Land use/land cover (LULC) changes significantly impact spatiotemporal groundwater levels, posing a challenge for sustainable water resource management. This study investigates the long-term (2000–2022) influence of LULC dynamics, particularly urbanization, on groundwater depletion in Kabul, Afghanistan, using geospatial techniques. A time series of Landsat imagery (Landsat 5, 7 ETM+, and 8 OLI/TIRS) was employed to generate LULC maps for five key years (2000, 2005, 2010, 2015, and 2022) using a supervised classification algorithm based on Support Vector Machines (SVMs). Our analysis revealed a significant expansion of urban areas (70%) across Kabul City between 2000 and 2022, particularly concentrated in Districts 5, 6, 7, 11, 12, 13, 15, 17, and 22. Urbanization likely contributes to groundwater depletion through increased population growth, reduced infiltration of precipitation, and potential overexploitation of groundwater resources. The CA-Markov model further predicts continued expansion in built-up areas over the next two decades (2030s and 2040s), potentially leading to water scarcity, land subsidence, and environmental degradation in Kabul City. The periodic assessment of urbanization dynamics and prediction of future trends are considered the novelty of this study. The accuracy of the generated LULC maps was assessed for each year (2000, 2005, 2010, 2015, and 2022), achieving overall accuracy values of 95%, 93.8%, 85%, 95.6%, and 93%, respectively. These findings provide a valuable foundation for the development of sustainable management strategies for Kabul’s surface water and groundwater resources, while also guiding future research efforts.

New+Geology +https://doi.org/10.33271/nvngu/2023-5 +/jdownloads/pdf/2023/5/05_2023_contents-en-GB.pdf

Purpose. To establish the mineral-formforming sequence and clarify the features of gold-telluride-sulfide mineralization at the Kokkiya deposit based on the study of mineral assemblages, typomorphic characteristics of ore minerals, modes of occurrence of native gold and tellurides, and their spatial and paragenetic relationships. Methods. A total of 120 ore and host-rock samples collected from drill core were studied. The analytical methods included optical microscopy in reflected and transmitted light, scanning electron microscopy, electron-probe microanalysis, EDS/WDS analysis, and EDS mapping. Gold fineness and composition were additionally compared with depth, pyrite generations, structural and textural characteristics of the ores, and hypogene and supergene mineral assemblages. Findings. Two main stages of mineralization were distinguished: hypogene and supergene. Four successive stages were identified within the hypogene stage: pre-ore hydrothermal-metasomatic, early pyrite, main telluride-polymetallic, and late pyrite-polymetallic. Pyrite is the principal ore mineral and is represented by several generations differing in morphology and paragenesis. Native gold is associated with pyrite, quartz, sericite, galena, and tellurides. The later stages are characterized by calaverite, petzite, altaite, tsumoite, native tellurium, and Bi-bearing minerals. Gold fineness in intergrowths with altaite and calaverite ranges from 944-977‰, whereas in oxidized ores it ranges from 634-820‰. EDS mapping confirmed the close spatial association of micron-scale gold inclusions with telluride phases. The most intense mineralization is confined to the inner, most strongly altered parts of the metasomatic zonation. Originality. The mineralogical-genetic model of the Kokkiya deposit has been refined by linking pyrite generations, gold fineness, telluride mineralization, and the sequence of ore-forming stages. The distribution of gold and tellurides is shown to reflect the multistage evolution of the hydrothermal system and subsequent supergene alteration. Practical implications. Sericitolites, Te- and Bi-bearing minerals, characteristics of pyrite generations, and gold-telluride associations can be used as mineralogical exploration criteria for evaluating prospective zones and the potential continuation of productive mineralization at depth.

Gold in the coarse-grained alluvial sediments of the Irgaity placer deposit (Kazakhstan) occurs predominantly as finely dispersed particles associated with mineral matrices, which limits the efficiency of conventional recovery methods. The proposed processing flowsheet demonstrated that thermal pre-treatment is an effective approach for enhancing ultrafine gold recovery, achieving an overall recovery of 86% from the treated concentrate. The Tescan TIMA “Bright Phase Search” workflow, optimized for gold detection by applying a minimum BSE brightness threshold of 75% and an Au phase filter calibrated using a gold standard, successfully identified gold-bearing grains within the analyzed mounts. Further mineralogical investigations revealed that gold particles ≤10 μm occur as native gold and Au-Ag-As-bearing phases, with silver content reaching up to 14 wt.% in some coarser grains. The significant association of silver with gold-bearing particles indicates the potential for incorporating silver recovery into the processing flowsheet, thereby improving the overall economic value of the deposit. Despite the low average gold grade (0.3–0.4 g/t), the large dimensions of the Irgaity placer deposit (approximately 12 km long, 1.5 km wide, and 60–70 m thick) suggest the presence of a substantial large-volume mineral resource. The combination of extensive mineralized sediments and high recovery achieved through thermal activation supports the potential economic viability of the deposit and warrants further evaluation of its development potential.