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This file documents the strontium isotope data, and the manner in which it has been processed, to supply the reference data for isotope domains of the Biosphere Isotope Domains GB (V1) map. It includes a summary of the analytical methods used to determine the isotope ratios though time.
These plagioclase and clinopyroxene mineral chemical and Sr isotope data come from Unit 10, Rum Layered Suite, NW Scotland. They underpin a publication entitled 'Rapid crystallisation of precious metal-mineralised layers in mafic magmatic systems', to be published in Nature Geoscience in 2020.
This dataset comprises neodymium (Nd) and strontium (Sr) isotope compositions measured on 72 sediment samples, from IODP Expedition 374 Site U1521 to the Ross Sea. These were collected on the RV JOIDES Resolution. Shipboard biostratigraphy and magnetostratigraphy suggests the samples are mainly early Miocene in age (McKay et al., 2019). The uppermost samples do, however, include younger Plio-Pleistocene sediments. Neodymium and Sr isotope analyses were conducted using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) and a thermal ionisation mass spectrometer (TIMS), respectively, in the MAGIC laboratories at Imperial College London. Neodymium and Sr isotopes in sediments can be compared to measurements from terrestrial rock samples, allowing the changing provenance of the sediments to be traced. This dataset therefore provides information on how erosion by Antarctica’s ice sheets bordering the Ross Sea has changed over time. Neodymium isotopes are reported in the epsilon notation, which denotes the deviation in parts per 10,000 from the present-day composition of the Chondritic Uniform Reservoir (143Nd/144Nd = 0.512638) (Jacobsen and Wasserburg, 1980).
The database contains a range of geochemical data for metamorphosed limestones from the Dalradian of Scotland and Northern Ireland. The data include a) whole-rock geochemical analyses by XRF (X-Ray Fluorescence) for major oxides and a range of trace elements for several hundred samples, b) a number of whole-carbonate O (oxygen) and C (carbon) stable isotope and Sr (strontium) data, c) electron microprobe mineral data on carbonates and calc-silicate minerals and d) ion-probe O stable isotope and mineral trace element data for calcites in a small number of samples. The samples from which the data have been derived were collected from a wide range of outcrops within the Scottish and Irish Dalradian, mainly concentrated in the North East Grampian Highlands of Scotland. The data have been collected mainly to support the mapping and scientific work being undertaken in the Grampian Highlands by BGS since the early 1980s. The database includes some data from the literature. All samples are located by British National Grid coordinates to the nearest 10m or better. The isotope data were acquired as part of a PhD study by C W Thomas in the late 1990s. The database is not currently being added to, but is still being used in various studies. The combined data provide wide-ranging insights into marine chemistry contemporary with deposition of the limestones and the way in which this chemistry changed with time during the Neoproterozoic, and they elucidate subsequent effects of diagenesis and metamorphism and the outcrop and grain-scale. The data set is largely complete with regard to geochemical data, but still requires some editing to bring all fields up to date, particularly with regard to lithostratigraphical assignation. The data are currently held in MS Access tables and can conveniently be displayed via GIS or abstracted in tabular form and used in spreadsheets, statistical analysis and graphing software.
Paired water and river sediment samples were collected from Vietnam Australia, Cambodia and Nepal. Waters were analysed for major ions, Sr isotopes and Mg isotopes. Sediments were sequentially extracted using ammonium chloride, acetic acid and hydrochloric acid to target exchangeable ions, calcite and dolomite respectively. They were analysed for major ions and selected isotopes.