The data collection presented here is the data inventory of the VARved sediments DAtabase (VARDA) in version 1.3. VARDA is freely accessible and was created to assess outputs from climate models with high-resolution terrestrial palaeoclimatic proxies. All data were collected as raw data from freely available online sources, either from online data repositories (Pangaea, NOAA, and Neotoma) or data archives within the supplementary materials section of online publications. The current data collection consists of meta information and datasets from 95 lake archives. The data is stored in JSON and CSV format. All datasets are stored as individual files (JSON and CSV). Each dataset consists of samples for either i) chronologies; ii) radiocarbon data; iii) tephra layer; or iv) varve thickness data. Meta-information for each dataset is summarized in one csv and seven JSON files. Additional paleoclimate proxy data will be provided in forthcoming updates of VARDA.
The data collection of VARDA Version 1.3 is provided as an archive (.tar.gz) with the following files/folders. Overview lists with categories, cores, countries, datasets, lakes and publications included in VARDA. Each item in the lists is cross-referenced with the other files via its $ref property which includes the corresponding list index or the dataset's UUID (from the VARDA database). The data points themselves are provided in the "records" folder and named with each dataset's UUID respectively. For more information on the data structure please read the "index.html" file included in the archive and available on the DOI landing page.
VERSION HISTORY:
26 July 2020: release of Version 1.3:
1. Fix issues with chronologies in the export
2. Provide recalculated machine readable error estimates
3. Correct some metadata values (e.g. core labels)
5 March 2020: release of Version 1.1
1. Added fields:
"distributor" - Field containing name of data distributor
"url" - Field containing DOIs and URLs, which lead to the original data publications
2. Correction of publication DOIs in 9 cases
The version 1.0 is available in the "previous-versions" subfolder via the Data Download link. The index file is unchanged.
This database contains major and trace element compositions of European tephra and metadata for the datasets and lakes they were found in. It was created by collecting data from scientific literature to support the synchronisation of annually-resolved lake sediment records during the Last Glacial Interglacial Transition (25 ka BP to 8 ka BP).
49 individual tephra layers across 19 varved lake records have been included, with Lago di Grande Monticchio being the largest contributor of geochemical data with 28 layers. The Vedde Ash and Laacher See tephra are the most common layers, being found in 6 different varved records, and highlight the potential of refining the absolute age estimates for these tephra layers using varve chronologies and for synchronising regional paleoclimate archives.
This project is the first stage in a 5-years plan funded by the Past Global Changes (PAGES) Data Stewardship Scholarship to incorporate a global dataset of tephra geochemical data in varved sediment records. Further stages of this project will focus on different regions and timescales.
The data result from a sedimentological and geochemical multiproxy approach to study a Holocene palaeolake record north of Tayma, NW Saudi Arabia. The lacustrine, partly varved record was analysed in the frame of the DFG founded project CLEAR “Holocene climatic events in Northern Arabia - Environmental changes and human response”.
The Tayma palaeolake record comprises continuous lacustrine sediments covering the early to mid-Holocene. The dataset allows detailed palaeoenvironmental and palaeoclimate interpretations from the early Holocene humid period and subsequent dryer conditions during the mid-Holocene.
The dataset is part of the supplementary material to “Neugebauer et al. (submitted)” where further details about the locality, core composite, age model, sampling and analytical methods and data processing are given. The data are provided in individual xlsx-files per type of data.
The different files include sedimentological and geochemical data determined on the ca. 6 m long master core from the sediment cores (Tay 220/221 and Tay 253/254/255/256): (i) sediment core microfacies data, (ii) bulk total organic carbon (TOC) and carbonate delta13C_carb and delta18O_carb data, (iii) single aragonite laminae delta13C_arag and delta18O_arag data, (iv) concentrations of n-alkanes n-C29 and n-C31 and hydrogen isotope composition deltaD, (v) XRF core scanning data. All data are provided on composite depths and age scales (based on Bayesian age modelling of radiocarbon dates, varve counting and one tephrochronological anchor; see details in the Supplementary material of Neugebauer et al., submitted).