Filters: Tags: radiometric dating (X)86 results (130ms)
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.
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...
Sediment chemistry and characteristics of samples collected in 2019 from the Similkameen River above Enloe Dam, Okanogan County, Washington (ver. 3.0, March 2022)
This data release provides information on the chemistry and character of bed sediments accumulated in the 1.6-mile long impoundment behind Enloe Dam on the Similkameen River in Okanogan County, WA. Sediment samples were collected during four weeks in October – December 2019. The sampling locations were distributed among 10 transects that ranged from 0.1-0.2 miles apart along the length of the reservoir. Surficial grab samples of bed material were collected at 27 locations representing the left, right or center of the channel cross-section where sampling was possible using a Ponar sampler. Sediment cores were collected with a Vibracore at 12 locations at or near the surficial grab sample transects, and discrete sediment...
Data release for cosmogenic beryllium-10 exposure ages of moraine boulders in the Stura Valley, Maritime Alps, northwestern Italy
This report summarizes the cosmogenic beryllium-10 (10Be) geochronologic results from boulders deposited on moraines in the Stura Valley of the Maritime Alps, the southwestern most extent of the European Alpine mountain chain, northwestern Italy. Within this report are detailed the methodologies used to collect samples of whole rock, determine the concentrations of cosmogenic 10Be in purified quartz isolated from those samples, and use those nuclide concentrations to calculate surface exposure ages. This report should be used as supplementary material for any publication(s) that uses the nuclide concentrations and/or ages reported herein. This version supersedes all previous age estimates and reports.
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...
Potential Explanatory Variables for Groundwater Quality in the Redding-Red Bluff Shallow Aquifer Assessment Study Unit, 2018-2019: California GAMA Priority Basin Project
This data release codifies and attributes explanatory variables that could potentially influence groundwater quality at 50 groundwater wells used for domestic water supply and 43 groundwater sites used for public water supply in the U.S. Geological Survey’s Priority Basin Project Redding-Red Bluff shallow aquifer (NSV-SA) study unit in 2018-2019 and Northern Sacramento Valley public-supply (NSV-PA) study unit in 2007, respectively. Water quality from domestic and public-supply groundwater sites was assessed as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) program. The NSV-SA and NSV-PA study units include domestic and public-supply wells within...
Static chamber gas fluxes and carbon and nitrogen isotope content of age-dated sediment cores from a Phragmites wetland in Sage Lot Pond, Massachusetts, 2013-2015
Coastal wetlands are major global carbon sinks, however, they are heterogeneous and dynamic ecosystems. To characterize spatial and temporal variability in a New England salt marsh, static chamber measurements of greenhouse gas (GHG) fluxes were compared among major plant-defined zones (high marsh dominated by Distichlis spicata and a zone of invasive Phragmites australis) during 2013 and 2014 growing seasons. Two sediment cores were collected in 2015 from the Phragmites zone to support previously reported core collections from the high marsh sites (Gonneea and others 2018). Collected cores were up to 70 cm in length with dry bulk density ranges from 0.04 to 0.33 grams per cubic centimeter and carbon content 22.4%...
U-Pb zircon data for volcanic and sedimentary units within the Kittitas Valley, central Washington State
This data release includes laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb zircon geochronology data from four samples collected from syn- and post-Columbia River Basalt Group strata. Samples were collected from within alluvial fan strata and gravel-mantled hillslopes. Sample 16MANC2-01 was collected from an excavation into rounded fluvial gravel deposits along the Manastash Ridge. The unit collected includes Cascadian derived volcanic clasts and is interpreted as an inset terrace of fluvial strata deposited on the Manastash Ridge. Sample 16MANC1-06 is a rhyodacitic boulder collected on a nearby exposure of gravel mantled hillslopes along Manastash Ridge. Sample 16MRF01 was collected...
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.
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...
Concentrations of Per- and Polyfluoroalkyl Substances (PFAS) in Lake-Bottom Sediments of Ashumet Pond on Cape Cod, Massachusetts, 2020
Lake-bottom sediment and associated quality-control samples were collected in August 2020 from one coring location (U.S. Geological Survey station 413756070321301, ASHUMET POND, MASHPEE MI-ASHPD-0011) in Ashumet Pond downgradient from a former fire-training area on Cape Cod, Massachusetts. The core was collected to determine if per- and polyfluoroalkyl substances (PFAS) were present in the bottom sediments of a lake known to have elevated concentrations of PFAS in surface water and groundwater (Tokranov and others, 2021), and whether the sediments could act as a continuous source of PFAS to the lake. Processing the sediment core entailed collection of discrete samples at intervals ranging from 1-5 centimeters (cm)...
Radiocarbon measurements, census counts of benthic foraminifera, diatoms, and palynomorphs, and geochemistry from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay
The urbanized area of downtown Menlo Park is subject to persistent flooding and sediment deposition by San Francisquito Creek in South San Francisco Bay. To mitigate these events, a suite of cores was collected in 2002 at the mouth of the creek to determine sediment depositional rates on the delta. One of those cores (721-1) was selected for microbiological (pollen, diatoms, and foraminifera) and geochemical analyses to reconstruct a depositional record over the past two millennia. This data release provides radiocarbon dates, census counts of benthic foraminifera, diatoms, and palynomorphs, and the measurement of anthropogenic metals and other elements in sediments from this core.
Geochemistry of surface sediment and sediment cores in Bellingham Bay, Whatcom County, Washington, in February 2020
Geochemical data are reported for surface sediments and long sediment cores from Bellingham Bay, Whatcom County, Washington, collected in early February 2020 after flood conditions on the Nooksack River. Data include total organic carbon content (TOC), carbonate content (CaCO3), ratios of stable carbon 13/12 isotopes (d13C), ratios of total carbon to total nitrogen (C:N), short-lived cosmogenic radionuclide activities (Beryllium-7, Cesium-137, and excess Lead-210), and elemental chemistry.
Backscatter electron (BSE) and panchromatic cathodoluminescent (CL) imagery of minerals from samples dated by 40Ar/39Ar are for the study of the Butte mining district, U.S.A. Results of the study are described and interpreted in Lund and others (2018).These data are shared to meet open data requirements.
U-series isotope data used to date a 130,000-year-old archaeological site in southern California, U.S.A.
This dataset includes tables with physical information and isotopic data that are used to calculate uranium-series ages (230Th/U method) and initial 234U/238U activity ratios on a suite of mastodon bones from the Cerutti Mastodon site near San Diego, CA area.