VG Isocarb preparation system. Isotopic ratios of purified CO2 gas were measured on-line by a triple-collector VG Prism Series II mass spectrometer
"When the lake was open (i.e., lake level was high and water was lost by outflow), the 18O/16O ratio of lakewater was low and rela- tively constant because the isotopic composition was controlled mainly by the 􏰆18O of input waters. When the basin was closed (i.e., lake level was low and water was lost predominantly by evaporation), the lakewater was isotopically enriched in 18O due to preferential evaporative loss of 16O. At low stage, the lake was not only isotopically enriched in 18O, but the isotopic composition of the lake was more variable because of the high sensitivity of a small lake volume to changes in the ratio of evaporation to pre- cipitation."
DK: Most complete of three ostracode species analyzed.
For stable isotope analysis, each 1 cm subsample was disaggregated by soaking in 3% H2O2 and subsequently sieved at 250 mm. The .250 mm fraction was collected on filter paper, dried at 60�C and transferred to glass scintillation vials. Ostracods and gastropods were separated from the matrix using a dissecting microscope at 10 � magnification. Adult specimens of the ostracod Cytheridella boldi were picked from the sieved 425?500 mm fraction, Heterocypris communis were picked from the 351?500 mm fraction, and Cypria obtusa were picked from the 250?300 mm fraction. Specimens of the gastropod Pyrgophorus sp. were separated from the sieved .1000 mm fraction. Ostracod valves were cleaned of organic material using 15% H2O2, then washed in deionized water, rinsed in methanol, and dried. Gastropods were cleaned in the same manner, except that specimens were cleaned further by sonication. Samples consisting of many monospecific ostracod carapaces (|15 C. boldi, |20 H. communis, |25 C. obtusa) were loaded into a stainless-steel carrying boat, crushed with a glass rod dipped in methanol and allowed to dry overnight. Numerous monospecific ostracod valves were used to constitute a sample to reduce variance that might result from running single, short-lived individuals whose isotopic signatures might reflect short-term (i.e., seasonal) water-column temperature and salinity conditions (Heaton et al., 1995)
Lake level also important as lake not always closed but Since ,3000 14C yr BP the level of Lake Valencia has been dropping. Lake closed in present day, but last 2k isotoeps realtively fresh suggesting more open system?
NA; paleoData_isPrimary has been standardized
DK: Reject and defer to ostracode-based timeseries. Good for replication
NA; paleoData_isPrimary has been standardized; paleoData_datum has been standardized
fraction of modern 14C activity uncertainty
210Pb, 239+240Pu or 137Cs activity uncertainty
Y if supported 210Pb activity, N if unsupported 210Pb activity
model used to convert 210Pb activity to age (e.g., constant rate of supply)
One ostracod species used here but other shell typrsd show similar trends with values offset with a smaller range
originalDataUrl: 'https://www.ncei.noaa.gov/access/paleo-search/study/5489' has been replaced by 'https://doi.org/10.25921/7z2j-zn40'
d18O (LS99CUVAa): paleoData_QCCertification: '' has been replaced by 'CR'
d18O (LS99CUVAb): paleoData_QCCertification: 'DK' has been replaced by 'DK, CR'
d18O (LS99CUVAc): paleoData_QCCertification: 'DK' has been replaced by 'DK, CR'
d18O (LS99CUVAa): interpretation2_variable: 'P-E' has been replaced by 'effectivePrecipitation'
d18O (LS99CUVAb): interpretation2_variable: 'P-E' has been replaced by 'effectivePrecipitation'
d18O (LS99CUVAc): interpretation2_variable: 'P-E' has been replaced by 'effectivePrecipitation'
d18O (LS99CUVAa): paleoData_proxyGeneral: 'isotope' has been replaced by 'isotopic'
d18O (LS99CUVAb): paleoData_proxyGeneral: 'isotope' has been replaced by 'isotopic'
d18O (LS99CUVAc): paleoData_proxyGeneral: 'isotope' has been replaced by 'isotopic'
d18O (LS99CUVAa): interpretation1_variable: 'P-E' has been replaced by 'effectivePrecipitation'
d18O (LS99CUVAb): interpretation1_variable: 'P-E' has been replaced by 'effectivePrecipitation'
d18O (LS99CUVAc): interpretation1_variable: 'P-E' has been replaced by 'effectivePrecipitation'
Updated lipdverse database entry with a changed file.
geo_elevation: '' has been replaced by '400'
d18O (LS99CUVAa): interpretation1_seasonality: 'annual' has been replaced by 'Annual'
d18O (LS99CUVAa): interpretation2_variable: 'P_E' has been replaced by 'P-E'
d18O (LS99CUVAa): interpretation3_variable: 'T' has been replaced by 'temperature'
d18O (LS99CUVAb): interpretation1_seasonality: 'annual' has been replaced by 'Annual'
d18O (LS99CUVAb): interpretation2_variable: 'P_E' has been replaced by 'P-E'
d18O (LS99CUVAb): interpretation3_variable: 'T' has been replaced by 'temperature'
d18O (LS99CUVAc): interpretation1_seasonality: '1,2,3,4,5,6,7,8,9,10,11,12' has been replaced by 'Annual'
d18O (LS99CUVAc): interpretation2_variable: 'P_E' has been replaced by 'P-E'
d18O (LS99CUVAc): interpretation3_variable: 'T' has been replaced by 'temperature'
depth (MAT453770a586): paleoData_notes: '' has been replaced by 'NA; paleoData_isPrimary has been standardized'
depth (MAT453770a586): paleoData_isPrimary: '' has been replaced by 'TRUE'
year (MATe80b9fa4c1): paleoData_notes: '' has been replaced by 'NA; paleoData_isPrimary has been standardized'
year (MATe80b9fa4c1): paleoData_units: 'AD' has been replaced by 'yr AD'
year (MATe80b9fa4c1): paleoData_isPrimary: '' has been replaced by 'TRUE'
age (WEBab09259b): paleoData_notes: '' has been replaced by 'NA; paleoData_isPrimary has been standardized; paleoData_datum has been standardized'
age (WEBab09259b): paleoData_units: 'BP' has been replaced by 'yr BP'
age (WEBab09259b): paleoData_datum: '' has been replaced by '1950'
age (WEBab09259b): paleoData_isPrimary: '' has been replaced by 'TRUE'
geo_elevation: '400' has been replaced by ''
originalDataUrl: 'https://www.ncdc.noaa.gov/cdo/f?p=519:1:::::P1_STUDY_ID:5489' has been replaced by 'https://www.ncei.noaa.gov/access/paleo-search/study/5489'
Column 'chron15', with variable name 'age', was removed from the dataset
d18O (LS99CUVAa): interpretation1_seasonalityOriginal: '' has been replaced by 'Annual'
d18O (LS99CUVAa): interpretation1_variableGroup: '' has been replaced by 'P-E'
d18O (LS99CUVAb): interpretation1_seasonalityOriginal: '' has been replaced by 'Annual'
d18O (LS99CUVAb): interpretation1_variableGroup: '' has been replaced by 'P-E'
d18O (LS99CUVAc): interpretation1_variableGroup: '' has been replaced by 'P-E'
d18O (LS99CUVAa): paleoData_proxyLumps: '' has been replaced by 'isotope'
d18O (LS99CUVAa): paleoData_proxyLumpsOriginal: '' has been replaced by 'd18O'
d18O (LS99CUVAb): paleoData_proxyLumps: '' has been replaced by 'isotope'
d18O (LS99CUVAb): paleoData_proxyLumpsOriginal: '' has been replaced by 'd18O'
d18O (LS99CUVAc): paleoData_proxyLumps: '' has been replaced by 'isotope'
d18O (LS99CUVAc): paleoData_proxyLumpsOriginal: '' has been replaced by 'd18O'
age (WEBab09259b): paleoData_units: 'yr BP' has been replaced by 'BP'
age (WEBab09259b): paleoData_unitsOriginal: '' has been replaced by 'yr BP'
d18O (LS99CUVAc): interpretation1_seasonality: 'Annual' has been replaced by '1,2,3,4,5,6,7,8,9,10,11,12'
geo_gcmdLocation: '' has been replaced by 'South America>Venezuela'
d18O (LS99CUVAa): paleoData_notes: '; archiveType changed - was originally Lake sediment (LS)' has been replaced by '"When the lake was open (i.e., lake level was high and water was lost by outflow), the 18O/16O ratio of lakewater was low and rela- tively constant because the isotopic composition was controlled mainly by the 􏰆18O of input waters. When the basin was closed (i.e., lake level was low and water was lost predominantly by evaporation), the lakewater was isotopically enriched in 18O due to preferential evaporative loss of 16O. At low stage, the lake was not only isotopically enriched in 18O, but the isotopic composition of the lake was more variable because of the high sensitivity of a small lake volume to changes in the ratio of evaporation to pre- cipitation."'
d18O (LS99CUVAa): paleoData_proxy: '' has been replaced by 'd18O'
d18O (LS99CUVAa): paleoData_proxyDetail: '' has been replaced by 'H. communis'
d18O (LS99CUVAa): paleoData_proxyGeneral: '' has been replaced by 'isotope'
d18O (LS99CUVAb): paleoData_notes: '; archiveType changed - was originally Lake sediment (LS)' has been replaced by '"When the lake was open (i.e., lake level was high and water was lost by outflow), the 18O/16O ratio of lakewater was low and rela- tively constant because the isotopic composition was controlled mainly by the 􏰆18O of input waters. When the basin was closed (i.e., lake level was low and water was lost predominantly by evaporation), the lakewater was isotopically enriched in 18O due to preferential evaporative loss of 16O. At low stage, the lake was not only isotopically enriched in 18O, but the isotopic composition of the lake was more variable because of the high sensitivity of a small lake volume to changes in the ratio of evaporation to pre- cipitation."'
d18O (LS99CUVAb): paleoData_proxy: '' has been replaced by 'd18O'
d18O (LS99CUVAb): paleoData_proxyDetail: '' has been replaced by 'Pyrgophorus sp'
d18O (LS99CUVAb): paleoData_proxyGeneral: '' has been replaced by 'isotope'
d18O (LS99CUVAc): paleoData_notes: '; archiveType changed - was originally Lake sediment (LS)' has been replaced by '"When the lake was open (i.e., lake level was high and water was lost by outflow), the 18O/16O ratio of lakewater was low and rela- tively constant because the isotopic composition was controlled mainly by the 􏰆18O of input waters. When the basin was closed (i.e., lake level was low and water was lost predominantly by evaporation), the lakewater was isotopically enriched in 18O due to preferential evaporative loss of 16O. At low stage, the lake was not only isotopically enriched in 18O, but the isotopic composition of the lake was more variable because of the high sensitivity of a small lake volume to changes in the ratio of evaporation to pre- cipitation."'
d18O (LS99CUVAc): paleoData_proxy: '' has been replaced by 'd18O'
d18O (LS99CUVAc): paleoData_proxyDetail: '' has been replaced by 'C. boldi'
d18O (LS99CUVAc): paleoData_proxyGeneral: '' has been replaced by 'isotope'
d18O (LS99CUVAa): interpretation1_direction: '' has been replaced by 'negative'
d18O (LS99CUVAa): interpretation1_variable: '' has been replaced by 'P-E'
d18O (LS99CUVAa): interpretation1_seasonality: '' has been replaced by 'Annual'
d18O (LS99CUVAa): interpretation1_seasonalityGeneral: '' has been replaced by 'Annual'
d18O (LS99CUVAa): interpretation1_variableDetail: '' has been replaced by 'lakebalance@surface'
d18O (LS99CUVAb): interpretation1_direction: '' has been replaced by 'negative'
d18O (LS99CUVAb): interpretation1_variable: '' has been replaced by 'P-E'
d18O (LS99CUVAb): interpretation1_seasonality: '' has been replaced by 'Annual'
d18O (LS99CUVAb): interpretation1_seasonalityGeneral: '' has been replaced by 'Annual'
d18O (LS99CUVAb): interpretation1_variableDetail: '' has been replaced by 'lakebalance@surface'
d18O (LS99CUVAc): interpretation1_direction: '' has been replaced by 'negative'
d18O (LS99CUVAc): interpretation1_variable: '' has been replaced by 'P-E'
d18O (LS99CUVAc): interpretation1_seasonality: '' has been replaced by 'Annual'
d18O (LS99CUVAc): interpretation1_seasonalityGeneral: '' has been replaced by 'Annual'
d18O (LS99CUVAc): interpretation1_variableDetail: '' has been replaced by 'lakebalance@surface'
Column 'WEBab09259b', with variable name 'age', was added to the dataset
materialDated (chron10): chronData_units: '' has been replaced by 'unitless'
supportedActivity (chron13): chronData_units: '' has been replaced by 'unitless'
x210PbModel (chron14): chronData_units: '' has been replaced by 'unitless'
useInAgeModel (chron19): chronData_units: '' has been replaced by 'unitless'
fractionModern (chron4): chronData_units: '' has been replaced by 'unitless'
fractionModernUncertainty (chron5): chronData_units: '' has been replaced by 'unitless'
labID (chron9): chronData_units: '' has been replaced by 'unitless'
d18O (LS99CUVAa): interpretation1_basis: 'Lake level also important as lake not always closed but Since ,3000 14C yr BP the level of Lake Valencia has been dropping. Lake closed in present day, but last 2k isotoeps realtively fresh suggesting more open system?' has been replaced by ''
d18O (LS99CUVAa): interpretation1_direction: 'negative' has been replaced by ''
d18O (LS99CUVAa): interpretation1_inferredMaterial: 'lake water' has been replaced by ''
d18O (LS99CUVAa): interpretation1_integrationTimeUnits: 'years' has been replaced by ''
d18O (LS99CUVAa): interpretation1_rank: '1' has been replaced by ''
d18O (LS99CUVAa): interpretation1_scope: 'isotope' has been replaced by 'climate'
d18O (LS99CUVAa): interpretation1_variable: 'P_E' has been replaced by ''
d18O (LS99CUVAa): interpretation1_variableGroup: 'EffectiveMoisture' has been replaced by ''
d18O (LS99CUVAa): interpretation1_variableGroupDirection: 'negative' has been replaced by ''
d18O (LS99CUVAa): interpretation1_variableGroupOriginal: 'P_E' has been replaced by ''
d18O (LS99CUVAa): interpretation2_rank: '2' has been replaced by '1'
d18O (LS99CUVAa): interpretation2_variable: 'T' has been replaced by 'P_E'
d18O (LS99CUVAa): interpretation2_variableGroup: 'Temperature' has been replaced by 'EffectiveMoisture'
d18O (LS99CUVAa): interpretation2_variableGroupOriginal: 'T' has been replaced by 'P_E'
d18O (LS99CUVAa): interpretation2_variableOriginal: 'temperature' has been replaced by ''
d18O (LS99CUVAa): interpretation2_basis: '' has been replaced by 'Lake level also important as lake not always closed but Since ,3000 14C yr BP the level of Lake Valencia has been dropping. Lake closed in present day, but last 2k isotoeps realtively fresh suggesting more open system?'
d18O (LS99CUVAa): interpretation2_direction: '' has been replaced by 'negative'
d18O (LS99CUVAa): interpretation3_inferredMaterial: '' has been replaced by 'lake water'
d18O (LS99CUVAa): interpretation3_integrationTimeUnits: '' has been replaced by 'years'
d18O (LS99CUVAa): interpretation3_rank: '' has been replaced by '2'
d18O (LS99CUVAa): interpretation3_scope: '' has been replaced by 'isotope'
d18O (LS99CUVAa): interpretation3_variable: '' has been replaced by 'T'
d18O (LS99CUVAa): interpretation3_variableGroup: '' has been replaced by 'Temperature'
d18O (LS99CUVAa): interpretation3_variableGroupDirection: '' has been replaced by 'negative'
d18O (LS99CUVAa): interpretation3_variableGroupOriginal: '' has been replaced by 'T'
d18O (LS99CUVAa): interpretation3_variableOriginal: '' has been replaced by 'temperature'
d18O (LS99CUVAb): interpretation1_basis: 'Lake level also important as lake not always closed but Since ,3000 14C yr BP the level of Lake Valencia has been dropping. Lake closed in present day, but last 2k isotoeps realtively fresh suggesting more open system?' has been replaced by ''
d18O (LS99CUVAb): interpretation1_direction: 'negative' has been replaced by ''
d18O (LS99CUVAb): interpretation1_inferredMaterial: 'lake water' has been replaced by ''
d18O (LS99CUVAb): interpretation1_integrationTimeUnits: 'years' has been replaced by ''
d18O (LS99CUVAb): interpretation1_rank: '1' has been replaced by ''
d18O (LS99CUVAb): interpretation1_scope: 'isotope' has been replaced by 'climate'
d18O (LS99CUVAb): interpretation1_variable: 'P_E' has been replaced by ''
d18O (LS99CUVAb): interpretation1_variableGroup: 'EffectiveMoisture' has been replaced by ''
d18O (LS99CUVAb): interpretation1_variableGroupDirection: 'negative' has been replaced by ''
d18O (LS99CUVAb): interpretation1_variableGroupOriginal: 'P_E' has been replaced by ''
d18O (LS99CUVAb): interpretation2_rank: '2' has been replaced by '1'
d18O (LS99CUVAb): interpretation2_variable: 'T' has been replaced by 'P_E'
d18O (LS99CUVAb): interpretation2_variableGroup: 'Temperature' has been replaced by 'EffectiveMoisture'
d18O (LS99CUVAb): interpretation2_variableGroupOriginal: 'T' has been replaced by 'P_E'
d18O (LS99CUVAb): interpretation2_variableOriginal: 'temperature' has been replaced by ''
d18O (LS99CUVAb): interpretation2_basis: '' has been replaced by 'Lake level also important as lake not always closed but Since ,3000 14C yr BP the level of Lake Valencia has been dropping. Lake closed in present day, but last 2k isotoeps realtively fresh suggesting more open system?'
d18O (LS99CUVAb): interpretation2_direction: '' has been replaced by 'negative'
d18O (LS99CUVAb): interpretation3_inferredMaterial: '' has been replaced by 'lake water'
d18O (LS99CUVAb): interpretation3_integrationTimeUnits: '' has been replaced by 'years'
d18O (LS99CUVAb): interpretation3_rank: '' has been replaced by '2'
d18O (LS99CUVAb): interpretation3_scope: '' has been replaced by 'isotope'
d18O (LS99CUVAb): interpretation3_variable: '' has been replaced by 'T'
d18O (LS99CUVAb): interpretation3_variableGroup: '' has been replaced by 'Temperature'
d18O (LS99CUVAb): interpretation3_variableGroupDirection: '' has been replaced by 'negative'
d18O (LS99CUVAb): interpretation3_variableGroupOriginal: '' has been replaced by 'T'
d18O (LS99CUVAb): interpretation3_variableOriginal: '' has been replaced by 'temperature'
d18O (LS99CUVAc): interpretation1_basis: 'Lake level also important as lake not always closed but Since ,3000 14C yr BP the level of Lake Valencia has been dropping. Lake closed in present day, but last 2k isotoeps realtively fresh suggesting more open system?' has been replaced by ''
d18O (LS99CUVAc): interpretation1_direction: 'negative' has been replaced by ''
d18O (LS99CUVAc): interpretation1_inferredMaterial: 'lake water' has been replaced by ''
d18O (LS99CUVAc): interpretation1_integrationTimeUnits: 'years' has been replaced by ''
d18O (LS99CUVAc): interpretation1_rank: '1' has been replaced by ''
d18O (LS99CUVAc): interpretation1_scope: 'isotope' has been replaced by 'climate'
d18O (LS99CUVAc): interpretation1_variable: 'P_E' has been replaced by ''
d18O (LS99CUVAc): interpretation1_variableGroup: 'EffectiveMoisture' has been replaced by ''
d18O (LS99CUVAc): interpretation1_variableGroupDirection: 'negative' has been replaced by ''
d18O (LS99CUVAc): interpretation1_variableGroupOriginal: 'P_E' has been replaced by ''
d18O (LS99CUVAc): interpretation2_rank: '2' has been replaced by '1'
d18O (LS99CUVAc): interpretation2_variable: 'T' has been replaced by 'P_E'
d18O (LS99CUVAc): interpretation2_variableGroup: 'Temperature' has been replaced by 'EffectiveMoisture'
d18O (LS99CUVAc): interpretation2_variableGroupOriginal: 'T' has been replaced by 'P_E'
d18O (LS99CUVAc): interpretation2_variableOriginal: 'temperature' has been replaced by ''
d18O (LS99CUVAc): interpretation2_basis: '' has been replaced by 'Lake level also important as lake not always closed but Since ,3000 14C yr BP the level of Lake Valencia has been dropping. Lake closed in present day, but last 2k isotoeps realtively fresh suggesting more open system?'
d18O (LS99CUVAc): interpretation2_direction: '' has been replaced by 'negative'
d18O (LS99CUVAc): interpretation3_inferredMaterial: '' has been replaced by 'lake water'
d18O (LS99CUVAc): interpretation3_integrationTimeUnits: '' has been replaced by 'years'
d18O (LS99CUVAc): interpretation3_rank: '' has been replaced by '2'
d18O (LS99CUVAc): interpretation3_scope: '' has been replaced by 'isotope'
d18O (LS99CUVAc): interpretation3_variable: '' has been replaced by 'T'
d18O (LS99CUVAc): interpretation3_variableGroup: '' has been replaced by 'Temperature'
d18O (LS99CUVAc): interpretation3_variableGroupDirection: '' has been replaced by 'negative'
d18O (LS99CUVAc): interpretation3_variableGroupOriginal: '' has been replaced by 'T'
d18O (LS99CUVAc): interpretation3_variableOriginal: '' has been replaced by 'temperature'
Curtis, J.H. , Hodell, D.A. , Brenner, M.
Climate change in the Lake Valencia Basin, Venezuela, |12600 yr BP to present
Curtis, J. H., Brenner, M. and Hodell, D. A.: Climate change in the Lake Valencia Basin, Venezuela, ~12600 yr BP to present, The Holocene, 9(5), 609–619, doi:10.1191/095968399669724431, 1999.