Sedimentologic Data from Vibracores Collected in 2023 from St. Andrew Bay, Florida

Vibracore acquisition- Sediment vibracores were collected using the Rossfelder P-3, which was powered by a 208v 3-phase power supply. The Rossfelder P-3 coring system was deployed from the R/V Apalachee using a knuckle boom crane and placed on the seabed. The core barrel was vibrated into the subsurface until refusal. After extraction, each core was capped, sealed, and labeled with the core number and orientation. All cores were transported to the SPCMC sediment laboratory for processing and analysis. Horizontal positions associated with each core site was determined using the R/V Apalachee's GPS Antenna, which were plotted in real-time by the Navnet Furuno 3D System. Location data were saved as waypoints on the Furuno chart plotter and recorded in the NAD 83 coordinate system. Locations were recorded in a digital file and in a paper log book. Horizontal positions in paper logs were recorded in .xlsx and .csv files and converted into a shapefile in ArcGIS Pro 3.1.2. Horizontal positions were transformed from NAD 83 coordinate systems to Universal Transverse Mercator zone 16 North (UTM16N). Vertical positions (elevations) associated with each core site was determined by extracting the depth at each core site using ArcGIS Pro 3.1.2. The multibeam bathymetry surface from Stalk and others (2023) was loaded into ArcGIS Pro and the 'Extract Values to Points' geoprocessing tool was used to determine the bathymetric depth in the NAVD88 GEOID 12B coordinate system and model at each core site; see Stalk and others (2023) for more information. Core information was compiled into a comma-separated values file (.csv) and Microsoft Excel Worksheet (.xlsx) for inclusion in this data release. The 2023-309-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 zipped keyhole markup language (.kmz) file using the ‘Layer to KML’ tool in ArcGIS Pro. These geospatial files can be found in 2023-309-FA_CoreSites.zip.

Vibracore processing and analysis- At the SPCMSC sediment laboratory, vibracores were frozen for storage. Before splitting, vibracores were defrosted and then split lengthwise, photographed, described macroscopically using standard sediment-logging methods, and subsampled for grain-size analysis and age control. The split vibracores were photographed in approximately 20- to 25-cm, overlapping segments with a Nikon D3500 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) version 2.10 software, cropped to the same extent (to remove areas outside of the core barrel), and "stitched" together using The Panorama Factory version 4.5 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. Descriptive core logs were compiled using Rockware LogPlot 8 2021.6.2 software and exported as Joint Photographic Experts Group (JPG) images. 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. The subsamples collected for radiocarbon dating were labeled, dried, and weighed prior to shipping to Beta Analytic, Inc. (Miami, FL) for analysis. Core VC05 was selected for OSL dating, so care was taken not to expose the sediment to light, and 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. The sample collected for OSL dating was then placed in a lightproof film canister, labeled, and sent to the USGS Luminescence Dating Laboratory (Denver, Colorado) for analysis. The results from this analysis are available in a separate data release (Mahan and others, 2024).

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 microns 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 for 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 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. GRADISTAT also 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 (4 runs per set; 8 runs per sample). Runs that varied from the set average by more than ±1.5 standard deviations were removed from the results and the sample average was recalculated using the remaining runs. The results for the summary and sieve statistics are included in individual CSV and XLSX files, in 2023-309-FA_GrainSize.zip. The results for both the summary and sieve statistics are also compiled into an Excel workbook (2023-309-FA_GrainSizeStats.xlsx), separated by tabs.

Grain-size plots- The LS13 320 averaged results (coarse sand, medium sand, fine sand, very fine sand, and mud classes) for each sample were normalized to 100%. The down-core grain-size distributions were plotted in Matlab version R2021A and exported as two JPG images. These images can be found in the 2023-309-FA_GrainSize.zip of this data release.

Organic matter (OM) content was determined with a mass loss technique, referred to as loss on ignition (LOI). The dry sediment from the previous process was homogenized with a porcelain mortar and pestle. Approximately 3 grams (g) of the dry sediment was placed into a pre-weighed porcelain crucible. The mass of the dried sediment was recorded with a precision of 0.01 g on an analytical balance. The sample was then placed inside a laboratory muffle furnace with stabilizing temperature control. The furnace was heated to 110° Celsius (C) for a minimum of 6 hours to remove hygroscopic water absorbed onto the sediment particles. The furnace temperature was then lowered to 60°C, at which point the sediments could be reweighed. The dried sediment was returned to the muffle furnace. The furnace was heated to 550°C for over 30 minutes and kept at 550°C for 6 hours. The furnace temperature was then lowered to 60°C, at which point the sediments could be reweighed. The mass lost during the 6-hour baking period relative to the 110°C-dried mass is used as a metric of organic matter content (Dean, 1974). These data files can be found in the 2023-309-FA_LossOnIgnition.zip of this data release.

Radiocarbon dating- Both the organic sediment fraction and plant material from selected organic-rich or peat sediment samples were analyzed using accelerated mass spectrometry (AMS) radiocarbon (14C) dating at Beta Analytic, Inc. (Miami, Florida). For each sample, the conventional 14C radiocarbon age as well as calibrated age ranges are reported. Calibrated ages are based on terrestrial calibration curves from INTCAL20 (Reimer and others, 2020) using the High Probability Density (HPD) Range Method (Ramsey, 2009). For additional information on understanding calibrated radiocarbon ages, refer to the Beta Analytic, Inc. (https://www.radiocarbon.com/calendar-calibration-carbon-dating.htm) or University of Oxford Radiocarbon Accelerator Unit (https://c14.arch.ox.ac.uk/calibration.html, https://c14.arch.ox.ac.uk/explanation.php) websites. These data files can be found in the 2023-309-FA_AgeControl.zip of this data release.

Populating image headers- Credit, contact information, copyright, usage terms, image descriptions, attribution url, metadata link, and georeferencing information were added to the exchangeable image file format (EXIF) header of each image using Phil Harvey’s ExifTool (version 12.44). The images were grouped by image type (core logs and photographs) into separate folders: 2023-309-FA_CoreLogs (11 images), 2023-309-FA_CorePhotos (52 images). Grain-size plots are in the folder: 2023-309-FA_GrainSize (2 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 to populate those headers (see the third script). The core logs and photographs are published as JPGs. Image header information was also populated for 2023-309-FA_GrainSizeDistributions.jpg in 2023-309-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/P1AFJDNE" -XMP:Event="2023-309-FA" -EXIF:GPSAreaInformation="Location of core collection site, GPS coordinates are in NAD83" -XMP:ExternalMetadataLink="https://www1.usgs.gov/pir/api/identifiers/USGS:4ee2764f-c629-4176-ac61-e064ed2fcede" -EXIF:GPSMapDatum="EPSG:6318 NAD83 (2011)" *.JPG Third, the following command was run on each image in the folder to populate the unique image headers for each core. This command called on a .csv file containing the File name, GPS Latitude, and GPS Longitude of each core, called “TYND_core_photos_GPS_info.csv ” as well as a text file that contained header tags, called “in.args-tyndall_core_photos.txt”. The command run to populate the Latitude and Longitude information was: exiftool -@ in.args-tyndall_core_photos.txt -csv=TYND_core_photos_GPS_info.csv *.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 extract the information from the image headers using ExifTool, run the following command after connecting to the unzipped folder containing the images: exiftool a.jpg, where 'a' is replaced with the filename. Example: TYND-VC03_0-90_FullStitch.jpg