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  • 1
    Publication Date: 2023-03-08
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Samuel, B., & Danny, H. MineralMate: a standalone MATLAB-based aide for the magnetic separation of minerals. Heliyon, 8(9), (2022): e10411, https://doi.org/10.1016/j.heliyon.2022.e10411.
    Description: MineralMate is a standalone MATLAB-based program designed to optimize the workflow associated with the magnetic separation of minerals. For nearly every bulk geochemical analysis some amount of mineral separation must occur, and the use of an electromagnetic separator is ubiquitous and considered as standard practice in many fields. Despite the commonality in which magnetic separation is used, there are considerable shortcomings. Electromagnet overheating and composite mineral grains are frequently encountered, as well as poorly constrained mineral behavior. These complications ultimately reduce the quality of downstream geochemical data. MineralMate is designed to alleviate these shortcomings by quickly and efficiently producing a magnetic separation workflow allowing the user to: (1) identify and compare optimal recovery ranges for different minerals from a bulk mineral assemblage, (2) identify the parameters on a conventional magnetic separator required to magnetically separate composite grains, (3) create/update user-specific magnetic susceptibility databases through empirical data collection, and (4) utilize an alternative magnetic separation equation.
    Description: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
    Keywords: Frantz ; Geochemistry ; Geochronology ; MATLAB ; Magnetic separation ; Mineral separation
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
    Publication Date: 2023-11-16
    Description: Submarine methane emissions in the Tuscan Archipelago have been studied since the 1960s, both for economic and research purposes. Offshore gas seepage is mainly concentrated southward and westward of Elba island, along N–S faults related to recent extensional activity in the Tuscan shelf and N–S trending positive magnetic anomalies, which have been interpreted as serpentinites associated with ophiolitic rocks due to their very high magnetic susceptibility. This study focuses on the gas chemistry of a new emission site corresponding to a shallow water mud volcano in the Scoglio d’Affrica area. The Scoglio d’Affrica seep has a gas composition typical of mud volcanoes, with methane as the prevalent component (95 vol%) and minor gases which include carbon dioxide, nitrogen and trace amounts of helium. The combined stable C and H isotope composition of CH4 (δ13C and δ2H) and the enrichment in heavy carbon isotopes of CO2, highlight a prevalent secondary microbial origin for these fluids (δ13C~− 35.8‰ vs VPDB; δ2H~− 166‰ vs VSMOW; δ13CCO2 up to + 21.7‰ vs VPDB). Thus, in spite of the occurrence of positive magnetic anomalies, a possible abiotic origin of methane is excluded. Moreover, the gas from the mud volcano is extremely depleted in 3He and presents typical 3He/4He ratios of a geological setting in which radiogenic crustal helium is strongly predominant. A photo-mosaic of the mud volcano is also reported. A possible connection with other submarine methane emissions in the Tuscan Archipelago is limited to emissions located few kilometers from the Scoglio d’Affrica area. Recent emissions in the area suggest that gases similar in composition from distinct reservoirs, find their way to the surface from Eocene deposits in different time intervals and through different faults and fractures, placed along the Elba-Pianosa ridge.
    Description: Published
    Description: 104722
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: Submarine emission ; Mud volcano ; Methane ; Gas geochemistry ; Tyrrhenian sea ; Geochemistry ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2023-11-21
    Description: Azerbaijan hosts the highest density of subaerial mud volcanoes on Earth. The morphologies characterizing these structures vary depending on their geological setting, frequency of eruption, and transport processes during the eruptions. Lokbatan is possibly the most active mud volcano on Earth exhibiting impressive bursting events every ∼5 years. These manifest with impressive gas flares that may reach more than 100 meters in height and the bursting of thousands of m3 of mud breccia resulting in spectacular mud flows that extend for more than 1.5 kilometres. Unlike other active mud volcanoes, to our knowledge Lokbatan never featured any visual evidence of enduring diffuse degassing (e.g., active pools and gryphons) at and near the central crater. Only a very small new-born gryphon was intermittently active in 2019 (with negligible flow). Gas flux measurements completed with a closed-chamber technique reveal extremely low values throughout the structure with average CH4 = 1.36 tonnes yr−1 and CO2 = 11.85 tonnes yr−1. We suggest that after eruptive events, the mud breccia is able to seal the structure preventing gas release and thereby promoting overpressure build-up in the subsurface. This self-sealing mechanism allows a fast recharge of Lokbatan resulting in more frequent and powerful explosive episodes. Our field observations reveal the presence of large (up to ∼50,000 m3) stratified blocks that were originally part of a large crater cone. These blocks were rafted 〉1 km from the vent on top of mud breccia flows. We use a model based on lubrication theory to show that it is reasonable to transport blocks this large and this far provided the underlying mud flow was thick enough and the blocks are large enough. The presence of large rafted blocks is not a unique phenomenon observed at Lokbatan mud volcano and is documented at other large-scale structures both onshore and offshore.
    Description: Published
    Description: 116699
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: Lokbatan mud volcano Azerbaijan ; rafted mud breccia megablocks ; gas flux ; self-sealing ; explosive eruptions ; lubrication theory ; Solid Earth ; Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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