Tectonostratigraphy and major structures of the Georgian Greater Caucasus: Implications for structural architecture, along-strike continuity, and orogen evolution

Although the Greater Caucasus Mountains have played a central role in absorbing late Cenozoic convergence between the Arabian and Eurasian plates, the orogenic architecture and the ways in which it accommodates modern shortening remain debated. Here, we addressed this problem using geologic mapping along two transects across the southern half of the western Greater Caucasus to reveal a suite of regionally coherent stratigraphic packages that are juxtaposed across a series of thrust faults, which we call the North Georgia fault system. From south to north within this system, stratigraphically repeated ~5–10-km-thick thrust sheets show systematically increasing bedding dip angles (<30° in the south to subvertical in the core of the range). Likewise, exhumation depth increases toward the core of the range, based on low-temperature thermochronologic data and metamorphic grade of exposed rocks. In contrast, active shortening in the modern system is accommodated, at least in part, by thrust faults along the southern margin of the orogen. Facilitated by the North Georgia fault system, the western Greater Caucasus Mountains broadly behave as an in-sequence, southward-propagating imbricate thrust fan, with older faults within the range progressively abandoned and new structures forming to accommodate shortening as the thrust propagates southward. We suggest that the single-fault-centric “Main Caucasus thrust” paradigm is no longer appropriate, as it is a system of faults, the North Georgia fault system, that dominates the architecture of the western Greater Caucasus Mountains.

The main characteristics of the wrinkled relief on the southern slope of the Greater Caucasus

Like other mountainous regions of the Caucasus, the South-Eastern Caucasus is an epigeosynclinal mountain system formed by the first and middle alpine folds. Between the Alpine fold stage and the orogenic stage, the South-East Caucasus Mountains were denuded and turned into hilly, low mountain plains in the Oligocene and Miocene. Wrinkled structures were destroyed by denudation and a mostly neutral relief type was formed. Key words: Greater Caucasus, southern slope of the Greater Caucasus, morphostructure, wrinkled relief, geological development

Two new Palaearctic species of moth flies (Diptera, Psychodidae, Psychodinae) from the Caucasus Mts.

Psychodid specimens were sorted from samples collected during fieldwork in areas in and around the Caucasus Mountains in 2019. Thornburghiella montana sp. nov. (from Georgia) and Pericoma inopinata sp. nov. (from Azerbaijan and Georgia) are described. Differential diagnoses are given and diagnostic characters illustrated.

SEL VƏ DAŞQIN AXINLARINDA DAĞ ÇAYLARI MƏCRASININ YUYULMA DƏRİNLİYİNİN TƏYİNİ

The article is dedicated to the determination of the wash depth of mountain rivers in floods and overflows. As well-known, hydrotechnical equipment is exposed to destructive damages of the floods and overflows. The undersurface of bridge basement and coast guards are washed away, the surface of drainage devices in water supply and dams (Düker) at river crossings are opened up. Therefore, the protection of the equipment against the destructive damage of the floods and overflows should be ensured. To this aim, first of all, the depth of the fortification of the equipment basement in riverbeds and the width through which the river can flow should be determined and the works of installing coast guards should be accordingly implemented. Since the flow regime of rivers due to floods in the course of mountain riverbeds dramatically changes, the width, depth, roughness and cross-sectional area of the riverbed also changes. To that reason, in the smallest case, calculation formulas includes the average width and wash depth of the riverbed in the course of the floods and overflows, average diameter of undersurface soils, the slope of the location of hydrotechnical structures, velocity due to the average diameter of the riverbed soils and so on. The article contains the analyses of theoretical and practical materials about the floods and overflows in mountain rivers. For the rivers flowing through the southern hills of Great Caucasus Mountains, the expressions for determining the riverbed parameters and hydrological parameters of rivers are used. According to the expressions, average width due to non-washing of the riverbed in floods in accordance with flood flow and slope of the studied part of the riverbed, the average depth of the riverbed crossing the flood, the average velocity of the flow and the wash depth in accordance with them are determined. basing on all these, the determining method of the wash depth of mountain riverbeds in floods have been worked out and determining the wash depth have been recorded. The studied methodology can be used in determining the riverbed parameters in floods and overflows. Keywords: Flood, riverbed deformation, mountain river, wash depth, average diameter of undersurface sediments, riverbed stability, flood velocity

Environmental Issue in the Caucasus Mountains: Prospects for Solving the Issue

The modern stage in the development of civilization is characterized by the growth of contradictions between society and nature. In this regard, the study, the assessment, and the protection of biological and current landscape diversity have become a serious global environmental issue. The search for solutions is not merely an item of theoretical significance, but also great practical importance. This is not only a matter of the increasing pressure on various components of the anthropogenic environment and even on an entire ecosystem. At the same time, particularly regarding reform, there has been a clear shortage of theoretical and experimental studies of ecological systems at the regional and local levels. The Caucasus is noted for its high biodiversity and is among 200 priority regions. The North Caucasus is an integral part of the whole Caucasus, and currently is one of Russia’s most densely populated and developed regions. The region is facing a serious problem of developing a set of measures to maintain biological diversity, preserve biological resources, as well as optimize environmental management. Contemporary international studies (for example, the Johannesburg Memorandum, 2002) do not provide adequate tools for achieving the ideals of sustainable development, especially from a regional perspective. Classical ecology makes it possible to identify and formulate problems that threaten biodiversity. However, realistic and constructive proposals for their implementation have not yet been developed. The purpose of the study is to assess the current state of the ecosystems of the Caucasus Mountains for the development of ecological networks as the basis for the conservation of biological diversity.