Abstract:

This dataset contains short-lived radioisotope (SLRad) data collected aboard R/V Point Sur cruise PS18-25 in the northern Gulf of Mexico from 2018-05-18 to 2018-05-23. Short-lived radioisotope (SLRad) data are generated for selected core sub-samples at 2mm sampling intervals for “surficial unit” and 5mm sampling resolution intervals to the base of cores. SLRad data generated include sample activity as disintegrations per minute per gram (dpm/g) of 1) Excess Thorium-234 (234Thxs) activity, which is calculated by measuring the total Thorium-234 (234ThTot) activity and the subtraction of the measured or estimated “Supported” Thorium-234 (234ThSup) activity, 2) Excess Lead-210 (210Pbxs) activity, which is calculated by measuring the total Lead-210 (210PbTot) activity and subtraction of the measured background Lead-210 (210PbSup) activity {average of Lead-214 (214Pb) at 295 kiloelectron volts (keV), 214Pb at 351keV, and Bismuth-214 (214Bi) at 609keV}, 3) Cesium-137 (137Cs) activity, and 4) Berilium-7 (7Be) activity. The dataset also includes the date and location of sample collection. The cruise documentation was provided for the R/V Point Sur cruise PS18-25 led by chief scientist Dr. Arne Diercks.

Suggested Citation:

Brooks, G.R. and Larson, R.A.. 2020. Short-lived radioisotope (SLRad) data collected aboard R/V Point Sur cruise PS18-25 in the northern Gulf of Mexico from 2018-05-18 to 2018-05-23. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-h6gj-1m18

Publications:

Diercks, A. R., Romero, I. C., Larson, R. A., Schwing, P., Harris, A., Bosman, S., … Brooks, G. (2021). Resuspension, Redistribution, and Deposition of Oil-Residues to Offshore Depocenters After the Deepwater Horizon Oil Spill. Frontiers in Marine Science, 8. doi:10.3389/fmars.2021.630183

Romero, I. C., Chanton, J. P., Brooks, G. R., Bosman, S., Larson, R. A., Harris, A., … Diercks, A. (2021). Molecular Markers of Biogenic and Oil-Derived Hydrocarbons in Deep-Sea Sediments Following the Deepwater Horizon Spill. Frontiers in Marine Science, 8. doi:10.3389/fmars.2021.637970

Purpose:

Provide age control and sedimentation rates for sediment cores.

Data Parameters and Units:

Blank cell denotes analysis not performed for the interval, no data generated. ND = Not detected, specific parameter was below detection/measurement. Latitude of core site (decimal degrees) Longitude of core site (decimal degrees) Water depth of core site in meters (m) Core collection Date (MM/DD/YYYY) Site Identification (ID) Core Identification (ID) Top Depth of Interval in millimeters (mm) Bottom Depth of Interval in millimeters (mm) Average Depth of Interval in millimeters (mm), average of Top and Bottom Depths Total 210Pb (210PbTot) measured at 46keV activity as disintegrations per minute per gram (dpm/g) Total 210Pb (210PbTot) measured at 46keV error in activity as disintegrations per minute per gram (dpm/g) Total 234Th (234ThTot) measured at 63keV activity as disintegrations per minute per gram (dpm/g) Total 234Th (234ThTot) measured at 63keV error in activity as disintegrations per minute per gram (dpm/g) Re-Analysis for 234Th (234ThSup estimate) activity (dpm/g) after >120 day from core collection. Re-Analysis for 234Th (234ThSup estimate) activity error (dpm/g) after >120 day from core collection. 137Cs measured at 661keV activity as disintegrations per minute per gram (dpm/g) 137Cs measured at 661keV error in activity as disintegrations per minute per gram (dpm/g) 7Be measured at 477keV activity as disintegrations per minute per gram (dpm/g) 7Be measured at 477keV error in activity as disintegrations per minute per gram (dpm/g) 214Pb measured at 295keV activity as disintegrations per minute per gram (dpm/g) 214Pb measured at 295keV error in activity as disintegrations per minute per gram (dpm/g) 214Pb measured at 351keV activity as disintegrations per minute per gram (dpm/g) 214Pb measured at 351keV error in activity as disintegrations per minute per gram (dpm/g) 214Bi measured at 609keV activity as disintegrations per minute per gram (dpm/g) 214Bi measured at 609keV error in activity as disintegrations per minute per gram (dpm/g) Supported 210Pb (210PbSup) activity calculated by averaging the activities (dpm/g) of 214Pb (295keV), 214Pb (351keV), and 214Bi. Supported 210Pb (210PbSup) activity error calculated by averaging the errors (dpm/g) of 214Pb (295keV), 214Pb (351keV), and 214Bi. Excess 210Pb (210Pbxs) activity calculated by subtracting 210PbSup activity (dpm/g) from 210PbTot activity (dpm/g). Excess 210Pb (210Pbxs) activity error (compound error of 210PbSup activity error (dpm/g) and 210PbTot activity error (dpm/g)). Excess 234Th (234Thxs) calculated by subtracting 234ThSup activity (dpm/g) from 234ThTot activity (dpm/g). Excess 234Th (234Thxs) activity error (dpm/g). Decay Corrected (DC) Excess 234Th (234Thxs) calculated using the 234Thxs activity, time between core collection and sample analysis, and to correct for lost activity due to decay during this time. Decay Corrected (DC) Excess 234Th (234Thxs) activity error (dpm/g). Laboratory/Facility where the analysis was performed.

Methods:

The detail methods on short-lived radioisotope geochronology can be found at Larson et al., 2018.

Instruments:

Ocean Instrument MC-800 Multicore, gravity corer.

Provenance and Historical References:

Larson, R. A., Brooks, G. R., Schwing, P. T., Holmes, C. W., Carter, S. R., & Hollander, D. J. (2018). High-resolution investigation of event driven sedimentation: Northeastern Gulf of Mexico. Anthropocene, 24, 40–50. doi:10.1016/j.ancene.2018.11.002

Individual Files: