scholarly journals Near real-time management of spectral interferences with portable XRF spectrometers: Application to Sc quantification in nickeliferous laterite ores

2021 ◽  
pp. geochem2021-015
Author(s):  
Elodie Lacroix ◽  
Jean Cauzid ◽  
Yoram Teitler ◽  
Michel Cathelineau
Keyword(s):  
Time Management ◽  
Chemical Elements ◽  
Fe Method ◽  
Portable Xrf ◽  
Experimental Conditions ◽  
Spectral Interferences ◽  
Content Type ◽  
Spectral Fitting ◽  
Supplementary Material ◽  
Geochemical Analyses

Since the development of portable XRF (pXRF) spectrometers, few studies have been conducted on the influence of spectral interferences between chemical elements. This study aims to improve the management of these interferences to obtain more reliable geochemical analyses. We specifically investigate Ca-related interferences on Sc analysis for the case of Ni-rich laterite samples using the Niton XL3t GOLDD+ pXRF analyser. Three quantification methods were tested on 59 pelletised samples using the ‘Soil’ mode. The first named ‘Manufacturer’, represents the elemental quantification directly provided by the device based on Regions of Interest (ROI) and multilinear corrections of spectral interferences configured during the spectrometer design. The second, the ‘20 Cu’ method, is based on spectral fitting using the PyMCA software. The third, the ‘18 Fe’ method, combines spectral fitting with modified experimental conditions. For each, a quantification methodology was developed, establishing (i) Ca and Sc calibration lines and (ii) Ca/Sc threshold values delimiting fields of ‘reliable’, 'to be confirmed,’ and ‘unreliable’ measurements. The ‘20 Cu’ and ‘18 Fe’ methods greatly extend the ‘reliable measurements’ field concerning the Ca/Sc ratio compared to the ‘Manufacturer’ method. The ‘18 Fe’ method was also found to provide the most negligible measurement dispersion.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5511838

Volcaniclastic deposits and sedimentation processes around volcanic ocean islands: the central Azores

2021 ◽  
pp. SP520-2021-62
Author(s):  
Yu-Chun Chang ◽  
Neil C. Mitchell ◽  
Thor H. Hansteen ◽  
Julie C. Schindlbeck-Belo ◽  
Armin Freundt
Keyword(s):  
Volcanic Glass ◽  
Sedimentary Facies ◽  
Turbidity Currents ◽  
Content Type ◽  
Core Logging ◽  
Supplementary Material ◽  
Geochemical Analyses ◽  
Lithological Composition ◽  
Volcaniclastic Deposits ◽  
Ocean Islands

AbstractGeological histories of volcanic ocean islands can be revealed by the sediments shed by them. Hence there is an interest in studying cores of volcaniclastic sediments that are particularly preserved in the many flat-floored basins lying close to the Azores islands. We analyse four gravity cores collected around the central group of the islands. Three sedimentary facies (F1-F2a, F2b) are recognized based on visual core logging, particle morphometric and geochemical analyses. F1 is clay-rich hemipelagite comprising homogeneous mud with mottled structures from bioturbation. F2a and F2b are both clay-poor volcaniclastic deposits, which are carbonate-rich and carbonate-poor, respectively. More biogenic carbonate in F2a reflects the incorporation of unconsolidated calcareous material from island shelves or bioturbation. Within F2a and F2b we identify deposits emplaced by pyroclastic fallout, primary or secondary turbidity currents by combining multiple information from lithological composition, sedimentary structures, chemical composition of volcanic glass shards and morphometric characteristics of volcanic particles. Primary volcaniclastic sediments were found in all four cores, echoing activity known to have occurred up to historical times on the adjacent islands. These preliminary results suggest that greater details of geological events could be inferred for other volcanic islands by adopting a similar approach to core analysis.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5602176

scholarly journals Stable isotopes (δ13C, δ18O) and element ratios (Mg/Ca, Sr/Ca) of Jurassic belemnites, bivalves and brachiopods from the Neuquén Basin (Argentina): challenges and opportunities for palaeoenvironmental reconstructions

2020 ◽  
Vol 178 (1) ◽  
pp. jgs2020-163
Author(s):  
Matthias Alberti ◽  
Horacio Parent ◽  
Alberto C. Garrido ◽  
Nils Andersen ◽  
Dieter Garbe-Schönberg ◽  
...  
Keyword(s):  
Environmental Parameters ◽  
Global Pattern ◽  
Content Type ◽  
Marginal Seas ◽  
Temperature Reconstructions ◽  
Challenges And Opportunities ◽  
Neuquen Basin ◽  
Supplementary Material ◽  
Neuquén Basin ◽  
Geochemical Analyses

Fossils from the Jurassic succession of the Neuquén Basin (Argentina) were analysed for their stable isotope (δ13C, δ18O) and elemental (Mg/Ca, Sr/Ca) composition. Mg/Ca ratios point to comparatively stable temperature conditions from the Bajocian to Early Oxfordian and during the Tithonian, but do not allow a reliable reconstruction of absolute water temperatures. Sr/Ca ratios follow the general global pattern, indicating water exchange between the basin and the open ocean. The δ18O values can be translated into water temperatures between 20 and 25°C for most of the studied intervals with possible shorter cold spells in the Late Pliensbachian, Bajocian and Late Tithonian. However, precise temperature reconstructions are complicated by bivalve shells from the northern–central part of the basin pointing to local fluctuations in the δ18O values of seawater. Potential reasons for these variations are discussed, but it seems most likely that they are caused by phases of enhanced freshwater input leading to meso- to brachyhaline conditions in the northern study areas. This paper therefore exemplifies the particular challenges for temperature reconstructions in marginal seas and highlights the opportunities of combining different geochemical proxies to disentangle the influence of different environmental parameters.Supplementary material: Detailed results of the geochemical analyses, geographical coordinates and information on biostratigraphy are available at https://doi.org/10.6084/m9.figshare.c.5173466

scholarly journals Marie Byrd Land lithospheric mantle: A review of the xenolith record

2021 ◽  
pp. M56-2020-17
Author(s):  
Monica R. Handler ◽  
Richard J. Wysoczanski ◽  
John A. Gamble
Keyword(s):  
Lithospheric Mantle ◽  
Rift System ◽  
Type I ◽  
Content Type ◽  
Partial Melt ◽  
West Antarctic ◽  
Supplementary Material ◽  
Geochemical Analyses ◽  
West Antarctic Rift System ◽  
West Antarctic Rift

AbstractThe Marie Byrd Land (MBL) lithospheric mantle xenolith record comprises over 100 samples from a range of localities spanning both major crustal terranes that comprise MBL: Ross and Amundsen provinces. Coarse granular to porphyroclastic in texture, the xenoliths are predominantly Type I spinel-bearing lherzolites to harburgites, but include rare dunite and pyroxenite examples. Garnet is absent and no hydrous phases, such as amphibole or mica, have been reported to date, although traces of apatite may be present. Characterisation of the lithospheric mantle composition and its evolution however, is hampered by patchy and uneven geochemical analyses across the xenolith suite. Nonetheless, a picture emerges of a heterogeneous lithosphere beneath both Ross and Amundsen Provinces. Previously published and new data reported here are consistent with samples ranging from variably cryptically metasomatised residua from variable (10 - 25%) degrees of partial melt extraction to refertilised compositions. Limited isotopic data point to a complex history, providing evidence for both ancient Proterozoic lithospheric mantle and preservation of Ordovician events. The Sr-Nd-Pb composition of the sampled lithospheric mantle overlaps the common low-µ isotopic endmember identified in Cenozoic magmatism from MBL and the wider West Antarctic Rift System.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5309814

scholarly journals Reduction of the Temperature Sensitivity of Halomonas hydrothermalis by Iron Starvation Combined with Microaerobic Conditions

2015 ◽  
Vol 81 (6) ◽  
pp. 2156-2162 ◽  
Author(s):  
Jesse P. Harrison ◽  
John E. Hallsworth ◽  
Charles S. Cockell
Keyword(s):  
Physicochemical Parameters ◽  
Marine Bacterium ◽  
Chemical Elements ◽  
Extreme Environments ◽  
Iron Availability ◽  
Iron Starvation ◽  
Specific Chemical ◽  
Content Type ◽  
Distribution And Ecology ◽  
Microaerobic Conditions

ABSTRACTThe limits to biological processes on Earth are determined by physicochemical parameters, such as extremes of temperature and low water availability. Research into microbial extremophiles has enhanced our understanding of the biophysical boundaries which define the biosphere. However, there remains a paucity of information on the degree to which rates of microbial multiplication within extreme environments are determined by the availability of specific chemical elements. Here, we show that iron availability and the composition of the gaseous phase (aerobic versus microaerobic) determine the susceptibility of a marine bacterium,Halomonas hydrothermalis, to suboptimal and elevated temperature and salinity by impacting rates of cell division (but not viability). In particular, iron starvation combined with microaerobic conditions (5% [vol/vol] O2, 10% [vol/vol] CO2, reduced pH) reduced sensitivity to temperature across the 13°C range tested. These data demonstrate that nutrient limitation interacts with physicochemical parameters to determine biological permissiveness for extreme environments. The interplay between resource availability and stress tolerance, therefore, may shape the distribution and ecology of microorganisms within Earth's biosphere.

RBS-sponsored Sprint as Springboard for women undergraduates ' success

2016 ◽  
Vol 48 (1) ◽  
pp. 9-15
Author(s):  
Bob Little
Keyword(s):  
Time Management ◽  
Well Being ◽  
Self Esteem ◽  
Career Goals ◽  
Gender Pay Gap ◽  
Pay Gap ◽  
Life Balance ◽  
Content Type ◽  
Personal Lives ◽  
Research Findings

Purpose – The purpose of this paper is to set out the results of research which showed the gender pay gap among graduates and outline some of the steps being taken to combat this. In particular, it outlines the Sprint programme, developed for women undergraduates. This programme aims to add value to the overall student experience at university, improve employability and help to ensure that each undergraduate – regardless of her subject, department or career aspirations – can develop to her fullest potential. Design/methodology/approach – This paper comprises results of research carried out by Oxford University’s Careers Service. It also contains the results of interviews with the developers, deliverers, sponsors and users of the Sprint programme – a programme which was developed as a response to these research findings. Findings – The Sprint programme helps women focus on their studies at university, achieving results such as improved visibility and effectiveness in tutorials, better time management, less study stress, a boost in confidence and self-esteem. They also use Sprint to sharpen their career goals, raise their aspirations, explore possibilities and to take advantage of the work shadowing, internships and mentoring often offered by corporate sponsors. Participants in the Sprint programme also tend to find it also helps them to achieve results in their personal lives – such as sorting out difficult relationships, improving fitness and gaining a better study/life balance. Research limitations/implications – It is possible to bridge the gender pay gap as well as benefit women in other ways via learning and development activities, such as those promoted via the Sprint programme. Practical implications – With help from programmes such as Sprint, women can achieve improved work visibility and effectiveness, better time management, reduced stress, increased confidence and self-esteem. This helps them achieve their career goals, raise their aspirations and generally develop their careers. Social implications – Women can be helped to compete effectively with men in the workplace as well as be successful in their personal lives (in terms of sorting out difficult relationships, improving fitness and gaining a better study/life balance). This offers many benefits for women – and for the well-being of society in general. Originality/value – The Sprint programme, along with the approach of The Springboard Consultancy, is unique. Although the Sprint programme is relatively new – having started in 2013 – it is already bearing positive results.

Effect of 3D printer enabled surface morphology and composition on coral growth in artificial reefs

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ilse Valenzuela Matus ◽  
Jorge Lino Alves ◽  
Joaquim Góis ◽  
Augusto Barata da Rocha ◽  
Rui Neto ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Chemical Composition ◽  
Chemical Elements ◽  
Three Dimensional ◽  
Coral Growth ◽  
Coralline Algae ◽  
Textured Surface ◽  
Crustose Coralline Algae ◽  
Statistical Parameters ◽  
Content Type

Purpose The purpose of this paper is to prove and qualify the influence of textured surface substrates morphology and chemical composition on the growth and propagation of transplanted corals. Use additive manufacturing and silicone moulds for converting three-dimensional samples into limestone mortar with white Portland cement substrates for coral growth. Design/methodology/approach Tiles samples were designed and printed with different geometries and textures inspired by nature marine environment. Commercial coral frag tiles were analysed through scanning electron microscopy (SEM) to identify the main chemical elements. Raw materials and coral species were selected. New base substrates were manufactured and deployed into a closed-circuit aquarium to monitor the coral weekly evolution process and analyse the results obtained. Findings Experimental results provided positive statistical parameters for future implementation tests, concluding that the intensity of textured surface, interfered favourably in the coralline algae biofilm growth. The chemical composition and design of the substrates were determinant factors for successful coral propagation. Recesses and cavities mimic the natural rocks aspect and promoted the presence and interaction of other species that favour the richness of the ecosystem. Originality/value Additive manufacturing provided an innovative method of production for ecology restoration areas, allowing rapid prototyping of substrates with high complexity morphologies, a critical and fundamental attribute to guarantee coral growth and Crustose Coralline Algae. The result of this study showed the feasibility of this approach using three-dimensional printing technologies.

Volcano-sedimentary processes at Las Derrumbadas rhyolitic twin domes, Serdán-Oriental basin, Eastern Trans-Mexican Volcanic Belt

2021 ◽  
pp. SP520-2021-144
Author(s):  
Marie-Noëlle Guilbaud ◽  
Corentin Chédeville ◽  
Ángel Nahir Molina-Guadarrama ◽  
Julio Cesar Pineda-Serrano ◽  
Claus Siebe
Keyword(s):  
Volcanic Belt ◽  
Debris Avalanche ◽  
Density Currents ◽  
Content Type ◽  
Mexican Volcanic Belt ◽  
Wide Range ◽  
Eruptive Episode ◽  
Basin Floor ◽  
Supplementary Material ◽  
Trans Mexican Volcanic Belt

AbstractThe eruption of the ∼10 km3 rhyolitic Las Derrumbadas twin domes about 2000 yrs ago has generated a wide range of volcano-sedimentary deposits in the Serdán-Oriental lacustrine basin, Trans-Mexican Volcanic Belt. Some of these deposits have been quarried, creating excellent exposures. In this paper we describe the domes and related products and interpret their mode of formation, reconstructing the main phases of the eruption as well as syn-and-post eruptive erosional processes. After an initial phreatomagmatic phase that built a tuff ring, the domes grew as an upheaved plug lifting a thick sedimentary pile from the basin floor. During uplift, the domes collapsed repeatedly to form a first-generation of hetero-lithologic hummocky debris avalanche deposits. Subsequent dome growth produced a thick talus and pyroclastic density currents. Later, the hydrothermally-altered over-steepened dome peaks fell to generate 2nd generation, mono-lithologic avalanches. Subsequently, small domes grew in the collapse scars. From the end of the main eruptive episode onwards, heavy rains remobilized parts of the dome carapaces and talus, depositing lahar aprons. Las Derrumbadas domes are still an important source of sediments in the basin, and ongoing mass-wasting processes are associated with hazards that should be assessed, given their potential impact on nearby populations.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5752296

Jurassic–Cretaceous arc magmatism along the Shyok–Bangong Suture from NW Himalaya: Formation of the peri-Gondwana basement to the Ladakh Arc

2021 ◽  
pp. jgs2021-035
Author(s):  
Wanchese M. Saktura ◽  
Solomon Buckman ◽  
Allen P. Nutman ◽  
Renjie Zhou
Keyword(s):  
Late Cretaceous ◽  
Nw Himalaya ◽  
Content Type ◽  
Magmatic Arc ◽  
Basement Rocks ◽  
Ladakh Himalaya ◽  
Accreted Terranes ◽  
Volcaniclastic Rocks ◽  
Supplementary Material ◽  
Depositional Age

The Jurassic–Cretaceous Tsoltak Formation from the eastern borderlands of Ladakh Himalaya consists of conglomerates, sandstones and shales, and is intruded by norite sills. It is the oldest sequence of continent-derived sedimentary rocks within the Shyok Suture. It also represents a rare outcrop of the basement rocks to the voluminous Late Cretaceous–Eocene Ladakh Batholith. The Shyok Formation is a younger sequence of volcaniclastic rocks that overlie the Tsoltak Formation and record the Late Cretaceous closure of the Mesotethys Ocean. The petrogenesis of these formations, ophiolite-related harzburgites and norite sill is investigated through petrography, whole-rock geochemistry and U–Pb zircon geochronology. The youngest detrital zircon grains from the Tsoltak Formation indicate Early Cretaceous maximum depositional age and distinctly Gondwanan, Lhasa microcontinent-related provenance with no Eurasian input. The Shyok Formation has Late Cretaceous maximum depositional age and displays a distinct change in provenance to igneous detritus characteristic of the Jurassic–Cretaceous magmatic arc along the southern margin of Eurasia. This is interpreted as a sign of collision of the Lhasa microcontinent and the Shyok ophiolite with Eurasia along the once continuous Shyok–Bangong Suture. The accreted terranes became the new southernmost margin of Eurasia and the basement to the Trans-Himalayan Batholith associated with the India-Eurasia convergence.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5633162

Geochemical evaluation of the in-situ regolith of Madengi hills of Dodoma, Tanzania. Implication on bedrock mapping and delineating gold mineralization target

2021 ◽  
pp. geochem2021-074
Author(s):  
Godson Godfray
Keyword(s):  
Gold Mineralization ◽  
Early Stage ◽  
Shear Zones ◽  
Soil Geochemistry ◽  
Residual Soils ◽  
Content Type ◽  
Geochemical Evaluation ◽  
Supplementary Material ◽  
Pathfinder Elements

Successful gold exploration projects depend on a piece of clear information on the association between gold, trace elements, and mineralization controlling factors. The use of soil geochemistry has been an important tool in pinpointing exploration targets during the early stage of exploration. This study aimed to establish the gold distribution, the elemental association between gold and its pathfinder elements such as Cu, Zn, Ag, Ni, Co, Mn, Fe, Cd, V, Cr, Ti, Sc, In, and Se and identify lithologies contributing to the overlying residual soils. From cluster analysis, a high similarity level of 53.93% has been shown with Ag, Cd, and Se at a distance level of 0.92. Au and Se have a similarity level of 65.87% and a distance level of 0.68, hence is proposed to be the most promising pathfinder element. PCA, FA, and the Pearson's correlation matrix of transformed data of V, Cu, Ni, Fe, Mn, Cr, and Co and a stronger correlation between Pb and U, Th, Na, K, Sn, Y, Ta and Be shows that source gold mineralization might be associated with both hornblende gneisses interlayered with quartzite, tonalite, and tonalitic orthogneiss. From the contour map and gridded map of Au and its pathfinder elements, it has been noted that their anomalies and target generated are localized in the Northern part of the area. The targets trend ESE to WNW nearly parallel to the shear zones as a controlling factor of Au mineralization emplacement.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5721965

First evidence for tooth-tooth occlusion in a ctenochasmatid pterosaur from the Early Cretaceous Jehol Biota

2021 ◽  
pp. SP521-2021-141
Author(s):  
Chang-Fu Zhou ◽  
Xinyue Wang ◽  
Jiahao Wang
Keyword(s):  
Early Cretaceous ◽  
Feeding Strategy ◽  
Three Dimensional ◽  
Tooth Wear ◽  
First Record ◽  
Jehol Biota ◽  
Content Type ◽  
Dimensional Reconstruction ◽  
Supplementary Material ◽  
Ct Data

AbstractCtenochasmatid pterosaurs flourished and diversified in the Early Cretaceous Jehol Biota. Here, a partial mandible of Forfexopterus is described based on a three-dimensional reconstruction using high-resolution X-ray Computed Tomography (CT) data. The first nine pairs of functional teeth of the rostral dentition revealed along with their replacements. The functional teeth are evenly arranged with a tooth density of 2.2 teeth/cm. The tooth crown is distinctly reduced from its base to the tip, and framed by two weak ridges, possibly as a pair of vestigial carinae. The replacement teeth are sharp and pointed, and have erupted slightly against the medial surface of the functional teeth. Surprisingly, tooth wear is observed in this specimen, the first record of tooth-tooth occlusion in ctenochasmatids. The wear facets exhibit high-angled lingual and lower-angled labial facets, implying a tooth-tooth occlusion in pterosaur clade. This discovery indicates that the Jehol ctenochasmatids possibly employed a more active feeding strategy than other filter-feeding pterosaurs (e.g. Ctenochasma, Pterodaustro, Gnathosaurus).Supplementary material at https://doi.org/10.6084/m9.figshare.c.5722060

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