The nature and timing of Mid-Devonian–Visean plutonic activity in the Variscan Bohemian Massif (BM) and the Central Western Carpathians (CWC) differed profoundly. In the BM, most of this period was marked by vigorous arc-related magmatism that ceased only at ~340 Ma by the collision and the ensuing slab break-off. The oceanic subduction passed to deep continental underthrusting, and relamination of felsic metaigneous material of Saxothuringian origin, soon thereafter transformed into (U)HP–HT granulites. The Visean activity in the BM was characterized by an emplacement of voluminous (ultra-)potassic plutons and countless dykes of matching chemistry, but practically no syn- to early post-collisional S-type granitoids. In the BM, the bulk of S-type magmas was produced in Serpukhovian or younger. In the CWC, the evolution started later but was considerably faster; the classic magmatic arc seems not to be preserved here. Subduction, evidenced by Frasnian back-arc mafic magmatism and anatexis, was terminated by collision and early (Late Devonian) slab break-off. The attendant heat pulse produced dioritic rocks, and then a Tournaisian late-collisional flare-up of the I- and immature (biotite-bearing) S-type granitoids. The mature (muscovite-bearing) Visean S-type granites were already post-collisional. In the CWC, the (ultra-)potassic magmatic rocks are conspicuously missing, as are the (U)HP–HT granulites. This reflects a too early slab break-off and/or inappropriate composition of the downgoing continental slab. The contrasting Mid-Devonian to Visean magmatic histories clearly reflect distinct paleogeographic positions of the BM vs. CWC crustal segments, probably along the two unconnected sutures in the widely separated branches of the Variscan orogenic collage.
Trace element geochemical and LA-ICP-MS U–Pb data of detrital rutile grains from Jurassic sandstones of the Bayırköy Formation exposed in the western part of the Sakarya Zone were presented to characterize and differentiate potential source lithologies. The Bayırköy Formation commence with coarse-grained conglomerate at the bottom and passes up to medium to coarse-grained sandstone. Fine-grained marl occurs on top of the Bayırköy Formation. This uppermost level of the Bayırköy Formation is separated as nodular limy levels, clayey and marly nodular levels. The Jurassic Bayırköy Formation in northwestern Türkiye was deposited in a mixed continental–marine setting, reflecting the transition from fluvial–deltaic systems into shallow marine environments. The Jurassic sandstones are yellowish brown-colored, medium to coarse-grained and well-bedded, which exhibits shoreface to tidal flat facies suggesting a coastal transition zone with tidal influence. The Nb and Cr contents in rutile grains are in the range of 40–11900 μg/g and 6–5700 μg/g, respectively. According to the Cr–Nb discrimination, the great majority of detrital rutile grains (70 %) are sourced from metapelitic rocks such as mica schists and paragneisses, the rest of detrital rutile grains (30 %) are derived from metamafic rocks such as amphibolites, eclogites and metagabbros. Trace element composition of detrital rutile grains demonstrate that the source rock lithology is predominantly metapelitic in origin. The Zr-in-rutile temperatures range from 480 °C to 790 °C, which indicates amphibolite-facies metamorphic conditions. The U–Pb age data of detrital rutile grains range from 313 Ma (n = 72, MSWD = 2.6) to 330 Ma (n = 53, MSWD = 2.5), which yields the age of metamorphism for the potential source rocks of detrital rutile grains in the Sakarya Zone. Trace element composition, Zr-in-rutile temperatures and rutile U–Pb age data exhibit potentially derivation from metamorphic source rocks which underwent metamorphism in amphibolite-facies conditions during Early Carboniferous. Exposures with Variscan amphibolite-facies metamorphic basement rocks can be assumed as likely sources for these sandstones in the Jurassic Bayırköy Formation. Amphibolite-facies metamorphic rocks in the Sakarya Zone seem to be the primary source lithologies for the detrital rutiles in the Jurassic sandstones. Another conceivable source for detrital rutile grains could be syn- to post-tectonic Carboniferous granites, mesothermal gold deposits and granite-pegmatite-hosted W–Sn mineralization owing to high elevated Sn and W concentrations in detrital rutile grains.
The geological structure of the Male Karpaty Mountains reflects a complex, multiphase tectonic evolution. The Tatric crystalline basement and its Permian-to-Cretaceous sedimentary cover have been thrust over the Jurassic formations of the Borinka Subunit. The basement comprises Lower Paleozoic metamorphic rocks of the Pezinok and Pernek groups, intruded by Lower Carboniferous granitoids. Variscan deformation, particularly the development of pervasive foliation (S-2(V)) and mineral and stretching lineations (L-2t(V)), records syn-metamorphic processes predating granitoid emplacement. Later Variscan phases (D-3(V), D-4(V) ) introduced folding and localised structural overprints. Alpine deformation overprinted the older structures through several discrete deformational phases. Early Alpine deformational phase (D-1(A)) was marked by NW-directed shear, asymmetric folding, and greenschist facies metamorphism (Cretaceous). Later phases (D-2(A), D-3(A)) reflect exhumation and Miocene compression, with the latest deformation associated with southvergent folding and reverse faulting. Together, these events document a long-lived tectonic history shaped by both Paleozoic and Cenozoic orogenic processes.
This study investigates the metabasic rocks forming the core series of the southern Menderes Massif (MM) within the Anatolide-Tauride Block (ATB). In the Babada & gbreve; (Denizli) region, these rocks are exposed as sills and stocks intruding the schist units, and are classified as amphibolite, garnet amphibolite, and hornblende gabbro. The metabasic rocks of the southern MM provide important insights into regional geotectonic evolution through major and trace element geochemistry, rare earth element (REE) systematics, and Sr-Nd isotope analyses. These rocks typically display similar mineral assemblages, with widespread retrograde metamorphism and hydrothermal alteration, while primary magmatic textures are locally preserved, especially in hornblende gabbros. Geochemical classification based on immobile element systematics indicates that the metabasic rocks are derived from magmatic protoliths and display transitional alkaline- tholeiitic characteristics, predominantly plotting in the alkali basalt field and partly overlapping the tholeiitic basalt field. Variation diagrams of major and trace elements reveal systematic fractionation, controlled by the removal of clinopyroxene, olivine, and spinel, as reflected by decreasing CaO/Al2O3 ratios, Ni (60-511 ppm), and Cr (22-1265 ppm) concentrations with declining MgO contents (6.07-14.85 wt. %). The enrichment of incompatible elements such as TiO2, Y, Zr, and Th further supports the cogenetic relationship of these rocks and indicates fractional crystallization from a common parental magma. Primitive mantle-normalized multi-element patterns display enrichment relative to N-MORB and transitional signatures between E-MORB and OIB, with a dominant OIB-like affinity. Chondrite-normalized REE patterns are characterized by strong LREE enrichment ((La/Yb)cn = 5-16) and nearly flat HREE profiles, suggesting melt generation within the spinel-garnet transition zone. The Sr-Nd isotopic compositions (measured) (87Sr/86Sr = 0.706633- 0.710964; 143Nd/144Nd = 0.512518-0.51267), together with mantle-like Nb/U (16-63) and low Ce/Pb (1.9-7.6) ratios, point to an enriched and compositionally heterogeneous mantle source. Tectonic discrimination diagrams indicate that the magmatism took place in an intraplate extensional setting related to Paleo-Tethyan lithospheric extension along the northern margin of Gondwana.
The study area is situated in the easternmost segment of the North Anatolian Fault System (NAFS), including the Karl & imath;ova triple junction (KTJ) where the NAFS intersects the East Anatolian Fault System (EAFS). The regional angular unconformity between intensely deformed pre-Quaternary rocks and the overlying undeformed neotectonic deposits clearly indicates that the onset of the strike-slip neotectonic regime and the formation of the related structures, namely the NAFS and EAFS, occurred in the early Quaternary (2.588 Myr). The present study focuses on the long-term (241-year) Tanyeri-Yedisu seismic gap, the onset age of the strike-slip neotectonic regime, and several key parameters of the Erzincan-Varto section of the NAFS. These are total dextral displacement, average slip rate, and the return period of the peak earthquake expected from the Tanyeri-Yedisu seismic gap. New field data, obtained from the detailed field geological mapping of the region, using the displacement of the Inner Tauride Suture as a structural marker and the Yedisu River as a geographic marker, clearly show that the total dextral displacement is 57 km. This offset was accumulated over an approximately a 2.6 Myr time interval. These values correspond to an average slip rate of 22 mm/yr and a return period of 205 +/- 50 years for the peak earthquake originating from the Tanyeri-Yedisu seismic gap.
In the northwesternmost part of the Dinarides, which is a part of the southwestern segment of the Zagorje- Mid-Transdanubian Zone within the Mt. Medvednica area, localized occurrences of blueschists with an OIB-type protolith affinity preserve evidence of vestiges of high-pressure, low-temperature metamorphism. New 40Ar/39Ar ages from glaucophane (160.0 +/- 1.5 to 164.9 +/- 1.0 Ma) and phengitic muscovite (154.4 +/- 1.0 Ma), obtained from phengite- ferroglaucophane and glaucophane-Mg-riebeckite schists, constrain the metamorphism to the Middle to Late Jurassic (Callovian to Kimmeridgian). This indicates the formation of the analysed rocks within an accretionary prism above an intra-oceanic subduction zone in the northwestern Neotethys. In a regional context, these data are consistent with a diachronous, northeast-dipping subduction system operating across parts of the western Neotethys. Metamorphic soles in the Dinaridic Ophiolite Belt, dated at 174 to 157 Ma, mark the onset of early hot subduction, whereas Jurassic to Early Cretaceous HP/LT assemblages in Pelagonia and Mt. Fru & scaron;ka Gora record continued convergence and progressive cooling at comparable depths. Coeval HP/LT rocks in the Western Carpathians broadly document comparable subduction depths and thermal gradients farther northeast. Mt. Medvednica occupies a temporally and structurally-intermediate position within this regional framework and preserves the northwesternmost record of Middle to Late Jurassic HP/LT metamorphism in the Dinarides. Together, these observations suggest regionally distributed and diachronous subduction-related processes, with ridge-proximal subduction initiating in the Bajocian, maturing during the Callovian to Kimmeridgian, and progressively shifting southeastward in response to trench retreat across the Dinaridic-Vardar realm.
An integrated mineralogical and geochemical study was conducted to evaluate links between carbonate replacement siderite-polysulphide (Cu, Pb, Ag +/- Ba) deposits, associated gossans, archaeological slag and distal bog-iron ores in the Trgovska Gora and Petrova Gora Mountains, Dinarides. A total of 45 samples were collected from ten mining sites located at hilly area (primary ore, proximal gossans, archaeological slag) and three lowland bog-iron occurrences up to 100 km away. Primary deposits and gossans are hosted by synorogenic flysch sequence, covered by soil and vegetation. Degree of weathering is high (median value of Chemical Alteration Index is 85 %). Petrographic analysis, X-ray diffraction, and multivariate geochemical analysis of major, trace, and rare-earth elements were used to reconstruct pathways of iron and base-metal mobilization. Results support three-stage weathering model for carbonate replacement deposits: (1) chemical weathering of primary siderite-polysulphide mineralisation and oxidation in vadose zone to gossan; (2) mechanical weathering and transportation of weathered Fe-ore (together with associated host-rocks) and its deposition as distal, reworked or pedogenical gossan, (3) chemical transportation of dissolved metals in saturated zone by reductive groundwater via gravitational flow to 50-100 km distance and reprecipitation in topsoil as bog-iron ore. Immobile trace elements (Zr, Nb, Ta, Hf, W), redox-sensitive elements (Mo, V, U), and REEs are consistently enriched in the aluminosilicate matrix and traceable from primary ore to gossans, bog iron, and slag. The persistent geochemical signature despite dilution in distal deposits.
The Dudince Spa, which is located on the southwestern fringe of the Central Slovak Neogene volcanic field, is renowned for its thermomineral waters, enriched in CO2 and H2S. Historically, mineral water springs had been located on several travertine mounds; however, these are now inactive due to the extraction of mineral water through wells. This research focuses on the travertine formations within the spa, and considers them essential for understanding the Quaternary tectono-hydrogeological evolution, notably through the analysis of reorientations in the paleostress field. Leveraging high-resolution LiDAR (Light Detection and Ranging)-derived digital terrain models (DTMs) and geomorphometric analyses, this study evaluates the potential to identify travertine deposits (geobodies) partially concealed by vegetation, while clarifying their spatial distribution and genesis. These travertine mounds are located along the northwestern and northeastern rims of the NW-SE-oriented Gestenec Elevation, which is directly linked to the horst found in the pre-Cenozoic basement. The structure forms a barrier to the inflow of mineral water from the northeast. The tectonic evolution of this elevated structure is connected to a shift in the orientation of the stress field from a NW-SE to NE-SW (ENE-WSW) direction up towards a ESE-WNW (SSE-NNW) direction, which had been generated by dextral movement along the Central Slovak Fault System during the period between the Middle Pleistocene and the Holocene. Faults oriented in the NW-SE to NE-SW directions facilitate the upward flow of both mineral water and the juvenile carbon dioxide that saturates it. The applied methodology (geospatial analysis and field geological research) illuminates the dynamics of stress field rotation, influencing the tectonic and hydrogeological properties of the study area. The results highlight the efficacy of LiDAR mapping and geomorphometry in geological exploration beneath a dense vegetation cover, thus providing a model for similar studies in geothermal fields and tectonically-active regions worldwide.
Sediment geochemistry and 165 detrital zircon grains U-Pb ages are analyzed from the Ventosa beach sediments in the Gulf of Tehuantepec, Mexican Pacific. The objective is to investigate the sediment weathering condition, compositional variations, and to locate the source areas delivering sediments to the coast. Weathering indices reveal a moderate chemical weathering, indicating that the sediments are chemically immature. The SiO2 content (similar to 72-78 wt. %) and the trace element concentrations indicate that the beach sediments are dominantly derived from the felsic igneous rocks. The rare earth element (REE) patterns of the Ventosa sediments are homogeneous and are depleted relative to the average upper continental crust (UCC) values. The environmental indices reveal a "moderately severe enrichment" for Cu content (Enrichment Factor EF= 5.62-8.87; and Geo Accumulation Index I-geo= 1.41-1.98). Anthropogenic enrichment in Pb, Ba, and Zn contents with the possibility of adverse aquatic biota effect is also observed. Th/U ratios in zircon grains are >0.3, indicate an igneous origin. Two major U-Pb age groups are identified i.e. (1) Miocene (similar to 23-12.9 Ma) and (2) Proterozoic (Neoproterozoic: similar to 999-545 Ma; Mesoproterozoic: similar to 2549-1006 Ma). These ages suggest that the zircon grains were originated from the nearby source terranes, most likely from the Cenozoic plutons exposed along the southern Oaxaca coastal region, as well as the volcanic and sedimentary rocks of the Todos Santos Formation.
The Bosnian Flysch, deposited within the Dinaric foreland basin in eastern Herzegovina, consists of thick deep-sea turbiditic successions represented by the Lower Cretaceous Vranduk Formation and the Upper Cretaceous- Paleogene Ugar Formation. The Vranduk Formation in eastern Herzegovina is predominantly siliciclastic in nature, sourced from the northeasterly positioned Adria-derived continental basement units and Neotethys ophiolites. Biostratigraphic data suggest a Barremian to Albian age for the Vranduk Formation in this area. The Ugar Formation in eastern Herzegovina consists of three members: (i) basal Upper Cretaceous limestone breccias and conglomerates; (ii) Upper Cretaceous carbonate-clastic sediments; and (iii) Paleocene carbonate-siliciclastic sediments, derived from the SW situated Adriatic Carbonate Platform, and redeposited into the foreland basin. Our biostratigraphic data indicate a Turonian to Lower Santonian age for the basal breccias and conglomerates, an Upper Santonian to Maastrichtian age for the Upper Cretaceous carbonates, and a Paleocene age for the carbonate-clastic sediments. Kinematic analysis of faults and the reconstruction of paleostress fields have identified three significant and temporally distinct tectonic phases. Reverse and strike-slip faults were active during the Cretaceous-Paleogene deformation phase, which developed under compression of a general NE-SW orientation. The second deformation is characterized by a regional event, the Oligocene-Miocene extension, during which older reverse structures were reactivated as normal faults, and new normal faults were also developed. Here, normal faults active in extension parallel to the orogen (NW-SE orientation) and those active in extension perpendicular to the orogen (NE-SW orientation) can be distinguished. The youngest, Late Miocene deformation phase is documented by a group of faults active in compression that affected the entire Dinarides. This stress field was characterized by reverse and strike-slip faults active in N-S oriented compression.
The formation of the Elatsite deposit is related to the emplacement of several Upper Cretaceous porphyritic intrusions with the most significant intrusions of quartz-monzodiorite and granodiorite porphyries. The surface exposure of the Elatsite deposit provides an opportunity for investigating the lithogeochemical features of different hydrothermal alteration types. Petrographic observation combined with detailed geochemical analysis of the hydrothermal alteration types and chemical features of secondary biotite, amphibole, plagioclase and chlorite, led to the assessment of gains and losses of major, trace and REE elements and the origin of fluids for the variety of alterations. The Na-Ca alteration is probably formed from a mixture of magmatic and external fluids. The Na-Ca-K-silicate alteration is formed during fluid-fluid interaction of magmatic and external fluid, with predominance of the magmatic one, and occurs in the zone of primary neutralization. The K-silicate alteration is formed by magmatic fluids with a high oxygen fugacity, high temperature, high aK+ and aMg2+. The upward superimposition of the K-silicate-sericitic alteration is related to the incorporation of meteoric fluids into magmatic fluids in an initial high oxygen fugacity environment and a high aMg2+. The quartz- sericitic alteration occurs from admixture of meteoric fluid into evolving magmatic fluids, with the predominance of the meteoric fluid, inducing an environment with a low aK+/aH+ ratio. The quartz-adularia-carbonate alteration is probably resulting of the admixture of a magmatic fluid with external and meteoric fluids, in an environment with high aK+. The propylitic alteration is observed only in the periphery zones of the deposit and clear relations with other alteration types were not observed.
Temporal changes in the composition and ultrastructure of hyaline walls of calpionellids during the Late Jurassic, coinciding with the massive increase of abundance of calcareous nannoplankton and with the onset of maiolica and biancone deposition, are poorly known. Here, we investigate the microtexture of pelagic deposits and the preservation, ultrastructure and chemical composition of three calpionellid genera in the upper Tithonian-lower Berriasian of the Kysuca-Pieniny and Orava successions (Pieniny Klippen Belt, Western Carpathians), using scanning electron microscopy (SEM), backscattered electron imaging (BSE), and wavelength-dispersive spectroscopy (WDS). The microtexture of these facies consists of interlocked pelagic skeletal remains and micritic or microsparitic pore-filling cements. Low-Mg calcitic calpionellid loricae and nannofossils are affected by (1) small-scale dissolution, which causes irregular and locally very thin wall thickness of loricae and (2) aggrading neomorphism, which produces coarser lorica crystals and results in the loss of inter-crystalline boundaries relative to the original lorica ultrastructure. In spite of these diagenetic effects, calpionellid genera differ in their test ultrastructure. Crystals in the hyaline layer of Praetintinnopsella and Crassicollaria are similar to 1 mu m long and almost equidistant (length/width ratio similar to 1.3), whereas in Calpionella, they are similar to 2.2 mu m long, more elongated (length/width ratio similar to 2), and oriented perpendicularly or obliquely to the inner surface of the lorica. The ultrastructure of the Praetintinnopsella hyaline layer more closely resembles that of Crassicollaria that of Calpionella, indicating a calcification trend characterised by the formation of larger crystals with lower surface area-to-volume crystal ratio. The loricae of these genera are enriched in Mg and S and impoverished in Mn relative to surrounding micritic and microsparitic grains. The initial diagenetic phase was represented by (1) dissolution of micro- and nannoplankton calcitic remains, (2) by precipitation of micritic and microsparitic cements within pore spaces among uncompacted skeletal particles and inside loricae, and (3) release of Mg from echinoderms coupled with microdolomite precipitation within ossicles or along syntaxial rims. This stage was followed by a phase with small-scale aggrading neomorphism, and ultimately by a late-diagenetic phase characterized by the precipitation of authigenic quartz and albite. Although dissolution, cementation and neomorphism probably reduced abundance of identifiable micritic fraction and abundance of dissolution-sensitive nannofossils, diagenesis did not obliterate differences in chemical composition between calpionellids and other components.
Metamorphosed manganese mineralisation from the RHV-1 borehole near Rudnany (northern Gemeric Unit, Western Carpathians, Slovakia) occurs in the form of synsedimentary Mn nodules up to 1 cm in size with Mn3+/Fe3+-rich aureoles hosted in quartz-muscovite phyllites. These nodules show internal zoning with compact yellowish spessartinerich cores, transitional quartz-spessartine rims, and outer reddish aureoles enriched in epidote, piemontite, hematite, Mn-rich calcite, fluorapatite, and clinochlore. Spessartine represents the dominant Mn-bearing phase (78.9-90.5 mol. % Sps), formed during the Variscan prograde metamorphism under low-temperature greenschist-facies conditions (similar to 350- 450 degrees C). The surrounding aureole comprises of epidote and piemontite with variable Mn3+/Fe3+ substitutions, recording metamorphic reactions under oxidising conditions and elevated fO(2), with hematite acting as the red coloration cause. Fluorapatite occurs as an important accessory phase in two generations: early As-poor fluorapatite enclosed in later As-enriched fluorapatite rims (up to 0.29 apfu As5+) formed during recrystallisation and fluid (re)mobilisation, possibly enhanced by Alpine tectonometamorphism. Quartz, muscovite, albite, and titanite represent phases inherited from the host phyllites. The studied mineral assemblage reflects a polyphase evolution of Mn mineralisation derived from volcaniclastic-sedimentary precursors deposited in an Early Paleozoic basin. Subsequent Variscan metamorphism produced spessartine nodules and aureoles, while Alpine metamorphism caused recrystallisation, quartz veinlet formation, and As5+ (re)mobilisation in outer fluorapatite zones. Compared to other occurrences in the northern Gemeric Unit (e.g., Porac), the Rudnany assemblage is prominent for its dominance of spessartine and epidote-piemontite aureoles and a different protolith composition.
This study investigates the internal deformation of the Fatric Unit in the Mal & eacute; Karpaty Mountains during the Alpine orogeny, with the aim of clarifing the structural evolution and thrusting history of the Vysok & aacute; and Zliechov nappes. A comprehensive dataset of primary and deformation-related planar structures was collected and analysed to reconstruct the tectonic evolution of the Fatric Unit. Three main Alpine deformation phases ( - ) were identified, reflecting significant changes in the regional stress field. (1) The earliest phase (D1A) is associated with northwest-directed thrusting and NW-SE crustal shortening during the Eo-Alpine orogeny, as documented by asymmetric folds, stretching lineations, and large-scale recumbent folding. (2) The subsequent phase (D2A) reflects a shift to a W-E compression axis during the Late Cretaceous to Early Eocene and is expressed by the development of extensional structures, predominantly calcite-filled veins. (3) The youngest phase (D3A) records a return to the N-S-oriented compression associated with south-vergent backthrusting during the Late Oligocene to Early Miocene, probably related to the soft docking of the ALPACA Mega-Unit with the European Platform. Overall, the tectonic analysis of the Fatric Unit in the Mal & eacute; Karpaty Mts. characterises three principal Alpine deformation stages of the Western Carpathians by constraining their timing and kinematics.
The Str & aacute;zsa Hill quarry is an exceptional outcrop in the central part of the Pannonian Basin. It exposes one of the major structures of the Transdanubian Range, the V & eacute;rtessoml & oacute; thrust. In this study, we investigated Str & aacute;zsa Hill from a structural point of view, documenting its complex structural evolution through interpreted outcrop photographs and fault slip analysis. Our findings show that the exposed part of the V & eacute;rtessoml & oacute; thrust comprises an imbricate system of south-vergent thrust sheets composed of Middle and Upper Triassic rocks. Major thrusting occurred before the Middle Eocene, most probably during the mid-Cretaceous. Sedimentological and structural evidence at Str & aacute;zsa Hill indicates that the thrusts underwent dextral-reverse reactivation during the Oligocene, resulting in the formation of a growth syncline in the footwall. The V & eacute;rtessoml & oacute; thrust and associated E-W striking structures were later overprinted by several NW-SE to N-S striking normal faults during the Middle to Late Miocene. Some of these faults were reactivated during neotectonic strike-slip faulting. Our observations provide an important basis for understanding the tectonic evolution of the northern part of the Transdanubian Range.
About 2000 microprobe analyses of zircon were evaluated in order to characterize typical compositions of zircon from common and rare-metal granites of different geotectonic/geochemical affiliations. Generally, zircon is chemically variable at all scales of research. This detailed study shows that the contents of minor elements vary more widely than usually expected from individual analyses. While the Zr/Hf ratio is a reliable indicator of the degree of fractionation of the parent magma, all proposed indicators of the geotectonic position of the source magma, like Y contents or Y/Yb and U/Th values, were found to be merely indicative. Zircon from peraluminous (S-type) granites crystallizes early, is often enriched in P, Al, U, W, Nb and Bi, its (Y+REE)/P values are usually <<1, and the Zr/Hf values mostly evolved from 100 to 10. Zircon in A-type granites is often a relatively late mineral, mostly enriched in HREE and Th, having low Y/Yb and high (Y+REE)/P values, and its Zr/Hf values evolved from 100 to 5. Zircon in peralkaline rocks either crystallizes primarily or results from the transformation of older zirconosilicates. In both cases, it is rich in Y, poor in U and Th, displays high (Y+REE) / P values and Zr/Hf values >50. The effect of the geotectonic environment of crystallization is particularly evident in late, more evolved rocks, while zircons from the early and less fractionated rocks of all geochemical types are similar.
To learn more about the growth zones of distinctly zoned tourmalines from the well-studied Rosina aplite–pegmatite dike of the Monte Capanne pluton near San Piero in Campo, Elba Island, Italy, four tourmaline crystals rooted in the pegmatitic rock and developed into three different small cavities, as well as one additional crystal growing frozen in the pegmatitic rock, were chemically characterized. The light element contents and the unit cell parameters of the four samples were also determined. Black Fe2+-rich tourmaline, grown directly within the pegmatite, with unit cell parameters a = 15.97–15.98 Å, c = 7.15–7.16 Å, can be assigned to schorl and fluor-schorl with only 4 % Fe3+. The Fe content decreases during crystallization, whereas Mn and F contents increase (up to 8 wt % MnO and 1.4 wt % F), forming a growth sector of olive-green colour. Such olive-green tourmaline exhibits unit cell parameters of a = 15.87–15.94 Å, c = 7.12–7.14 Å and can be assigned to fluor-tsilaisite and Mn2+-rich fluor-elbaite. Later, the Mn content decreases and the Al and Li contents increase (up to 44 wt % Al2O3 and 1.7 wt % Li2O). These zones can have Ga and Pb contents of up to ~1100 and ~500 ppm, respectively. The colour of such tourmaline can be pale olive-green, pale pink, or colourless. These crystal zones have unit cell parameters of a = 15.78–15.82 Å, c = 7.08–7.10 Å, and can be assigned to fluor-elbaite, elbaite, rossmanite, and darrellhenryite. In the final stage of tourmaline crystallization, the F content in the investigated crystal terminations can drop down to 0.1 wt % F, while the (Fe + Mn) content increases. Usually, these terminations can be assigned to elbaite (a = 15.79–15.83 Å, c = 7.08–7.10 Å). When comparing the F content and the X-site charge (Na, Ca), all zones grown in the pegmatite pocket, except for the termination, show a strong positive correlation for each crystal examined. This observation is interpreted as evidence that the caps of the tourmaline crystals in the pegmatite pockets formed during a different event than the previously grown crystals.
Detrital white mica from two distinct Cretaceous stratigraphic levels and tectonic settings within the Apuseni Mountains (Mts.) and northernmost South Carpathians was dated using the single-grain 40Ar/39Ar technique in order to monitor the geodynamic evolution of this peculiar segment of the Cretaceous-aged Carpathian orogen. 40Ar/39Ar mica ages of a Lower Cretaceous synorogenic flysch succession in the Apuseni Mts. indicate the preservation of Early Variscan and Late Variscan orogenic metamorphic crust in the source region. By contrast, only a low percentage of Variscan micas have been detected in the post-orogenic Late Cretaceous Gosau-type Vl & abreve;deasa collapse basin of the Northern Apuseni Mts., which postdates the emplacement of the Mure & scedil; ophiolite belt and the Early to early Late Cretaceous formation of the low-grade metamorphic orogenic wedge. There, the studied micas are dominantly of early Late Cretaceous age and argue for the erosion of a medium-grade early Alpine metamorphic unit, which is not exposed in the surroundings of the present-day Apuseni Mts. Consequently, the Apuseni Mts. must have been either disrupted from such a source area and shifted along major strike-slip faults to the present position, or the source is now hidden. In contrast, the Late Cretaceous Gosau-type Rusca Montan & abreve; basin of the South Carpathians comprises dominantly Variscan and a few Triassic detrital mica grains, consistent with Variscan and subordinate Triassic ages of the underlying and surrounding basement exposed in the Supra-Getic/Getic nappes.
The Dyn & oacute;w Marls occur in the lower part of the Menilite Beds throughout the Carpathian Arc. These siliceous marls record decreasing salinity, anoxic bottom conditions, and pronounced endemism during the Lower Oligocene age (Nannozone NP 23), referred to as the Solenovian Event (loss of connection of the Paratethys with the world ocean). Until recently, these beds, and the rest of the Menilite Beds in the Outer Carpathians, were considered to be a product of deep-water sedimentation, rather than shallow-water sedimentation as interpreted, for example, in Austria and the Czech Republic. To explain this discrepancy, detailed sedimentological studies of the Dyn & oacute;w Marls were undertaken in the south-eastern part of the Silesian Nappe of the Polish Outer Carpathians, in three selected sections: A - in Gorlice; B - Zborowice; and C - Jab & lstrok;onica Polska. Six facies are identified: F1 - Black mudstone (Menilite shale); F2 - Chert; F3 - Stratified marls; F4 - Sandy-pebbly marls; F5 - Marly-mudstone heterolithics; and F6 - Stratified and laminated sandstone. The facies are grouped into three facies associations that confirm deposition of the Dyn & oacute;w Marls in shallowwater rather than deepwater environments. Interpretation of the facies and their associations suggests conditions typical of a shallow lake or fresh to brackish shelf that was significantly influenced by tides and wave action. In addition to carbonate deposition, siliceous material was supplied by terrestrial rivers but partly produced in situ. Periodic tsunamitype events also occurred and can be traced over considerable distances. Section A at Gorlice provides clear evidence of a facies succession characteristic of deposition in shallow water. These facies exhibit cyclic repetitions that reflect fluctuations in relative sea level, i.e., in the depth of the shallow-water sedimentary basin. This interpretation is supported by the presence of tidal rhythmites, attributed to spring-neap tidal cycles. Moreover, the succession of facies across the Menilite Beds profile indicates both fluctuations in basin depth and a progressive deepening of the shallow shelf. A shallow deltaic system (Magdalena Sandstone), located above the Dyn & oacute;w Marls, has also been documented in this area. The proposed shallow-water interpretation of the study strata does not preclude the existence of deep-water deposits elsewhere in the Paratethys sedimentary basin during the Lower Oligocene. The evidence for tides in the studied lacustrine or shelf succession sections likely reflects the basin's connection to the open ocean in this area. The discovery and documentation of these shallow-water features mark an important advancement in understanding the paleoenvironmental evolution of the Carpathians. It also contributes significantly to knowledge of the depositional conditions of the Menilite Beds. The results support and refine previous interpretations and paleogeographic reconstructions.
During its evolution, the Zemplinic basement underwent a polyphase of regional deformation. Distinctions between pre-Variscan and Variscan events have been widely discussed in previous studies. In order to assess the polyphase, detrital monazites from four Pennsylvanian-Permian sandstones, as well as one Permian vitroclastic tuff, were dated using the Th-U-Pb electron-microprobe method. In total, four monazite generations were recognized in the analyzed sediments and associated acid volcaniclastic rock: Cambrian-Ordovician, Mississippian, Pennsylvanian, and Cisuralian. All monazite phase analyses can be categorized as monazite-(Ce), with the extent of cheralite versus huttonite exchange. Detrital monazites from the Zemplinic Pennsylvanian-Permian sediments were determined by monazite dating and subdivided to several age populations. Early Paleozoic age population was recorded in a relatively large range, from 507 to 435 Ma, with a calculated average age of 461 +/- 6.7 Ma. These ages roughly correspond to previously published detrital zircon (SHRIMP) age determinations (Middle/Late Ordovician with the age peak ca. 459 Ma) from the same stratigraphic horizons. Nevertheless, the majority of detrital monazite age data span between 360 and 300 Ma, thus forming significant spikes at 320 and 330 Ma and resulting in a calculated average age of 327 +/- 1.6 Ma. This population of detrital monazites indicates the predominance of Bashkirian-Moscovian tectonic events in the assumed source area. Derivation of monazites from the Kasimovian-Gzhelian synsedimentary acid volcanism is indicated by ages in the range of 308-299 Ma. Interestingly, only a few monazite grains derived from the volcaniclastic rock yield the age indications for the Permian extensional thermal re-heating, which has long been associated with the manifestations of acid volcanism (270-290 Ma). The monazite age data from the Zemplinic Pennsylvanian-Permian sedimentary formations reflect the main stages of tectonothermal progress in the Zemplinic crystalline basement.
