Filters: Tags: Detrital Zircon (X)
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Twenty-two igneous and metamorphic rock samples were collected in a 20-km-long swath centered on the Alaska Highway between Tetlin Junction, Alaska, and the Canada border. Igneous and metamorphic rock samples were submitted to the Apatite to Zircon, Inc. laboratory (A2Z), where zircon U-Pb age analysis, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), was performed by Paul O'Sullivan. The 15 felsic plutonic rock samples and one gabbro sample yield Cretaceous zircon U-Pb weighted-mean ages ranging from 95.7 Ma to 106.2 Ma. Zircons from a metadiorite yield a Triassic weighted-mean age of about 241.9 Ma. Metamorphic zircons from two samples with felsic igneous protoliths yield Mississippian...
A physiographically prominent, approximately 40 square km plateau lies roughly 20 km east of Mount Spurr volcano, northwestern Cook Inlet region, Alaska, and comprises the preserved remnant of a volcaniclastic succession, designated in this study as map unit Qvc. Although this readily mappable package of volcaniclastic rocks has been recognized in numerous studies during the past five decades, uncertainties regarding its age and origin have persisted. We describe the general characteristics of the volcaniclastic plateau, provide new age constraints for deposits, present lithofacies descriptions and interpretations of the volcaniclastic strata, and synthesize our observations and lithofacies analysis to propose an...
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 archives geochronology and geochemistry measurements from detrital zircons collected from samples taken from the Bering Sea and its major feeder rivers.
Categories: Data;
Tags: Bering Sea,
Geochemistry,
Marine Geology,
Sedimentology,
USGS Science Data Catalog (SDC),
This document includes sandstone provenance data for Upper Cretaceous to Paleocene strata preserved in the Crazy Mountains Basin of western Montana, USA. The dataset includes detrital zircon data for six samples from the Upper Cretaceous Hoppers Formation (1 sample), Upper Cretaceous Billman Creek Formation (1 sample), and Paleocene Fort Union Formation (4 samples). Detrital zircon data were acquired at the University of Arizona LaserChron Center in 2017.
Categories: Data;
Tags: Montana,
Sedimentology,
Stratigraphy,
USGS Science Data Catalog (SDC),
basin,
This Laser ablation ICPMS U-Pb detrital zircon data set supports mapping and stratigraphic interpretations of the Upper Devonian Ignacio Formation in southwestern Colorado (Silverton area). All samples were collected from a measured stratigraphic section called "Sultan Creek South" located at 37.710010 and -107.67530 (Evans and others, 2019). The Ignacio Formation was previously interpreted as Cambrian, but evidence that it is Devonian includes reexamined fossil data and detrital zircon U-Pb geochronology. The Ignacio Formation has a stratigraphic trend of detrital zircon ages shifting from a single ca. 1.7 Ga age peak to bimodal ca. 1.4 Ga and ca. 1.7 Ga age peaks, which represents local source-area unroofing history....
Categories: Data;
Tags: Colorado,
Detrital Zircon,
East Lime Creek Conglomerate,
GGG,
Geochronology,
This document includes two suites of zircon U-Pb ages that help to characterize the magmatic and sedimentary history of the North American Cordillera between ~28 and 50 degrees north. The first dataset is a compilation of published zircon U-Pb ages of igneous rocks associated with the Mesozoic-Cenozoic North American Cordilleran arc. The compilation of igneous zircon data includes 1,492 U-Pb ages from the Peninsular Ranges, Sierra Nevada, Idaho, Boulder, and Coast Mountains batholiths, as well as spatially and temporally associated igneous bodies. The second dataset is a compilation of published detrital zircon U-Pb ages from Jurassic to Paleocene strata preserved in forearc and foreland basins of the North American...
Categories: Data;
Tags: North America,
Sedimentology,
Stratigraphy,
USGS Science Data Catalog (SDC),
basin analysis,
Select samples were collected from boreholes in Arctic Alaska to determine the U-Pb ages of zircon to determine a maximum depositional age of the geologic units and/or provenance of the zircon in the samples. Samples were collected from the Department of Natural Resources-Alaska Geologic Materials Center in Anchorage Alaska and sent to U.S. Geological Survey-Geology, Geophysics and Geochemistry Science Center, Denver, CO for mineral separation and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb geochronology analyses. The information is this report includes LA-ICPMS analyses conducted between 2016 and 2018 of at least 120 zircon grains or more (if recovered from sample) from twenty samples...
Geologic mapping, characterization of geologic structures, and sampling for geochronology was completed in two areas of the northwestern Sangre de Cristo Mountains from 2011 through 2017. This data release provides the raw analytical data, metadata and sample information for 20 zircon U-Pb age analyses from laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The two areas include the Poncha Pass area where the entire 71/2’ Poncha Pass quadrangle and parts of five other quadrangles (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville) were mapped at a scale of 1:24,000 (see Minor and others, 2019). The Deadman thrust fault is the second area, approximately 80 km southwest of the Poncha...
This dataset includes U-Pb detrital zircon age data for samples from the Ingleside and Lyons formations in north-central Colorado collected from Owl Canyon and Park Creek Reservoir, from the Molas and Hermosa formations in southwestern Colorado collected from Molas Pass, and from the Lykins formation and its equivalents along the Front Range and in southeastern Colorado. It accompanies publications 'The Permian-Triassic Transition in Colorado' published in Unfolding the Geology of the West: Geological Society of America Field Guide 44, and 'Detrital zircon geochronology of Pennsylvanian-Permian strata in Colorado: evidence for Appalachian-derived sediment and implications for the timing of Ancestral Rocky Mountains...
This laser ablation ICPMS U-Pb zircon data set supports stratigraphic, biostratigraphic and age interpretations of the of the fossil-plant-bearing El Gameño Formation of west-central Sonora, Mexico and the potentially age-correlative fossil-plant-bearing Santa Clara and Coyote formations of southeastern Sonora, Mexico. The zircon data provides minimum age constraints (maximum depositional ages) for Late Triassic to Jurassic sedimentary rocks that don’t have precisely known absolute ages.
From 2017-2019, framework metallogenic studies were completed in the eastern Yukon-Tanana upland in eastern Alaska. Numerous previously undated plutons known or suspected to contain components of porphyry, epithermal, and intrusion-related gold systems and associated deposit types were sampled for age and zircon trace element determinations between the Black Mountain area and the Yukon border, north of the Tanana River and south of the Yukon River. A collection of 54 samples were collected by Douglas Kreiner (USGS, Alaska Science Center). Zircon grains were separated from each sample. The samples were examined by U-Pb analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) in a USGS laboratory...
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