Dicranomyia (Idiopyga) nigristigma Nielsen, 1919 (Diptera, Limoniidae) recorded for the first time from calcareous springs in Romania

Dicranomyia (Idiopyga) nigristigma Nielsen, 1919 (Diptera, Limoniidae) is recorded for the first time from Romania. The species was collected in some calcareous springs in the Apuseni Mountains and highlight an overlooked Limoniidae diversity in similar habitats from the karstic area from here.

Geochemical Features of the Thermal and Mineral Waters From the Apuseni Mountains (Romania)

The Apuseni Mountains are located between the large geothermal area of the Pannonian Basin and the low thermal flux Transylvanian Basin. Thermal and mineral waters have been sampled from 42 points along a NW-SE transect. The general chemistry and the water isotope (deuterium and oxygen-18) composition were analyzed. Most of the thermal aquifers are located in carbonate reservoirs. The waters mainly belong to the Ca-HCO3 hydrochemical type, excepting the western side, towards the Pannonian Basin, where the Na-HCO3 type may occur. The isotope composition indicates aquifer recharge from precipitation. The geochemical characteristics and the structural position of the study area suggest two distinct geothermal contexts. The Southern Apuseni area geothermal features are likely connected to the Neogene—Early Quaternary magmatic activity from the Mureş Valley and Zarand Depression. The geothermal manifestations in the north-western part of the study area, at the border between the Northern Apuseni and the Pannonian Depression, share features of the latter one.

Natural hazards of Izvorul Crișului.

" The presence of the Izvorul Crisului local territorial administrative unit (commune), in the western part of the Transylvanian Depression, not far from its border with the Apuseni Mountains, implies the existence of various natural hazardous processes. Their manifestation, in the presence of anthropic components and their activities and goods, determines their hazard attributes. Of the possible natural hazards (geological, geomorphological, atmospheric, hydrological, biological, etc.), only the geomorphological, hydrological, and meteorological ones will be addressed in this paper. The presence of these natural processes may cause material damage and victims, for this it is necessary to know their magnitude. Thus, the present study aims to identify the potential hazards which exist in the Izvorul Crisului administrative unit and to assess the susceptibility to these natural processes. To achieve this objective, specific maps will be made, which finally, beside the supporting role for the analysis of natural processes, will become tools for the management of these conditions, tools to reduce the induced risks."

Sphalerite Composition in Low- and Intermediate-Sulfidation Epithermal Ore Bodies from the Roșia Montană Au-Ag Ore Deposit, Apuseni Mountains, Romania

We evaluated the significance of the iron and manganese content in sphalerite as a tool for distinguishing between low-sulfidation and intermediate-sulfidation epithermal deposits on the basis of new and previously published electron probe microanalyses data on the Roșia Montană epithermal ore deposit and available microchemical data from the Neogene epithermal ore deposits located in the Apuseni Mountains and Baia Mare region, Romania. Two compositional trends of the Fe vs. Mn content in sphalerite were delineated, a Fe-dominant and a Mn-dominant, which are poor in Mn and Fe, respectively. The overlapping compositional range of Fe and Mn in sphalerite in low-sulfidation and intermediate-sulfidation ores suggests that these microchemical parameters are not a reliable tool for distinguishing these epithermal mineralization styles.

Miocene Tuffs from the Dinarides and Eastern Alps as Proxies of the Pannonian Basin Lithosphere Dynamics and Tropospheric Circulation Patterns in Central Europe

Tuffaceous layers are regularly preserved in Miocene carbonate and siliciclastic sediments of the Dinarides and Eastern Alps in southeastern and central Europe. Detailed mineralogical and geochemical analyses of 13 tuffs of known ages acquired from sedimentary successions of the intramontane Dinarides basins and the southwestern Pannonian Basin were carried out to infer on plausible source areas, relative strengths of volcanism, and ash distribution patterns. Studied tuffs were altered to various degrees with illite-smectite and smectite as dominant phases while volcanic glass, carbonates, and other silicates are minor constituents. Tuffs’ compositions range from andesite through trachyandesite to rhyolite and trachyte. Trace-element based correlation with regional data reveal that lower (LM) and lower middle Miocene (LMM) tuffs (17.0-14.0 Ma) likely originated in the Western Carpathians (the Bükkalja volcanic field) while source areas of upper middle Miocene (UMM) tuffs (13.8-12.5 Ma) were in the Apuseni Mountains and/or Eastern Carpathians. The spatial relation of LM/LMM and UMM tuffs with respect to their source areas (Bükkalja and Apuseni Mountains, respectively) is most consistent with tropospheric easterly trade winds that carried ash hundreds of kilometres to the south-west toward an azimuth of ∼200-250°.Supplementary material: Annotated X-ray diffractograms of the global and clay fraction of studied tuffs and AFM classification diagram are available at https://doi.org/10.6084/m9.figshare.c.5429592

Water Quality and Hydrogeochemical Characteristics of Some Karst Water Sources in Apuseni Mountains, Romania

Human activities and natural factors determine the hydrogeochemical characteristics of karst groundwaters and their use as drinking water. This study assesses the hydrogeochemical characteristics of 14 karst water sources in the Apuseni Mountains (NW Romania) and their potential use as drinking water sources. As shown by the Durov and by the Piper diagrams, the chemical composition of the waters is typical of karst waters as it is dominated by HCO3− and Ca2+, having a circumneutral to alkaline pH and total dissolved solids ranging between 131 and 1092 mg L−1. The relation between the major ions revealed that dissolution is the main process contributing to the water chemistry. Limestone and dolostone are the main Ca and Mg sources, while halite is the main Na and Cl source. The Gibbs diagram confirmed the rock dominance of the water chemistry. The groundwater quality index (GWQI) showed that the waters are of excellent quality, except for two waters that displayed medium and good quality status. The quality of the studied karst waters is influenced by the geological characteristics, mainly by the water–rock interaction and, to a more limited extent, by anthropogenic activities. The investigated karst waters could be exploited as drinking water resources in the study area. The results of the present study highlight the importance of karst waters in the context of good-quality water shortage but also the vulnerability of this resource to anthropogenic influences.

The occurrence of gold in Voia deposit, South Apuseni Mountains, Romania

<p>Voia deposit belongs to the Săcărâmb-Cetraș-Cordurea Miocene volcano-tectonic alignment of the South Apuseni Mountains, Romania. This large volcanic complex represents a Sarmatian-Pannonian magmatic-hydrothemal mega-system of around 5 km<sup>2</sup> with an estimated 3–4 Ma time-space evolution, consisting of seven andesitic volcanic structures grouped in a circle, three subvolcanic andesite-quartz porphyry microdiorite and associated porphyry Cu-Au(Mo), pyrite Ca-Mg skarns and epithermal Au-Ag-Pb-Zn-Cu mineralizations.</p><p>The mineral assemblages of alteration and mineralization processes belong to several mineralized zones on a vertical scale, according to sampling evidence and laboratory studies. HS products are found in the upper part of the structure (300-500 m), with dominant advanced and intermediate argillic alterations and sulfide-sulfate gold-poor veins (pyrite, marcasite, base metal sulfides, Fe-Ti oxides, vuggy quartz, alunite, gypsum, anhydrite). Within the 500-1200 m depth, the HS mineral assemblages gradually decrease in favor of IS and LS products. It is characterized by the coexistence of gold-rich LS assemblage (native gold, base metal sulfide, adularia, sericite-illite, chlorite, carbonates ± anhydrite veins), with the IS assemblage (iron oxides, chalcopyrite, pyrite, quartz, anhydrite). These assemblages overprint the HS mineral associations, resulting in a transition zone characterized by gold - pyrite - chalcopyrite - iron oxides - quartz - anhydrite mineral assemblage characteristic for HS and native gold - pyrite - base metal sulfides - carbonates - quartz mineral assemblage corresponding to IS+LS type.</p><p>Gold is present in all of the identified mineralization forms: porphyry-epithermal Cu-Au, epi-mesothermal carbonate veins with gold - base metal sulfides, quartz veins with pyrite - chalcopyrite - magnetite ± hematite ± anhydrite, anhydrite veins with base metal sulfides and sulfosalts, anhydrite veins with pyrite - anhydrite ± quartz, vuggy quartz (silica residue) with gold-poor pyrite veins and impregnations in porphyry systems.</p><p>Drilling core samples revealed that in Voia deposit, gold is concentrated in chalcopyrite (drills no. 7, 19, 37) along with pyrite - magnetite - hematite - quartz assemblage from the late potassic stage. The major amount of gold associated with chalcopyrite tends to be mainly submicroscopic. Pyrite from anhydrite veins of the early potassic stage ± phyllic alteration is relatively poor in gold (drills no. 1-6, 8-14). However, the highest gold contents are present in pentagonal dodecahedron pyrites (drills no. 33, 38, 39) of pyrite-chalcopyrite-magnetite ± hematite-quartz assemblage from late potassic stage ± phyllic alteration. Pyrite associated with magnetite from anhydrite veins tends to be poor in gold (drills no. 8, 11, 15, 28, 29). A carbonate vein containing gold-bearing base metal sulfides that was intercepted at 960,00-960,30m depth by drill no. 17 is one of the richest in gold.</p><p>Native gold occurs as fine inclusions in ore minerals (5-20 μm). Large irregular grains of native gold (>50 μm) appear at mineral boundaries and along the fissures. The gold color is bright yellow and has a measured Au:Ag ratio of 5:1, suggesting that native gold has been formed at a relatively high temperature.</p><p>Acknowledgments: This work was supported by two Romanian Ministry of Research and Innovation grants: PN-III-P4-ID-PCCF-2016-4-0014 and PN-III-P1-1.2-PCCDI-2017-0346/29.</p>