AI-based algorithms have increasingly found applications across various fields of geology, emerging as robust alternatives to conventional thermobarometric calibration strategies. In this study, the compatibility, distinctions, and reliability of these novel AI-driven approaches were assessed through a comparative analysis with conventional methods. Focusing on three representative case-study samples from the Oligo-Miocene plutons in northwestern Turkey, the pressure-temperature (P-T) conditions governing clinopyroxene, amphibole, and biotite crystallization were evaluated. The comparative analysis revealed significant methodological divergences. Conventional clinopyroxene barometers yielded widely scattered and often petrologically unrealistic pressure estimates (frequently > 10 kbar), whereas AI-based algorithms provided tightly clustered results consistent with shallow-to-mid crustal emplacement (2-4 kbar). For hydrous phases, while conventional methods indicated only shallow crystallization depths (< 2 kbar), AI-based models for amphibole and biotite consistently revealed deeper, mid-crustal crystallization conditions (similar to 5-6 kbar). These findings suggest that the studied plutons underwent polybaric crystallization, a history that is effectively captured by AI algorithms but partially obscured by conventional calibrations. Consequently, while AI-based approaches offer superior resolution for complex magmatic systems, the observed discrepancies highlight the necessity of integrating whole-rock geochemistry with mineral chemistry for robust geological interpretations.
This study evaluates panned alluvial gold grains recovered from the Uneme-Dangbala drainage systems and the Lom river basin, both located within the Pan-African metasedimentary belts that define the mobile belt zone between the West African Craton and the Congo Craton, to infer their source rocks and the evolution of the gold grains during their transport into their depositional surficial . The Lom grains lack inclusions. They possess secondary gold precipitates, and evidence of amalgamation and bacterial growth in crevices. Gold grains from the Igarra schist belt contain Bi-Te bearing mineral inclusions such as hedleyite, sulphotsumoite, and aleskite with variable contents of Pb, S, andAu. Their drop-like shapes and multimineral composition suggest precipitation from a Bi-Te-Pb-Au melt. Compositionally, the inclusions vary from Bi-Te-Pb-S, Pb-S-Bi-Te, Bi-Te-Au-Pb-S, Pb-S-Bi, Pb-S, Bi-Te, Bi-Au to Au-Bi. The characteristic Bi-Pb-Te-S cluster indicates an oxidized calc-alkaline magmatic-hydrothermal origin. Thus, granitoids that intrude the metasedimentary rocks are the potential source of the hypogene gold mineralization. Gold from both schist belts, although derived from granitoids, has a different composition. The detrital gold particles from both areas correspond primarily to an Au-Ag alloy, although grains from the Lom basin reveal traces of Cu.- nesses of 884 in the Igarra schist belt and 925 in the Lom basin is lower than that of gold from most orogenic deposits.
The studies on mineral resources modelling and reserve estimation require a rigorous methodological framework and a multidisciplinary analytical infrastructure to ensure that quantitative assessment results accurately reflect geological reality and are presented reliably. The uncertainties inherent in reserve estimation, production planning, and economic valuation processes necessitate the characterization of project risks based on scientific facts. In this context, our study aims to evaluate the resource potential of the Samh Iron Ore Deposit through three-dimensional geological modelling and geostatistical methods. The studied ore deposit, located in the north of Balikesir, western Turkey, exhibits skarn/iron -copper- (IOCG) type mineralization. The study integrated data from 161 diamond core drillholes, totaling 16,283.40 m, using Leapfrog Geo, Snowden Supervisor, and Datamine Studio RM software. Four main mineralization zones were defined, and solid models were constructed and integrated with block modelling. Geostatistical analyses revealed that iron (Fe) grade exhibits moderate spatial continuity with an influence range of 150 meters and a nugget effect accounting for 8 % of the total structural variance. According to the Ordinary Kriging method with optimized parameters, the estimated resource potential of the deposit, at a cut-off grade of 28 % Fe, was determined to be 2,031,657 tons with an average grade of 48 % Fe. The high reconciliation level (92.3 %) between the predicted grades of mined blocks and the actual production data confirms the operational accuracy of the model. These results reveal that the adopted methodology provides a reliable framework for evaluating iron deposits in similar geological settings and can significantly mitigate project risks.
Single crystals of a new uranyl carbonate (NH4,Na)(4)[UO2(CO3)(3)] (1) have been prepared by evaporation at room temperature from aqueous solution. The structure was solved by direct methods [orthorhombic, Cmcm, a = 15.712(3), b = 9.039(2), c = 8.915(3) & Aring;, V = 1266.2(6) & Aring;(3) and Z = 4] and refined to R-1 =0.0314 (wR(2) = 0.0704). The crystal structure of the novel compound is based on pseudo-layered complexbuilt by [(UO2)(CO3)(3)](4)-uranyl tricarbonate clusters (UTC) linked together through Na+ and NH4+ ions. Such layered complexes of UTC are typical for a number of uranyl compounds of both natural and synthetic origin, including & ccaron;ejkaite. However, the relative arrangement of layers in 1 is distinct due to the specific interlayer content and can be described as a novel polytype.
The new synthetic counterpart of a potentially new member of the svornostite group of minerals, "magnesiorietveldite", ideally Mg(UO2)(SO4)(2)(H2O)(5), is orthorhombic, space group Pmn2(1), a = 12.7950(9), b = 8.3288(4), c = 11.2962(4) & Aring;, V = 1203.80(11) & Aring;(3) and Z = 2. The crystal structure (R-1 = 0.0168 for 3113 I > 3 sigma I reflections) contains uranyl-sulfate chains that are linked into sheets by M1O(2)(H2O)(4 )and M2O(2)(H2O)(4) octahedra, where Mg is a dominant cation over Zn at both sites. The structure is well known and has already been described for other members of the svornostite group; the fundamental building unit - an infinite [(UO2)(SO4)(2)(H2O)](2-) chain - is common in several uranyl minerals and synthetic compounds. Synthetic "magnesiorietveldite" was obtained after treatment of a specimen containing pitchblende with sulfuric acid. Electron microprobe analyses yielded the empirical formula (Mg0.63Zn0.22Cu0.09Fe0.05)(& sum;0.99)(UO2)(SO4)2 & centerdot;5H(2)O, confirming the predominance of Mg over the other divalent cations. Infrared and Raman spectroscopy confirmed the presence of structurally non-equivalent molecular H2O and sulfate tetrahedra. We append an extensive discussion on the role of molecular H2O in the svornostite-group of minerals based on the bond-valence approach.
Szilagyiite (IMA 2024-063), NaCa3(UO2)(CO3)(3)(SeO3)F(H2O)(6), is a new uranyl-carbonate-selenite mineral from the Pickett Corral mine, Montrose County, Colorado, USA. The new mineral occurs on sandstone and asphaltite matrix in close association with ferroselite, andersonite, schrockingerite, magselite, and an unidentified Na-Ca-uranyl carbonate-selenite-sulfate. Szilagyiite is trigonal, space group R3c (#161), with unit cell parameters a = 9.6542(9), c = 33.465(5) angstrom, V = 2701.2(6) angstrom(3) and Z = 6. Crystals occur as dense yellow-green rosettes up to 1 mm wide and individual tablets up to similar to 200 mu m. Szilagyiite crystals are predominantly tabular on {001} and exhibit {001}, {00-1}, {102}, and {0-1-2} forms, with frequent twinning by inversion and perfect {001} cleavage. It has a pale yellow-green streak and fluoresces dimly green under longwave UV and 405 nm illumination, but has no apparent fluorescence under SWUV. Crystals are transparent with vitreous luster and exhibit a brittle, uneven fracture, with a Mohs hardness between 2-3. The calculated density based on the empirical formula is 3.17 g/cm(3), and 3.16(2) g/cm(3) as measured by flotation in a mixture of diiodomethane and toluene. The mineral is optically uniaxial (-), with omega = 1.628(2), epsilon = 1.538(2) measured in white light. It is pleochroic: O yellow, E colorless; O > E. The empirical formula is Na0.76Ca3.11(UO2)(CO3)(3)(Se1.16O3)F0.82O20.18H13.19 based on 21 O + F, U = 1, with C = 3 apfu based on the structure and H set to achieve charge balance. The eight strongest powder X-ray diffraction lines are [d(obs) angstrom(I)(hkl)]: 5.916(100)(104), 4.836(58)(110), 3.744(77)(018), 3.125(33)(211,122), 2.960(60)(214), 2.795(62)(300), 1.828(40)(410) and 1.744(35)(238,146). The structure of szilagyiite (R-1 = 0.0314 for 2335 reflections with I > 2 sigma I) is based on infinite sheets built from 3 major components: distorted cubane-like [(SeO3) Ca-3(F,OH)(H2O)(3)] units, NaO4(H2O)(3) monocapped trigonal antiprisms, and hexagonal bipyramidal uranyl tricarbonate cluster units, [UO2(CO3)(3)]. The sheets are cross-linked by a thin layer of hydrogen bonds formed between interlayer H2O bound to Na, with F/OH, and O in the sheets.
Hubbardite (IMA 2025-041), Mg(H2O)(6)[(UO2)(2)O(OH)(SO4)](2)& centerdot;H2O, is a new zippeite-like mineral from the Hubbard Homestead mine, Mesa County, Colorado, USA. The new mineral occurs on sandstone matrix in close association with gypsum and an unknown Al-bearing uranyl-oxide hydroxy-hydrate. Hubbardite is orthorhombic, space group Fddd (#70), with unit cell parameters a = 8.8698(17), b = 34.183(7), c = 39.377(9) & Aring;, V = 11939(4) & Aring;(3) and Z = 16. Crystals are plates up to about 0.3 mm in diameter, commonly forming subparallel or divergent aggregates. Crystals are flattened on {001} and exhibit the forms {100}, {001} and {140}. Hubbardite is yellow in color but sometimes appears dark brown, especially on edges. It has a pale-yellow streak and is nonfluorescent. It is transparent with vitreous luster. The mineral is flexible, but not elastic, and has a curved and stepped fracture. The Mohs hardness is about 21/2. The measured density is 3.59(5) g/cm(3). The mineral is optically biaxial (-), with alpha = 1.570(5), beta = 1.625(5), gamma = 1.646(5) (white light). The measured 2V is 62(2)degrees. Dispersion is r < v strong. The optical orientation is X = c, Y = b, Z = a, and the pleochroism is X light yellow, Y yellow, Z brownish yellow; X < Y < Z. The empirical formula is {(Mg-0.92 square(0.08))(Sigma 1.00)(H2O)(6)[(NH4)(0.69)(H2O)(7.31)] (Sigma 8.00)} {(U0.98O2)(2)[O-1.02(OH)(0.98)](Sigma 2.00)(SO4)]}(2) based on O + N = 34 and S = 2 apfu. The crystal structure of hubbardite (R-1 = 0.0616 for 1348 reflections with I > 2 sigma(I)) contains zippeite-type sheets between which are Mg(H2O)(6) octahedra and isolated H2O groups.
The new mineral vegrandisite (BaCl2) was discovered at the porphyry gold deposit Biely Vrch, 3.5 km southeast of the town Detva, in the Central Slovak Volcanic Field. It occurs as a minor phase in salt melt inclusions hosted by vein quartz, where it forms small anhedral and transparent crystals up to 4 mu m long, accompanied by halite and several other daughter minerals, mainly javorieite, rinneite, chlorocalcite and hibbingite. Vegrandisite was identified by techniques embedded in transmission electron microscopy but many mineral properties, including optical and structural ones, are known from the synthetic BaCl2 analogue. Strongest bands in the Raman spectra include 114, 125, 187 cm(-1) and in the IR spectra in the region between 2852 and 2944 cm(-1). Vegrandisite in inclusions approaches the composition of BaCl2, but Sr (up to similar to 4.5 wt. %) and Br (up to similar to 2.1 wt. %) are also incorporated. It is orthorhombic, belongs to the space group Pnma. Obtained unit-cell parameters a = 7.80(3) angstrom; b = 4.71(2) angstrom; c = 9.60(9) angstrom, V = 352.68 (54) angstrom 3 are consistent with the published parameters of alpha-BaCl2 that exhibits a PbCl2-type (cotunnite) structure. Solid phases in salt melt inclusions, including vegrandisite, have crystallized from the salt melt on cooling of the inclusions. Late crystallization of BaCl2 is related to accumulation of the incompatible element barium in the residual salt melt. Parental salt melt evolved from a hypersaline liquid, accompanied by a magmatic vapor, that were exsolved from a shallow dioritic magma.
A new occurrence of three rare supergene uranyl molybdates, calcurmolite, iriginite and umohoite was recently discovered at the Majersk & aacute; valley U-Mo prospect near & Ccaron;u & ccaron;ma, Spi & scaron;sko-gemersk & eacute; rudohorie Mts., Slovakia. Calcurmolite is the most common uranyl molybdate at the studied locality, followed by relatively common iriginite and rare umohoite. In this paper, we present their detailed mineralogical study, including paragenetic observations, X-ray powder diffraction, chemical composition, and a Raman spectroscopic study. The quantitative chemical (WDS) data indicate a significant presence of Fe (around 0.35 apfu) in both iriginite and umohoite, whereas Na and K are typical minor elements observed in calcurmolite. The studied assemblage of supergene uranyl molybdates was formed by in-situ weathering of uraninite-molybdenite aggregates under the relatively acidic conditions, caused by breakdown of abundant pyrite and absence of carbonates.
An unusual hydrothermal Mn-Be mineralization was recently discovered at the Bansk & aacute; Hodru & scaron;a intermediate-sulfidation epithermal deposit, Slovakia. Mn-Be mineralization occurs in dense stockwork of the stage 2 quartz-rhodonite-rhodochrosite veins (Karol & iacute;na type) and it is represented by helvine, minerals of the rhodonite and epidote group, johannsenite-diopside series and axinite-(Mn) accompanied by minor Mn-rich clinochlore, adularia, pyrite, sphalerite, chalcopyrite, hematite as well as abundant younger Ca-rich rhodochrosite and calcite and rarely also anhydrite. Helvine from the Bansk & aacute; Hodru & scaron;a deposit is compositionally close to the end member (content of Mn is between 3.50 to 3.98 apfu) with only minor presence of genthelvine (Zn up to 0.22 apfu) and danalite (Fe up to 0.20 apfu) constituents. Rare occurrence of hydrothermal axinite-(Mn) containing dominant Mn (1.83 to 2.10 apfu) and only subordinate amounts of Fe (up to 0.29 apfu) and Mg (0.11 apfu) is also notable. Beryllium and boron at the Bansk & aacute; Hodru & scaron;a deposit were likely introduced by magmatic-hydrothermal fluids with increased activity of manganese. Homogenisation temperatures and salinities obtained from fluid inclusions hosted directly in helvine and associated quartz are typical for intermediate sulfidation epithermal deposits (259 to 309 degrees C, 1.9 to 6.3 wt. % NaCl eq.) with a slightly increased salinities compared to most fluid inclusions at the studied deposit. Persistent boiling is probably responsible for increased salinity of fluids and fractionation of Be and B in residual fluids which were trapped in cavities and fissures in veins. The resulting increased activities of Be and B along with cooling are probably responsible for the precipitation of helvine, axinite-(Mn) and associated minerals.
A Microsoft (R) Visual Basic software, WinGadclas, has been developed to calculate the chemical formulae of gadolinite supergroup minerals based on data obtained from wet-chemical and electron-microprobe analyses. WinGadclas currently evaluates 13 valid mineral species using the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA) nomenclature scheme for the gadolinite-supergroup minerals in the general chemical formula A(2)MQ(2)T(2)O(8)phi(2). The program recalculates and estimates the chemical formulae of gadolinite-supergroup species based on 10 oxygen atoms, with the 2 T, 2 A, and T + Q = 4 atoms per formula unit normalization options. Mineral formulae of the gadolinite-supergroup minerals are calculated based on the occupancy of A, M, Q, T, and phi sites, as well as the application of the dominant-valency and dominant-constituent rules. WinGadclas operates in four stages: (1) it estimates cation and anion contents provided by input chemical data; (2) it determines the dominant cation and anion at the A, M, Q, T, and phi sites; (3) it assigns the gadolinite-supergroup minerals to one of the four subgroups, including datolite, gadolinite, herderite, and drugmanite; and (4) it classifies the gadolinite-supergroup species into appropriate groups, such as gadolinite and herderite. WinGadclas allows users to: (1) enter up to 46 input variables for mineral-chemical analyses; (2) type and load multiple gadolinite-supergroup mineral compositions in the data entry section; (3) edit and load the Microsoft (R) Excel files used in calculating, classifying, and naming the gadolinite-supergroup minerals, and (4) store all the calculated parameters in the output of a Microsoft (R) Excel file for further data evaluation. The program is distributed as a self-extracting setup file for Windows 7 or later operating system, including the necessary support files used by the program, a help file, and representative sample data files.
The Cucma - Cierna ba & ncaron;a manganese deposit (Slovakia, Western Carpathians) hosts barium-rich mineralisation within the Early Paleozoic metacarbonate lenses associated with graphite-, quartz-muscovite phyllites and metalydites. The main metacarbonate mineral is represented by calcite containing up to 94.2 mol. % CaCO3, with minor amounts of Mn, Fe and Mg constituents. The Ba-mineralisation consists of silicates such as cymrite, celsian, Ba-rich muscovite and baryte along with clinochlore, quartz, spessartine and accessory fluorapatite and rutile. Cymrite forms prismatic to tabular aggregates, commonly associated with celsian and Ba-rich muscovite, it displays a stable chemical composition close to the theoretical end-member formula. Celsian (89.0-97.3 mol. % Cls) with minor Na, K, Ca, and Sr contents typically occurs as anhedral grains and is overgrown by cymrite, indicating a possible hydration transformation. Ba-rich muscovite shows complex chemical zoning, suggesting variable Ba incorporation through multiple substitutions predominantly in Ba-enriched zones (up to 0.32 apfu Ba). Clinochlore lacks any Ba and is interpreted as a retrograde phase. Textural, chemical and structural evidence studied by optical microscopy, electron microprobe analyses (EPMA) and Raman spectroscopy indicates a multi-stage development involving baryte or barium enrichment during sedimentation influenced by submarine basic volcanism, subsequently followed by Variscan and Alpine metamorphic events. Metamorphic recrystallisation mobilised Ba, leading to the formation of Ba-rich silicates. The Ba-rich mineral assemblage and associated textures reflect the complex metamorphic evolution of the deposit and highlight cymrite and celsian as a key indicator of low-grade metamorphism in the studied Ba-rich environment. The presence of spessartine (up to 60.0 mol. % Sps) and other accessory phases further illustrates a close relation with associated manganese mineralisation.
Spatial distribution and mutual relations of large amygdales were studied in a texturally stratified basaltic lava flow in the Permian Krkono & scaron;e Piedmont Basin in northern part of the Czech Republic, Central Europe. Clusters of distinctively shaped large amygdales were observed in lensoidal domains of altered trachybasalt between massive, amygdale-free zones below and scoriaceous lava above. The shapes and orientations of amygdales - from vertically elongated forms in lower parts to horizontally flattened types near the base of the upper scoriaceous zone - indicate a progressive shape evolution influenced by cooling dynamics of the nearly static lava body. Fluids creating the large vesicles likely originated from underlying water-saturated older volcanic rocks or local sediments, while the alteration of surrounding trachybasalt is expected to proceed at least partly as higher-temperature processes in the cooling lava rather than purely by later stage percolation of meteoric groundwater. These results allow for a comprehensive model of formation of large vesicles and their possible immediate filling with agate, carbonates or goethite liberated by water-dominated fluids from cooling lava in their immediate surroundings, potentially explaining also meteoric isotopic signatures observed in amygdales elsewhere, without need for Si-rich nor vapour-rich parent magma. The implications are broadly relevant for studies of large agates, geodes and other amygdales in mafic lava flows in water-rich volcano-sedimentary environments within continental basins.
Julgoldite-(Fe2+) and Fe-rich prehnite were found in pectolite veins filling fissures in basaltic andesite at the Kost'alov quarry near Semily (Liberec region, Czech Republic). Empirical formula of julgoldite-(Fe2+) based on EPMA and M & ouml;ssbauer spectroscopy considering so-called intervalence electron hopping in the structure may be written as Ca-2.01(Fe0.562+Fe0.252.5+Mg0.14)(Sigma 0.95)(Fe1.193+Fe0.252.5+Al0.57)(Sigma 2.01)Si3O9.94(OH)(4.06). Refined unit-cell parameters for monoclinic space group A2/m are a = 8.927(3) & Aring;, b = 6.080(2) & Aring;, c = 19.428(7) & Aring;, beta = 97.59(4)degrees, V = 1045.2(8) & Aring;(3). Prehnite with the empirical formula Ca-2.01(Al0.53Fe0.45)(Sigma 0.98)(AlSi3O10)(OH)(1.93)F-0.02 is located approximately in the middle of the prehnite-ferriprehnite series. M & ouml;ssbauer spectroscopy indicated that all Fe is present in the trivalent form. The increased Fe content is also reflected in this unit-cell: a = 18.617(5) & Aring;, b = 5.502(2) & Aring;, c = 4.672(2) & Aring;, V = 478.5(2) & Aring;(3). Pectolite is the main mineral in the mineral assemblage. Its unit-cell parameters refined from powder X-ray diffraction are a = 7.9848(14) & Aring;, b = 7.0391(19) & Aring;, c = 7.0243(11) & Aring;, alpha = 90.53(2)degrees, beta = 95.19(1)degrees, gamma = 102.48(2)degrees and V 383.7(1) & Aring;(3). Chemical composition of pectolite corresponds to ideal stoichiometry and give the empirical formula Na-1.00(Ca2.02Mn0.01Fe0.01)(Sigma 2.04)Si3O8(OH1.04)F-0.02. Other minor minerals of the association are hematite, pyrite and the youngest calcite. The source of mineralization of the circulating fluids can be found in alteration of rock components (feldspars, olivine, glass); however, external input from the surrounding calcareous sediments cannot be excluded.
Arsenogoldfieldite is a new mineral discovered in a sample collected from the North Star mine, Mammoth, Tintic district, Juab County, Utah, U.S.A (type locality). It occurs as anhedral grains, up to 300 mu m in size, in a quartz gangue, associated with tellurium, emargite including Sn-bearing variety and supergene jubate. Arsenogoldfieldite is black, with a metallic luster. Mohs hardness is ca. 3 1/2 -4; calculated density is 4.954 gcm(-)(3). In reflected light, arsenogoldfieldite is grey with a brownish shade; it is isotropic. Internal reflections were not observed. Reflectance values for the four COM wavelengths in air [R (%) lambda (nm)] are: 30.2 (470); 29.9 (546); 29.9 (589); and 30.4 (650). The empirical formula of arsenogoldfieldite is Cu-1(0).Zn-7(5)0.Fe-1(1)0.(0)(4)(As-4.Sb-8(5)0.Bi-4(9)0.(1)(3))(5).Te-4(7)0.S-9(0)1(3).(1)(1). The ideal formula is Cu-1(2)(As4Te2)S-1(3), which requires (in wt. %) Cu 48.13, As 9.46, Te 16.11, S 26.30, total 100.00. Arsenogoldfieldite is cubic, I43m, with unit-cell parameters a = 10.2868(4) & Aring;, V = 1088.53(13) & Aring;(3), Z = 2. The strongest reflections of the X-ray powder diffraction pattern [d, & Aring; (I) hkl] are: 3.638 (8) 220, 2.969 (100) 222, 2.573 (9) 400, 1.8187(21) 440 and 1.5504(9) 622. According to the single-crystal X-ray diffraction data (R = 0.0221 on the basis of 380 unique reflections with F > 4 sigma F and 22 refined parameters), arsenogoldfieldite is isotypic with other tetrahedrite-group minerals. Arsenogoldfieldite is named in agreement with the nomenclature of the tetrahedrite group as the (As/Te) end-member in the goldfieldite series. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (2022-084). The description of arsenogoldfieldite from the Pefka mine, Alexandroupoli, Western Thrace, Greece (cotype locality), its chemical composition and crystal structure data are also given in the paper.
Among enstatite-rich meteorites are included enstatite chondrites and enstatite achondrites (aubrites). The reducing conditions of origin are reflected in their mineralogy. Due to the lack of oxygen-bearing mineral assemblages allowing the application of traditional geothermometers, sulfides are used as a tool to constrain the conditions of their origin. In general, sulfide-based geothermometers rely on the contents of major or minor elements traditionally determined by electron probe microanalysis. This method requires the analyzed material to be a homogenous single phase in the analytical volume. However, sulfides of enstatite-rich meteorites frequently contain tiny lamellar inclusions of different phases, and therefore, the inclusions might affect the overall composition of sulfides. Consequently, the results of such analyses might influence the estimates of the conditions under which the given meteorite formed. This study discusses the effect of using the low-overvoltage approach to analyze iron and nickel (10 kV) in the primary sulfides of enstatiterich meteorites and how results compare to those obtained with the traditional analytical protocol (20 kV). The sulfides analyzed included Cr-Ti-bearing troilite, daubr & eacute;elite (FeCr2S4), and (Mg,Fe,Mn)S-monosulfide. Unfortunately, troilite often contains lamellar inclusion of daubr & eacute;elite. Moreover, troilite inclusions are occasionally also included in (Mg,Fe,Mn) S-monosulfide. Therefore, obtaining an unbiased analysis of these minerals is intricate. Due to this, the main objective of using a lower accelerating voltage is to reduce the analytical volume to the minimum to increase the probability of avoiding tiny inclusions. Even if the analytical volume is inclusion-free, another complication might occur as the analysis of troilite may be affected by the neighboring daubr & eacute;elite due to boundary fluorescence. Consequently, both phenomena bias the Cr content measured in troilite similarly, and due to the complexity of troilite-daubr & eacute;elite assemblage, it is nearly impossible to quantify the amount of Cr content unbiased. Subsequently, to obtain the best possible dataset, precise sample screening and careful analytical point location setting are required in general. Using lower accelerating voltage brings many advantages as it allows better observation of the inclusions, and due to reducing the analytical volume, it reduces the chance of the presence of inclusions and suppresses the bias in Cr from boundary fluorescence. However, it also has disadvantages as the analysis is not trivial and does not favor trace elements analysis in general. Results demonstrate the importance of point-by-point inspection of the acquired data and subsequent elimination of biased analyses from the final datasets.
Raman spectroscopy was used to measure the thermal maturity of organic matter in widespread low-grade Ordovician and Silurian metasedimentary rocks of the Kaczawa Metamorphic Complex. The suitability of different Raman-based geothermometer formulations for estimating peak metamorphic temperatures in the studied rocks was evaluated. Among the tested geothermometers, the formulation based on the full width at half maximum of the D1 band, and the calculations performed with the IFORS software yielded most consistent results, reproducing with sufficient accuracy and reliability the peak metamorphic temperatures obtained by other authors. Disruptions in the regional temperature distributions due to thermal overprint caused by local volcanic activity were identified by studying the contact aureole around a large body of the Wielis & lstrok;awka Rhyolite. It was found that the influence of contact metamorphism on the measured spectral parameters becomes insignificant at about 150 m away from the contact. The regional distribution of peak temperatures not affected by late thermal overprinting shows a clear pattern with the record of higher temperatures preserved in the southern part of the Kaczawa Metamorphic Complex. Depending on the tectonic unit, peak temperatures vary from 312 to 352 degrees C, with an average of about 331 degrees C. Temperatures calculated for the units in the northern Kaczawa Metamorphic Complex branch range from 278 to 301 degrees C, with an average of 289 degrees C. With estimated geothermal gradient of 15 degrees C/ km for the peak thermal conditions, the difference of 40 degrees C indicates the southern branch was buried 2.5-3.0 km deeper than the northern branch.
