Other language confidence: 0.9974112730415471
OIB localities (e.g., Tristan, Samoa) have been considered ideal natural laboratories for studying mantle heterogeneity. Indeed, Sr, Nd, and Pb isotopes of lavas collected from OIB systems have provided insights into the existence of distinct mantle reservoirs, the origins of which are closely related to local tectonic processes: DMM, HIMU, EM1, and EM2. In this context, we aim to investigate the isotopic composition of noble gases in fluid inclusions trapped in xenoliths and lavas from Samoa and Tristan islands, two well-known enriched mantle (EM) localities. Our goal is to evaluate the role of noble gas cycling and active tectonic processes on the composition of the upper mantle. Our results show that CO2 is the most abundant volatile in all samples (lavas and xenoliths) from both localities. The 4He/20Ne ratio in most samples is lower than 150, suggesting the presence of atmospheric components in the fluid inclusions. This is further confirmed by the relatively low 40Ar/36Ar ratios, particularly in Tristan samples, which show values below 360. It is worth noting that the Samoa sample exhibits a 40Ar/36Ar ratio of 1000.4, the highest of the dataset. The Rc/Ra values (3He/4He corrected for atmospheric contamination) observed in the Samoa samples align with the Ar ratios mentioned above, as the 3He/4He ratio is the highest reported (13.32Ra). This is above the MORB range, indicating a contribution from lower mantle fluids, likely derived from the Samoan hotspot. In contrast, Tristan samples exhibit low Rc/Ra values, with an average of 5.12Ra. These low helium ratios suggest the presence of a more radiogenic, 4He-rich mantle. The low helium ratios may be related to the EM nature of the mantle. Previous studies in the Canary Islands have shown a decrease in 3He/4He ratios in the eastern part of the archipelago, where EM components have been identified (Hoernle et al., 1993; Simonsen et al., 2001; Day and Hilton, 2011, 2021; Sandoval-Velasquez et al., 2021). However, it is confirmed that an EM component can show a wide range of variation for the 3He/4He ratio, ranging from low values of 5-6Ra to values beyond the typical MORB range, which overlaps (and complicates the distinction) with other OIB contexts with HIMU signature. This publication results from work conducted under the transnational access/national open access action at INGV-Palermo- Noble gas laboratory supported by WP3 ILGE - MEET project, PNRR - EU Next Generation Europe program, MUR grant number D53C22001400005.
This dataset is a continuously growing collection of lead isotope reference data. Lead isotopes are an established method to reconstruct the raw material provenance of archaeological objects. They are typically applied to artefacts made of copper, lead, silver, and their alloys. However, also the raw material provenance of other materials such as glass, pigments and pottery was already investigated using lead isotopes. To successfully reconstruct the origin of the raw material, lead isotope signatures from as many as possible suitable raw material occurrences must be known. In the past, large-scaled research projects were carried out to characterise ore deposits especially in the Mediterranean area and Western Europe. However, many of these data are dispersed in the literature and were published in scientific articles or monographs. Consequently, each researcher or at least each research group had to build their own up-to-date database of reference data from the literature. To overcome these restrictions, to facilitate work with lead isotope reference data and particularly to make the data FAIR, i.e., findable, accessible, interoperable and reusable (Wilkinson et al. 2016), these published data are compiled and transferred into a uniform layout. They are further enhanced with additional metadata to facilitate their use in raw material provenance studies. Currently, the database is restricted to ores and minerals as these are the most relevant materials for provenance studies of ancient metals. Future updates will include hitherto uncovered regions but also additional data from countries already present. Slag and other metallurgical (by-) products from ancient sites in close vicinity to ore deposits generally are a genuine representation of the ores utilised in historic times. As such, they are highly relevant for provenance studies and an extension to these materials is therefore planned. GlobaLID is a representation of the collective work of researchers on Pb isotope studies. As such, the database is seen as a community engagement project that invites scientists all over the world to become active contributors of GlobaLID. The initiators of the database dedicate their effort to the continuation and maintenance of the database but only the support of the whole community will allow a rapid and successful growth of GlobaLID.
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:
The dataset contain full 40Ar/39Ar geochronological data completed by multi collector noble gas mass spectrometry on plagioclase and glass separates from a tuff sample interbedded in Pleistocene marine claystone (Argille di Spadafora) of northeastern Sicily (Italy). Tuff unit VU7 was identified in the field using the published base map and stratigraphic nomenclature of Di Bella et al. (2016), which correlates to bathyal marine marl (Argille di Vito Superiore) in southern Calabria. The tuff contains stratified white lapilli with abundant fresh volcanic glass shards and was deposited by a submarine turbidity current from a single volcanic eruption. The Ar laserprobe facility was realized with the financial support of CNR. The CO2 laser system was acquired within the PNRR – Mission 4, “Education and Research” - Component 2, “From research to business” - Investment line 3.1, “Fund for the creation of an integrated system of research and innovation infrastructures” - Project IR0000025 MEET. EPOS JRU Italia is acknowledged for support in the Laboratory maintenance.
The data publication presented is concerned with the collection of geochemical results enhanced with metadata of archaeologic, stylistic, geographic and other crucial information. The publication covers analytical and metadata sets of analysed projectiles, both from own and published works. Starting point for the data collection was the PhD thesis Müller 2018 were projectiles from different find sites, dating into the Roman Republic, were analysed and published. The objects up to date included in the current database are from various find sites with varying archaeological background, which have been collected and evaluated by the authors for diachronic comparison within a supra-regional frame. Own unpublished data are also included. These data are of objects, which are too isolated in terms of a research question to be published in a journal. However, our intention is to make them accessible in the context compiled here for any further use. We hereby encourage other researchers to contribute to this database either with their published or even their unpublished data so that it can continuously develop for the specific objects presented here. The samples taken by the project group were analysed in the laboratories of FIERCE, the Frankfurt Isotope and Element Research Center of Goethe-University Frankfurt and the Research Laboratory of the Deutsches Bergbau-Museum Bochum, a central unit within its research department using Multicollector ICP mass spectrometry. We are initiating this database with the goal that it will grow through collective contributions from researchers working on this topic. It should therefore be seen as a project of collaborative engagement. The research team is dedicating its efforts to the continuation and maintenance of the database. Anyone who contributes data will be named as a contributor in subsequent versions of the database.
The data presented are whole-rock geochemical analyses (major and minor elements, REE) of highliy deformed and metamorphosed rocks of the Middle and Eastern Erzgebirge nappe stacks. Geochemical discrimination was used to identify the protolith nature of a sample series representing metasedimentary, metagranitoidic, metarhyolitic, and metabasaltic rock types. Discrimination between para- and orthogneisses was also supported by mathematical factor analysis. According to new geochronological data, ages of the sample series range between Neoproterozoic to Ordovician. Analyses with different methods (ICP, AAS, XRF, OES, WET) were made between 1979 and 1991 in different laboratories of the German Democratic Republic (GDR) and the early GFZ German Research Centre for Geosciences. Economical constraints limited the capacity of and access to labs, and also available techniques in the GDR - limiting the spectrum of elements to be analysed, especially that of REE, as well. Switching from lab to lab (see table) became a neccessary tool. Despite these problems, all data proved to be comparable. This also applies in comparison to data from later used techniques (ICP, from 1991 on) on some additional sample material, regardless of its higher resolution. In few cases, detection limits have not been communicated (see template). The data are reported with the EarthChem Templates (https://doi.org/10.26022/IEDA/112263). German title: Gesamtgesteins-Geochemie (Haupt-, Spurenelemente, REE) an hoch-deformierten und metamorphosierten Gesteinen der Mittel- und Osterzgebirgirgischen Deckenstapel
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