# Lake Bosumtwi, Ghana Late Quaternary Magnetic Mineral Data #---------------------------------------------------- # World Data Service for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program # National Centers for Environmental Information (NCEI) #---------------------------------------------------- # 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 downloaded data. If there is no publication information, please cite investigator, study title, NOAA Landing Page URL, and date accessed. # # Description/Documentation lines begin with # # Data lines have no # # # NOAA_Landing_Page: https://www.ncei.noaa.gov/access/paleo-search/study/5454 # 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-5454.json # Study_Level_JSON_Description: JSON metadata of this data file's parent study, which includes all study metadata. # # Data_Type: Paleolimnology # # Dataset_DOI: 10.25921/149q-tg68 # # Science_Keywords: #-------------------- # Resource_Links # # Data_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/paleolimnology/africa/bosumtwi2004-org-noaa.txt # Data_Download_Description: NOAA Template File; Composite Cores 12P and 15P Organic Matter Data # #-------------------- # Contribution_Date # Date: 2007-01-01 #-------------------- # File_Last_Modified_Date # Date: 2024-04-22 #-------------------- # Title # Study_Name: Lake Bosumtwi, Ghana Late Quaternary Magnetic Mineral Data #-------------------- # Investigators # Investigators: Peck, J.A.; Green, R.R.; Shanahan, T.M.(https://orcid.org/0000-0002-3831-3198); King, J.W.; Overpeck, J.T.(https://orcid.org/0000-0002-3843-9313); Scholz, C.A. #-------------------- # Description_Notes_and_Keywords # Description: Lake Bosumtwi, Ghana (6°30'N, 1°25'W, 99m. elev.). In June, 2000, 19 piston cores were extracted from Lake Bosumtwi. Eight short piston cores (1N-8N), ranging from 108 to 134 cm in length, were used to capture the sediment-water interface. These cores were supplemented by two freeze cores obtained from the deepest portion of the lake. The remaining 11 longer cores, ranging from 5.5 to 10.9 m in length, did not preserve the sediment-water interface, but were correlated with the shorter cores using well-defined marker bands. Physical property logging of whole core volumetric magnetic susceptibility and gammaray attenuation (an estimation of wet bulk density) was conducted on the piston cores using an automated Geotek multisensor core logger. #-------------------- # Publication # Authors: Peck, J.A., R.R. Green, T. Shanahan, J.W. King, J.T. Overpeck, C.A. Scholz # Journal_Name: Palaeogeography, Palaeoclimatology, Palaeoecology # Published_Title: A magnetic mineral record of Late Quaternary tropical climate variability from Lake Bosumtwi, Ghana # Published_Date_or_Year: 2004-12-02 # Volume: 215 # Pages: 37-57 # Issue: 1-2 # Report_Number: # DOI: 10.1016/j.palaeo.2004.08.003 # Full_Citation: # Abstract: We report magnetic hysteresis results from sediment cores obtained from Lake Bosumtwi, Ghana. As a hydrologically closed basin, the water budget of Lake Bosumtwi is extremely sensitive to changes in the precipitation/evapotranspiration balance. Lake Bosumtwi lies in the path of the seasonal migration of the intertropical convergence zone (ITCZ); hence, the lake is ideally situated to study monsoon variability in West Africa. Five distinctive magnetic mineral zones (A-E) were identified in the 11-m-long sediment cores that span the last 26,000 calendar years. Prior to 12 calendar (cal) ka, low concentrations of multidomain, high-coercivity magnetic minerals are present. Three prominent shifts towards very high concentrations of high-coercivity iron sulfide (greigite) magnetic minerals are centered at 12,470, 17,290, and 22,600 calendar years during the last glacial period (magnetic zones D1-3). Between 12 and 3.2 cal ka, there is an abrupt shift to moderately high concentrations of mixed multidomain and single-domain, low-coercivity minerals and an organic-rich sapropel lithology. Since 3.2 cal ka, the magnetic mineral parameters reveal a shift to increased amounts of high-coercivity magnetic minerals. # # These magnetic mineral zones document tropical climate variability on a variety of temporal scales. Glacial age sediments have a high-coercivity magnetic mineralogy due to increased aeolian dust transport from the Sahel to Lake Bosumtwi as well as postdepositional reductive diagenesis. During the last glacial period, the increased strength of Harmattan and North African continental trade winds, the southward depression of the ITCZ, and weakened summer monsoon strength resulted in increased regional aridity and greater dust flux out of Sahel source regions. The greigite-bearing D magnetic zones correspond to brief lowstands in the level of Lake Bosumtwi and likely represent periods of intensified aridity in West Africa. The D magnetic zones closely resemble the timing and duration of Heinrich events and suggest a hemispheric-scale climatic coupling between the tropics and poles. The well-documented African humid period (AHP) is characterized by abrupt shifts in magnetic parameters between 12 and 3.2 cal ka. Dust flux to Lake Bosumtwi is inferred to be very low during this humid interval due to the strengthening of the summer monsoon. Since 3.2 cal ka, the magnetic mineral parameters suggest increased aridity as compared to the AHP. This work demonstrates that the magnetic properties of Lake Bosumtwi sediment are a sensitive recorder of abrupt climate change of global significance. #-------------------- # Funding_Agency # Funding_Agency_Name: US National Science Foundation # Grant: ATM-0117019 #-------------------- # Site_Information # Site_Name: Lake Bosumtwi # Location: Ghana # Northernmost_Latitude: 6.5 # Southernmost_Latitude: 6.5 # Easternmost_Longitude: -1.4167 # Westernmost_Longitude: -1.4167 # Elevation_m: 99 #-------------------- # Data_Collection # Collection_Name: Lake Bosumtwi Peck2004 LOI # First_Year: 26655 # Last_Year: 152 # Time_Unit: cal yr BP # Core_Length_m: # Parameter_Keywords: physical properties # Notes: Standardized (composited) depth, calendar age, and LOI values for piston cores 12P and 15P #-------------------- # Chronology_Information # Chronology: Radiocarbon # Chronology_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/templates/noaa-wds-paleo-14c-terms.csv # Chronology_Download_Description: Radiocarbon terms and definitions. # Chronology_Notes: # Rejection_Rationale: # Reservoir_Method: # Calibration_Method: CALIB 3.0 using the INTCAL98 calibrated dataset (Stuiver and Reimer, 1993, Stuiver et al., 1998). Some AMS 14C dates extended beyond the INTCAL98 calibration range. The equation of a linear regression line through the 14C ages younger than 19,000 years BP, which were converted to calendar years, was used to estimate the calibrated age of 14C samples older than 19,000 14C years BP. # Age_Model_Method: Above 705.25 cm standardized depth, the age model line was derived from linear interpolation between selected clusters of more reliably dated wood and sapropel organic material. Below 705.25 cm standardized depth, the age model was constructed using a linear regression, ignoring two ages. # Missing_Values: NaN # Chronology_Table: # lab_code core_id date_type depth_raw_cm depth_cm age_14C_BP1950 age_14C_1s_yr age_calib_pos2s_BP1950 age_calib_BP1950 age_calib_neg2s_BP1950 date_used calib_curve # NA NA 210Pb NA 29.4 NA NA NA 154 NA yes None # AA43709 12P 14C AMS 75 157 3356 46 3679 3608 3482 no IntCal98 # AA43981 12P 14C AMS 93 181.2 3061 49 3354 3302 3174 yes IntCal98 # AA43708 19P 14C AMS 90 182.2 3012 47 3321 3233 3081 yes IntCal98 # AA43710 12P 14C AMS 95 183.7 3129 43 3382 3358 3270 yes IntCal98 # AA43982 19P 14C AMS 92 184.7 2949 70 3239 3128 2971 yes IntCal98 # AA43980 12P 14C AMS 115 204 4193 52 4832 4747 4630 yes IntCal98 # AA51280 12P 14C AMS 225.4 314.4 9604 89 11165 10940 10705 yes IntCal98 # AA47363 15P 14C AMS 84 315 9586 82 11159 10825 10701 yes IntCal98 # AA51284 12P 14C AMS 292.7 381.7 12890 240 15859 15520 14475 no IntCal98 # AA46922 15P 14C AMS 276 408 12317 65 15301 14298 14135 yes IntCal98 # AA47364 15P 14C AMS 304 432 13460 100 16422 16168 15923 no IntCal98 # AA51276 12P 14C AMS 346.1 434.9 19950 1135 NA 23975 NA no IntCal98 # AA51278 12P 14C AMS 346.9 435.9 12970 320 16032 15600 14955 yes IntCal98 # AA51277 12P 14C AMS 412.6 501.6 13750 100 16761 16500 16252 yes IntCal98 # AA51279 12P 14C AMS 413.6 502.6 13800 110 16825 16560 16303 yes IntCal98 # AA47366 15P 14C AMS 494 558.2 14211 91 17300 17032 16778 yes IntCal98 # AA51275 12P 14C AMS 506.5 595.5 15540 410 19120 18560 18021 no IntCal98 # AA51274 12P 14C AMS 563.5 652.5 17460 630 21568 20771 19981 no IntCal98 # AA51273 12P 14C AMS 616.3 705.3 15090 250 18444 18044 17660 yes IntCal98 # AA51272 12P 14C AMS 689.8 778.8 17060 520 20990 20310 19638 yes IntCal98 # AA47365 15P 14C AMS 748.9 803.2 18200 170 22014 21623 21243 yes IntCal98 # AA46924 15P 14C AMS 761.9 818.2 14412 75 17530 17264 17012 no IntCal98 # AA51270 12P 14C AMS 760.1 849.1 17360 300 21130 20660 20189 yes IntCal98 # AA51271 12P 14C AMS 844.1 933.1 20260 800 NA 24355 NA yes IntCal98 # AA51287 15P 14C AMS 1002 1046 19860 890 NA 23865 NA yes IntCal98 # AA51286 15P 14C AMS 1006 1050 20310 420 NA 24416 NA yes IntCal98 # AA51288 15P 14C AMS 1010 1054 20900 690 NA 25139 NA yes IntCal98 # OS27967 15P 14C AMS 1029 1073 23600 160 NA 28445 NA no IntCal98 # AA51285 15P 14C AMS 1074 1118 21480 850 NA 25849 NA yes IntCal98 # OS27966 15P 14C AMS 1083.5 1127.5 22900 180 NA 27588 NA yes IntCal98 # OS28023 16P 14C AMS 407 NA 13600 90 16581 16329 16088 no IntCal98 # OS28024 16P 14C AMS 416 NA 13600 75 16574 16329 16095 no IntCal98 # OS28025 16P 14C AMS 445 NA 14800 120 18009 17710 17427 no IntCal98 #-------------------- # Variables # PaST_Thesaurus_Download_Resource: https://www.ncei.noaa.gov/access/paleo-search/skos/past-thesaurus.rdf # PaST_Thesaurus_Download_Description: Paleoenvironmental Standard Terms (PaST) Thesaurus terms, definitions, and relationships in SKOS format. # # Data variables follow that are preceded by '##' in columns one and two. # Variables list, one per line, shortname-tab-var components: what, material, error, units, seasonality, data type, detail, method, C or N for Character or Numeric data) # ## core_id sample identification,,,,,paleolimnology,,,C,core name ## depth_comp_cm depth,,,centimeter,,paleolimnology,composited,,N,standardized core depth ## age_calBP age,,,calendar year before present,,paleolimnology,,,N, ## LOI-Organic organic matter,sediment,,weight percent,,paleolimnology,composited,loss on ignition,N, #-------------------- # Data: # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing_Values: core_id depth_comp_cm age_calBP LOI-Organic B2000 12P 29.02 152.3 17.7 B2000 12P 42.08 418.2 16 B2000 12P 55.14 689.3 18.1 B2000 12P 68.2 960.4 23.1 B2000 12P 81.27 1231.8 22.5 B2000 12P 94.33 1502.9 17.9 B2000 12P 107.39 1774 21.9 B2000 12P 120.45 2045.1 24.3 B2000 12P 133.52 2316.4 20.6 B2000 12P 146.58 2587.5 22 B2000 12P 159.64 2858.6 33 B2000 12P 172.7 3129.7 8.5 B2000 12P 185.77 3500 34.6 B2000 12P 193.45 4026.8 37.6 B2000 12P 201.45 4575.5 39.1 B2000 12P 209.45 5055.5 36.8 B2000 12P 217.45 5504.3 31.4 B2000 12P 225.45 5953.1 32.7 B2000 12P 233.45 6401.8 32.3 B2000 12P 241.45 6850.6 34 B2000 12P 242.45 6906.7 31.2 B2000 12P 250.45 7355.5 28.2 B2000 12P 258.45 7804.2 23.4 B2000 12P 266.45 8253 34.6 B2000 12P 274.45 8701.8 31.5 B2000 12P 282.45 9150.5 33 B2000 12P 290.45 9599.3 32.1 B2000 12P 298.45 10048.1 20.6 B2000 12P 306.45 10496.8 28 B2000 12P 314.45 10943.6 31.5 B2000 12P 322.45 11230.4 25.2 B2000 12P 330.45 11517.3 34 B2000 12P 338.45 11804.2 27.2 B2000 12P 346.45 12091 28 B2000 12P 354.45 12377.9 15.3 B2000 12P 362.45 12664.7 17.6 B2000 12P 370.45 12951.6 19.8 B2000 12P 378.45 13238.4 17.3 B2000 12P 386.45 13525.3 17.8 B2000 12P 394.45 13812.1 18.8 B2000 12P 402.95 14116.9 17.3 B2000 12P 410.95 14435.7 15.2 B2000 12P 418.95 14809 18 B2000 12P 426.95 15182.3 12.9 B2000 12P 434.95 15555.7 11 B2000 12P 442.95 15696.6 18.2 B2000 12P 450.95 15806.2 17.4 B2000 12P 458.95 15915.8 15.8 B2000 12P 466.95 16025.3 17.1 B2000 12P 474.95 16134.9 15.8 B2000 12P 482.95 16244.5 13.9 B2000 12P 490.95 16354.1 17.6 B2000 12P 498.95 16463.7 16.2 B2000 12P 506.95 16540.5 17.4 B2000 12P 514.95 16601 15.4 B2000 12P 522.95 16661.4 15.5 B2000 12P 530.95 16721.9 16.5 B2000 12P 538.95 16782.4 17.8 B2000 12P 545.95 16835.4 18.6 B2000 12P 553.95 16895.9 14.2 B2000 12P 561.95 16956.4 25.8 B2000 12P 569.95 17016.9 12.6 B2000 12P 577.95 17077.4 20.5 B2000 12P 585.95 17137.9 19.7 B2000 12P 593.95 17198.4 15.6 B2000 12P 601.95 17258.8 15.6 B2000 12P 609.95 17319.3 20 B2000 12P 617.95 17379.8 18.9 B2000 12P 625.95 17440.3 13.4 B2000 12P 633.95 17500.8 16.9 B2000 12P 641.95 17561.3 13.4 B2000 12P 649.95 17621.8 13.6 B2000 12P 657.95 17682.3 11.8 B2000 12P 665.95 17742.8 14.1 B2000 12P 673.95 17803.3 20.3 B2000 12P 681.95 17863.8 18.5 B2000 12P 689.95 17924.3 19.2 B2000 12P 697.95 17984.8 25 B2000 12P 705.95 18048.2 19.8 B2000 12P 713.95 18217.3 27.2 B2000 12P 721.95 18380.3 20.6 B2000 12P 729.95 18543.3 20.1 B2000 12P 737.95 18706.4 15.3 B2000 12P 745.95 18869.4 19.7 B2000 12P 753.95 19032.4 19.9 B2000 12P 761.95 19195.5 17.3 B2000 12P 769.95 19358.5 23.8 B2000 12P 777.95 19521.5 22.4 B2000 12P 785.95 19684.5 20.8 B2000 12P 793.95 19847.6 28.5 B2000 12P 801.95 20010.6 18.6 B2000 12P 809.95 20173.6 19.3 B2000 12P 817.95 20336.6 16.4 B2000 12P 825.95 20499.7 12.5 B2000 12P 833.95 20662.7 16.9 B2000 12P 841.95 20825.7 18.8 B2000 12P 846.95 20927.6 19.1 B2000 12P 854.95 21090.7 28.3 B2000 12P 862.95 21253.7 16.9 B2000 12P 870.95 21416.7 16.1 B2000 12P 878.95 21579.7 22.1 B2000 12P 886.95 21742.8 22 B2000 12P 894.95 21905.8 20.7 B2000 12P 902.95 22068.8 17.1 B2000 12P 910.95 22231.8 14.2 B2000 12P 918.95 22394.9 19 B2000 12P 926.95 22557.9 17.1 B2000 15P 929.5 22609.9 8.6 B2000 15P 937.5 22772.9 11.4 B2000 12P 942.95 22884 12.1 B2000 15P 945.5 22935.9 13.4 B2000 12P 950.95 23047 12.7 B2000 15P 953.5 23098.9 15.7 B2000 12P 958.95 23210 13.1 B2000 15P 961.5 23262 12.9 B2000 12P 966.95 23373 19.6 B2000 15P 969.5 23425 21.2 B2000 15P 977.5 23588 18.1 B2000 12P 982.95 23699.1 11.5 B2000 15P 985.5 23751.1 10.2 B2000 15P 993.5 23914.1 19.5 B2000 15P 1001.5 24077.1 11.5 B2000 15P 1009.5 24240.1 10.4 B2000 15P 1025.5 24566.2 13.6 B2000 15P 1057.5 25218.3 23.8 B2000 15P 1065.5 25381.3 13.6 B2000 15P 1072 25513.8 18 B2000 15P 1080 25676.8 14.5 B2000 15P 1088 25839.8 16.1 B2000 15P 1096 26002.9 18.5 B2000 15P 1104 26165.9 17.2 B2000 15P 1120 26492 14.6 B2000 15P 1128 26655 11.9