VOLUMETRIC AND SPATIAL SEGMENTATION OF THE TIEN SHAN LITHOSPHERE ACCORDING TO GEOPHYSICAL DATA

This article consolidates the results of studying the deep structure of the lithosphere of the Central Tien Shan, which aimed to identify the main tectonic elements in its geophysical models. We have compared the structural and geological data with the information on the deep structure obtained by geophysical methods and from the positions of earthquake hypocenters in the study area. According to geological concepts, the Tien Shan orogenic belt is characterized by longitudinal and transverse segmentation. The boundaries of the Northern, Middle, Southern Western and Eastern segments of the Tien Shan are deep-seated fault structures. In deep faults and channels of heat and mass transfer, endogenous processes are localized. High-velocity, geoelectrical and thermal models consider such faults and channels as contrasting objects that can be referred to as indicators of these processes.Our analysis of the locations of earthquake hypocenters from NNC, KNET, CAIIG, KRNET, SOME catalogues shows that seismic events are strongly confined to the fault zones and the boundaries of large blocks. A correlation between the anomalies of geophysical fields suggests the degree of inheritance of tectonic structures and the boundaries of the main tectonic segments of the Tien Shan. To compare the crustal and upper mantle heterogeneities reflected in different geophysical fields, we have analyzed seismic tomographic sections based on volumetric seismotomographic models geoelectric and velocity sections along profiles across the main tectonic elements of the study area. The sections are used to identify the zones with relatively low (i.e. reduced) seismic wave velocities and detect the deep-seated longitudinal segmentation of the folded belt. Objects showing anomalous seismic wave velocities are found in the seismotomographic sections at all the depths under consideration. The most contrasting differences in the velocities of P- and S-waves are typical of the depths of 0-5 km and 50-65 km, showing the most clearly observed Northern, Southern and Western segments of the Tien Shan. In general, the velocities of P- and S-waves at the Northern Tien Shan are higher than those at the Middle and Southern segments. We have analyzed the distribution of geoelectric heterogeneities identified from magnetotelluric sounding data in order to determine the boundaries of the main tectonic elements that are considered as the zones of increased electrical conductivity confined to the boundaries of the fault structures. The distribution of earthquake epicenters clearly reflects the segmentation of the Tien Shan into the Northern, Middle and Southern segments and shows the Western and Eastern Tien Shan relative to the Talas-Fergana fault. Ourstudies of the crust and the upper mantle of the Tien Shan have confirmed that the abovementioned tectonic segments have differences in their deep structures Based on a comprehensive analysis of the study results, we can qualitatively identify a relationship between the distribution of the velocity and geoelectric heterogeneities in the crust and upper mantle, seismicity and the stress-strain state of the crust

ОБЪЕМНО-ПРОСТРАНСТВЕННАЯ СЕГМЕНТАЦИЯ ЛИТОСФЕРЫ ТЯНЬ-ШАНЯ ПО ДАННЫМ ГЕОФИЗИЧЕСКИХ ИССЛЕДОВАНИЙ

This article consolidates the results of studying the deep structure of the lithosphere of the Central Tien Shan, which aimed to identify the main tectonic elements in its geophysical models. We have compared the structural and geological data with the information on the deep structure obtained by geophysical methods and from the positions of earthquake hypocenters in the study area. According to geological concepts, the Tien Shan orogenic belt is characterized by longitudinal and transverse segmentation. The boundaries of the Northern, Middle, Southern Western and Eastern segments of the Tien Shan are deep-seated fault structures. In deep faults and channels of heat and mass transfer, endogenous processes are localized. High-velocity, geoelectrical and thermal models consider such faults and channels as contrasting objects that can be referred to as indicators of these processes.Our analysis of the locations of earthquake hypocenters from NNC, KNET, CAIIG, KRNET, SOME catalogues shows that seismic events are strongly confined to the fault zones and the boundaries of large blocks. A correlation between the anomalies of geophysical fields suggests the degree of inheritance of tectonic structures and the boundaries of the main tectonic segments of the Tien Shan. To compare the crustal and upper mantle heterogeneities reflected in different geophysical fields, we have analyzed seismic tomographic sections based on volumetric seismotomographic models geoelectric and velocity sections along profiles across the main tectonic elements of the study area. The sections are used to identify the zones with relatively low (i.e. reduced) seismic wave velocities and detect the deep-seated longitudinal segmentation of the folded belt. Objects showing anomalous seismic wave velocities are found in the seismotomographic sections at all the depths under consideration. The most contrasting differences in the velocities of P- and S-waves are typical of the depths of 0-5 km and 50-65 km, showing the most clearly observed Northern, Southern and Western segments of the Tien Shan. In general, the velocities of P- and S-waves at the Northern Tien Shan are higher than those at the Middle and Southern segments. We have analyzed the distribution of geoelectric heterogeneities identified from magnetotelluric sounding data in order to determine the boundaries of the main tectonic elements that are considered as the zones of increased electrical conductivity confined to the boundaries of the fault structures. The distribution of earthquake epicenters clearly reflects the segmentation of the Tien Shan into the Northern, Middle and Southern segments and shows the Western and Eastern Tien Shan relative to the Talas-Fergana fault. Ourstudies of the crust and the upper mantle of the Tien Shan have confirmed that the abovementioned tectonic segments have differences in their deep structures Based on a comprehensive analysis of the study results, we can qualitatively identify a relationship between the distribution of the velocity and geoelectric heterogeneities in the crust and upper mantle, seismicity and the stress-strain state of the crust.Статья посвящена обобщению результатов изучения глубинного строения литосферы Центрального Тянь-Шаня с целью выявления основных тектонических элементов в существующих геофизических моделях. Приведены результаты сопоставления данных структурно-геологических исследований с данными о глубинном строении, полученными комплексом геофизических методов, и положением гипоцентров землетрясений. Согласно геологическим представлениям Тянь-Шаньский орогенический пояс характеризуется продольной и поперечной сегментацией. Границами Северного, Срединного и Южного Тянь-Шаня, а также Западного и Восточного служат разломные структуры глубинного заложения. Глубинные разломы и каналы тепломассоперетока характеризуются обособленным (локализованным) проявлением эндогенных процессов, представляют собой контрастные объекты в скоростных, геоэлектрических, тепловых моделях и могут служить индикаторными признаками. Анализ каталогов (NNC, KNET, CAIIG, KRNET, SOME) на предмет расположения гипоцентров очагов землетрясений показывает высокую степень пространственной приуроченности сейсмических событий к разломным зонам и границам крупных блоков. Корреляция аномалий геофизических полей позволяет установить степень унаследованности тектонических структур и выявить границы основных тектонических сегментов Тянь-Шаня. Для сопоставления коровых и верхнемантийных неоднородностей, выраженных в различных геофизических полях, проанализированы сейсмотомографические срезы, построенные на основе объемных сейсмотомографических моделей, геоэлектрические и скоростные разрезы вдоль профилей, секущих основные тектонические элементы Тянь-Шаня. Обзор построенных разрезов позволил определить области относительно низкоскоростных зон (с пониженными скоростями сейсмических волн) и глубинные проявления продольной сегментации складчатого пояса. Во всем интервале рассматриваемых глубин на сейсмотомографических срезах наблюдаются аномальные скоростные объекты. Наиболее контрастными по перепаду скоростей продольных и поперечных сейсмических волн являются срезы на глубине 0–5 км и 50–65 км, где наиболее ярко прослеживается масштабная сегментация Тянь-Шаня на северный, южный и западный сегменты. В целом, скорости P- и S-волн для Северного Тянь-Шаня выше скоростей Срединного и Южного. Анализ распределения геоэлектрических неоднородностей, полученных при исследовании Тянь-Шаня методом магнитотеллурического зондирования, позволил определить границы основных тектонических элементов как зоны повышенной электропроводности, приуроченные к границам разломных структур. В распределении эпицентров землетрясений четко проявляются зоны Северного, Срединного и Южного Тянь-Шаня, а также проявляется сегментация Западного и Центрального Тянь-Шаня относительно Таласо-Ферганского разлома. Выполненные исследования земной коры и верхней мантии Тянь-Шаня подтвердили существование различий в глубинном строении между рассматриваемыми тектоническими сегментами. Комплексный анализ полученных результатов позволил на качественном уровне выявить взаимосвязь между распределением скоростных и геоэлектрических неоднородностей в земной коре и верхней мантии, сейсмичностью и напряженно-деформированным состоянием земной коры

Ion-Optics Systems Of Multiply Charged High-Energy Ions For High Emittance Beams

INTRODUCTION The development of technological processes based on the use of beams of protons and heavy ions accelerated to energies of 1 to 10 Mev/nucleon, as well as the use of such beams for determining the elemental composition of samples and elemental concentration profiles have stimulated the development of ion-optics systems that form high-energy beams of various configurations. Quadrupole magnetic lenses (QML) are the heart of such systems now. The literature on the basic principles of QML calculation and operation is quite extensive (see, for example, [1,2]). The chief lines of investigations now are optimization of experiments and widening the scope of exploiting of accelerators with high emittance ion beams. Both of these problems have risen during creation of microprobe and nuclear track membrane equipment for our cyclotron. An analysis shows that the most convenient ion-optic systems that solves these problems are triplet or quadruplet of QMLs. We have derived a

Stenting of precerebral arteries in acute period of ischemic stroke

OBJECTIVE. The study aimed to raise an efficacy of motor functions after stenting of precerebral arteries in acute period of ischemic stroke in patients of elderly and senile age. MATERIAL AND METHODS. Treatment efficacy was assessed according to dynamics of neurological status, data of duplex scanning of brachiocephalic vessels, index of mobility «Rivermed», scale «Bartel» in 30 patients. RESULTS. Stenting of precerebral arteries in acute period of ischemic stroke facilitated to regress of motor disorders and normalized cerebral hemodynamics. CONCLUSIONS. Stenting is an alternative method to carotid endarterectomy. This approach should be applied in patients with expressed carotid stenosis in combination with accompanied diseases and high surgical risk