Ship-board determination of whole-rock (ultra-)trace element concentrations by laser ablation-inductively coupled plasma mass spectrometry analysis of pressed powder pellets aboard the D/V Chikyu
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AuthorRospabé, Mathieu; Giampouras, Manolis; Oman Drilling Project "ChikyuOman2018 Leg 3" Science Team
Rospabé, M... [et al.]. Ship-board determination of whole-rock (ultra-)trace element concentrations by laser ablation-inductively coupled plasma mass spectrometry analysis of pressed powder pellets aboard the D/V Chikyu, Sci. Dril., 30, 75–99, [https://doi.org/10.5194/sd-30-75-2022], 2022.
SponsorshipInternational Continental Scientific Drilling Project (ICDP); Sloan Foundation -Deep Carbon Observatory 2014-3-01; National Science Foundation (NSF) NSF-EAR-1516300; NASA -Astrobiology Institute NNA15BB02A; German Research Foundation (DFG) KO 1723/21-1; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science 16H06347 Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science; Grants-in-Aid for Scientific Research (KAKENHI) 16H02742; European Research Council (ERC) European Commission 669972; Swiss National Science Foundation (SNSF) 20FI21_163073; JAMSTEC; TAMU-JR Science Operator; Sultanate of Oman Ministry of Regional Municipalities and Water Resources; Oman Public Authority of Mining; Sultan Qaboos University; CNRS-Univ. Montpellier; Columbia University of New York; University of Southampton; Centre National de la Recherche Scientifique (CNRS); IODP-France (regular fund)
The Oman Drilling Project (OmanDP), performed under the International Continental Scientific Drilling Program (ICDP), is an international scientific research project that undertook drilling at a range of sites in the Semail ophiolite (Oman) to collect core samples spanning the stratigraphy of the ophiolite, from the upper oceanic crust down to the basal thrust. The cores were logged to International Ocean Discovery Program (IODP) standards aboard the D/V Chikyu. During ChikyuOman2018 Leg 3 (July–August 2018), participants described cores from the crust–mantle transition (CM) sites. The main rock types recovered at these sites were gabbros, dunites and harzburgites, rocks typically forming the base of the oceanic crust and the shallow mantle beneath present-day spreading centres. In addition to the core description, selected samples were analysed by X-ray fluorescence spectrometry (XRF) for their chemical compositions, including major, minor and some trace elements. To complement these standard procedures, we developed new approaches to measure ultra-trace element concentrations using a procedure adapted from previous works to prepare fine-grained pressed powder pellets coupled with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis using instrumentation aboard the D/V Chikyu. First, three (ultra)mafic reference materials were investigated to test and validate our procedure (BHVO-2, BIR-1a and JP-1), and then the procedure was applied to a selection of gabbro and dunite samples from the CM cores to explore the limitations of the method in its current stage of development. The obtained results are in good agreement with preferred values for the reference materials and with subsequent solution replicate analyses of the same samples performed in shore-based laboratories following Leg 3 for the CM samples. We describe this procedure for the determination of 37 minor and (ultra-)trace elements (transition elements and Ga, Li and Large-Ion Lithophile Elements (LILE), Rare Earth Elements (REE), High-Field-Strength Elements (HFSE), U, Th, and Pb) in mafic and ultramafic rocks. The presented method has the major advantage that it allows the determination at sea of the (ultra-)trace element concentrations in a “dry”, safe way, without using acid reagents. Our new approach could be extended for other elements of interest and/or be improved to be adapted to other rock materials during future ocean drilling operations aboard the D/V Chikyu and other platforms.