Isotope ratio
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Geochemical measurements which quantify the lithium isotope ratios (d7Li) of Paleozoic (541–251 Mya) mudstones. Samples were obtained from various field locations across Scotland, Wales, England and New Brunswick, Nova Scotia, Canada. Sampled mudstones are listed under their formation name, with information on the locations of each outcrop belt and further details on lithological characteristics, including environment of formation, freely available on the British Geological Survey Lexicon of named rock units (https://www.bgs.ac.uk/technologies/the-bgs-lexicon-of-named-rock-units/) and Government of Canada weblex (https://weblex.canada.ca/weblexnet4/weblex_e.aspx), for UK and Canadian samples, respectively. Stratigraphic age is given in accordance to the GSA geological timescale v.5.0. Following sampling, specific methodologies for preparation for Lithium isotope analysis are provided in the Metadata Lineage. The data was collected to understand changes in weathering intensity coeval with the Paleozoic expansion of land plants, with lithium isotopes a powerful trace for silicate weathering as they are sensitive to the balance between rock dissolution and clay formation. The tabulated lithium isotope ratios were compared at different temporal stages of plant evolution through the Paleozoic. Samples were collected by the University of Cambridge. Lithium isotope ratios were obtained by William McMahon and supervised by Edward Tipper and Mohd Tarique. Mass spectrometry was carried out by William McMahon and David Wilson at University College London.
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Major, trace element and Pb isotope data are reported here for basalts recovered by drilling at the flanks of the Reykjanes Ridge, south of Iceland, during IODP Expedition 395C (2020-2022). The drilling targeted V-shaped ridges and V-shaped troughs forming the flanks of the Reykjanes Ridge. There were 4 sites drilled and sampled, and these include holes: U1554 (4F) - located on V-shaped trough 2B, holes U1555 (5I + 5G) - located on V-shaped trough 1, U1562 (2B), located on V-shaped ridge 3, and U1563 (3B) - located on V-shaped ridge 2A. Samples are predominately volcanic glasses and were recovered from cores drilled from up to 150m below the sediment-basement interface where they penetrated a series of pillow and sheet flow lavas. The sample name corresponds to the site, hole, core section and depth interval (see IODP Exp 395 site reports for details). Fresh volcanic glass was separated, cleaned in deionised water, picked under a binocular microscope to remove and altered material, cleaned again and then dissolved in HF and HCl prior to analyses. Major and trace elements abundances were analysed on an ICP-MS with a selection of geological reference materials (GRMs) used as standards. Pb isotopes ratios (206/204, 207/204 and 208/204) were measured on a neptune multicollector ICP-MS following using a double spike technique applied to the sample solutions. Reported here are the measured values of the GRMs and their uncertainties. The aim of this study was to test the hypothesis that the V-shaped ridges are the result of temperature and compositional pulses in a mantle plume, that is postulated to rise beneath Iceland and spread outward where it intersects the mid-ocean ridge to the south, and the effects of those pulses on climate over the last ~20Ma.
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Elemental and stable isotope data measured in Eocene foraminiferal calcite from Ocean Drilling Program Site 865 and Tanzanian Drilling Project Site 18 published in Edgar et al. (2015) "Assessing the impact of diagenesis on δ11B, δ13C, δ18O, Sr/Ca and B/Ca values in fossil planktic foraminiferal calcite" in Geochimica et Cosmochimica Acta, v. 166, p. 189-209. Table 1. δ18O and δ13C values for glassy and frosty foraminifera from TDP Site 18 and ODP Site 865, respectively. Table 2. Sr/Ca and B/Ca values, and test weights for glassy and frosty foraminifera from TDP Site 18 and ODP Site 865, respectively. Table 3. δ11B values for glassy and frosty foraminifera from TDP Site 18 and ODP Site 865, respectively.
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