The western Eger Rift in the Czech Republic is a currently inactive volcanic area characterized by earthquake swarms and degassing of mantle-derived fluids. Gases obtained from minerals and from repeatedly sampled free gases are used to trace the origin and evolution of volatiles and determine the conditions of the magma reservoir. Helium isotopes in fluids and minerals are up to 5.95 RA, with 20Ne/22Ne ratios up to ~11.0 and 21Ne/22Ne ratios up to ~0.048, suggesting a mixed atmospheric-mantle source for neon. Some crustal input may also be present. The slightly lower-than-mantle He isotopic ratios and the variability in Ne isotopic compositions indicate that these gases may have been impacted by a subduction-related crustal component during the Variscan (or Hercynian) Orogeny. 40Ar/36Ar ratios are higher than atmospheric levels and arrive up to 4680, indicating a mixture of atmospheric and mantle sources. Thermobarometry of pyroxene mineral grains reveals temperatures and pressures suggesting that the crystallization started at ~75 km depth and ended at ~20 km depth following a smooth p-T course. This implies diverse magma ascent conditions. A total of 56 gas samples were collected from two intensively degassing areas in the western Eger Rift (Czech Republic), namely the mofette fields of Bublák and Hartoušov. From the Hartoušov mofette field, 24 gas samples of fluids ascending in two boreholes (F1:∼28 m depth and F2: ∼108 m depth) and 22 samples of gases emerging in two nearby ponds [surface expressions Hartoušov Mofette (HM) and Hartoušov Mofette South (HMS)] were taken. Ten samples were collected from a pond in the Bublák mofette field (Bbl). In addition to the gas samples, ten rock samples were collected from rock exposures [i.e. Libá (LI) and Číhaná (CI) in quarries, Horní Slavkov (HS1&2), Pila (PI), Dolní Dražov (DD), Kadaň (KN), Horní Paseky (HP), and Slapany (SL) in natural cliffs, and Hlinky (HL) in an outcrop] within the western Eger rift area. In addition, six samples of ultramafic nodules/xenoliths were obtained from the Quaternary tephra deposit of the Mýtina maar and from Železná hůrka scoria cone. Gas and rock sampling:
This data set is Part 2 of the compiles whole-rock chemical data for late-Variscan low-F biotite and two-mica granites in the German Erzgebirge, in the Saxothuringian Zone of the Variscan Orogen. The group of F-poor biotite granites is represented by the composite massifs of Kirchberg and Niederbobritzsch, the Plohn Granite Suite (PGS), the Aue Granite Suite (AGS), and the subsurface granites of Beiersdorf und Bernsbach. For the group of two-mica granites, compositional data for the multi-stage Bergen massif and the granites from Lauter and Schwarzenberg are reported (Figure 1). Crystal-melt fractionation was the dominant process controlling the evolution of bulk composition in the course of massif/pluton formation. However, metasomatic and hydrothermal processes involving late-stage residual melts and high-T late- to post-magmatic fluids became increasingly more important in highly evolved units and have variably modified the abundances of mobile elements. Interaction with the various metamorphic country rocks and infiltration of meteoric low-T fluids have further disturbed the initial chemical patterns in the endocontact zones and zones influenced by surface weathering. The data set reports whole-rock geochemical analyses for enclaves, granites, aplites, endocontact rocks, and some facial varieties. The data are presented as Excel (xlsx) and machine-readable txt formats. The content of the excel sheet and further information on the granites and regional geology are provided in the data description file.
This data set is the 1st part of a mini-series assembling whole-rock chemical data for late-Variscan granites of the Erzgebirge-Vogtland metallogenic province in the German Erzgebirge, in the Saxothuringian Zone of the Variscan Orogen, which is dedicated to the group of P-F-rich Li-mica granites. Listed are data from the massifs/plutons of Eibenstock in the western Erzgebirge and Annaberg, Geyer, Pobershau, and Seiffen in the central Erzgebirge (Figure 1). All these occurrences represent composite bodies made-up of texturally and geochemically distinct, but cogenetic sub-intrusions, which are associated with intra- und perigranitic aplitic dykes, pegmatitic schlieren, and frequently mineralized quartz veins and greisens (Tables 1-3). These granites exhibit moderately to strongly elevated concentrations of P, F, Li, Rb, Cs, Ta, Sn, W and U, but are low to very low in Ti, Mg, V, Sc, Co, Ni, Sr, Ba, Y, Zr, Hf, Th, and the REEs. Crystal-melt fractionation was the dominant process controlling the evolution of bulk composition in the course of massif/pluton formation. However, metasomatic processes involving late-stage residual melts and high-T late- to postmagmatic fluids became increasingly more important in highly evolved units and have variably modified the abundances of mobile elements (P, F, Li, Rb, Cs, Ba, Sr). Interaction with the various country rocks and infiltration of meteoric low-T fluids have further disturbed the initial chemical patterns. The data set reports whole-rock geochemical analyses for granites, aplites, and endocontact rocks obtained for the massifs/plutons of Eibenstock, Pobershau, Satzung, Annaberg, and Geyer. Data are provided as separate excel and csv files. The content of the excel sheet and further information on the granites and regional geology are provided in the data description file.
South Wales is characterised by a rich variety of geologic formations and rocks of different ages and periods, and a large asymmetric syncline, as perhaps its most significant structural geological feature, extending from east to west over a length of approximately 96 km and 30 km from north to south, respectively. This oval-shaped syncline is part of the Variscan orogenic thrust and fold belt in Central Europe and covers some 2,700 km2, with coal-bearing rocks from the Upper Carboniferous (Westphalian Stage) deposited in the central syncline and older rocks outcropping in a peripheral belt around it. The coal-bearing sequence begins with Namurian grits and shales, overlain by the more productive Lower, Middle and Upper Coal Measures. A 3D structural geological model has been implemented for the central part of the South Wales Syncline and its bedrock geology. The oldest rocks in the model domain date back to the Pridoli Series from the uppermost Silurian, the youngest to the Westphalian Stage of the Upper Carboniferous. For model implementation, mainly open access data from the British Geological Survey (BGS) has been used. The final 3D structural geological model covers the entire Central South Wales Syncline and is 32.8 km wide and 36.6 km long. In total, the 3D model includes 21 fault zones and the elevation depth of ten surfaces: (1) Top Upper Coal Measures Formation; (2) Top Middle Coal Measures Formation; (3) Top Lower Coal Measures Formation; (4) Top Millstone Grit Group; (5) Top Dinantian Rocks; (6) Top Upper Devonian Rocks; (7) Top Lower Devonian Rocks (sandstone dominated); (8) Top Lower Devonian Rocks (mudstone dominated); (9) Top Pridoli Rocks; (10) Top Ludlow Rocks (in parts).
This data set is Part 9 of a series of data sets dealing with the composition of accessory minerals from felsic igneous rocks compiles chemical data for monazite-(Ce), xenotime-(Y) and zircon from several, late-Variscan granite occurrences in the Aue-Schwarzenberg Granite Zone (ASGZ) located in the Western Erzgebirge−Vogtland metallogenic province of Germany. The rocks treated in this data set encompass the biotite granites of the Aue suite, Bernsbach and Beierfeld, and the two-mica granites from Lauter and the Schwarzenberg suite. The data set contains the complete pile of electron-microprobe analyses for monazite-(Ce) (MONA-ASGZ-2021), xenotime-(Y) (XENO-ASGZ-2021) and zircon (ZIRC-ASGZ-2021). Tables are presented as Excel (xlsx) resp. machine-readable csv formats. The content of the tables and further information on the granites and regional geology are provided in the data description file and the supplementary literature. The ASGZ (about 325 Ma) is located within the deep-reaching Gera-Jáchymov Fault Zone and includes the F-poor biotite granites of the Aue suite (including the granite occurrences at Schlema-Alberoda, Aue, Auerhammer, and Schneeberg), Bernsbach and Beierfeld, and the F-poor two-mica granites of the Schwarzenberg suite (covering the granite occurrences at Schwarzenberg, Neuwelt, and Erla) and Lauter (Fig. 1). The granite encountered by drilling at the village Burkersdorf does not represent an independent intrusion, but is instead a subsurface exposure of the westerly Kirchberg granite, at the contact to the metamorphic country rock. The petrography, mineralogy, geochemistry, isotopic composition, and geochronology of the ASGZ rocks have been comprehensively described by Förster et al. (2009). The paper of Förster (2010) reports a selection of results of electron-microprobe analyses of monazite-(Ce), xenotime-(Y) and zircon, but the bulk of the obtained data remained unpublished. This paper also provides a mineralogical mass-balance calculation for the lanthanides and actinides of the Aue and Schwarzenberg granite suites and a selection of back-scattered electron images displaying the intergrowths, texture, and alteration patterns of the radioactive and REE-Y-Zr-bearing accessory species. The F-poor biotite granites of the ASGZ are weakly to mildly peraluminous (A/CNK = 1.07 – 1.14; SiO2 = 70 – 76 wt.%). The F-poor two-mica granites are mildly to strongly peraluminous (A/CNK = 1.17 – 1.26) and cover a similar range in silica concentration (69 – 77 wt%). From this granite group, only more fractionated, higher evolved sub-intrusions were subjected to the study of accessory-mineral composition. Some granites of this zone are genetically related with ortho-magmatic W-Mo veins and para-magmatic vein-type U mineralization.
This data set is the sixth part of a series reporting chemical data for accessory minerals from felsic igneous rocks. It assembles the results of electron-microprobe spot analyses of monazite-(Ce), xenotime-(Y) and zircon from the late-Variscan granites of the Fichtelgebirge/Smrčiny in the Saxothuringian Zone of the Variscan Orogen in Germany/ Czech Republic.The granites form an older, Namurian intrusive complex (OIC-p and OIC-e) and a younger, post-Westphalian intrusive complex (YIC-1 and YIC-2). Both complexes have distinct radioactive accessory-mineral assemblages and compositions. The OIC-p biotite monzogranites contain monazite-(Ce) and minor thorite, but apparently lack magmatic xenotime-(Y) and uraninite. The more evolved OIC-e two-mica granites bear monazite-(Ce) occasionally rich in Th (up to 21 wt% ThO2) and U (8 wt% UO2), xenotime-(Y) of moderate U content (< 3.3 wt% UO2), and uraninite poor in Th and the REE. The most fractionated YIC Li-mica granites (YIC-2) may contain monazite extremely high in Th (40.5 wt% ThO2) and U (8.6 wt% UO2), which classify as cheralite-(Ce), xenotime-(Y) rich in U (6.3 wt% UO2) and such with elevated Y/Ho ratios (up to 48), and also a Th–REE-poor uraninite. In these granites, zircon may contain up to 5 wt% HfO2 and display low, fractionated Zr/Hf ratios (down to 10).The data set contains the complete pile of electron-microprobe analyses for monazite-(Ce) (MONA-FICH-2020), xenotime-(Y) (XENO-FICH-2020), and zircon (ZIRC-FICH-2020). All tables are presented as Excel (xlsx) and machine-readable txt formats. The content of the tables and further information on the granites and regional geology are provided in the data description file.
Part seven of a series of data sets dealing with the composition of accessory minerals from felsic igneous rocks reports chemical data for monazite-(Ce) and zircon from eight occurrences of high-Si felsic microgranites/rhyolites in the Erzgebirge−Vogtland metallogenic province of Germany, which possibly emplaced between 305 and 295 Ma. The subvolcanic rocks are discriminated into three groups according to whole-rock geochemistry. Mineral data are acquired between about 1995 and 2005 on surface rocks and borehole samples. The data set contains the complete pile of electron-microprobe analyses for monazite-(Ce) (MONA-VOLC-2020) and zircon (ZIRC-VOLC-2020). All tables are presented as Excel (xlsx) and machine-readable csv formats. The content of the tables and further information on the granites and regional geology are provided in the data description file. Information on xenotime-(Y), which is commonly rare and did not precipitate in all rhyolites, and rhabdophane-(Ce), which was observed only ones as alteration product of monazite-(Ce), is provided elsewhere (cf. data description file).
This data set is the 5th fifth part of a series reporting chemical data for accessory minerals from felsic igneous rocks. Most data refer to plutonic rocks from the Saxothuringian Zone of the Variscan Orogen (Erzgebirge−Vogtland metallogenic province) in Germany performed between about 1995 and 2005 on surface rocks and borehole samples.This data set assembles the results of electron-microprobe spot analyses of monazite-(Ce), xenotime-(Y) and zircon from two concealed, genetically distinct occurrences of evolved, F-rich Li-mica granite, that are the transitional S-I-type P-rich granites of Pobershau-Satzung (POB-SZU) and the P-poor granite of Seiffen (SEI), a representative of the class of aluminous A-type granites.Of all three species, grains of abnormal composition are present, reflecting the evolved nature and specific composition of their granite hosts. The most striking differences in mineral composition between the two granite occurrences are displayed by a) the substitution reaction governing the incorporation of Th+U in monazite (cheralite substitution, Ca(Th,U)REE-2, in POB-SZU and huttonite substitution, Th(U)SiREE-1P-1, in SEI) and b) the chondrite-normalized REE patterns of xenotime (peaking at Tb-Dy in POB-SEI and Yb-Lu in SEI).The data set contains the complete pile of electron-microprobe analyses for monazite-(Ce) (MONA-POB-SEI-NBZ2019), xenotime-(Y) (XENO-POB-SEI2019), and zircon (ZIRC-POB-SEI2019). All tables are presented as Excel (xlsx) and machine-readable csv formats. The content of the tables and further information on the granites and regional geology are provided in the data description file.
This data set is the part 8 of a series reporting chemical data for accessory minerals from felsic igneous rocks. Compositional data were acquired by electron-probe microanalysis (EPMA) between about 1995 and 2005 on surface rocks and borehole samples. This data set assembles the results of EPMA of fluorapatite from felsic rocks representing three groups of granites in the Erzgebirge−Vogtland metallogenic province of Germany emplaced in the late Carboniferous: F-poor biotite granites, F-poor two-mica granites, and P-F-rich Li-mica granite. In these rocks, fluorapatite is typically omnipresent. It has to be noted that apatite has not yet been in the focus of mineralogical studies of the granites in this province and a comprehensive survey of its compositional signature and variability in space and time is still pending. However, the data listed in this data set provide a valuable glimpse into the similarities and differences in apatite chemistry between geochemically distinct felsic rocks, and into the evolution in composition from early to late crystallizing apatite populations. The data underpin that apatite is a sensitive monitor of the compositional properties of the media (melts and fluids) from which it was deposited or with which it interacted. Apatite from the studied rocks is basically fluorapatite with little or no Cl and OH detected respectively inferred. Elemental variations are observed at various scales, i.e., between granite groups, subsequently crystallized sub-intrusion within composite massifs, grains present in a single thin section, or between the center and the rim of a particular grain. These variations in particular refer to the following elements: Mn, Fe, Na, and the rare-earth elements (REE). For example, measured Mn concentrations range from 0.15 to 8.8 wt% MnO. The data set contains the complete pile of electron-microprobe analyses for fluorapatite (APAT-ERZ-2020). The data are presented as Excel (xlsx) and tab-delimited text (txt) formats. The content of the tables and further information on the granites and regional geology are provided in the data description file.
This data set compiles the results of electron-microprobe spot analyses of monazite-(Ce), xenotime-(Y) and zircon from the two-mica granite massif of Bergen. This massif is composed of compositionally and texturally distinct sub-intrusions, which occasionally contain dark microgranular enclaves and are cross-cut by aplitic dikes. These late-Variscan (c. 325 Ma) granites are evolved, Si-rich (70.6−76.3 wt% SiO2), of transitional I−S-type affinity, and spatially associated with minor W−Mo mineralization.Data indicate that the composition of monazite-(Ce) and zircon changes with fractionation-driven evolution of magma chemistry. In the course of magma differentiation, monazite-(Ce) chemistry evolves towards enrichment Th and U and development of “irregular” chondrite-normalized LREE patterns, with negative anomalies at La or Nd, or both. Monazite-(Ce) precipitated from more evolved magma batches also tends to be richer in MREE and HREE relative to that occurring in early-stage granites. Composition of zircon in more differentiated sub-intrusions displays a large variability. A greater number of grains or domains are distinguished by enrichment in P, Hf, Al, Sc, Y+HREE and low analytical totals, reflecting their crystallization from volatile-rich magmas and/or their interaction with late-magmatic fluids. Xenotime-(Y) chemistry is comparatively insensitive to changes of magma composition that characterized the Bergen massif.The data set published here contains the complete pile of elecron-microprobe analyses for the three accessory minerals monazite-(Ce) (MonaBrg2018), xenotime-(Y) (XenoBRG2018) and zirkon (ZircBRG2018). All tables are presented as Excel (.xlsx) and csv formats. The content of the tables and further data description are given in the data description file.
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