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The influence of tectonic setting on groundwater chemical composition in the Peshkopi gypsum karst area, Korab Mountains, Eastern Albania

Eftimi Romeo, Andreychouk Viacheslav, Niedoba Tomasz, Różkowski Jacek

Geological Quarterly

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2023

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Vol. 67, No. 2

art. no. 19

EN

The diversity of groundwater chemistry in the Peshkopi gypsum karst area may be related to its setting within the tectonically active Korab Massif (Albania), as shown by field tests of temperature, pH, Eh and EC, and sampling of the waters for chemical analysis (both major and trace components) from cool brackish springs and mineralized thermal springs. The relationship between the chemical composition of the spring waters and of the reservoir rocks was elucidated by analysis of anhydrite-gypsum rocks and experimental dissolution of an anhydrite-gypsum sample. Statistical analysis was used in the processing of hydrochemical data. Comparison of analytical results from 2019 with earlier data indicates compositional stability of the groundwaters over time. Our results together with statistical analysis of the hydrochemical data support an earlier hypothesis of two systems of groundwater circulation within the anhydrite-gypsum deposits of the Peshkopi region. A shallow circulation system involves cold (10-14°C), mainly brackish SO4-Ca waters with very low concentrations of Na+ and Cl- ions, reflecting their formation in a sulphate rock environment that probably corresponds spatially with a gypsum layer formed by hydration of anhydrite in the near-surface zone. A deep circulation system conditioned, inter alia, by the presence of a large fault, brings to the surface water at up to 44°C, saturated with H2S, mineralized, of the SO4-Ca type with an increased content of Na, K, HCO3, Cl, BO3 and SiO2>/sub>. The chemical composition of these waters, regardless of the presence of large amounts of sulphates, is significantly different and suggests the influence of other factors on their formation, such as slow circulation, contact with flysch rocks in the fault zone and the mixing of deep and near-surface waters in the final part of their ascent to the surface.

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Karst relief of the Mali me Gropa Massif, central Albania

Andreychouk Viacheslav, Eftimi Romeo, Nita Jerzy, Klimchouk Alexander

Geological Quarterly

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2022

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Vol. 66, No. 1

art. no. 6

EN

The mid-altitude mountain massif of Mali me Gropa is located in the central part of Albania, rises to an altitude of 1500–1800 m a.s.l., is composed mostly of Mesozoic limestone, and is characterized by extensive surface karst development. The karst relief is dominated by “doline” morphology including “polygonal” karst. Detailed geomorphological analysis of the western part of the Mali me Gropa massif (so-called Western Massif) by means of GIS methods is used to determine and explain the morphometric and morphological diversity of the area’s topography. Based on a homogeneity criterion, a number of geomorphological units with specific kinds of karst relief have been distinguished within the massif. The differences in karst sculpture concern the size (diameter) of dolines and depressions, their depth, shape and symmetry, orientation, density of occurrence and spatial pattern, which provide the basis for distinguishing geomorphological units. The spatial differentiation of the karst relief is explained by the influence of factors which are evolutionary (geological and geomorphological evolution of the massif), hypsometric (altitude difference of terrains) and geomorphologic-structural (inclination of the slopes and layers). The relatively poor expression of open karst conduits (i.e. caves and vertical shafts) on the surface of the massif may result from the relative immaturity of the epikarst zone, the widespread occurrence of residual cover on the plateau, and the accumulation of large amounts of clay material in dolines and depressions. Detailed hydrogeological studies show, however, high karst permeability and dominance of conduit flow. Considering the high geomorphological landscape and ecological value of the area, it should be granted the status of a nature reserve or national park. Geomorphological and karstological research within the massif should be continued as it represents a type of karst found also in other parts of Albania. This type of karst area is of great economic (groundwater reserves) and natural protection (environmental) importance.

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Geomorphology and hydrogeology of an exposed evaporite dome : the Dumre karst area, Central Albania

Andreychouk Viacheslav, Eftimi Romeo, Nita Jerzy, Klimchouk Alexander

Geological Quarterly

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2021

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Vol. 65, No. 4

art. no. 55

EN

The Dumre area, located in Central Albania, is distinguished by a landscape whose main features consist of low altitude, mosaic and irregular relief, and the presence of a large number of depressions with lakes. These features result from karst development related to the presence of a tectonically affected dome of Triassic evaporite rocks, mainly gypsum. Gypsum karstification has operated since the Pliocene, and the present-day geomorphological appearance of the area indicates an advanced, mature stage of karst development. Signs of this maturity include the widespread occurrence of large depressions, many of which are water-filled, forming lakes, the occasional presence of gypsum hills in the form of monadnocks, a thick “coating” of residual sediments largely isolating the karstic gypsum substrate from precipitation and surface waters, and the fragmentary pattern of a degraded river network. The karst character of the relief is largely “camouflaged” by clastic terrigenous and residual deposits of considerable thickness which cover the gypsum and form a caprock. At the present stage, the caprock is being strongly reshaped and eroded. Chemical analyses show a mean dissolved gypsum content of 1.9 g/l and mean dissolved NaCl content of 0.4 g/l. The mean flow rate of subaqueous springs is calculated as 1.84 m3. The density of gypsum is 2.3, and that of rock salt is 2.17, thus the total volume of gypsum dissolved each year is 47,420 m3 and of rock salt 10,680 m3, making a total volume of dissolved material released by the subaqueous springs in one year of 58,100 m3. This corresponds to a cubic void of side length 38.7 m.