Age determination methods
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The concentration of both L and D amino acid isomers was determined by HPLC (High-performance liquid chromatography) for multiple amino acids. 30 samples of proboscidean enamel were taken from the collections at BGS. Samples of enamel (~30 mg) was removed from the teeth of proboscideans using a small electric drill. All of the samples were from UK sites dating to the Quaternary. These samples were used to build a regional geochronology based on the extent of racemisation of amino acids from the intra-crystalline fraction (Dickinson, 2018). Thesis http://etheses.whiterose.ac.uk/22261. A published paper 'A new method for enamel amino acid racemization dating: A closed system approach' is also available; https://doi.org/10.1016/j.quageo.2018.11.005
This dataset presents tephra layers, Ar-dates, age-model & stable isotope data from the >250 kyr-long Lake Chala sediment record, Kenya/Tanzania. The file is split into six tables: (1) metadata on the 30 tephra layers (29 visible tephra layers, one cryptotephra) studied to date, including sample and core codes, summary characteristics and ages; (2) summary of Ar-dating results on ten of the Lake Chala tephra layers; (3) the DCH_TephraAge Bayesian age model, which combines tephra, 210Pb and 14C age-estimates for the length of the core; (4) Raw single-grain WDS-EPMA results for all tephra layers studied in the DeepCHALLA sediment record; and (5) secondary standard data; (6) unpublished Diatom ?18O (‰ VSMOW), Bulk organic ?13C (‰), %C and Diatom d13C (‰) measurements for the full length of the core (given on a composite depth scale). These chronological data (Tables 1-5) are central to the reconstruction of palaeoclimate from a multi-proxy analyses of the Lake Chala sediment sequence and are included in publications by Baxter et al. (2023) and Martin-Jones et al. (2020, in review), for which references are given in the appropriate files. Stable isotope data (produced by Barker and Leng) remains unpublished at the time of upload. The data was generated by Catherine Martin-Jones, Christine Lane, Maarten Blaauw, Darren Mark, Melanie Leng and Phil Barker between 2017-2022. Much of the tephra data is published and references are provided.
Data from the IODP Expedition will be archived by the International Ocean Discovery Program, including all data generated during the shipboard palaeomagnetic and magnetic anisotropy analyses and all of the logging data (FMS tool, GBM data), plus associated explanatory notes. Shore based palaeomagnetic and magnetic anisotropy data, FMS---based reorientation parameters, and downhole magnetizations inferred from modelling of the GBM borehole magnetometer data will be made available to the international community via appropriate IODP Data Reports (in addition to primary journal articles). Data Includes: Shipboard cryogenic magnetometer data Shipboard and shore based discrete sample remanence data Shipboard and shore based magnetic anisotropy data FMS---based reorientation parameters Magnetic parameters modelled using borehole magnetometer data