Search Results (4)

The manganese deposits at the Kato Nevrokopi area are located in the Drama Basin (Northern Greece) and belong to the Rhodope Metamorphic Province. The deposits were previously exploited for several supergene Mn-oxide ore bodies of massive, battery-grade nsutite, spatially associated with fault zones in the vicinity of Oligocene granitic intrusions. We conducted detailed geological, mineralogical, and geochemical investigations at the Mavro Xylo deposit, which led to the identification of Ag-rich Mn-Zn±Pb vein-type mineralization. The studied paragenesis appears to have developed during two hydrothermal stages: stage I, characterized by the mineral assemblage rhodonite–quartz–rhodochrosite–pyrophanite–pyrite–galena–Te bearing argentite–sphalerite–wurtzite–alabandite, and stage II, dominated by Ag-rich, Mn-Zn±Pb oxides in the form of fracture-fills along a high-angle NE-SW fault zone in brecciated marbles. Bulk analyses of the stage-II oxide assemblage yielded concentrations of Ag up to 0.57 wt.%. In the veins, wurtzite is present in bands, succeeded by manganese oxides, while calcite and quartz are the main gangue minerals. We placed particular emphasis on the occurrence of Ag in high concentrations within distinct manganese oxides. Major silver carriers include Zn-bearing todorokite, chalcophanite, and hydrous Pb-Mn oxide. The vein-type mineralization at Mavro Xylo shares many characteristics with other intermediate-sulfidation epithermal precious metal-rich deposits associated with high Mn concentrations. The evolution of the mineral paragenesis indicates a change in the physicochemical attributes of the ore-forming fluids, from initially reducing (stage I) to oxidizing (stage II). Although the origin of the initial ore-forming fluid remains to be constrained, the above redox change is tentatively attributed to the increasing incursion of meteoric waters over time. Full article

Davallia mariesii T. Moore ex Baker, a member of the section Trogostolon (Copel.) M. Kato and Tsutsumi (Davalliaceae M.R. Schomb.), is a lithophytic or epiphytic herb that grows on rocks and tree trunks in montane forests. This study analyzed the morphological, anatomical, micromorphological, and palynological characteristics of D. mariesii using a digital slide scanner and a field-emission scanning electron microscope and presented an expanded and updated description. A circumendodermal band was observed in the anatomical structure of the stipe, making D. mariesii the second species in the family Davalliaceae with such a band. The frond anatomical studies revealed that the epidermal cells of the indusium were thicker than those of the epidermis on both sides and that hypostomatic fronds with stomata chambers were present. Diacytic, anisocytic, and tetracytic stomatal complexes were observed on abaxial surfaces. The indusia covered numerous sporangia. Leptosporangium consisted of an apical cap, a basal cap, an annulus, and a stalk. The spore had an ellipsoidal outline, a monolete aperture, and verrucae with colliculate ornamentation. The obtained results provide systematic data for the phylogeny of Davalliaceae and establish a basis for future taxonomic delimitation of other taxa. Full article

We studied the kinematic behaviour of active landslides at several localities in the area of Panachaikon Mountain, Achaia (Peloponnese, Greece) using Sentinel (C-band) InSAR time series analysis. We processed LiCSAR interferograms using the SBAS tool, and we obtained average displacement maps for the period 2016–2021. We found that the maximum displacement rate of each landslide is located at about the center of it. The average E-W velocity of the Krini landslide is ~3 cm/year (toward the east) and 0.6 cm/year downward. The line-of-sight (LOS) velocity of the landslide (descending orbit) compares well to a co-located GNSS station within (±) 3 mm/yr. Our results also suggest a correlation between rainfall and landslide motion. For the Krini landslide, a cross-correlation analysis of our data suggests that the mean time lag was 13.5 days between the maximum seasonal rainfall and the change in the LOS displacement rate. We also found that the amount of total seasonal rainfall controls the increase in the displacement rate, as 40–550% changes in the displacement rate of the Krini landslide were detected, following to a seasonal maximum of rainfall values at the nearby meteorological station of Kato Vlassia. According to our results, it seems that large part of this mountainous region of Achaia suffers from slope instability that is manifested in various degrees of ground displacement greatly affecting its morphological features and inhabited areas. Full article

A model based on the known high correlation between photosynthetically active radiation (PAR) and global horizontal irradiance (GHI) was implemented to estimate PAR from GHI measurements in this present study. The model has been developed using satellite-derived GHI and PAR estimations. Both variables can be estimated using Kato bands, provided by Satellite Application Facility on Climate Monitoring (CM-SAF), and its ratio may be used as the variable of interest in order to obtain the model. The study area, which was located in mainland Spain, has been split by cluster analysis into regions with similar behavior, according to this ratio. In each of these regions, a regression model estimating PAR from GHI has been developed. According to the analysis, two regions are distinguished in the study area. These regions belong to the two climates dominating the territory: an Oceanic climate on the northern edge; and a Mediterranean climate with hot summer in the rest of the study area. The models obtained for each region have been checked against the ground measurements, providing correlograms with determination coefficients higher than 0.99. Full article