THE ROLE OF MESOZOIC GEODYNAMIC EVENTS IN FORMATION OF SEDIMENTARY BASINS ON THE FRAMING OF THE EASTERN MONGOL-OKHOTSK OROGENIC BELT

The Mongol-Okhotsk orogenic belt, finally formed in the end of the Mesozoic as a result of later tectonic events, is divided into two flanks: western and eastern. Its formation is obviously due to a regular change in geodynamic events significantly obscured by late tectonic and magmatic processes in the western flank and more clearly defined in the eastern flank from both magmatic and stratified formations. The early changes in geodynamic environment are most clearly determined by the formation of magmatic complexes whose completion is usually accompanied by the strata formation. Stratons framing the eastern flank of the Mongol-Okhotsk orogenic belt in the Mesozoic were formed in sedimentary basins, which are currently isolated to the Krestovkinsky and Ogodzhinsky basins along the southern border and to the Strelkinsky, Malotyndinsky, Toromsky and Udsky basins along the northern border. The deposition environment varied from deep-sea marine to continental. The article attempts to correlate the cross-sections of sedimentary basins on the framing of the eastern Mongol-Okhotsk orogenic belt and considers similarity or difference in their structure, conditions of sedimentation, tectonic positions and dependence of their evolution on geodynamic processes in the regio

Позднемезозойские адакитовые граниты южного обрамления восточного звена Монголо-Охотского орогенного пояса: вещественный состав, геодинамические условия формирования

Granitoids of the Magdagachi complex were studied using new and published petrochemical, geochemical and isotopic (Sm-Nd, Rb-Sr) data. Granitoid samples were taken from the southern frame of the eastern flank of the Mongol-Okhotsk orogenic belt (MOOB). Their analysis shows increased concentrations of Sr, Ba, Eu; reduced concentrations of Nb, Ta; abnormally low concentrations of HREE, Y and Yb; significant fractionation of REE; and high Sr/Y ratios. Therefore, the Magdagachi granitoids are "classical" adakites that may have formed at a depth of more than 45 km due to melting of eclogite with a garnet content of 20–50 %. Such conditions could exist under subduction as a result of melting of the frontal or lateral parts of the slab in subduction windows formed during oblique subduction at an orthogonal sinking angle. Highly metamorphosed lower crust Precambrian formations were also melted, and a source of parental melts could have been composed of both the mantle and crustal materials. Two tectonic scenarios are proposed that could have been accompanied by the formation of Magdagachi granitoids. Both scenarios refer to subduction processes, but differ in interactions between various regional structures in the Late Mesozoic. Согласно новым и уже опубликованным петрохимическим, геохимическим и изотопным (Sm-Nd, Rb-Sr) данным, для гранитоидов магдагачинского комплекса южного обрамления восточного звена Монголо-Охотского орогенного пояса установлено, что они характеризуются повышенными концентрациями Sr, Ba, Eu и пониженными содержаниями Nb, Ta, аномально низкими концентрациями HREE, Y и Yb; значительным фракционированием редкоземельных элементов; высокими соотношениями Sr/Y. Эти данные говорят о принадлежности пород комплекса к «классическим» адакитам. Предполагается, что они формировались на глубине более 45 км за счет плавления эклогита с содержанием граната 20–50 %. Такие условия могли существовать в обстановке субдукции в результате плавления фронтальной составляющей или боковых частей слэба в субдукционных окнах, образующихся при косой субдукции и ортогональном угле погружения. При этом плавлению подвергались также высокометаморфизованные нижнекоровые докембрийские образования, а в составе источника родоначальных расплавов принимало участие как мантийное, так и коровое вещество. Предложено два тектонических сценария, которые могли сопровождаться становлением гранитоидов магдагачинского комплекса. Оба сценария соответствуют условиям субдукционных процессов, но отличаются взаимодействием различных региональных структур в позднемезозойское время.

РОЛЬ МЕЗОЗОЙСКИХ ГЕОДИНАМИЧЕСКИХ СОБЫТИЙ В ФОРМИРОВАНИИ ОСАДОЧНЫХ БАССЕЙНОВ ОБРАМЛЕНИЯ ВОСТОЧНОГО ФЛАНГА МОНГОЛО-ОХОТСКОГО ОРОГЕННОГО ПОЯСА

The Mongol-Okhotsk orogenic belt, finally formed in the end of the Mesozoic as a result of later tectonic events, is divided into two flanks: western and eastern. Its formation is obviously due to a regular change in geodynamic events significantly obscured by late tectonic and magmatic processes in the western flank and more clearly defined in the eastern flank from both magmatic and stratified formations. The early changes in geodynamic environment are most clearly determined by the formation of magmatic complexes whose completion is usually accompanied by the strata formation. Stratons framing the eastern flank of the Mongol-Okhotsk orogenic belt in the Mesozoic were formed in sedimentary basins, which are currently isolated to the Krestovkinsky and Ogodzhinsky basins along the southern border and to the Strelkinsky, Malotyndinsky, Toromsky and Udsky basins along the northern border. The deposition environment varied from deep-sea marine to continental. The article attempts to correlate the cross-sections of sedimentary basins on the framing of the eastern Mongol-Okhotsk orogenic belt and considers similarity or difference in their structure, conditions of sedimentation, tectonic positions and dependence of their evolution on geodynamic processes in the regionМонголо-Охотский орогенный пояс, окончательно сформировавшийся в конце мезозоя, в результате более поздних тектонических событий был разделен на два фланга: западный и восточный. В его формировании прослеживается закономерное изменение геодинамических процессов, которые в пределах западного фланга значительно «затушеваны» поздними тектоническими и магматическими событиями, тогда как в пределах восточного фланга эти процессы менее искажены и фиксируются по наличию как магматических, так и стратифицированных образований. Начало изменения геодинамических условий наиболее четко определяется по формированию магматических комплексов, а их завершение, как правило, сопровождается образованием стратонов. Стратоны в обрамлении восточного фланга Монголо-Охотского орогенного пояса в мезозое формировались в осадочных бассейнах, фрагменты которых в настоящее время обособлены вдоль южной границы в Крестовкинский и Огоджинский бассейны, а вдоль северной – в Стрелкинский, Малотындинский, Торомский и Удский бассейны. Накопление осадков происходило в различных условиях: от глубоководных морских до континентальных. В статье выполнена корреляция разрезов осадочных бассейнов в обрамлении восточного фланга Монголо-Охотского орогенного пояса; рассматривается сходство или различие составов, возраста, условий осадконакопления, тектонических позиций и зависимость их эволюции от изменения геодинамических процессов в регионе

Late Mesozoic adakite granites of the southern frame of the eastern flank of the Mongol-Okhotsk orogenic belt: material composition and geodynamic conditions of formation

Granitoids of the Magdagachi complex were studied using new and published petrochemical, geochemical and isotopic (Sm-Nd, Rb-Sr) data. Granitoid samples were taken from the southern frame of the eastern flank of the Mongol-Okhotsk orogenic belt (MOOB). Their analysis shows increased concentrations of Sr, Ba, Eu; reduced concentrations of Nb, Ta; abnormally low concentrations of HREE, Y and Yb; significant fractionation of REE; and high Sr/Y ratios. Therefore, the Magdagachi granitoids are "classical" adakites that may have formed at a depth of more than 45 km due to melting of eclogite with a garnet content of 20–50 %. Such conditions could exist under subduction as a result of melting of the frontal or lateral parts of the slab in subduction windows formed during oblique subduction at an orthogonal sinking angle. Highly metamorphosed lower crust Precambrian formations were also melted, and a source of parental melts could have been composed of both the mantle and crustal materials. Two tectonic scenarios are proposed that could have been accompanied by the formation of Magdagachi granitoids. Both scenarios refer to subduction processes, but differ in interactions between various regional structures in the Late Mesozoic

Secure and Efficient Matrix Multiplication with MapReduce

International audienceMapReduce is one of the most popular distributed programming paradigms that allows processing big data sets in parallel on a cluster. MapReduce users often outsource data and computations to a public cloud, which yields inherent security concerns. In this paper, we consider the problem of matrix multiplication and one of the most efficient matrix multiplication algorithms: the Strassen-Winograd (SW) algorithm. Our first contribution is a distributed MapReduce algorithm based on SW. Then, we tackle the security concerns that occur when outsourcing matrix multiplication computation to a honest-but-curious cloud i.e., that executes tasks dutifully, but tries to learn as much information as possible. Our main contribution is a secure distributed MapReduce algorithm called S2M3 (Secure Strassen-Winograd Matrix Multiplication with MapReduce) that enjoys security guarantees such as: none of the cloud nodes can learn the input or the output data. We formally prove the security properties of S2M3 and we present an empirical evaluation devoted to show its efficiency