to the depleted mantle), which is typical for volcanic arcs. Fuzzy separation of stages II and III and strong variability of the peak ages of zircons from the studied samples (which we associate with these stages) can be due both to changes in magmatic activity in different segments of the belt, and to changes in the erosion intensity of crystalline complexes of the belt during the subsequent stages evolution caused by tectonic rearrangements within the Paleo-Tethys ocean and its peri-oceanic structures. В статье представлены результаты U-Pb изотопного датирования зерен детритового циркона из толщи юрских грубообломочных пород, залегающих в вершинной части и на западном склоне г. Биюк-Синор (южный борт Байдарской котловины, около села Орлиное). Сопоставление этих датировок с полученными ранее результатами изучения зерен детритового циркона из песчанистых пород, участвующих в строении разрезов верхнеюрских грубообломочных толщ, слагающих склоны г. Спилия около Балаклавской бухты и г. Южная Демерджи около г. Алушты, а также среднеюрских битакских конгломератов около с. Строгановка (пригород г. Симферополя), показало высокую степень сходства осредненных возрастных характеристик основных популяций зерен детритового циркона. Результаты изучения зерен детритового циркона из песчанистых пород юрских грубообломочных толщ в четырех локациях Горного Крыма вместе с аналогичными данными для суммарного набора возрастов зерен детритового циркона из проб песчаников Южного берега Крыма, попадающих в стратиграфический интервал от средней юры до неогена, позволили статистически надежно охарактеризовать каменноугольно-триасовый (360–200 млн лет) интервал магматической активности, проявленной в пределах Причерноморья и ограниченной во времени позднедевонским и раннеюрским относительными магматическими затишьями. Ни в одном из зерен циркона каменноугольно-триасового возраста не выявлены Hf-изотопные характеристики, указывающие на сколько-нибудь значительный вклад корового материала старше мезопротерозоя в протолит материнских пород циркона. В выделяемом каменноугольно-триасовом интервале магматической активности можно обособить три этапа: (I) 360–315 млн лет, (II) 315–270 млн лет и (III) 270–200 млн лет. Этап магматизма I (360–315 млн лет) соотносится с закрытием океана Реик, завершившимся «отрывом и обрушением» субдуцируемого слэба в мантию и сопровождавшимся повсеместно проявленным HT-LP метаморфизмом. Для зерен циркона этого этапа магматизма характерны пиковые значения возраста около 325–340 млн лет и доминирование отрицательных εHf. Этапы магматизма II (315–270 млн лет) и III (270–200 млн лет) соотносятся с функционированием вулканического надсубдукционного пояса Скифско-Понтидской дуги. Для зерен циркона этих этапов магматизма характерен разброс величин εHf от слабоотрицательных до существенно положительных (характерных для деплетированной мантии), что типично для вулканических дуг. Нечеткое разделение II и III этапов магматизма и сильная вариабельность в изученных пробах пиковых значений возраста зерен циркона, которые мы связываем с этими этапами, могут быть обусловлены как изменениями магматической активности в различных сегментах пояса, так и изменениями интенсивности эрозии кристаллических комплексов пояса на последующих этапах эволюции, вызванных тектоническими перестройками внутри океана Палеотетис и его периокеанических структур.

Stages of Carboniferous-Triassic magmatism in the Black Sea region based on isotope-geochronological study of detrital zircons from jurassic coarse clastic strata of the Mountainous Crimea

The article presents the results of U-Pb isotope dating of detrital zircons from the Jurassic coarse rocks in the apex and the western slope of Mnt. Biyuk-Sinor (the southern wall of the Baidar basin, near the village of Orlinoe). These dates are compared with the detrital zircon dates obtained for sandy rocks from the Upper Jurassic coarse clastic strata composing the slopes of Mnt. Spilia near Balaklava Harbor and Mnt. Southern Demerdzhi near Alushta city, as well as the Middle Jurassic Bitak conglomerates near the village of Strogonovka (suburb of Simferopol city). The comparison shows a high degree of similarity of the averaged age characteristics of the main detrital zircon populations. Sandy rocks of Jurassic coarse clastic strata for zircon dating were sampled in four locations of the Mountaineous Crimea. Based on their dates and a summary set of ages of detrital zircon grains from sandstones of the Southern Coast of Crimea, spanning the stratigraphic interval from the Middle Jurassic to Neogene, we can provide a statistically reliable specification of the Carboniferous-Triassic time interval (360–200 Ma) of magmatic activity within the Black Sea region. This period was bounded in time by the Late Devonian and Early Jurassic relative magmatic lulls. None of the zircon grains of the Carboniferous-Triassic age has revealed Hf-isotopic characteristics indicating any significant contribution of crustal material older than the Mesoproterozoic into the protolith of the parent zircon rocks. Within the Carboniferous-Triassic interval of magmatic activity, three stages are distinguished: (I) 360–315 Ma, (II) 315–270 Ma, and (III) 270–200 Ma. Magmatic stage I (360–315 Ma) is related to the closure of the Reik ocean, which completed after the subducted slab ‘broke off’ into the mantle and was accompanied by the ubiquitously manifested HT-LP metamorphism. Zircon grains of stage I are characterized by peak ages of about 325–340 Ma and the dominance of negative εHf. Magmatic stages II (315–270 Ma) and III (270–200 Ma) correlate with functioning of the Scythian-Pontian volcanic suprasubduction belt. In these magmatic stages, zircon εHf values scatter from weakly negative to substantially positive (referred to the depleted mantle), which is typical for volcanic arcs. Fuzzy separation of stages II and III and strong variability of the peak ages of zircons from the studied samples (which we associate with these stages) can be due both to changes in magmatic activity in different segments of the belt, and to changes in the erosion intensity of crystalline complexes of the belt during the subsequent stages evolution caused by tectonic rearrangements within the Paleo-Tethys ocean and its peri-oceanic structures