Gulf of Mexico Sediment Trap Foraminifera Data
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The U.S. Geological Survey (USGS) deployed a sediment trap (McLane PARFLUX 78H) mooring in the northern Gulf of Mexico (27.5 °N and 90.3°W, water depth 1150 meters [m]) in January 2008 to collect seasonal time-series data on the flux and assemblage composition of planktic foraminifers. The trap was positioned in the water column at a depth of 700 m on the mooring cable to enable the collection of deeper dwelling species of planktic foraminifera. The trap contains 21 collection cups that were programmed to rotate every 7 to 14 days (resulting in weekly to biweekly sampling resolution). Upon retrieval, samples were subsequently wet split into four aliquots using a precision rotary splitter, stored in buffered deionized water, and refrigerated. A quarter split was wet sieved over a 150-micron (μm) sieve and subsequently wet picked for all foraminifers. In samples containing fewer than 300 foraminifers in the first quarter split, an additional split was processed and picked in its entirety. The counts were then summed. All planktic foraminifers were identified to the species level. This report gives information on the raw counts and foraminifera flux (tests m−2 day−1) through May 2014. Flux was calculated based on the total number of foraminifera for each sub-sample, the fraction of the total sample used, the duration (days) the sediment trap was opened and collecting data for a given sample, and the aperture area of the sediment trap (0.5 meter-squared [m2]). The sediment trap mooring is currently deployed, and foraminifera data will be updated as new samples are processed.
Globorotalia truncatulinoides Trace Element Geochemistry (Barium, Magnesium, Strontium, Manganese, and Calcium) from the Gulf of Mexico Sediment Trap
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Observations of elevated barium-to-calcium ratio (Ba/Ca) in Globorotalia truncatulinoides have been attributed to contaminant phases, deep calcification depth and diagenetic processes. U.S. Geological Survey (USGS) scientists and their collaborators investigated intra- and inter-test Ba/Ca variability in the non-spinose planktic foraminifer, G. truncatulinoides, from a sediment trap time series (2009-2017) in the northern Gulf of Mexico (generally 27.5°N and 90.3°W) to gain insights into the environmental influences on barium enrichment in this and other non-spinose species. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was used to differentiate between the elemental composition of the crust and lamellar calcite in non-encrusted (< 150 meters [m] calcification depth) and encrusted (> 250 meters calcification depth) specimens of G. truncatulinoides. For further information regarding data collection, processing methods, and/or results and interpretive study refer to Richey and others (2022).
2008-2017 Globigerinoides ruber Sediment Trap Data Collected from the Gulf of Mexico
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This data release includes results of a high-resolution (1–2 weeks) and long-term sediment trap time series collected from the northern Gulf of Mexico. This dataset allows for a detailed assessment of the seasonal distribution, size, morphological variability and geochemistry of co-occurring pink and white chromotypes of the shallow-water foraminifera, Globigerinoides ruber. The flux of both chromotypes is highly correlated, and both represent mean annual conditions in the marine surface mixed layer. Under modern climatic conditions in the Gulf of Mexico, USGS researchers found no significant offset in the Magnesium/Calcium (Mg/Ca) and delta Oxygen-18 (d18O) of co-occurring pink and white G. ruber (Richey and others, 2019). Furthermore, findings show the d18O and delta Carbon-13 (d13C) among the two morphotypes (sensu stricto and sensu lato) of both pink and white G. ruber to be indistinguishable. The test size distribution within the population varies seasonally, with the abundance of large individuals increasing (decreasing) in summer (winter). For further information regarding data collection and/or processing methods as well as the associated published manuscript refer to Richey and others (2019).
Sediment Core Microfossil Data Collected from the Coastal Marsh of Grand Bay National Estuarine Research Reserve, Mississippi, USA
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To aid in geologic studies of sediment transport and environmental change in coastal marsh, 1-centimeter (cm) foraminiferal subsamples were taken from seven sediment push cores collected in the Grand Bay National Estuarine Research Reserve (GNDNERR), Mississippi, in October 2016. The push cores were collected along two, shore-perpendicular transects at 5, 15, 25, and 50 meters (m) from the shoreline, on opposite sides of Middle Bay during U.S. Geological Survey (USGS) Field Activities Number (FAN) 2016-358-FA, also known as alternate FAN 16CCT07. Foraminiferal subsamples were processed and analyzed at the USGS St. Petersburg Coastal and Marine Science Center (SPCMSC). Sediment characteristics, loss-on-ignition (LOI), and site location information for the core sites can be found in Marot and others (2019; https://doi.org/10.5066/P9FO8R3Y). Downloadable data are available as Excel spreadsheets (.xlsx), comma-separated values text files (.csv), and Federal Geographic Data Committee (FGDC) metadata (.txt and .xml).
Surficial and Downcore Sedimentological and Foraminiferal Microfossil Data from St. Marks National Wildlife Refuge, Florida
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In October 2019, five marsh push cores (core names appended with M for marsh push core) and 18 surface sediment samples (top 1 cm of sediment) were collected from the estuary (sample name appended G for PONAR grab) near the mouth of the St. Marks River and some of the surrounding marshes (sample name appended with S for surface), along with elevation transects and peat augers (sample name appended with R or R50, depending on length, for Russian peat auger). The purpose of the study was to 1) evaluate peat thickness relative to the shoreline and upland, 2) compare marsh accretion rates with other marshes along the northern Gulf of Mexico, 3) determine whether sea-level or storm history records are recorded and viable, and 4) compare elevation and shoreline data with post-Michael lidar imagery. Cores and surficial sediment samples were processed and analyzed for organic content and grain-size. Cores and select surface samples were analyzed using gamma spectroscopy for determination of background and excess lead-210 with cesium-137, while the modern foraminiferal microfossil assemblage was determined using surface sediment samples. Foraminiferal samples (appended with F for foraminifera) were collected at surface sample sites and stained in the field with rose Bengal for determination of live (stained) and dead (unstained) microfossils. All samples in the dataset are referred to by field activity number (FAN) 2019-366-FA (alternate FAN 19CCT05) and are part of the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center's (USGS-SPCMSC) Estuarine and MaRsh Geology (EMRG) research project, which works to understand how and where short- and long-term marsh and estuarine coastal processes interact, how they influence coastal accretion or erosion, and how they pre-condition a marsh’s resiliency to storms, sea-level change, and human alterations along the northern Gulf of Mexico.
Geophysical properties, geochronologic, and geochemical data of sediment cores collected from San Pablo Bay, California, October 17-20, 2016
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Geophysical properties (P-wave velocity, gamma ray density, and magnetic susceptibility), geochronologic (radiocarbon, excess Lead-210, and Cesium-137), and geochemical data (organic carbon content and 60 element contents) are reported for select vibracores collected aboard the S/V Retriever October 17-20, 2016, in San Pablo Bay, California. Geophysical properties were measured with a Geotek Multi-Sensor Core Logger (MSCL). Radiocarbon was measured by accelerator mass spectrometry (AMS). Excess Lead-210 and Cesium-137 activities were measured by gamma-ray counting in a high purity, low background germanium well detector (HPGe). Total organic carbon was measured in bulk sediment. Element contents were determined on the less than 0.063 mm (fine) size fraction of sediment by inductively coupled plasma mass spectrometry (ICP-MS).