Filters: Tags: radiometric dating (X)94 results (36ms)
Cyst and radionucleotide evidence for the recent introduction of the toxic dinoflagellate Gymnodinium catenatum into Tasmanian waters
Collection, analysis, and age-dating of sediment cores from salt marshes on the south shore of Cape Cod, Massachusetts, from 2013 through 2014
The accretion history of fringing salt marshes located on the south shore of Cape Cod is reconstructed from sediment cores collected in low and high marsh vegetation zones. These marshes are micro-tidal, with a mean tidal range of 0.442 m. Their location within protected embayments and the absence of large rivers results in minimal sediment supply and a dominance of organic matter contributions to sediment peat. Age models based on 210-lead and 137-cesium are constructed to evaluate how vertical accretion and carbon burial rates have changed over the past century. The continuous rate of supply age model was used to age date 11 cores (10 low marsh and 1 high marsh) across four salt marshes. Both vertical accretion...
These data are U-Pb sensitive high-resolution ion microprobe (SHRIMP) geochronology data from quartz porphyry dikes for the study of the Butte mining district, U.S.A. Results of the study are described and interpreted in Lund and others (2018).
Specific activities of cesium-137 (half life = 30.17 years), lead-210 (half life = 22.3 years), radium-226 (half life = 1,600 years), thorium-234 (half life = 24.1 days), and potassium-40 (half life = 1.277 billion years) in disintegrations per minute per gram (dpm/g) were determined for the Lake Lanier cores. The laboratory errors (plus or minus) and the critical levels are included for each sample.
In 2016, with National Park Service support, several previously undated plutons were sampled in Glacier Bay National Park and Preserve along the west side of Glacier Bay for age determinations. Geochronologic analyses were conducted to determine the ages of the plutonic rocks in the Glacier Bay area. Five samples were collected by Frederic Wilson (USGS Alaska Science Center), from Dundas Bay and Geikie Inlet, and dated by laser ablation-inductively coupled plasma mass spectrometry U-Pb methods. The dates obtained ranged from approximately 112-118 Ma, indicating that these samples are younger than the Saint Elias plutonic suite (ca. 160 Ma-130Ma), which runs along the same trend as the sampled rocks to the south.
This dataset accompanies planned publication 'Determining fault geometry through the transport-parallel distribution of thermochronometer cooling ages'. The Ar/Ar data is for samples that record the thermal history of the area. The geochronology provides time constraints for the thermal histories studied in the manuscript. Samples were collected from Nepal, overseen by Nadine McQuarrie (University of Pittsburgh), who sent them to the USGS Denver Argon Geochronology Laboratory for Ar/Ar analysis.
U-Pb age determinations of uraninite by electron microprobe analyses of ore samples from two solution-collapse breccia pipe uranium deposits, Grand Canyon region, northwest Arizona, USA
This data release compiles the electron microprobe spot analyses of U, Th, and Pb concentrations in uraninite (U oxide) particles, and corresponding calculated age determinations, measured in samples of ore from two uranium-copper breccia pipe ore bodies, the Canyon (Pinyon Plain) and Hack II deposits. The U-rich samples that were analyzed typify the deposits hosted by solution-collapse breccia pipes in the Grand Canyon region of northwestern Arizona. Applying procedures outlined by Bowles (1990), the U, Pb, and Th measurements from each spot analysis were used to calculate a model age for the formation of each uraninite particle. The U, Pb, and Th analyses and calculated age determinations are provided as additional...
Precise U-series Dating of Coral Reefs from the South China Sea and the High Sea Level during the Holocene
Toxic chemicals and trace metals from urban and rural Louisiana lakes: Recent historical profiles and toxicological significance
Recent environmental changes inferred from the sediments of small lakes in Yellowstone's northern range.
The drilling project at Owens Lake commenced in April,1991. This Open-File Report represents an effort to makeavailable to other researchers our preliminary datacollected during the first year of study followingcompletion of the core-drilling phase. Nineteen datacollections and preliminary interpretations are presentedin the following sections. They are the work of fifteenfirst-authors and their numerous co-authors. Broadly,their topics include a field log of the core(1 contribution), sedimentological analyses (1), clay-mineral identification (1), geochemical analyses (5),dating and age estimates of the cored sediments (4), andidentifications of fossil materials (7).
Pits of Virginia Beach - insights into Quaternary sea level geochronology and details of Atlantic coastal plain stratigraphy
Evidence for the Timing and Duration of the Last Interglacial Period from High-Precision Uranium-Series Ages of Corals on Tectonically Stable Coastlines
Implications of a sediment-chemistry study on subalpine marsh conservation in the Lake Tahoe Basin, USA
Collection, analysis, and age-dating of sediment cores from mangrove wetlands in San Juan Bay Estuary, Puerto Rico, 2016
The San Juan Bay Estuary, Puerto Rico, contains mangrove forests that store significant amounts of organic carbon in soils and biomass. There is a strong urbanization gradient across the estuary, from the highly urbanized and clogged Caño Martin Peña in the western part of the estuary, a series of lagoons in the center of the estuary, and a tropical forest reserve (Piñones) in the easternmost part with limited urbanization. We collected sediment cores to determine carbon burial rates and vertical sediment accretion from five sites in the San Juan Bay Estuary. Cores were radiometrically-dated using lead-210 and the Plum age model. Sites had soil C burial rates ranging from 50 grams per meter squared per year (g m-2...
Uranium-, thorium-, strontium-, carbon- and oxygen-isotope data used to evaluate a 300,000-year history of water-table fluctuations at Wind Cave, South Dakota, USA — scale, timing, and groundwater mixing in the Madison Aquifer
Tables of U- and Th-isotopic data used to calculate uranium-series age estimates and initial 234U/238U activity ratios as well as 87Sr/86Sr, δ13C, and δ18O for samples of phreatic speleothems from Wind Cave National Park and U- and Sr-isotopic compositions of waters from the southern Black Hills of South Dakota, USA
This dataset accompanies planned publication 'Detrital record of the Late Oligocene – Early Miocene mafic volcanic arc in the Southern Patagonian Andes (~51°S) from single-clast geochronology and trace element geochemistry'. The Ar/Ar data is for samples that record the detrital sedimentary record of the basin. The geochronology provides time constraints for the sedimentation studied in the manuscript. Samples were collected from the Magallanes-Austral Basin, and collection was supervised by Julie Fosdick, who sent them to the USGS for Ar/Ar analysis.
Argon and geochemical data for: 40Ar/39Ar geochronology and petrogenesis of the Table Mountain Shoshonites, Golden, CO
This dataset accompanies publication '40Ar/39Ar geochronology and petrogenesis of the Table Mountain Shoshonites, Golden, CO', to be published in Rocky Mountain Geology, which analyzed lava flows on North and South Table Mountain in Golden, CO, for argon geochronology and geochemistry.
Isotopic data for soil cores collected during 2000 from Sand Lake National Wildlife Refuge, South Dakota
A study was conducted to assess the vertical accretion of sediment in the Mud Lake impoundment of Sand Lake National Wildlife Refuge, located in Brown County, South Dakota. Sediment cores were collected from the Mud Lake impoundment during 2000 for determination of vertical accretion rates, which were estimated using cesium-137 and lead-210 isotopic dating techniques. These data directly support the associated publication “Sedimentation Rates in the Marshes of Sand Lake National Wildlife Refuge, South Dakota” which is referenced within the Metadata.