Core descriptions and sedimentologic data from vibracores collected in 2021 from Central Florida Gulf Coast Barrier Islands

Vibracore acquisition- Vibracores were collected using an 8-horsepower Briggs and Stratton motor connected via an 8.5-meter-long (27.9-foot-long) shaft to a Dreyer 2 1/8-inch (5.4 centimeter [cm]) concrete vibrator head. The vibrator was attached to a 7.6-cm (3-inch) diameter aluminum core barrel using a clamp, and the core barrel was vibrated into the subsurface until refusal. Measurements were taken on the inside and outside of the core barrel prior to extraction to determine the amount of compaction, which is the difference between the recovered core length and the total depth the core barrel penetrated below the sediment surface. After extraction, each core was capped, sealed, and labeled with the core number and orientation. All cores were transported to the SPCMSC core laboratory for processing and analysis. Position and elevation data at each vibracore site were recorded using a Spectra Precision SP80 DGPS receiver and GNSS antenna receiving RTK corrections from the Florida Permanent Reference Network (FPRN) real-time network. RTK x,y positions were acquired in the Florida State Plane coordinate system and transformed to the North American Datum of 1983 (NAD83) Universal Transverse Mercator Zone 17 North (UTM 17N) coordinate system using NGS VDatum software. RTK elevations were acquired as Florida State Plane ellipsoid heights and transformed to North American Vertical Datum 1988 (NAVD88) orthometric elevations, derived using the GEOID18 (G18) geodetic model. For SJK1, the raw position data were processed through OPUS. The OPUS-derived x,y coordinates were reported in NAD83, UTM 17N, and the OPUS-derived elevations were reported as NAVD88 G18 orthometric elevations. Core information was compiled into a comma-separated values file (.csv) and Microsoft Excel Worksheet (.xlsx) for inclusion in this data release. The 2021-308-FA_CoreSites.csv table was converted to a point shapefile (.shp) using the 'Table To Point Feature Class' geoprocessing tool in ArcGIS Pro to produce a geographic representation of the core sites. A non-proprietary version of the shapefile was created by converting the shapefile to a keyhole markup language (.kml) file in Google Earth Pro. These geospatial files can be found in 2021-308-FA_CoreSites.zip.

Vibracore processing- At the SPCMSC core laboratory, each vibracore was split lengthwise, photographed, described macroscopically using standard sediment-logging methods, and subsampled for grain-size analysis and age control. Because samples were collected for OSL dating, care was taken not to expose the sediment to light. Core splitting and sampling was conducted in the dark with only a photographer's red lamp and the sample half of each core was wrapped in lightproof material for storage prior to subsampling. The archive half of each core was photographed in approximately 20- to 25-cm overlapping segments with a Nikon D80 digital camera with a 70 mm zoom lens using consistent (manually programmed) settings with autofocus from a fixed height. The raw images were white-balanced using GNU Image Manipulation Program (GIMP) software, cropped to the same extent (to remove areas outside of the core barrel), and "stitched" together using The Panorama Factory software, providing seamless high-resolution whole-core images. Textural descriptions for the core logs are based on macroscopic observations. Sediment color is based on the Munsell soil color system (https://munsell.com/color-products/color-communications-products/environmental-color-communication/munsell-soil-color-charts/). Descriptive core logs were compiled using Rockware LogPlot 8 software, edited in Adobe Illustrator, and exported as Joint Photographic Experts Group (JPEG) images. Core photo and core log images are included in the 2021-308-FA_CorePhotos.zip and 2021-308-FA_CoreLogs.zip files of this data release. Grain-size and age-control samples consisted of 2-cm sections sampled at varying intervals down-core depending on the number and thickness of the observed sedimentologic units. Samples collected for OSL dating were placed in lightproof film canisters, labeled, and sent to the USGS Luminescence Dating Laboratory (Denver, Colorado) for analysis.

Grain-size PSA analysis- At the SPCMSC sediment laboratory, grain-size analyses were performed using a Coulter LS13 320 (https://www.beckmancoulter.com/) PSA. The LS13 320 uses laser diffraction to measure the size distribution of sediments from 0.4 µm to 2 mm, encompassing clay to very coarse-grained sand. To prevent large shell fragments from damaging the instrument, particles greater than 1 mm in diameter (coarse sand) were separated from all samples prior to analysis using a number 18 (1 mm) U.S. standard sieve, which meets the American Society for Testing and Materials (ASTM) E11 standard specifications for determining particle size using woven-wire test sieves. Two subsamples from each sample were processed through the instrument a minimum of four runs each. Once introduced into the LS13 320, the sediment in the sample well was sonicated with a sonicator wand for 30 seconds (s) to separate any aggregates before starting the first run for both subsamples. The LS13 320 measures the particle-size distribution of each sample by passing sediment suspended in solution between two narrow panes of glass in front of a laser. Light is scattered by the particles into characteristic refraction patterns measured by an array of photodetectors as intensity per unit area and recorded as relative volume for 92 size-related channels (bins).

Grain-size processing- The raw grain-size data was run through the free software GRADISTAT version 9, (Blott and Pye, 2001; kpal.co.uk/gradistat), which calculates the mean, sorting, skewness and kurtosis of each sample geometrically, in metric units, and logarithmically, in phi (Φ) units (Krumbein, 1934), using the Folk and Ward (1957) scale. The raw (run) LS13 320 output files for all samples were compiled by GRADISTAT during import; those raw data are included in this data release for advanced users in the file 2021-308-FA_GrainSizeData.zip. GRADISTAT also reports the descriptive sediment texture after Folk (1954) and calculates the fraction of sediment from each sample by size category (for example, clay, coarse silt, fine sand) based on a modified Wentworth (1922) size scale. A macro function in Microsoft Excel, developed by the USGS SPCMSC, was applied to the data to calculate average and standard deviation for each sample set (8 runs per sample), and highlight runs that varied from the set average by more than ±1.5 standard deviations. Excessive deviations from the mean are likely the result of equipment error or extraneous organic material in the sample and are not considered representative of the sample. The highlighted runs were removed from the results and the sample average was recalculated using the remaining runs. The averaged (summary) results for all samples are included as a tab in a Microsoft Excel workbook (2021-308-FA_GrainSizeStats.xlsx) and as a comma-separated values (2021-308-FA_GrainSize_SumStats.csv) data file. The raw LS13 320 run data are also included as tabs (separated by core) in an Excel workbook (2021-308-FA_GrainSize_RunData.xlsx) and as a comma-separated values (2021-308-FA_GrainSize_RunData.csv) data file.

Grain-size sieve analysis- To evaluate the contribution of particles larger than 1 mm in diameter (coarse sand), a subsample of each sediment sample was also analyzed by sieving. The sediment was passed through a stack of sieves with progressively smaller openings using the assistance of a mechanical sieve shaker to determine grain-size distribution. U.S. standard sieves numbers 230 (63 µm), 120 (125 µm), 60 (250 µm), 35 (500 µm), 18 (1 mm), and 10 (2 mm) were used, which meet the ASTM E11 standard specifications for determining particle size using woven-wire test sieves. All dry sieve data was reported as a percent fraction of the total bulk dry weight of each sample subset. The results for all samples are included as a tab in an Excel workbook (2021-308-FA_GrainSizeStats.xlsx) and as a comma-separated values (2021-308-FA_GrainSize_SieveStats.csv) data file.

Grain-size plots- The results of the sieve analyses (very coarse sand and gravel classes) were merged with the LS13 320 averaged results (coarse sand, medium sand, fine sand, very fine sand, and mud classes) for each sample in Microsoft Excel and re-normalized to 100%. The down-core grain-size distributions were plotted in Matlab and exported as a JPEG image (included with 2021-308-FA_GrainSizeData.zip), with the cores sorted from north to south.

Populating image headers- Additional metadata information were added to the exchangeable image file format (EXIF) and other imagery headers of each image using Phil Harvey’s ExifTool. The images were grouped by image type (core logs and photographs) into separate folders: 2021-308-FA_CoreLogs (11 images) and 2021-308-FA_CorePhotos (17 images). All information in the scripts were the same among all images, aside from the EXIF:ImageDescription, EXIF:DateTimeOriginal, EXIF:GPSLatitude and EXIF:GPSLongtitude information, as that information varies for each core. A separate script containing that header information was run on each image individually to populate those headers (see the third script). Image header information was also populated for 2021-308-FA_GrainSizeDistributions.jpg in 2021-308-FA_GrainSizeData.zip. However, since this image details grain-size distributions for all collected cores, the third script was not used, along with removing EXIF:GPSMapDatum and EXIF:GPSAreaInformation in the second script.
First, the following command was run on all images in a folder to preserve filenames: exiftool -P "-XMP:PreservedFileName<Filename" *.jpg.
Second, the following command was run on all images in a folder to populate the first set of headers. exiftool -IPTC:Credit="U.S. Geological Survey" -IPTC:Contact="gs-g-spcmsc_data_inquiries@usgs.gov" -EXIF:Copyright="Public Domain" -XMP:UsageTerms="Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty." -XMP:AttributionURL="https://doi.org/10.5066/P14L5SVG" -XMP:Event="2021-308-FA" -EXIF:GPSAreaInformation="Location of core collection site, GPS coordinates are in NAD83" -XMP:ExternalMetadataLink="https://data.usgs.gov/datacatalog/metadata/USGS:11f59ca9-28a3-4d5b-bb31-88c76ccfe9c8.xml" -EXIF:GPSMapDatum="NAD83" *.jpg
Third, the following command was run on each image in the folder to populate the unique image headers for each core. This example is for the 2021-308-FA-MK1 core photograph: exiftool -EXIF:ImageDescription="https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-308-FA; Core photograph for 2021-308-FA-MK1." -EXIF:GPSLatitude="27.62816" -EXIF:GPSLatitudeRef="N" -EXIF:GPSLongitude="82.73466" -EXIF:GPSLongitudeRef="W" -EXIF:DateTimeOriginal="2021:02:19 00:00:00" 2021-308-FA-MK1.jpg
Fourth, the following command run on all images in a folder to copy information into duplicate tags: exiftool -P "-XMP-photoshop:Credit<IPTC:Credit" "-XMP-iptcCore:CreatorWorkEmail<IPTC:Contact" "-XMP-dc:Rights<EXIF:Copyright" "-XMP-dc:Description<EXIF:ImageDescription" "-XMP-exif:all<GPS:all" "-XMP-photoshop:DateCreated<EXIF:DateTimeOriginal" "-EXIF:GPSDateStamp<EXIF:DateTimeOriginal" -overwrite_original *.jpg
To read out the imagery header information for a set of images to a .csv file, run the following command after connecting to the unzipped folder containing the images: exiftool -csv *.jpg > allheaders.csv Specific tags may be specified with this command, if preferred.