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Deformation in the continental interior, far from tectonic plate boundaries, is not fully understood. Due to its location, Mongolia is a prime natural laboratory for studying effects such as intracontinental deformation and intraplate volcanism. A previous regional magnetotelluric (MT) study, including three (2016-2018) field campaigns, identified a localized asthenospheric upwelling with a correspondingly thin lithosphere underneath the Hangai Dome (Central Mongolia).Compared with Central Mongolia, Eastern Mongolia is less studied with geophysical methods; consequently, its underlying lithospheric and asthenospheric properties are less constrained. At the same time, this region is of economic and scientific interest, as it hosts several mineral zones and relevant geological features, such as the Mongolia-Okhotsk suture zone. Furthermore, it is unknown to what extent the identified electrical conductivity anomalies in Central Mongolia extend to the east and how the crust and mantle differ in this region.This work presents the first results of a new MT field study covering Central-Eastern Mongolia. 64 broadband MT stations were deployed between 2020 and 2022 along five profiles east of the Hangai. The data were processed using a two-step multi-taper processing approach, simultaneously improving the quality at short and long periods, providing credible MT responses up to 2048 seconds. The previously acquired and new data were jointly inverted regarding 3-D conductivity variations. Furthermore, data from an 880 km long 2-D profile extending from the Selenga Basin to Gobi Desert were inverted independently. This study is part of a broader project aiming to constrain the electrical conductivity of entire Mongolia., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The South Hangai fault system, located between the uplifted Hangai Dome and the Gobi-Altai Mountains in central Mongolia, represents an ancient suture zone and terrane boundary, which is possibly an extension of the Mongol–Okhotsk suture that resulted from the closure of the Mongol–Okhotsk Ocean. The adjacent obducted Bayankhongor Ophiolite Belt is possibly the longest continuous ophiolite belt in the world. This area is important because it is associated with the Bayankhongor Metal Belt, which is an economically significant zone for ore extraction in Mongolia, including important sources of gold and copper. Electrical resistivity is a key parameter for mineral exploration. Because faults and suture zones are regions of fractured, weakened crust they often have circulating fluids that act to increase their electrical conductivity. Additionally, economic mineralization is commonly associated with a conductive signature from associated sulfide minerology. We present magnetotelluric data acquired in an array across the southern Hangai region, Valley of Lakes, Mongolia. The magnetotelluric data were used to generate 3-D electrical resistivity models of the shallow crustal structure. Because the cratonic upper crust is highly resistive (> 1000 Ωm), the low- resistivity (< 30 Ωm) South Hangai fault system is easily detected. It is revealed to be a major crustal-scale structure. A clear transition in crustal electrical properties was observed across the suture zone and may reflect both the rheological and petrological differences across accreted terranes. Furthermore, anomalous, low-resistivity zones in the crust are spatially associated with the surface expressions of known mineralization and resource extraction projects. By combining our electrical resistivity results with other geological and petrological data we attempt to gain insights into the potential mineral resources of this unique region, and their origin.

International audience; We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans-particularly well preserved in the arid environment of the Gobi region-allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is similar to 1 mm yr(-1) along the WIB and EIB segments and similar to 0.5 mm yr(-1) along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault.;Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at M-w 7.78-7.95.;Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of similar to 2500-5200 yr for past earthquakes along the different segments of the western Bogd Fault. This suggests that the three western segments of the Bogd Fault and the Gurvan Bulag thrust fault (a reverse fault bounding the southern side of the Ih Bogd range that ruptured during the 1957 earthquake) have similar average recurrence times, and therefore may have ruptured together in previous earthquakes as they did in 1957. These results suggest that the western part of the Bogd Fault system, including the Gurvan Bulag thrust fault, usually behaves in a 'characteristic earthquake' mode.

This paper presents new results of mathematical modeling of economy and environment interaction. A model of mutual interaction of livestock farming - one in a two main agricultural branches - and natural pastures that are the essential part of livestock farming forage reserve is proposed. Macrodescription of livestock farming such as: total and vintage number of livestock, number of young animals, livestock outputs and production inputs, demand for credit, and profit - follows from the initial microdescription of rational managing of vintage livestock. This description forms a block "Economy" of the model of mutual interaction of livestock farming and natural pastures - natural vegetable coenoses.

This work builds a macro model for livestock farming based on aggregation of initial micro description for rational control of total number of vintage livestock (age cohorts). All variety of animal kinds is reduced to one by given recount coefficients. An optimal problem on co-hort total number of livestock (planning problem for life cycle of animals) is resolved. As a result the optimum age limit for the operation of animals, the optimum volume of the credits for the farm, the optimum speed of slaughter, and the optimum conditions of the farm pur-chase of young animals are determined. The integral equation for the equilibrium price of young animals, which contains forward-looking values of variables, is obtained. It means that for constructing of the model it is necessary to know how the farms forecast the prices. The problem is solved by the application of the rational expectations hypothesis: within the model framework all farms have the precise forecast of necessary prices on the planned period (they exploit available information without making systematic mistakes). A steppe ecosystem model based on a carbon cycle with grazed animals as part of the ecosystem is constructed. The model takes into account some external influences. The pa-rameters of this model are identified on the basis of data on grassland ecosystems. Besides a model of credit-and-monetary system taking into account the organization of this system according to the Stanley Fischer currency board scheme with fixed exchange rate is constructed. In this case gold currency reserves change by the balance of payments. In the description of full ecological- economic model it is taken into account that the maintenance of animals damages the nature. Balance relationships on the product market and on the labor market are carefully extracted for closing the model. In the description of interac-tion of livestock farming and ecosystem and government regulated mechanisms it is assumed that the tax rate per head of animal grows when the degradation level exceeds a limiting value established by the law, and the raw material price changes proportional to the remainder of its biomass stock. Numerical experiments on the obtained ecological- economic model with the rational expectations are the complex computational problem, which is solved with the help of the highly productive calculations on the supercomputer MVS 1000M. Model is calibrated ac-cording to the Mongolian data. In the base scenario of the model calculations the basic indices of environment decrease down to 10% in one hundred years. Fluctuations of financial pa-rameters with the period in 36 years caused by price rational expectations are found out. On the basis of base scenario the developments of processes in complex system of in-teraction of livestock farming and steppe ecosystem several alternative scenarios are built and calculated. The calculations showed that the specified system maintains also more rigid rela-tion to the level of the environment degradation than in the base scenario. In this case it is possible to improve all macro indexes of the studied system. It is shown also that an increase of efficiency of actions for rational use of available resources improves the steppe ecosystem state, enables to increase the output of final production and the incomes of the population. One of scenarios demonstrates a regime in which the area of natural pastures is reduced by the virtue of external human activity (for example, space activity).

This paper presents new results of mathematical modeling of economy and environment interaction . A model of mutual interaction of livestock farming - one in a two main agricultural branches - and natural pastures that are the essential part of livestock farming forage reserve is proposed. Results of numerical experiments and analysis of various scripts of livestock farming is described. The work is in part supported by the Russian Foundation of Basic Research (Grant 01-01-00114) and the Program of State Support of Leading Scientific Schools (Grant 00-15-96118).