Local radiocarbon reservoir age (Delta-R) variability from the nearshore and open-ocean environments of the Florida Keys reef tract during the Holocene and associated U-series and radiocarbon data (Marine13 Radiocarbon Calibration Curve)

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What does this data set describe?

Title:
Local radiocarbon reservoir age (Delta-R) variability from the nearshore and open-ocean environments of the Florida Keys reef tract during the Holocene and associated U-series and radiocarbon data (Marine13 Radiocarbon Calibration Curve)
Abstract:
Holocene-aged corals from reef cores collected throughout the Florida Keys reef tract (FKRT) were dated using a combination of U-series and radiocarbon techniques to quantify the millennial-scale variability in the local radiocarbon reservoir age (ΔR) of the shallow water environments of south Florida. ΔR provides a measure of the deviation of local radiocarbon concentrations of marine environments from the global average and can be used as a tracer of oceanic circulation and local hydrology. U.S. Geological Survey (USGS) scientists combined coral-based estimates of ΔR, using statistical modeling, to reconstruct millennial-scale variability in ΔR at locations on the FKRT with (“nearshore”) and without (“open ocean”) terrestrial influence. USGS scientists also used the models to provide temporally-explicit estimates of ΔR that can be used in radiocarbon calibrations of marine samples from the region. For further information regarding data collection and analysis methods refer to Toth and others (2016, 2017). This research is a part of the USGS Coral Reef Ecosystem Studies Project (http://coastal.er.usgs.gov/crest/).
  1. How might this data set be cited?
    Toth, Lauren T., Cheng, Hai, Edwards, R. Lawrence, Ashe, Erica, and Richey, Julie N., 20170907, Local radiocarbon reservoir age (Delta-R) variability from the nearshore and open-ocean environments of the Florida Keys reef tract during the Holocene and associated U-series and radiocarbon data (Marine13 Radiocarbon Calibration Curve): U.S. Geological Survey Data Release doi:10.5066/F7P8492Q, U.S. Geological Survey, St. Petersburg, FL.

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  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -82.92
    East_Bounding_Coordinate: -80.0967
    North_Bounding_Coordinate: 25.5906
    South_Bounding_Coordinate: 24.45
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Jan-1991
    Ending_Date: 05-May-2016
    Currentness_Reference:
    Date range of U-series and radiocarbon analysis and modeling
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Tabular digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0198058733. Longitudes are given to the nearest 0.0217155309. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_North_American_1983.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.25722101.
  7. How does the data set describe geographic features?
    FKRT_Coral_Based_DeltaR
    ΔR estimates for the 68 corals from the FKRT, description of those coral samples, sample locations, and summary of data used to calculate ΔR. (Source: Sample information and DeltaR values: Lauren T. Toth (USGS-SPCMSC); U-series data: Hai Cheng (Xi’an Jiaotong University, China), R. Lawrence Edwards (University of Minnesota); Radiocarbon data: John McGeehin (USGS Radiocarbon Laboratory), Lawrence Livermore National Laboratories Center for Accelerator Mass Spectrometry, University of California, Davis Stable Isotope Laboratory, Beta Analytic, Inc., and Geochron Laboratories; Marine13 data: https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/16947/0)
    Sample ID
    Unique identifier for each coral sample dated in this study. (Source: USGS) Sample IDs are generated by abbreviating information about the region, site, core, and approximate water depth from which each sample was collected and are formatted as: Region abbreviation-Site abbreviation-Core number-Depth of coral in core.
    Latitude
    The approximate latitude, in North American Datum of 1983 (NAD83) coordinates, where the core containing the coral sample was collected (Source: USGS)
    Range of values
    Minimum:24.4500
    Maximum:25.5906
    Units:Decimal degrees
    Longitude
    The approximate longitude, in North American Datum of 1983 (NAD83) coordinates, where the core containing the coral sample was collected (Source: USGS)
    Range of values
    Minimum:-82.92
    Maximum:-80.0967
    Units:Decimal degrees
    Site
    Site name where the core containing the coral sample was collected (Source: USGS) The name of the reef or group of reefs where the core containing the sample was collected
    Subregion
    The subregion of the Florida Keys reef tract where the core containing the sample was collected (Source: USGS)
    ValueDefinition
    Dry Tortugas N.P.The westernmost subregion of the Florida Keys reef tract located within the boundaries of Dry Tortugas National Park
    MarquesasThe subregion of the Florida Keys reef tract located between Dry Tortugas National Park and the Lower Keys
    Lower KeysThe subregion of the Florida Keys reef tract located between the Marquesas and the Middle Keys
    Middle KeysThe subregion of the Florida Keys reef tract located between the Lower Keys and the Upper Keys
    Upper KeysThe subregion of the of the Florida Keys reef tract located between the Middle Keys and the Biscayne National Park
    Biscayne N.P.The northernmost subregion of the Florida Keys reef tract located within the boundaries of Biscayne National Park
    Coral genus
    The genus of the coral sample (Source: World Register of Marine Species: http://www.marinespecies.org/)
    ValueDefinition
    OrbicellaThe coral genus containing the species O. faveolata, O. franksii, and O. annularis
    AcroporaThe coral genus containing the species A. palmata and A. cervicornis
    DiploriaThe coral genus containing the species D. strigosa, D. clivosa, and D. labyrinthiformis
    MontastraeaThe coral genus containing the species M. cavernosa
    ColpophylliaThe coral genus containing the species C. natans
    230Th Age (years BP)
    Holocene 230Th (U-series) age of the coral sample used as age of the sample before present (where present is 1950) when calculating the local reservoir age, ΔR. The age has been corrected based on the assumption that the initial 230Th/232Th atomic ratio is 4.4 ± 2.2 x10-6: the value for a material at secular equilibrium, with the bulk earth 232Th/238U value of 3.8. (Source: USGS)
    Range of values
    Minimum:41
    Maximum:10242
    Units:Years before present (where present is 1950)
    230Th age error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the 230Th age. (Source: USGS)
    Range of values
    Minimum:6
    Maximum:55
    Units:years
    Conventional 14C age (years)
    The 14C age of the sample corrected for the fractionation of 13C, but not calibrated against the Marine13 calibration curve. (Source: USGS)
    Range of values
    Minimum:380
    Maximum:9485
    Units:years
    14C age error (1 SE)
    The 1-standard error (1 SE) analytical uncertainty of the conventional radiocarbon (14C) age. (Source: USGS)
    Range of values
    Minimum:20
    Maximum:70
    Units:years
    Marine13 14C age (years)
    The predicted 14C age of the sample from the marine calibration curve (Marine 13; Reimer and others, 2013; https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/16947/0), using the corrected 230Th age as age before present (cal BP) of the sample. (Source: USGS)
    Range of values
    Minimum:448
    Maximum:9438
    Units:years
    Marine13 14C age error (1 SE)
    The 1-standard error (1 SE) uncertainty associated with the modeled 14C ages of the Marine13 calibration curve. (Source: USGS)
    Range of values
    Minimum:23
    Maximum:31
    Units:years
    Delta-R (years)
    ΔR (Delta-R) values (in years) calculated by subtracting the predicted radiocarbon age of the sample from the marine calibration curve (Marine13 14C age), from the conventional radiocarbon age of that sample (Conventional 14C age). (Source: USGS)
    Range of values
    Minimum:-361
    Maximum:399
    Units:years
    Delta-R error (1 SE)
    The 1-standard error (1 SE) uncertainty associated with the estimates of ΔR (Delta-R). Calculated as the root-mean-square of the error associated with the conventional 14C age of the sample (14C age error) and the error associated with the predicted 14C age from the marine calibration curve (Marine13 14C age error). (Source: USGS)
    Range of values
    Minimum:27
    Maximum:75
    Units:years
    Data included in statistical models? (Y/N)
    An identifier to indicate whether the data were included in the subset used in the statistical models of ΔR variability. (Source: USGS)
    ValueDefinition
    YY=yes the data were included in the statistical models
    NN=no the data were not included in the statistical models for the reasons outlined in Toth and others, 2017.
    Model name
    Identifies which model of Delta-R the data were included in: nearshore or open ocean. This attribute is coded as "None" if data were not included in statistical models? (Source: USGS)
    ValueDefinition
    NearshoreIndicates that the data point were included in the nearshore model of Delta-R.
    Open OceanIndicates that the data point were included in the open-ocean model of Delta-R.
    NoneIndicates that the data point were not included in any statistical model.
    FKRT_Holocene_Radiocarbon_Data
    Radiocarbon data used to determine the conventional radiocarbon ages of 68 Holocene corals from the FKRT. (Source: Sample information and DeltaR values: Lauren T. Toth (USGS-SPCMSC); Radiocarbon data: John McGeehin (USGS Radiocarbon Laboratory), Lawrence Livermore National Laboratories Center for Accelerator Mass Spectrometry, University of California, Davis Stable Isotope Laboratory, Beta Analytic, Inc., and Geochron Laboratories)
    Sample ID
    Unique identifier for each coral sample dated in this study. (Source: USGS) Sample IDs are generated by abbreviating information about the region, site, core, and approximate water depth from which each sample was collected and are formatted as: Region abbreviation-Site abbreviation-Core number-Depth of coral in core.
    USGS 14C Laboratory #
    Laboratory ID number assigned by the USGS Radiocarbon Laboratory when samples were received for radiocarbon analysis. (Source: USGS Radiocarbon Laboratory) A sequential laboratory number that is generated by the USGS Radiocarbon Laboratory when the sample is received for radiocarbon analysis. Format is WW (the internal laboratory code) followed by a hyphen and a unique, sequential sample number (whole number). Blank values were not assigned a USGS laboratory number because they were not prepared for radiocarbon analysis at the USGS Radiocarbon Laboratory.
    14C or AMS Laboratory #
    Laboratory ID number assigned by the laboratory that conducted the radiocarbon analysis. (Source: Center for Accelerator Mass Spectrometry (CAMS) at the Lawrence Livermore National Laboratory, Beta Analytic Inc., or Geochron Laboratories) Laboratory ID number assigned by the laboratory that conducted the radiocarbon analysis. Formatted as laboratory identifier (CAMS=Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory, Beta=Beta Analytic, Inc., GX=Geochron Laboratories) followed by a hyphen and a unique, sequential sample number (whole number).
    delta-13C
    The measured ratio of the isotope 13C to 12C (delta-13C) in the sample relative to the mass-spectrometry standard (Pee Dee Belemnite; "PDB"). (Source: USGS)
    Range of values
    Minimum:-3.6
    Maximum:3.6
    Units:Pee Dee Belemnite (PDB)
    Conventional 14C age (years)
    The 14C age of the sample corrected for the fractionation of 13C, but not calibrated against the Marine13 calibration curve. (Source: USGS)
    Range of values
    Minimum:380
    Maximum:9485
    Units:years
    14C age error (1 SE)
    The 1-standard error (1 SE) analytical uncertainty of the conventional radiocarbon (14C) age. (Source: USGS)
    Range of values
    Minimum:20
    Maximum:70
    Units:years
    Fraction modern
    The measured fraction of modern carbon in the sample corrected for fractionation of 13C. This value is used to calculate radiocarbon ages when samples are dated using accelerator mass spectrometry (AMS). If fraction modern was not measured, a value of "not measured" is given. (Source: USGS)
    Range of values
    Minimum:0.3071
    Maximum:0.9535
    Units:unitless value
    Fraction modern error (1 SE)
    The 1-standard error (1 SE) uncertainty of the fraction modern carbon of the sample. If fraction modern was not measured, a value of "not measured" is given. (Source: USGS)
    Range of values
    Minimum:0.0009
    Maximum:0.0036
    Units:unitless value
    FKRT_Holocene_U-Series_Data
    U-series data used to determine the 230Th ages of 68 Holocene corals from the FKRT. (Source: Sample information and DeltaR values: Lauren T. Toth (USGS-SPCMSC); U-series data: Hai Cheng (Xi’an Jiaotong University, China), R. Lawrence Edwards (University of Minnesota))
    Sample ID
    Unique identifier for each coral sample dated in this study. (Source: USGS) Sample IDs are generated by abbreviating information about the region, site, core, and approximate water depth from which each sample was collected and are formatted as: Region abbreviation-Site abbreviation-Core number-Depth of coral in core.
    238U (ppb)
    The measured concentration of the isotope 238U in the sample in parts per billion (ppb). (Source: USGS)
    Range of values
    Minimum:1653
    Maximum:3875
    Units:parts per billion (ppb)
    238U error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the measured 238U of the sample. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:7
    Units:parts per billion (ppb)
    232Th (ppt)
    The measured concentration of the isotope 232Th in the sample in parts per thousand (ppt). (Source: USGS)
    Range of values
    Minimum:8
    Maximum:3144
    Units:parts per thousand (ppt)
    232Th error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the measured 232Th of the sample. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:63
    Units:parts per thousand (ppt)
    230Th / 232Th (atomic x 10^-6)
    The ratio of the isotope 230Th to the isotope 232Th in the sample (Source: USGS)
    Range of values
    Minimum:83
    Maximum:215972
    Units:atomic ratio times 10^-6
    Atomic 230Th / 232Th error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the measured atomic ratio of 230Th to 232Th. (Source: USGS)
    Range of values
    Minimum:4
    Maximum:52071
    Units:atomic ratio times 10^-6
    delta-234U (measured)
    δ234U (delta-234U) = ([234U/238U]activity – 1)x1000 (Source: USGS)
    Range of values
    Minimum:134.9
    Maximum:146.8
    Units:parts per thousand (ppt)
    Measured delta-234U error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the measured δ234U of the sample. (Source: USGS)
    Range of values
    Minimum:1.1
    Maximum:2.1
    Units:parts per thousand (ppt)
    230Th / 238U (activity)
    Activity ratio of 230Th to 238U in the sample. (Source: USGS)
    Range of values
    Minimum:0.0011
    Maximum:0.1029
    Units:ratio
    230Th / 238U activity error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the measured 230Th / 238U activity ratio of the sample. (Source: USGS)
    Range of values
    Minimum:0.0000
    Maximum:0.0005
    Units:ratio
    230Th Age (yr) (uncorrected)
    230Th age of the sample uncorrected for initial 230/232Th. (Source: USGS)
    Range of values
    Minimum:108
    Maximum:10307
    Units:years
    Uncorrected 230Th Age error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the uncorrected 230Th age of the sample. (Source: USGS)
    Range of values
    Minimum:2
    Maximum:53
    Units:years
    230Th Age (yr) (corrected)
    230Th age of the sample corrected for initial 230/232Th, but not corrected to age before present. Corrected 230Th ages assume the initial 230Th/232Th atomic ratio of 4.4 ±2.2 x10-6. Those are the values for a material at secular equilibrium, with the bulk earth 232Th/238U value of 3.8. (Source: USGS)
    Range of values
    Minimum:105
    Maximum:10306
    Units:years
    Corrected 230Th age error (2 SE)
    The 2-standard error (2σ) analytical uncertainty of the corrected 230Th age of the sample. The errors are arbitrarily assumed to be 50%. (Source: USGS)
    Range of values
    Minimum:6
    Maximum:55
    Units:years
    delta-234UInitial (corrected)
    Corrected initial δ234U (delta-234Initial). δ234Uinitial was calculated based on 230Th age (T), that is, δ234Uinitial = δ234Umeasured x e(λ234xT), where d234Umeasured=d234U = ([234U/238U]activity – 1)x1000 and λ234=2.82206x10-6 (Cheng and others, 2013) (Source: USGS)
    Range of values
    Minimum:137
    Maximum:147
    Units:parts per thousand (ppt)
    delta-234UInitial error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the corrected δ234UInitial (delta-234UInitial) of the sample (Source: USGS)
    Range of values
    Minimum:1
    Maximum:2
    Units:parts per thousand (ppt)
    230Th Age (years BP) (corrected)
    230Th age of the sample corrected for initial 230/232Th, corrected to age before present (BP) where the present is defined as the year 1950 C.E. Corrected 230Th ages assume the initial 230Th/232Th atomic ratio of 4.4 ±2.2 x10-6. Those are the values for a material at secular equilibrium, with the bulk earth 232Th/238U value of 3.8. (Source: USGS)
    Range of values
    Minimum:41
    Maximum:10242
    Units:years before present (1950 C.E.)
    Corrected 230Th age BP error (2 SE)
    The 2-standard error (2 SE) analytical uncertainty of the corrected 230Th age before present (BP) of the sample. The errors are arbitrarily assumed to be 50%. (Source: USGS)
    Range of values
    Minimum:6
    Maximum:55
    Units:years before present (1950 C.E.)
    U-series screening (Pass/Fail)
    Indicates whether the data point passed screening of the U-series data based on the following criteria: 1. d234U within 10 per mil of modern seawater (147 per mil) 2. 232Th less than 2 parts per billion (ppb) 3. 238U within taxon-specific ranges for modern or Holocene corals (Source: USGS)
    ValueDefinition
    PassThe data passed all three screening criteria.
    FailThe data failed one or more of the screening criteria.
    Reason for not passing U-series screening
    Description of the reason that the data failed the U-series screening. This attribute is left blank if the data passed the screening. (Source: USGS) A description of why the data failed the U-series screening.
    Modeled_OpenOcean_DeltaR_vs_230Th
    Statistical model output of open-ocean ΔR variability from 8,000 years BP to present with a 5-year time step using 230Th age to derive age before present. All statistical analyses were conducted using MATLAB ® software (v. 9.1). (Source: Sample information and DeltaR values: Lauren T. Toth (USGS-SPCMSC); Statistical model: Erica Ashe (Rutgers University).)
    230Th Age (years BP)
    Age before present (modeled from corrected 230Th age before present) from 8000-0 years before present (where present is 1950 C.E.) with a time step of 5 years. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:8000
    Units:years before present (where present is 1950 C.E.)
    Delta-R (14C years)
    Predicted (modeled) ΔR (Delta-R) values (in radiocarbon [14C] years) for every 5 years before present over the range of 8000-0 years before present. (Source: USGS)
    Range of values
    Minimum:-113.951885
    Maximum:1.613354
    Units:14C years
    Delta-R error (1 SE)
    The 1-standard error (1 SE) uncertainty associated with predicted (modeled) ΔR (Delta-R) values (in years) for every 5 years before present over the range of 0-8000 years before present. (Source: USGS)
    Range of values
    Minimum:18.531334
    Maximum:29.407334
    Units:14C years
    Modeled_OpenOcean_DeltaR_vs_Conventional_14C
    Modeled predictions of ΔR for open-ocean locations in south Florida over the range of conventional radiocarbon ages from 7,500 years ago to present with a 5-year time step. All statistical analyses were conducted using MATLAB ® software (v. 9.1). (Source: Sample information and DeltaR values: Lauren T. Toth (USGS-SPCMSC); Statistical model: Erica Ashe (Rutgers University).)
    Conventional 14C age (years)
    Conventional 14C age (years) from 7500-0 years before present (where present is 1950 C.E.) with a time step of 5 years. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:7500
    Units:conventional radiocarbon years
    Delta-R (14C years)
    Predicted (modeled) ΔR (Delta-R) values (in 14C [radiocarbon] years) for every 5 years conventional radiocarbon years over the range of 0-7500. (Source: USGS)
    Range of values
    Minimum:-110.858119
    Maximum:-4.400057
    Units:14C years
    Delta-R error (1 SE)
    The 1-standard error (1 SE) uncertainty associated with predicted (modeled) ΔR (Delta-R) values (in years) for every 5 years before present over the range of 0-7500 years before present. (Source: USGS)
    Range of values
    Minimum:17.068669
    Maximum:32.078851
    Units:14C years
    Modeled_Nearshore_DeltaR_vs_Conventional_14C
    Modeled predictions of ΔR for nearshore locations in south Florida over the range of conventional radiocarbon ages from 9,000 years ago to present with a 5-year time step. All statistical analyses were conducted using MATLAB ® software (v. 9.1). (Source: Sample information and DeltaR values: Lauren T. Toth (USGS-SPCMSC); Statistical model: Erica Ashe (Rutgers University).)
    Conventional 14C age (years)
    Conventional 14C age (years) from 9000-0 years before present (where present is 1950 C.E.) with a time step of 5 years. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:9000
    Units:14C years
    Delta-R (14C years)
    Predicted (modeled) ΔR (Delta-R) values (in 14C [radiocarbon] years) for every 5 years conventional radiocarbon years over the range of 0-9000. (Source: USGS)
    Range of values
    Minimum:-59.765176
    Maximum:11.726835
    Units:14C years
    Delta-R error (1 SE)
    The 1-standard error (1 SE) uncertainty associated with predicted (modeled) ΔR (Delta-R) values (in years) for every 5 years before present over the range of 0-9000 years before present. (Source: USGS)
    Range of values
    Minimum:24.813862
    Maximum:37.65283
    Units:14C years
    Modeled_Nearshore_DeltaR_vs_230Th
    Statistical model output of nearshore ΔR variability from 9,500 years ago to present with a 5-year time step using 230Th age to derive age before present. All statistical analyses were conducted using MATLAB ® software (v. 9.1). (Source: Sample information and DeltaR values: Lauren T. Toth (USGS-SPCMSC); Statistical model: Erica Ashe (Rutgers University).)
    230Th Age (years BP)
    Age before present (modeled from corrected 230Th age before present) from 9500-0 years before present (where present is 1950 C.E.) with a time step of 5 years. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:9500
    Units:years BP
    Delta-R (14C years)
    Predicted (modeled) ΔR (Delta-R) values (in radiocarbon [14C] years) for every 5 years over the range of 9500-0 years. (Source: USGS)
    Range of values
    Minimum:-56.823899
    Maximum:14.345498
    Units:14C years
    Delta-R error (1 SE)
    The 1-standard error (1 SE) uncertainty associated with predicted (modeled) ΔR (Delta-R) values (in years) for every 5 years over the range of 0-9500 years. (Source: USGS)
    Range of values
    Minimum:25.164612
    Maximum:38.55108
    Units:14C years
    DeltaR_Data_Screening_Summary
    Summary of screening procedures performed on the data and description of why some data were removed from the statistical models of DeltaR (Source: Lauren T. Toth (USGS-SPCMSC))
    Sample ID
    Unique identifier for each coral sample dated in this study. (Source: USGS) Sample IDs are generated by abbreviating information about the region, site, core, and approximate water depth from which each sample was collected and are formatted as: Region abbreviation-Site abbreviation-Core number-Depth of coral in core.
    U-series screening (Pass/Fail)
    Indicates whether the data point passed screening of the U-series data based on the following criteria: 1. d234U within 10 per mil of modern seawater (147 per mil) 2. 232Th less than 2 parts per billion (ppb) 3. 238U within taxon-specific ranges for modern or Holocene corals (Source: USGS)
    ValueDefinition
    PassThe data passed all three screening criteria.
    FailThe data failed one or more of the three screening criteria.
    Reason for not passing U-series screening
    Description of the reason that the data failed the U-series screening. This attribute is left blank if the data passed the screening. (Source: USGS) A description of why the data failed the U-series screening.
    XRD screening? (Y/N)
    Indicates whether the samples were screened for diagenesis by X-ray diffraction (XRD) prior to this study. Note that all samples that were analyzed with XRD passed the screening based on the criteria that the sample was <5% calcite. (Source: USGS)
    ValueDefinition
    YY=Yes the sample was analyzed using XRD
    NN=No the sample was not analyzed using XRD
    SEM screening? (Y/N)
    Indicates whether the samples were screened for diagenesis by Scanning Electron Microscopy (SEM) as part of this study. (Source: USGS)
    ValueDefinition
    YY=Yes the sample was screened using SEM
    NN=No the sample was not screened using SEM
    SEM results
    Description of the SEM image of the sample, indicating the presence and amount of secondary calcite cements, secondary aragonite needles, and/or dissolution features. This field also indicates if a sample was excluded on the basis of the SEM screening. (Source: USGS) Description of the SEM image of the sample, indicating the presence and amount of secondary calcite cements, secondary aragonite needles, and/or dissolution features. This field also indicates if a sample was excluded on the basis of the SEM screening.
    Data included in statistical models? (Y/N)
    An identifier to indicate whether the data were included in the subset used in the statistical models of ΔR variability. (Source: USGS)
    ValueDefinition
    YY=Yes the data were included in the statistical models
    NN=No the data were not included in the statistical models because it failed one of the screening procedures outlined previously

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Lauren T. Toth
    • Hai Cheng
    • R. Lawrence Edwards
    • Erica Ashe
    • Julie N. Richey
  2. Who also contributed to the data set?
    Previously-collected cores sampled from the USGS Core Archive (http://olga.er.usgs.gov/coreviewer/) were collected under permits from Dry Tortugas National Park (formerly Fort Jefferson National Monument), Biscayne National Park (formerly Biscayne National Monument), the Florida Keys National Marine Sanctuary (FKNMS), and the Florida State Department of Natural Resources. New cores from the Middle and Upper Keys were collected under permit number FKNMS-2013-097-A1 and FKNMS-2015-058, respectively by Lauren Toth. John "Jack" McGeehin of the USGS Radiocarbon Dating Laboratory provided support for the radiocarbon analysis for this study. This study was supported by a Mendenhall Research Fellowship awarded to Lauren Toth by the United States Geological Survey (USGS) Coastal and Marine Geology Program and the Natural Hazards Mission Area, and by the Climate and Land Use Research and Development Program of the USGS. Erica Ashe's work developing the statistical model was supported by the National Science Foundation (grants ARC-1203415 and OCE-1458904), National Oceanic and Atmospheric Administration grant NA11OAR431010, and the New Jersey Sea Grant Consortium.
  3. To whom should users address questions about the data?
    Lauren T. Toth
    USGS
    600 4th St. S
    St. Petersburg, FL
    USA

    727-502-8029 (voice)
    ltoth@usgs.gov

Why was the data set created?

Radiocarbon and U-series analyses were conducted to quantify the Holocene variability of the local marine radiocarbon reservoir age, ΔR, in south Florida. The reconstructions of ΔR variability from nearshore and open-ocean environments were used to make inferences about millennial-scale changes in oceanography and hydrology and to develop more accurate radiocarbon calibrations for marine samples collected from the region.

How was the data set created?

  1. From what previous works were the data drawn?
    Marine13 (source 1 of 1)
    Paula J Reimer, Edouard Bard, Alex Bayliss, J Warren Beck, Paul G Blackwell, Christopher Bronk Ramsey, Caitlin E Buck, Hai Cheng, R Lawrence Edwards, Michael Friedrich, Pieter M Grootes, Thomas P Guilderson, Haflidi Haflidason, Irka Hajdas, Christine Hatté, Timothy J Heaton, Dirk L Hoffmann, Alan G Hogg, Konrad A Hughen, K Felix Kaiser, Bernd Kromer, Sturt W Manning, Mu Niu, Ron W Reimer, David A Richards, E Marian Scott, John R Southon, Richard A Staff, Christian S M Turney, Johannes van der Plicht, 2013, IntCal13 and Marine13 radiocarbon age calibration curve 0-50,000 years cal BP: Radiocarbon, University of Arizona, Tucson, Arizona.

    Online Links:

    Type_of_Source_Media: Radiocarbon calibration curve
    Source_Contribution:
    Used to determine the predicted radiocarbon age of samples using their corrected 230Th as calibrated calendar years before present, where present is 1950 (Cal BP).
  2. How were the data generated, processed, and modified?
    Date: 21-Oct-2015 (process 1 of 6)
    Sample collection: Coral samples were extracted from coral-reef cores previously collected by USGS researchers and housed in the USGS core archive of the St. Petersburg Coastal and Marine Science Center (USGS-SPCMSC; Reich and others, 2012; http://olga.er.usgs.gov/coreviewer/) and one new core collected from Crocker Reef in the Upper Florida Keys, in 2014, and four new cores collected from Sombrero and Tennessee reefs in the Middle Florida Keys, in 2015, as part of the USGS Coral Reef Ecosystems Studies project (http://coastal.er.usgs.gov/crest/; Toth and others, 2016). Those cores were collected under Florida Keys National Marine Sanctuary (FKNMS) permit numbers FKNMS-2013-097-A1 and FKNMS-2015-058. Data were collected under USGS field activity numbers (FANs) 2014-321-FA, 2015-314-FA, and 2015-325-FA. The geographic locations of those cores were determined using a Garmin GPS and an Ashtec Z-Xtreme DGPS was also used in 2014. The geographic data for the 2014 and 2015 cores were recorded in NAD83. Details listed under the spatial reference information section only apply to the cores collected in 2014–2016. Additional survey details are available at: https://cmgds.marine.usgs.gov/data_search.php. Coral samples were cut from the cores using a tile saw at USGS-SPCMSC, which is dedicated to that purpose. The samples were split into two, 1-3 gram subsamples using the tile saw. The subsamples were then sonicated for 15 minutes in a bath of warm, deionized water and dried at 60 degrees Celsius. One subsample of each coral was sent to the USGS Radiocarbon Laboratory (Reston, VA) for radiocarbon analysis and one subsample of each coral was sent to the University of Minnesota, Minneapolis, MN, USA or Xi’an Jiaotong University, Xi'an, China for U-series analysis.
    Date: 07-Dec-2015 (process 2 of 6)
    Dating: All but two coral subsamples were processed at the USGS Radiocarbon Laboratory in Reston, VA and were radiocarbon dated using accelerator mass spectrometry (AMS) at the Center for AMS at Lawrence Livermore National Laboratory using standard techniques. The δ13C of those samples was either measured by the University of California, Davis Stable Isotope Laboratory or, if not measured, were assumed to be 0±3‰. Measured 14C ages were corrected for fractionation of 13C using the d13ccorr spreadsheet available at calib.org/calib/d13ccorr.xls. The other two samples were dated previously (Lidz and others, 2003; C. Reich, unpubl. data) using bulk, radiometric radiocarbon dating at Beta Analytic, Inc. or Geochron Laboratories. U-series ages were determined by H. Cheng and R.L. Edwards at the University of Minnesota and Xi’an Jiaotong University using multi-collector inductively coupled plasma mass spectrometry according to the procedures described in Cheng and others, 2013. Measured 230Th ages were corrected using an initial 230Th/232Th atomic ratio of 4.4 x 10^-6 with an uncertainty of 50% (±2.2 standard error). Those are the values for a material at secular equilibrium, with the bulk Earth 232Th/238U value of 3.8.
    Date: 07-Dec-2015 (process 3 of 6)
    ΔR was calculated as: ΔR = 14C (conventional) – 14C (expected from Marine13) where 14C (conventional) is the conventional radiocarbon age of the sample and 14C (expected from Marine13) is the predicted 14C age from the marine calibration curve using the corrected 230Th age before present as Cal BP. The error terms for ΔR were calculated by combining the two standard error uncertainties associated with the conventional 14C age (SE1) and expected 14C age from the appropriate calibration curve (SE2): SDcombined = square root (SE1^2 + SD2^2)
    Date: 16-May-2016 (process 4 of 6)
    Statistical modeling: Researchers combined the coral-based snapshots of ΔR using an empirical hierarchical model with Gaussian process priors to 1) reconstruct temporal variability in ΔR during the Holocene (ΔR versus 230Th ages) and 2) predict values of ΔR and ΔR uncertainty for use in calibrations of radiocarbon ages from the region (ΔR versus conventional 14C ages) for both the open-ocean and nearshore sites. The model outputs are found in the files: Modeled_OpenOcean_DeltaR_vs_230Th, Modeled_Nearshore_DeltaR_vs_230Th, Modeled_OpenOcean_DeltaR_vs_Conventional_14C, and Modeled_Nearshore_DeltaR_vs_Conventional_14C. Data that were not included in the model are indicated in the "Data included in statistical models? (Y/N)" attribute in FKRT_Coral_Based_DeltaR and DeltaR_Data_Screening_Summary, for the reasons described in DeltaR_Data_Screening_Summary. All statistical analyses were conducted in MATLAB ® version 9.1. For more information on the criteria for excluding data and details of the statistical model see: Toth and others, 2017.
    Date: 21-Feb-2017 (process 5 of 6)
    Data Screening: All of the corals included in this study were carefully examined prior to dating and were generally found to be in excellent condition. Sixteen of the samples included in this study were also previously screened for diagenesis by X-ray diffraction (XRD) using a Bruker D4 X-ray diffractometer. These analyses indicated that all samples contained <5% calcite and, in most cases, the samples were nearly 100% aragonite. Researchers screened an additional subsample (N=14) of corals using the S-3500N Hitachi scanning electron microscope (SEM) housed at the University of South Florida’s College of Marine Science. Researchers evaluated the corals for evidence of: secondary calcite precipitation, secondary aragonite needles, and/or dissolution. SEM imaging of the samples generally showed only the localized presence of secondary aragonite and suggested that diagenetic alteration was negligible overall; however, researchers did find evidence of significant diagenesis in three samples: LK-MG-2-0, MK-AR-2-0, and BP-FR-2-55. Researchers also screened the U-series data based on three criteria: 1) δ234U within 10 per mil of modern seawater (147 per mil), 2) 232Th less than 2 ppb, and 3) 238U within taxon-specific ranges for modern or Holocene corals (~2800–3800 ppb for Acropora spp. and ~2000–3200 for the massive coral taxa Orbicella spp., Diploria spp., Montastraea cavernosa, and Colpophyllia natans). Samples that did not meet the U-series or diagenetic criteria were excluded from statistical analysis. Descriptions of the screening procedures and reasons for exclusion are provided in: DeltaR_Data_Screening_Summary.zip
    Date: 13-Oct-2020 (process 6 of 6)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Toth, L.T., Stathakopoulos, A., and Kuffner, I.B., 20160721, The structure and composition of Holocene coral reefs in the Middle Florida Keys: U.S. Geological Survey Open-File Report 2016-1074, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    Reich, C., Streubert, M., Dwyer, B., Godbout, M., Muslic, A., Umberger, D., 20120104, St. Petersburg Coastal and Marine Science Center's Core Archive Portal: U.S. Geological Survey Data Series 626, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    Toth, L.T., Cheng, H., Edwards, R.L., Ashe, E., Richey, J., 2017, Millennial-scale variability in the local radiocarbon reservoir age of south Florida during the Holocene: Quaternary Geochronology, Elsevier, Amsterdam, Netherlands.

    Cheng H., Edwards, R.L., Shen, C.-C., Polyak, V.J., Asmerom, Y., Woodhead, J., Hellstrom, J., Wang, Y., Kong, X., Spötl, C., Wang, X., Alexander, E.C., 20130523, Improvements in 230Th dating, 230Th and 234U half-life values, and U–Th isotopic measurements by multi-collector inductively coupled plasma mass spectrometry: Earth and Planetary Science Letters, Elsevier, Amsterdam, Netherlands.

    Online Links:

    Lidz, B.H., Reich, C.D., Shinn, E.A., 20030701, Regional Quaternary submarine geomorphology in the Florida Keys: Geological Society of America Bulletin, Bolder, CO.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    All values in tables were cross-checked for accuracy against original versions of the tables and model/instrument outputs.
  2. How accurate are the geographic locations?
    No formal positional accuracy tests were conducted.
  3. How accurate are the heights or depths?
    No formal positional accuracy tests were conducted.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    The data were screened by the authors for accuracy and all data falls within acceptable/logical ranges.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Lauren T. Toth
    USGS
    600 4th St. S
    St. Petersburg, FL
    USA

    727-502-8029 (voice)
    ltoth@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data described or contained herein. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 24-Jun-2021
Metadata author:
Lauren T. Toth
USGS
Research Oceanographer
600 4th St. S
St. Petersburg, FL
USA

727-502-8029 (voice)
ltoth@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/FL_keys_radiocarbon_reservoir_age_variability_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:49 2021