# Sacred Lake, Mt. Kenya 47000 Year GDGT Temperature Reconstruction #----------------------------------------------------------------------- # World Data Service for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program #----------------------------------------------------------------------- # Template Version 4.0 # Encoding: UTF-8 # NOTE: Please cite original publication, NOAA Landing Page URL, dataset and publication DOIs (where available), # and date accessed when using these downloaded data. If there is no publication information, please cite investigator, study title, NOAA Landing Page URL, and date accessed. # # NOAA_Landing_Page: https://www.ncei.noaa.gov/access/paleo-search/study/13676 # Landing_Page_Description: NOAA Landing Page of this file's parent study, which includes all study metadata. # # Study_Level_JSON_Metadata: https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/json/noaa-lake-13676.json # Study_Level_JSON_Description: JSON metadata of this file's parent study, which includes all study metadata. # # Data_Type: Paleolimnology # # Dataset_DOI: 10.25921/krn2-jd84 # # Science_Keywords: Air Temperature Reconstruction #-------------------- # Resource_Links # # Data_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/sacred2012.txt # Data_Download_Description: NOAA Template File; Temperature Reconstruction # # Original_Source_URL: # Original_Source_Description: # #-------------------- # Contribution_Date # Date: 2013-01-16 #-------------------- # File_Last_Modified_Date # Date: 2022-11-02 #-------------------- # Title # Study_Name: Sacred Lake, Mt. Kenya 47000 Year GDGT Temperature Reconstruction #-------------------- # Investigators # Investigators: Loomis, S.E.(https://orcid.org/0000-0001-6342-3025); Russell, J.M.(https://orcid.org/0000-0002-1329-4613); Ladd, B.; Street-Perrott, F.A.(https://orcid.org/0000-0003-1149-9110); Sinninghe Damsté, J.S.(https://orcid.org/0000-0002-8683-1854) #-------------------- # Description_Notes_and_Keywords # Description: This dataset contains depth, age, reconstructed temperatures, and bootstrap errors on the temperature reconstruction from a core from Sacred Lake, Mt. Kenya. Temperatures were reconstructed from branched GDGTs using the Loomis et al. (2012) stepwise forward selection (SFS) calibration. #-------------------- # Publication # Authors: Shannon E. Loomis, James M. Russell, Bethany Ladd, F. Alayne Street-Perrott, Jaap S. Sinninghe Damsté # Journal_Name: Earth and Planetary Science Letters # Published_Title: Calibration and application of the branched GDGT temperature proxy on East African lake sediments # Published_Date_or_Year: 2012 # Volume: 357-358 # Pages: 277-288 # Issue: # Report_Number: # DOI: 10.1016/j.epsl.2012.09.031 # Full_Citation: # Abstract: Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a novel proxy for mean annual air temperature (MAAT) and have the potential to be broadly applicable to climate reconstruction using lacustrine sediments. Several calibrations have been put forth relating brGDGT distributions to MAAT using a variety of linear regressions, including the methylation (MBT) and cyclization (CBT) indices of brGDGTs, the relative abundances of the major, non-cyclized brGDGTs (MbrGDGTs), and best subsets regression (BSR) of the fractional abundances of the nine most common brGDGTs. However, these calibrations have rarely been applied to lake sediment cores to reconstruct temperatures and test the applicability of this proxy as a paleothermometer. # We present an expanded East African lakes surface sediment brGDGT dataset based upon 111 lakes and examine three methods of calibrating brGDGTs to MAAT. These methods include recalculations of the East African lake MBT/CBT calibration and MbrGDGTs calibrations, as well as a new stepwise forward selection (SFS) calibration that uses the four combined brGDGTs that explain the most variance in temperature in our calibration set. We apply these new calibrations as well as five previously published lacustrine brGDGT calibrations to the brGDGT distributions of our surface sediment dataset and a 48 kyr sediment core from Sacred Lake, Mt. Kenya, producing the first brGDGT temperature reconstruction available from a small tropical lake. We compare the reconstructed temperatures to previously published paleotemperature records from East Africa to help us assess the performance of the brGDGT calibrations. We find that the SFS calibration has a consistently low root mean squared error of prediction (RMSEP) over the entire range of MAAT, while the MBT/CBT and MbrGDGT calibrations have relatively large RMSEPs, particularly between lakes with similar temperatures but variable pH. This suggests that these techniques do not properly deconvolve the temperature and pH signals recorded in the distributions of the brGDGTs. We further find that only the SFS calibration produces a credible reconstructed temperature history from Sacred Lake when compared to other last glacial maximum paleotemperature estimates from East Africa. Thus, we advocate for the use of the SFS calibration when reconstructing paleotemperatures from brGDGTs in East Africa. #-------------------- # Funding_Agency # Funding_Agency_Name: American Chemical Society # Grant_Number: 49235-DNI2 #-------------------- # Funding_Agency # Funding_Agency_Name: European Research Council # Grant_Number: (FP7/2007-2013)/ERC 226600 #-------------------- # Site_Information # Site_Name: Sacred Lake GDGT # Location: Kenya # Northernmost_Latitude: .0833 # Southernmost_Latitude: .0833 # Easternmost_Longitude: 37.5333 # Westernmost_Longitude: 37.5333 # Elevation: 2350 #-------------------- # Data_Collection # Collection_Name: Sacred2012 # First_Year: 47730 # Last_Year: 63 # Time_Unit: cal yr BP # Core_Length: 14.43 # Parameter_Keywords: reconstruction # Notes: #-------------------- # Chronology_Information # Chronology: # Chronology Supplementary Table TA2 # # Depth(cm) 14Cage 14Cerror CalendarAge CalendarError EstimatedAge EstimatedError # 0 -- -- -39 -- -38 64 # 25 230 30 161 11 157 152 # 74 420 25 496 15 471 163 # 79 410 25 490 17 499 163 # 122 760 25 685 14 692 193 # 155 945 30 846 23 912 221 # 196 1510 25 1384 25 1282 256 # 242 1760 45 1667 62 1577 328 # 294 2160 25 2139 20 2235 258 # 366 3770 45 4134 50 4994 307 # 382 6100 35 6956 51 5807 305 # 449 7100 40 7947 20 8022 246 # 474 7890 40 8666 63 8717 297 # 538 9440 50 10687 43 10624 311 # 563* 9690 65 11143 64 11367 296 # 590* 10325 75 12128 95 12125 319 # 602* 10740 80 12637 61 12423 333 # 663* 11630 65 13480 98 13370 485 # 741* 11840 70 13699 100 13968 498 # 795* 12605 50 14938 149 14848 473 # 812* 12680 95 14986 211 15212 489 # 836* 13070 50 15823 347 15769 563 # 861* 13495 50 16690 113 16362 467 # 914* 14690 70 17857 138 17640 489 # 957* 15695 75 18813 95 19136 495 # 1041* 20265 80 24183 166 24969 656 # 1128* 30510 225 34945 183 33966 740 # 1244* 37415 405 42141 304 41887 943 # 1339* 40465 520 44358 429 44961 1310 # # *14C ages from Olago et al. (2001) # #------------------ # Variables # # PaST_Thesaurus_Download_Resource: https://www.ncdc.noaa.gov/paleo/skos/past-thesaurus.rdf # PaST_Thesaurus_Download_Description: Paleoenvironmental Standard Terms (PaST) Thesaurus terms, definitions, and relationships in SKOS format. # # variables format: shortname what,material,error,units,seasonality,data_type,detail,method, C(har) or N(umeric) data,additional information # ## depth_cm depth,,,centimeter,,climate reconstructions;paleolimnology,corrected,,N, ## age_calBP age,,,calendar year before present,,climate reconstructions;paleolimnology,,,N, ## temp surface air temperature,glycerol dialkyl glycerol tetraether index,,degree Celsius,annual,climate reconstructions;paleolimnology,,,N,brGDGT ## temp_err surface air temperature,glycerol dialkyl glycerol tetraether index,one standard deviation,degree Celsius,annual,climate reconstructions;paleolimnology,,,N,brGDGT #-------------------- # Data: # Missing_Values: NA depth_cm age_calBP temp temp_err 12.5 63 19.5 1.2 18.5 110 18.8 1.1 30.5 202 18.5 1.1 48.5 326 18.3 1.1 52.1 349 19.5 1.2 66.4 433 18.4 1.1 105 611 18.6 1.2 122.1 692 18.9 1.2 139.3 793 18.1 1.1 155.1 912 19.1 1.2 175.6 1100 18.4 1.1 202.8 1332 19.3 1.2 236.9 1544 18.7 1.1 246 1605 19.6 1.3 254.5 1670 19.8 1.3 266.2 1785 18.7 1.2 296.1 2296 19.3 1.2 320.8 3044 18.8 1.1 332.5 3491 19.4 1.2 346.8 4104 19.9 1.2 354.1 4440 19.6 1.2 371.5 5295 19.6 1.2 378.5 5641 19.8 1.0 387.8 6065 19.9 1.1 395.9 6394 19.6 1.0 402.9 6653 19.7 1.0 413.4 7003 21.1 1.4 423.8 7317 20.1 1.1 436.6 7675 20.1 1.1 449.4 8022 19.9 1.0 456.5 8218 18.6 0.9 463.5 8414 18.5 0.9 470.6 8616 19.7 1.0 481.2 8925 19.7 1.1 488.2 9133 19.4 1.1 495.3 9346 19.3 1.0 502.4 9561 19.4 1.0 509.4 9773 19.5 0.9 520 10095 19.4 0.9 532.9 10484 19.1 0.9 541.2 10731 19.4 0.9 547.1 10904 19.2 0.8 557.8 11216 19.9 0.7 572.3 11636 18.6 0.8 574.7 11705 18.7 0.9 579.5 11840 18.6 0.9 586.7 12038 18.8 0.9 594 12229 19.1 0.6 610.8 12616 19.8 0.5 618.1 12760 20.1 0.6 625.3 12889 20.0 0.6 641 13125 18.4 0.5 670.5 13434 18.4 0.6 675.9 13475 17.9 0.6 697.6 13618 17.1 0.6 719.3 13765 16.9 0.7 733.7 13890 17.7 0.6 757.6 14186 17.4 0.5 779.7 14558 16.6 0.4 806.4 15100 17.0 0.4 822.7 15468 17.8 0.4 839 15852 16.8 0.3 852.8 16181 17.4 0.3 879.8 16807 16.1 0.3 904.5 17403 16.4 0.3 919.1 17795 15.3 0.4 939.3 18434 15.5 0.3 948.3 18771 14.0 0.3 964.8 19502 15.2 0.3 984.6 20592 15.0 0.3 994.5 21224 14.3 0.3 1004.4 21914 16.1 0.4 1011 22407 13.7 0.3 1020.9 23194 12.4 0.3 1030.8 24038 12.7 0.4 1047.3 25574 17.2 0.5 1060.2 26871 14.2 0.7 1069.9 27885 12.8 0.4 1082.8 29263 13.7 0.4 1095.7 30648 14.8 0.3 1118.3 33009 13.8 0.3 1177 38061 16.5 0.5 1190.8 39004 12.4 0.4 1221.8 40822 16.6 0.5 1249.4 42118 14.5 0.3 1256.8 42419 16.8 0.5 1288.9 43547 16.3 0.4 1318.5 44409 16.1 0.4 1348.1 45203 17.0 0.5 1361.3 45554 16.4 0.6 1392.1 46374 16.8 0.4 1421.7 47163 15.5 0.4 1443 47730 15.2 0.4