Abstract:
The dataset comprises of site data and multiproxy analyses of LP08 lake sediment cores extracted from Lago Pato, a small lake basin at -51.3003, -72.6786 and approx 33 m a.s.l., which is topographically separated from Lago del Toro in Torres del Paine (TdP). The data are used to constrain glacier dynamics and lake level change in the TdP and Ultima Esperanza region over the last approx 30,000 cal a BP (30 ka).
Data for the LP08 sediment record consist of downcore measurements of biology, chronology, geochemistry, sedimentology proxy data collected from the current depocentre between November 2007 to March 2008.
This project was funded by the Natural Environment Research Council (NERC) through the British Antarctic Survey (BAS) and an UGent BOF bilateral collaboration project. RMcC was supported by Programa Regional R17A10002 and R20F0002 (PATSER) ANID. We gratefully acknowledge the University of Magallanes (UMAG) and the University of Santiago (Carolina Diaz) for assistance with fieldwork; the NERC/SUERC AMS Radiocarbon Facility for providing initial range-finder radiocarbon dates; the NERC Isotope Geosciences Laboratory (NIGL, now National Environmental Isotope Facility, NEIF, at the British Geological Survey) and Melanie Lang for stable carbon isotope analysis; Aberystwyth University (David Kelly), Durham University (Neil Tunstall and Christopher Longley) and Edinburgh University (Chris Hayward) for use of their core scanning and microprobe facilities and technical support.
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| Access Constraints: | No restrictions apply. |
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| Use Constraints: | This data is governed by the NERC data policy http://www.nerc.ac.uk/research/sites/data/policy/ and supplied under Open Government Licence v.3 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
| Creation Date: | 2022-02-26 |
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| Dataset Progress: | Planned |
| Dataset Language: | English |
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| Parameters: |
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| Personnel: | |
| Name | UK Polar Data Centre |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Dr Stephen J Roberts |
| Role(s) | Investigator, Technical Contact |
| Organisation | British Antarctic Survey |
| Name | Robert D McCulloch |
| Role(s) | Investigator |
| Organisation | Centro de Investigacion en Ecosistemas de la Patagonia (CIEP) |
| Name | Sarah J Davies |
| Role(s) | Investigator |
| Organisation | Aberystwyth University |
| Name | Joseph F Emmings |
| Role(s) | Investigator |
| Organisation | British Geological Survey |
| Name | Mieke Sterken |
| Role(s) | Investigator |
| Organisation | Ghent University |
| Name | Evelien Van de Vyver |
| Role(s) | Investigator |
| Organisation | Ghent University |
| Name | Dr Wim Van Nieuwenhuyze |
| Role(s) | Investigator |
| Organisation | Ghent University |
| Name | Katrien Heirman |
| Role(s) | Investigator |
| Organisation | Geological Survey of the Netherlands |
| Name | Jeroen Van Wichelen |
| Role(s) | Investigator |
| Organisation | Research Institute for Nature and Forest |
| Name | Carolina Diaz |
| Role(s) | Investigator |
| Organisation | Universidad de Santiago de Chile |
| Parent Dataset: | N/A |
| Reference: | Roberts, S.J., McCulloch, R.D.M., Emmings, J., et al. (2022) Late glacial and Holocene palaeolake history of the Última Esperanza region of Southern Patagonia. Frontiers in Earth Science, 10. https://doi.org/10.3389/feart.2022.813396 | |
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| Quality: | Geochemistry ITRAX-XRF Raw count per second (cps) data were analysed using the Q-spec software v8.6.0 (Cox Analytical), with MSE values minimised to optimise the fit of 'as measured' spectra to a modelled spectrum. data are presented as percentages of the Total Scatter Normalised ratio sum (%sigmaTSN or, more simply, %TSN, which are equivalent to percentages of the cps sum, or percentage cps) to account for downcore variations in count rate, density, water and organic content. Data less than mean minus two-sigma kcps (mainly due to gaps in the core) and greater than MSE plus two-sigma (representing a poor fit between measured to modelled spectra) were filtered before analysis. 'Noisy' elements were eliminated by comparing cps and using %TSN thresholds of more than 0.1% mean and more than 0.5% maximum, and by examining autocorrelation profiles for each element (Bishop, 2021). This left 12 'measurable' elements for the LP08 record (Si, S, K, Ca, Ti, Mn, Fe, Zn, Br, Rb, Sr, Zr, and inc., coh. scatter). Elements are presented as natural log (log n or Ln) ratios. Ti-normalised log n ratios are used to estimate changes in relation to the background bedrock input. Duplicates runs were undertaken on approx10% of the total core depth (LP08-1F at 2 mm and 200 microns). Chronology Radiocarbon ages were rounded to the nearest 10 calendar years (cal a BP) in file LP08 C14 data.csv and the results section and to the nearest 100 years (0.1 cal ka BP) in the discussion to reflect dating and age-depth modelling uncertainties. Sedimentology Carbon isotope delta13C data, values were calculated to the VPDB scale using a within-run laboratory standard calibrated against NBS-19 and NBS-22. Replicate analyses of sample material gave a precision of more or less 0.1 (per mil) for delta13Corg and 10% for C/N. Flux data (g cm a-2) were calculated from the product of dry mass accumulation rates (g cm a-1), dry bulk density (g cm-3), sedimentation rates (cm a-1) and proxy concentration measurements. Geochemical XRF-Core scanning data were measured at 2 mm contiguous intervals and for LP08 Unit 6 (equivalent to mean ± 2-sigma: 4.5±7.0 years), at 200 μm intervals for LP08 Unit 1 (1.3±4.2 years), with LP08 basal Unit 1 scanned at 100 μm. Data from finely laminated glaciolacustrine sediments in Units 1-2 were measured at or smoothed to 200 μm (from 100 μm interval data) before analysis. |
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| Lineage: | Sediment cores were collected using a UWITEC-gravity corer, Livingston piston corer from the deepest point (approx 3.5 m of water depth) in Lago Pato (LP08: 51.3003 S, 72.6786 W, 32 m a.s.l., 600 cm total recovered sediment depth). Biology Subsamples for diatom and stomatocyst analysis were taken at 4 cm and 8 cm intervals from the LP08 core. At least 400 valves were counted per slide and species were identified to at least genus level using taxonomic studies from the region. Microscopic pollen, charcoal and cryptotephra shards were counted at 8 cm intervals in the LP08 core) with Lycopodium spores of known concentration added for quantification. The total pollen sum from each subsample is at least 300 land pollen grains (Total Land Pollen, TLP) above 470 cm in the LP08. Charcoal was classified in five different size classes, more than 25 micrometers, 25-50 micrometers, 50-75 micrometers, 75-100 micrometers, and more than 100 micrometers, to distinguish between proximal and distal fires. Chronology A chronology was established using Accelerator Mass Spectrometry (AMS) radiocarbon dating of 21 samples. Calibration of radiocarbon ages was undertaken in OXCAL v.4.4 using the SHCal20.14C Southern Hemisphere atmosphere calibration curve (SH20). Radiocarbon ages are reported as conventional radiocarbon years BP (14C years BP) ±1sigma and calibrated ages as 2sigma (95.4%) ranges, median and mean calendar years BP (cal a BP and cal ka BP, relative to 1950 CE), rounded to the nearest ten years. Age-depth models were developed using Bayesian age-depth modelling software (rBACON v.2.5). Modelled age data mean ages produced by the SH20M1H (Southern Hemisphere, SHcal20, radiocarbon calibration curve) in rBACON, where M1 indicates Model 1 and H indicates the inclusion of a hiatus in the model. Geochemistry Contiguous downcore wet-sediment Energy Dispersive Spectrometry (EDS) X-ray fluorescence core scanning (XRF-CS) data was collected using an ITRAX XRF core scanner fitted with a Molybdenum (Mo) anode X-ray tube (settings: 30 kV, 50 mA, count time 10 seconds, at 2 mm contiguous intervals and for LP08 Unit 6 (equivalent to mean ±2-sigma: 4.5±7.0 years), at 200 micrometers intervals for LP08 Unit 1 (1.3±4.2 years), with LP08 basal Unit 1 scanned at 100 micrometers. Data from finely laminated glaciolacustrine sediments in Units 1-2 were measured at or smoothed to 200 micrometers (from 100 micrometers interval data) before analysis. Sedimentology Physical properties were measured with a Geotek multi-sensor core logger (MSCL) (gamma-ray wet density (gamma-density), resistivity and magnetic susceptibility (MSkappa; SI x 10-5) data (Bartington Instruments; LP08: MS2C loop sensor, 2 mm intervals, 10 seconds; LP16: MS2E point sensor, 0.5 mm intervals; 10 seconds) and density-corrected MSkappa (kappa/rho; kg m-3)). Digital X-radiographs were obtained from split cores using a rotating anode mobile digital Celtic SMR CR computerised X radiography unit at Cambridge University Vet School (48kV; 4 mAs; no grid) and as ITRAX generated digital X-radiographs (45 kV, 50 mA.ms, 200 ms, 60 micrometers interval) at Aberystwyth University. Subsample data includes Loss-on-ignition (LOI) (12 hrs drying at 110°C, 4 hrs at 550°C (LOI550), and 2 hrs at 950°C for carbonate-proxy (LOI950x1.36), TOC (Total Organic Carbon (%C or %Corg) and total nitrogen (%N) and carbon isotopic ratios (delta13C). Data were analysed in MATLAB v. R2021a, R v. 4.1.0/Rstudio v. 1.4.171, using the R packages Vegan, Rioja, Tidyverse, ggplot2, Ggally v. 2.1.2, and in Sigmaplot v. 14.0 and C2 v.1.7.7. Code is available from: https://github.com/stever60/Lago_Pato |
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| Spatial Coverage: | |
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| Latitude | |
| Southernmost | 51.30033 |
| Northernmost | 51.30033 |
| Longitude | |
| Westernmost | 72.67861 |
| Easternmost | 72.67861 |
| Altitude | |
| Min Altitude | 32 |
| Max Altitude | 32 |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Data Storage: | This entry contains the following data folders and subfolders (in alphabetical order) Biology Diatoms Count, percentage and flux diatom data for LP08 for all species and species that make up more than 10percent of the total counts Pollen Percentage and concentration pollen data for LP08 Chronology As measured radiocarbon age data and BACON age-depth model input and output data for LP08 LP08_C14_data.csv - Measured and calibrated Radiocarbon data from LP08. Aw= acid wash; a/a/a = acid-alkali-acid pre-treatment; M=Macrofossil age; P=paired bulk-macrofossil ages; R=age reversal and length of reversal in years in brackets. Reasons for rejection: X-a = Organic sediments emplaced on extraction; X-b = Drag down of younger roots during coring. Age_depth_models folder: LP08_SH20M1H_BACON_input.csv - data used in Southern Hemisphere (SH20) atmosphere calibration curve for LP08 Model 1 with hiatus included (M1H) LP08_SH20M1H_BACON_output.csv - calibrated age data for LP08 Geochemistry ITRAX_XRF_CS folder for LP08 containing: Cluster Analysis folder LP08_2mm_TSN_sqrt_CONISS_Element1.csv and LP08_2mm_TSN_sqrt_CONISS_Element2.csv - Square-root transformed percentageTSN data used in constrained cluster analysis (CONISS) to define the lithological zones undertaken on two different element combinations. Data folder LP08_3_3 subfolder, analysed in March 2013, containing the following core section subfolders. LP081A_XRF LP081B_XRF LP081C_XRF LP081D_XRF LP081E_XRF LP081F_XRF LP081G_XRF LP081H_XRF LP081IC_XRF Each core section subfolder contains: document.txt - run and set up data for the core section scan optical.tif - raw optical image of the core section scan optical1.tif - autotune/autocontrast/autocolour processed optical image of the core section scan in Photoshop v23.2.0 radiograph.raw - raw X ray image of the core section scan radiograph.tif - raw X ray image of the core section scan radiograph1.tif - autotune/autocontrast/autocolour processed X ray image of the core section scan section scan in Photoshop v23.2.0 result.txt - summary set up and cps datafile for the core section sumspectra.txt - average spectra output datafile the core section XRF data folder - individual run data and spectra channel energy data for the core section in sequence from the top of the section, e.g., L000001.txt, L00001.txt etc. Summary data LP08_filtered_2mm_MC.csv and LP08_filtered_200um_MC.csv -filtered cps mastercore (MC) X ray fluorescence (XRF) core scanning (XRF-CS) data LP08_LnFe_Mn_Ratio.txt and LP08_LnFe-Mn_Ratio_100yr.txt - natural log Fe/Mn ratio and Z-scores as measured and 100 year smoothed X ray fluorescence (XRF) core scanning (XRF-CS) data LP08_result_200um_ALL.csv - all as measured cps (count per second) X ray fluorescence (XRF) core scanning (XRF-CS) data LP08_TSN_percent_200um_PCA.csv - percentageTSN (percentage of the total scatter normalised sum) data and PCA input and output X ray fluorescence (XRF) core scanning (XRF-CS) data LP08_Unit1basal_100um.csv - cps X ray fluorescence (XRF) core scanning (XRF-CS) data from the basal section at 100 micron intervals Sedimentology GEOTEK_MSCL folder containing LP08_MSCL_2mm.csv - Geotek multi-sensor core logger data for LP08 and LP16 LP08_Sedimentology_4cm - subsample data summary (LOI, TOC, d13C, C/N) |
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