scholarly journals Machine learning-based prediction of trace element concentrations using data from the Karoo large igneous province and its application in prospectivity mapping

2021 ◽  
Author(s):  
Steven E. Zhang ◽  
Glen T. Nwaila ◽  
Julie E. Bourdeau ◽  
Lewis D. Ashwal
Keyword(s):  
Machine Learning ◽  
Trace Element ◽  
Large Igneous Province ◽  
Element Concentrations ◽  
Igneous Province ◽  
Using Data ◽  
Prospectivity Mapping

Spatial variability in Karoo dolerites

2021 ◽  
Author(s):  
Arnold Kotze ◽  
R. James Roberts
Keyword(s):  
South Africa ◽  
Trace Element ◽  
Basaltic Magma ◽  
Principal Component ◽  
Large Igneous Province ◽  
Appreciable Amount ◽  
Data Set ◽  
Igneous Province ◽  
Positive Loading ◽  
Project Data

<p>AD Kotze and RJ Roberts</p><p>Department of Geology, University of Pretoria, Hatfield, Pretoria, South Africa; [email protected]</p><p>The Karoo Large Igneous Province (KLIP) in South Africa consists of both a spatially limited extrusive basalt suite (Drakensberg Group) and a spatially extensive dolerite suite, both generally considered to be remarkable homogenous and of a “low-Ti” character (Luttinen, 2018). The homogeneity of the rocks requires that statistical analysis is necessary to look for spatial and geochemical trends in the data, which may yield clues to the mantle processes producing the 60 000 km<sup>2</sup> expanse of basaltic magma. In this project, data derived from several locations are used as proxies to check for lateral variability in the Karoo dolerites. A principal component analysis (PCA) on trace element data using a covariance matrix was performed, and comparisons based on variables that are 1) common to the Karoo dolerites and Lesotho basalts and, 2) responsible for the most amount of variation to the data set are made. Trace element modelling is then used to test different mantle melting scenarios possibly responsible for the variation seen in the dolerites.</p><p>Principal component analyses revealed several trace elements are responsible for most of the variability in the dolerites. Cr and Ni has the strongest positive loading on Component 1 whereas Cr and Ba has the strongest positive loading on Component 2. Ba has a strong negative loading on Component 1. Cu, Sr, V and Zr do impart an appreciable amount of variation to the data, but all four variables have weak negative loadings on both components. Interestingly, the activity of Cu and V seems to be the inverse of that of Cr and Ni.</p><p>Due to the nature of a PCA, this work is afforded an opportunity to place the geochemistry of the Karoo dolerites within a larger geodynamic context without bias. From the observed variation, the activity of Ba and Cr is interpreted as an assimilation-oxidation process, whereas the Ni signature reflects the mantle origin of the magmas. Further modelling of these processes will allow the testing of suggested mechanisms for the formation of the KLIP, especially whether the magmatism is plume-related or related to the foundering of crustal blocks.</p><p>Luttinen, A., 2018. Bilateral geochemical asymmetry in the Karoo large igneous province. Scientific Reports, 8(5223).</p>

scholarly journals Longevity of the Permian Emeishan mantle plume (SW China): 1 Ma, 8 Ma or 18 Ma?

2008 ◽  
Vol 145 (3) ◽  
pp. 373-388 ◽  
Author(s):  
J. GREGORY SHELLNUTT ◽  
MEI-FU ZHOU ◽  
DAN-PING YAN ◽  
YANBIN WANG
Keyword(s):  
Trace Element ◽  
Flood Basalt ◽  
Large Igneous Province ◽  
Flood Basalts ◽  
Geological Evidence ◽  
Ocean Island Basalts ◽  
Igneous Province ◽  
Emeishan Mantle Plume ◽  
Decompressional Melting ◽  
Shrimp Zircon

AbstractAfter the formation of the ~ 260 Ma Emeishan large igneous province, there were two volumetrically minor magmatic pulses at ~ 252 Ma and ~ 242 Ma, respectively. Alkaline mafic dykes intruding both 260 Ma and 252 Ma felsic plutons in the Panxi region, southwestern China, have compositions similar to the Emeishan flood basalts. One dyke is dated using the SHRIMP zircon U–Pb technique at 242 ± 2 Ma, ~ 18 Ma younger than the start of Emeishan magmatism. The dykes have enriched light rare earth element patterns (La/YbN = 4.4–18.8) and trace element patterns similar to the Emeishan flood basalts and average ocean-island basalts. Some trace element ratios of the dykes (Zr/Nb = 3.8–8.2, La/Nb = 0.4–1.7, Ba/La = 7.5–25.6) are somewhat similar to EM1 source material, however, there are differences. Their εNd values (εNd = +2.6 and +2.7) andISr (ISr = 0.704542 and 0.704554) ratios are indicative of a mantle source. Thus Emeishan magmatism may have lasted for almost 20 Ma after the initial eruption. However, geological evidence precludes the possibility that the post-260 Ma magmatic events were directly related to Emeishan magmatism, which began at and ended shortly after 260 Ma. The 252 Ma plutons and 242 Ma dykes represent volumetrically minor melting of the fossil Emeishan plume-head beneath the Yangtze crust. The 252 Ma magmatic event was likely caused by post-flood basalt extension of the Yangtze crust, whereas the 242 Ma event was caused by decompressional melting associated with the collision between the South China and North China blocks during the Middle Triassic.

scholarly journals Simultaneous Quantification of Forsterite Content and Minor–Trace Elements in Olivine by LA–ICP–MS and Geological Applications in Emeishan Large Igneous Province

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 634
Author(s):  
Shitou Wu ◽  
Yadong Wu ◽  
Yueheng Yang ◽  
Hao Wang ◽  
Chao Huang ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Large Igneous Province ◽  
Emeishan Large Igneous Province ◽  
Inductively Coupled ◽  
Minor Elements ◽  
Icp Ms ◽  
Igneous Province ◽  
Peridotitic Mantle

Olivine forsterite contents [Fo = 100 × Mg/(Mg + Fe) in mol%] and minor–trace element concentrations can aid our understanding of the Earth’s mantle. Traditionally, these data are obtained by electron probe microanalysis for Fo contents and minor elements, and then by laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) for trace elements. In this study, we demonstrate that LA–ICP–MS, with a simplified 100% quantification approach, allows the calculation of Fo contents simultaneously with minor–trace elements. The approach proceeds as follows: (1) calculation of Fo contents from measured Fe/Mg ratios; (2) according to the olivine stoichiometric formula [(Mg, Fe)2SiO4] and known Fo contents, contents of Mg, Fe and Si can be computed, which are used as internal standards for minor–trace element quantification. The Fo content of the MongOLSh 11-2 olivine reference material is 89.55 ± 0.15 (2 s; N = 120), which agrees with the recommended values of 89.53 ± 0.05 (2 s). For minor–trace elements, the results matched well with the recommended values, apart from P and Zn data. This technique was applied to olivine phenocrysts in the Lijiang picrites from the Emeishan large igneous province. The olivine compositions suggest that the Lijiang picrites have a peridotitic mantle source.

scholarly journals Major and Trace Element and Sr, Nd, Hf, and Pb Isotope Compositions of the Karoo Large Igneous Province, Botswana–Zimbabwe: Lithosphere vs Mantle Plume Contribution

2007 ◽  
Vol 48 (6) ◽  
pp. 1043-1077 ◽  
Author(s):  
F. Jourdan ◽  
H. Bertrand ◽  
U. Schärer ◽  
J. Blichert-Toft ◽  
G. Féraud ◽  
...  
Keyword(s):  
Trace Element ◽  
Mantle Plume ◽  
Large Igneous Province ◽  
Pb Isotope ◽  
Igneous Province

scholarly journals Supplemental Material: New constraints on the age, geochemistry, and environmental impact of High Arctic Large Igneous Province magmatism: Tracing the extension of the Alpha Ridge onto Ellesmere Island, Canada

2020 ◽  
Author(s):  
T.V. Naber ◽  
C. Tegner
Keyword(s):  
Environmental Impact ◽  
Trace Element ◽  
High Arctic ◽  
Ellesmere Island ◽  
Large Igneous Province ◽  
Supplementary Data ◽  
Bulk Rock ◽  
Igneous Province ◽  
Data Files ◽  
Discrimination Diagram

Supplementary Data Files: (1) Sample list and description; (2) GPS positions of samples; (3) Accuracy of major and trace element bulk rock compositions and precision of repeat analyses; (4) Photomicrographs; (5) Clinopyroxene, plagioclase and olivine compositions; (6) SHRIMP U-Pb methods and results; (7) 7. Nb-Zr-Y tectonic discrimination diagram; (8) Ti-Zr-Y tectonic discrimination diagram; (9) Ti-V tectonic discrimination diagram; (10) MgO-FeOtot_Al2O3 tectonic discrimination diagram; (11) AFM diagram; and (12) Th/Nb vs. SiO2 diagram.

scholarly journals Supplemental Material: New constraints on the age, geochemistry, and environmental impact of High Arctic Large Igneous Province magmatism: Tracing the extension of the Alpha Ridge onto Ellesmere Island, Canada

2020 ◽  
Author(s):  
T.V. Naber ◽  
C. Tegner
Keyword(s):  
Environmental Impact ◽  
Trace Element ◽  
High Arctic ◽  
Ellesmere Island ◽  
Large Igneous Province ◽  
Supplementary Data ◽  
Bulk Rock ◽  
Igneous Province ◽  
Data Files ◽  
Discrimination Diagram

Supplementary Data Files: (1) Sample list and description; (2) GPS positions of samples; (3) Accuracy of major and trace element bulk rock compositions and precision of repeat analyses; (4) Photomicrographs; (5) Clinopyroxene, plagioclase and olivine compositions; (6) SHRIMP U-Pb methods and results; (7) 7. Nb-Zr-Y tectonic discrimination diagram; (8) Ti-Zr-Y tectonic discrimination diagram; (9) Ti-V tectonic discrimination diagram; (10) MgO-FeOtot_Al2O3 tectonic discrimination diagram; (11) AFM diagram; and (12) Th/Nb vs. SiO2 diagram.

Geochemical and O-C-Sr-Nd Isotopic Constraints on the Petrogenetic Link between Aillikites and Carbonatites in the Tarim Large Igneous Province

2021 ◽  
Author(s):  
Changhong Wang ◽  
Zhaochong Zhang ◽  
Andrea Giuliani ◽  
Zhiguo Cheng ◽  
Bingxiang Liu ◽  
...  
Keyword(s):  
Trace Element ◽  
Oxygen Isotope ◽  
Secondary Ion Mass Spectrometry ◽  
Large Igneous Province ◽  
Nd Isotope ◽  
Isotopic Analyses ◽  
Igneous Province ◽  
Secondary Ion ◽  
Tarim Large Igneous Province

Abstract Aillikites are carbonate-rich ultramafic lamprophyres often associated with carbonatites. Despite their common field relationships, the petrogenetic links, if any, between aillikites and carbonatites remain controversial. To address this question, this study reports the results of a detailed geochemical and isotopic examination of the Permian Wajilitag aillikites in the northwestern Tarim large igneous province, including bulk-rock major-, trace-element and Sr-Nd isotope compositions, olivine major- and trace-element and (in-situ secondary ion mass spectrometry) oxygen isotope compositions, oxygen isotope data for clinopyroxene separates, and bulk-carbonate C-O isotopic analyses. Olivine in the aillikites occurs in two textural types: (i) microcrysts, 0.3-5 mm; and (ii) macrocrysts, 0.5-2.5 cm. The microcrysts exhibit well-defined linear correlations between Fo (79-89), minor and trace elements (e.g., Ni = 1304-3764 μg/g and Mn = 1363-3042 μg/g). In contrast, the olivine macrocrysts show low Fo79-81, Ni (5.3-442 μg/g) and Ca (477-1018 μg/g) and very high Mn (3418-5123 μg/g) contents, and are displaced from the compositional trend of the microcrysts. The microcrysts are phenocrysts crystallized from the host aillikite magmas. Conversely, the lack of mantle-derived xenoliths in these aillikites suggests that the macrocrysts probably represent cognate crystals (i.e., antecrysts) that formed from earlier, evolved aillikite melts. Olivine phenocrysts in the more primitive aillikite dykes (Dyke 1) have relatively higher Fo82-89 and mantle-like oxygen isotope values, whereas those in the more evolved dykes (Dyke 2 and 3) exhibit lower Fo79-86 and oxygen isotope values that trend toward lower than mantle δ18O values. The decreasing δ13C values of carbonate from Dyke 1 through to Dyke 2 and 3, coupled with the indistinguishable Sr-Nd isotopes of these dykes, suggest that the low δ18O values of olivine phenocrysts in Dyke 2 and 3 resulted from carbonate melt/fluid exsolution from a common progenitor melt. These lines of evidence combined with the overlapping emplacement ages and Sr-Nd isotope compositions of the aillikites and carbonatites in this area suggest that these exsolved carbonate melts probably contributed to the formation of the Tarim carbonatites thus supporting a close petrogenetic relationship between aillikites and carbonatites.

scholarly journals AI oriented prospectivity mapping to study relationships between Sb mineralization and geological framework

2021 ◽  
Author(s):  
Alex Vella ◽  
Charles Gumiaux ◽  
Guillaume Bertrand ◽  
Bruno Tourlière ◽  
Eric Gloaguen ◽  
...  
Keyword(s):  
Machine Learning ◽  
Multiple Scales ◽  
Mineral Exploration ◽  
Data Driven ◽  
Automated Classification ◽  
Geological Features ◽  
Data Driven Approach ◽  
Statistical Relationships ◽  
Using Data ◽  
Prospectivity Mapping

<p>Prospectivity mapping aims at producing favorability maps, outlining areas with the highest likelihood to host mineralization. This process can be done using data-driven approaches, based on statistical and spatial analyses on geological features and known mineral occurences. Besides, such approach contributes to better understand metallogenic processes by highlighting specific and systematic associations between deposits and geological features (structures, lithologies, contacts, geophysical anomalies, etc).</p><p>As part of the AUREOLE project, prospectivity maps of Sb throughout the West European Variscan Range are being produced using CBA (“Cell-Based Associations”). CBA is a prospectivity tool developped for mineral prospectivity mapping by the French Geological Survey (BRGM). This method divide at first space into a regular cells grid. Inside each cell, the associations of geological factors, such as lithological, structural, geophysical or geochemical features, are grouped together and define the geological framework in the vicinity of the given cell. This project aims at developing and improving this method by the addition of new machine learning methods and statistical and spatial analysis tools for the automated classification and the calculation of favorability score.</p><p>Application of this approach to the Ibero-Armorican Arc, relying heavily on Artificial Intelligence to process the data, will highlight statistical relationships between the Sb deposits and their surrounding geological framework. Computations will be performed at multiple scales and in different areas trough the Arc, in order to observe the influence of scale in the consistency of the results and to bring out general laws from local specificities in the metallogenic models. Results from this almost purely data-driven approach will be compared to the metallogenical models traditionnaly proposed for Sb deposits in the studied areas. We infer this new multiscale and multidomains study  would improve our understanding of the genetic processes resulting in  Sb deposits through the Variscan Range and give new metallotects or specify the common ones, to be used for mineral exploration purpose.</p><p>This Phd work is funded by the ERA-MIN2 AUREOLE project (ANR-19-MIN2-0002, https://aureole.brgm.fr).</p><p><strong>Keywords: </strong>Antimony, Prospective Mapping, Machine Learning, Data-Driven.</p>

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