API src

Found 7 results.

Other language confidence: 0.7567823340985442

Three Icelandic basalts for resampling of BIR basalt for production of ISO-certification of whole rock powder

The USGS has suspended the distribution of the widely used whole rock reference materials BHVO, BCR and BIR. The goal of this work is to identify a material as similar as possible to the original BIR Islandic basalt. This material can then undergo an ISO-compliant certification of the whole rock powder major and trace element contents. The sampling quarry east of Reykjavik has multiple basalt flows and it is not known which one was originally sampled in 1980 for production of above mentioned reference materials. In this study, three samples were tested to see which is most similar to what was published by Flanigan (1984). Here, the results of this exploratory sample collection are presented, but note that these data are not part of the certification process or represent certified results.

Mineralogy and Element geochemistry of volcanic rocks and sediments from the central Rift in Kenya

The Central Rift in Kenya (CRK) comprises the lakes Naivasha, Elementaita and Nakuru and the Longonot, Eburru and Menengai volcanos. The alkaline magmas, produced by the volcanoes within the CRK, lead to solid rocks likes trachytes, phonolites, and fewer basalts and accompanied soft rocks like ashes, tuffs, pumices and ignimbrites (e.g. Macdonald et al., 1987; Macdonald, 2014). Lacustrine sediments and beds of diatoms are remnants of former lake level variations caused by climate variability and topographic changes (e.g. Stoof-Leichsenring et al., 2011). The samples have been taken within the frame of a VW-Foundation funded project that tries to detect, map and monitor groundwater pollution from anthropogenic and natural sources. For a previous VW-Foundation funded project (grant 85465), also the groundwater fluoride enrichment in the CRK have been studied (Olaka et al., 2016).This data report presents the metadata, inclusive GPS data from 52 solid volcanic rock and sediment samples taken during a field excursion during May 2017. A geological map with all data locations is included in this report. After sample preparation, we performed X-ray diffraction (XRD) analyses to get the mineral content and X-ray fluorescence (XRF) as well as Ion-Chromatographic (IC) analyses to get the elemental concentration of those samples. The results are given together with analytical limitations and few additional information despite a graphic visualization of the XRD-data.The data are presented in tab-delimited text format and described in the dataset description.

Geochemical and isotopic compositions of minerals and bulk rocks of the Chachimbiro Volcanic Complex (Northern Andes, Ecuador)

This dataset provides geochemical data from from the Quaternary Chachimbiro Volcanic Complex (CVC), situated in the Western Cordillera of Ecuador, Northern Andes (0.468°N, 78.287°W). The CVC is subdivided into 4 eruptive stages (CH1, CH2, CH3, CH4) ranging in age between ~400 and ~4 ka ago (Bellver-Baca et al., 2020). The CH1 stage consists of andesitic flows erupted between 405.7 ± 20.0 and 298.6 ± 32.9 ka with collapse of the pre-existing cone at the end of the effusive period (File #1). The following CH2 stage (121.75 ± 23.2 -36.08 ± 2.8 ka) consists of andesitic to dacitic domes and pyroclastic rocks which also suffered a collapse event as shown by the scar and the uprooted domes in the hillside of the edifice (File #1). The CH3 unit (36.08 ± 0.28 – 22.73 ± 0.12 ka) consists of two main andesitic to dacitic domes (Hugá and Albují: H and A, respectively, in File #1) and effusive rocks. CH4 consists of a volumetrically small rhyodacitic pyroclastic unit which was produced by a lateral blast dated at 5.5-5.8 ky ago. A younger pyroclastic episode (<4.15 ka ago) has been related to the Pucará dome (Comida, 2012), but rocks of this event have not been investigated in the present study. The bulk rock and mineral data are used to reconstruct the plumbing system beneath the CVC during its ~400 ka long lifetime. Since the temporal geochemical evolution of CVC bulk rocks towards higher values of adakite-like indices (e.g., Sr/Y, La/Yb) bears strong similarities to that of magmatic systems associated with supergiant porphyry copper deposits, these data may serve to better understand how adakite-like signatures are acquired in fertile arc magmatic systems with metallogenic implications. Files included are: • 2024-018_Chiaradia-et-al_Table-1_Sample-overview: sample overview table with coordinates of and type of analyses carried out on each sample (Table #1) • 2024-018_Chiaradia-et-al_File_1_map: a geological map with location of investigated samples (File #1) • 2024-018_Chiaradia-et-al_File_2_WholeRocks: geochemical and radiogenic isotope data on bulk rocks (File #2). • 2024-018_Chiaradia-et-al_File_3_Pyroxene: contains microprobe and LA-ICP-MS major and trace element analyses of clino- and orthopyroxenes from the CVC and P-T conditions retrieved from clinopyroxene compositions (File #3) • 2024-018_Chiaradia-et-al_File_4_Amphibole: contains microprobe and LA-ICP-MS major and trace element analyses of amphiboles from the CVC and P-T-H2Omelt, fO2 conditions retrieved from amphibole compositions (File #4). • 2024-018_Chiaradia-et-al_File_5_Plagioclase: contains microprobe and LA-ICP-MS major and trace element analyses of plagioclases from the CVC (File #5). • 2024-018_Chiaradia-et-al_File_6_Equilibrium tests: reports the calculations to retrieve pressure and temperature data from clinopyroxene-melt equilibrium and clinopyroxene-only composition (File #6). • 2024-018_Chiaradia-et-al_File_7_CPX_Thermo_Barometry: reports the calculations to obtain P-T conditions from clinopyroxene-orthopyroxene equilibria in the same thin section (File #7). • 2024-018_Chiaradia-et-al_File_8_Cpx_Opx_Thermo_Barometry: reports the equilibrium tests between minerals (clinopyroxene, orthopyroxene, amphibole) and host rock compositions and the P-T values retrieved by clinopyroxene and amphibole analyses that passed the test (File #8). Associated RStudio Scripts are available as https://doi.org/10.5880/fidgeo.2025.010 (Chiarada, 2025).

Physical and geochemical data on a drill core from the semi-arid Coastal Cordillera, Chile

This dataset contains petrophysical, geochemical, and mineralogical data from a drilling core from the Coastal Cordillera, Chile. The drilling campaign in the semi-arid field site Reserve Santa Gracia was conducted in the framework of the “EarthShape” project (DFG SPP1803) to study deep weathering along a climate gradient. Previous studies in this area found that the weathering front is located much deeper than expected (Oeser et al., 2018). To explore the weathering profile and the depth of the weathering front, we performed various geochemical, petrophysical, and mineralogical analyses. The drilling campaign was conducted in March and April 2019, using the wireline drilling method with a standard industry truck-mounted PQ3-sized (85 mm core diameter, 123 mm hole diameter) rotary drilling rig (Sondajes Araos E.I.R.L.). A detailed description of the drilling activities is given in Krone et al. (2021). The retrieved core runs with a maximum length of 1.5 m were drilled using potable water, with added contamination control tracer for further microbiological analyses of the rock. As basis for our detailed study of deep weathering we determined the porosity, density, specific surface area, elemental composition, mineralogical composition, Fe oxidation, and the degree of weathering from chemical depletion, volumetric strain, and the weathering rate using the in situ cosmogenic nuclide beryllium-10 (10Be).

RStudio codes used to model AFC and FC processes for rocks and minerals of the Chachimbiro Volcanic Complex (CVC) (Ecuador)

Eight (8) RStudio codes written to model REE and Sr isotope compositions plus Y of bulk rocks and minerals from the four stages (CH1 to CH4) of the 400-6 ka old Chachmbiro Volcanic Complex (CVC) in the frontal arc of Northern Ecuador. RStudio Code REE_Modelling_WR_CH1 reports AFC modelling of REE compositions of the average composition of CH1 low SiO2 andesitic rocks from a basaltic parent RStudio Code REE_Modelling_WR_CH2_3 reports AFC modelling of REE compositions of the average composition of CH2-CH3 high SiO2 andesitic rocks from a CH1-type andesitic parent RStudio Code REE_Modelling_WR_CH4 reports AFC modelling of REE compositions of the average composition of CH4 rhyodacitic rocks from a CH1-type andesitic parent RStudio Code REE_Modelling_Cpx_CH1 reports FC modelling of REE compositions of the average composition of a melt in equilibrium with Cpx of CH1 rocks from a CH1-type andesitic parent RStudio Code REE_Modelling_AmphTr_A reports FC modelling of REE compositions of the average composition of a melt in equilibrium with AmphTr_A amphiboles of CVC rocks from a CH1-type andesitic parent RStudio Code REE_Modelling_AmphTr_B reports FC modelling of REE compositions of the average composition of a melt in equilibrium with AmphTr_B amphiboles of CVC rocks from a CH1-type andesitic parent RStudio Code REE_Modelling_AmphTr_C reports FC modelling of REE compositions of the average composition of a melt in equilibrium with AmphTr_C amphiboles of CVC rocks from a CH1-type andesitic parent RStudio Code Sriso_Y_Modelling_CVC reports AFC modelling of CVC rocks in the 87Sr/86Sr versus Y space. These Codes are related to the ms Chiaradia et al. "Progressive build-up of a trans-crustal system beneath an adakite-like volcanic complex (Chachimbiro, Ecuador): an example of an embryonic porphyry Cu system?" by Chiarada et al. (2025). The associated data is available under https://doi.org/10.5880/fidgeo.2024.018 (Chiarada, 2025)

Geochemical, isotopic, geochronological data and assimilation plus fractional crystallization model of The Pleiades Volcanic Field (Northern Victoria Land, Antarctica)

This dataset presents a set of geographical, geochemical and isotopic data, microphotos of thin sections and geochemical binary variation diagrams of sixteen samples of volcanic rocks collected in The Pleiades Volcanic Field, Northern Victoria Land, Antarctica (≈ 72° 42’ S; 165° 43’ E), made up of some 20 monogenetic, partly overlapping scoria and spatter cones, erupted in the last 900 ka, cropping out from the ice close to the head of Mariner Glacier. First two files of dataset (kmz files) contain locations of volcanic centres of The Pleaides Volcanic Fiels and the locations of the collected samples. File #3 contains analytical results of full major element, trace element and radiogenic (Sr, Nd, Pb) isotopic data of collected samples. File #4 contains analytical details of Ar-Ar geochronological data. File #5A and 5B contains modelling results, respectively, of major elements and trace elements-Sr isotope ratios of Assimilation plus Crystal Fractionation (AFC) applied to selected samples of The Pleiades Volcanic Field. Other files are images containing high-resolution pictures collected through optical microscopy of thin sections of collected samples showing their most important petrographic features and binary geochemical diagrams of variation of major elements and selected trace elements against SiO2 (wt%). This data are supplement to a manuscript currently submitted to G3 – Geochemistry, Geophysics, Geosystems, and are used to describe the main petrographic and geochemical features of the volcanic products outcropping at the Pleiades, define the characters of their mantle source, to define their evolutionary patterns. Through these data, we observed an unusual fractionation trend for this kind of volcanic fields, with a large assimilation rate of crustal material, ane we hypothesize a role of the thick-ice cap able to suppress the eruption potential and to increase the residence times of magma in crustal chambers.

A database of caldera collapse analogue models stretched under extensional conditions

This dataset presents the raw data from one experimental series (named CCEX, i.e., Caldera Collapse under regional Extension) of analogue models performed to investigate the process of caldera collapse followed by regional extension. Our experimental series tested the case of perfectly circular collapsed calderas afterward stretched under regional extensional conditions, that resulted in elongated calderas. The models are primarily intended to quantify the role of regional extension on the elongation of collapsed calderas observed in extensional settings, such as the East African Rift System. An overview of the performed analogue models is provided in Table 1. Analogue models have been analysed quantitatively by means of photogrammetric reconstruction of Digital Elevation Model (DEM) used for 3D quantification of the deformation, and top-view photo analysis for qualitative descriptions. The analogue materials used in the setup of these models are described in Montanari et al. (2017), Del Ventisette et al. (2019), Bonini et al., 2021 and Maestrelli et al. (2021a,b).

1