Project objectives are to (1) develop innovative analytical techniques for isotope geochemistry and U-Pb geochronology using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and (2) apply these techniques to collaborative research projects of high priority to the Mineral Resources Program, including studies related to the formation of "critical mineral" deposits, and studies related to Alaska and U.S. midcontinent regions.
Scientific Issue and Relevance
The Plasma Laboratory houses a new double-focusing multiple-collector plasma ionization mass spectrometer (MC-ICPMS), a Nu Plasma II, and a new 193 nm laser ablation system (RESOlution-SE). This LA-MC-ICPMS is designed to perform in-situ high-precision measurements of radiogenic and stable isotopes of trace elements. The other instrumentation in the Plasma Laboratory includes double-focusing single-collector lasma ionization mass spectrometer (SC-ICPMS), a Nu AttoM ES, and a new Agilent 7900 quadruple (Q) ICPMS. The latter two instruments are primarily used to perform rapid in situ measurements of Pb isotope ratios (i.e., common Pb for tracer studies or radiogenic Pb for U-Pb dating) and trace element abundances.
This project will allow us to (1) develop innovative in-situ analytical techniques for isotope geochemistry and U-Pb geochronology using plasma ionization mass spectrometry and (2) apply our new analytical techniques to collaborative research projects of high priority to the
Mineral Resources Program (MRP), including studies related to the U.S. midcontinent region and Alaska, and/or processes related to the formation of critical mineral deposits.

Methods to Address Issue
Our next major tasks are to refine our existing techniques and establish a series of new methods for isotopic and geochronological research using a philosophy of innovation through collaboration.
Innovation: Our goal is to improve the precision and accuracy of each technique to reach or surpass the cutting edge, while increasing efficiency (i.e., reducing the time and cost per analysis). We are following a phased approach of establishing or refining the analytical techniques from the basics (e.g., in situ U-Pb dating of zircon, apatite, titanite, and rutile, Hf isotopes in zircon; Nd isotopes in monazite) to those with higher risk and greater impact (e.g., St isotopes in apatite, feldspars, carbonates, and barite; Pb isotopes in feldspar and tourmaline; Li isotopes in tourmaline; Nd isotopes in bastnaesite or scheelite; Sn isotopes in cassiterite, or in situ U-Pb dating of ore-related minerals, such as bastnaesite, columbite, cassiterite, or scheelite).
Collaboration: The closely related fields of isotope geochemistry and geochronology are the power tools in the Geologist's tool chest. A major goal of this project is to increase the usage of these tools within the USGS through collaboration with other scientists on current and future MRP projects. We will involve USGS scientists in research with isotopes through a series of case studies related to high-priority Mineral Resources Program projects.
Project tasks are focused on the following activities:
- In-situ Isotope analysis of critical mineral isotope systems for geologic applications
- In-situ U-Pb geochronology of ore-forming and ore-related minerals applied to geologic processes
- In-situ U-Pb geochronology and trace element geochemistry of ore minerals and ore-forming processes
Return to: Mineral Resources Program | Geology, Geophysics, and Geochemistry Science Center
Below are other science projects associated with this project.
Analytical Chemistry
Uranium Mineral Systems
Geophysics of the Midcontinent Rift Region
Geologic Framework of the Intermountain West
Alaska Earth Mapping Resources Initiative (Earth MRI)
Gulf Coast Geologic Energy Research
Iron Oxide-Copper-Cobalt-Gold-Rare Earth Element Deposits of Southeast Missouri—From the Ore Deposit Scale to a Global Deposit Model
Antimony In and Around the Yellow Pine Deposit, Central Idaho
Mineville, Eastern Adirondacks – Geophysical and Geologic Studies
Macro and Micro Analytical Methods Development
Tectonic and Metallogenic Evolution of the Yukon-Tanana Upland, Alaska
Petrology, Tectonic Setting, and Potential for Concentration of Rare Earth Elements (REE) and High Field Strength Elements (HFSE) in the High-K Darby and Kachauik Plutons, Seward Peninsula, Alaska
Below are data releases associated with this project.
U-Pb zircon data for: Upper Triassic and Jurassic sedimentary rocks from Sonora, MX
Pb-Pb and U-Pb data of Proterozoic to Phanerozoic cassiterite deposits in Russia
In situ U-Pb dating of apatite and rutile from St. Francois Mountains IOA and IOCG deposits, southeast Missouri
U-Pb data for the Coles Hill uranium deposit, Virginia
U-Pb data for inherited cassiterite in "Tin Granites", an example from the Yazov Granite, Eastern Siberia
U-Pb zircon data for: Cretaceous plutonic rocks of western Glacier Bay National Park and Preserve
U-Pb data for Origin of Tin Mineralization in the Sullivan Pb-Zn-Ag Deposit, British Columbia: Constraints from Textures, Geochemistry, and LA-ICP-MS U-Pb Geochronology of Cassiterite
U-Pb data for: Monazite and cassiterite U-Pb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian Shield
U-Pb detrital zircon data for: lower Paleozoic sedimentary rocks near Silverton, CO USA
U-Pb data for: U-Pb geochronology of tin deposits associated with the Cornubian Batholith of southwest England: Direct dating of cassiterite by in situ LA-ICPMS
U-Pb data for: In situ LA-ICPMS U-Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to Tertiary
Below are publications associated with this project.
Provenance of Devonian-Carboniferous strata of Colorado: The influence of the Cambrian and the Proterozoic
The Coles Hill uranium deposit, Virginia, USA: Geology, geochemistry, geochronology, and genetic model
Major reorganization of the Snake River modulated by passage of the Yellowstone Hotspot
Pb-Pb and U-Pb dating of cassiterite by in situ LA-ICPMS: Examples spanning ~1.85 Ga to ~100 Ma in Russia and implications for dating Proterozoic to Phanerozoic tin deposits.
Postcaldera intrusive magmatism at the Platoro caldera complex, Southern Rocky Mountain volcanic field, Colorado, USA
Petrology and geochronology of 1.48 to 1.45 Ga igneous rocks in the St. Francois Mountains terrane, southeast Missouri
LA-ICPMS U-Pb dating reveals cassiterite inheritance in the Yazov granite, Eastern Siberia: Implications for tin mineralization
Evidence for a concealed Midcontinent Rift-related northeast Iowa intrusive complex
Monazite and cassiterite Usingle bondPb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian Shield
Geochronologic age constraints on tectonostratigraphic units of the central Virginia Piedmont, USA
New geologic mapping coupled with uranium-lead (U-Pb) zircon geochronology (sensitive high-resolution ion microprobe-reverse geometry [SHRIMP-RG] and laser ablation-inductively coupled plasma-mass spectrometry [LA-ICP-MS]) analyses of 10 samples, provides new constraints on the tectonostratigraphic framework of the central Virginia Piedmont. Detrital zircon analysis confirms that the Silurian-Devo
A new stratigraphic framework and constraints for the position of the Paleocene-Eocene boundary in the rapidly subsiding Hanna Basin, Wyoming
Recognition and significance of Late Devonian fluvial, estuarine, and mixed siliciclastic-carbonate nearshore marine environments in the San Juan Mountains (southwestern Colorado, U.S.A.): Multiple incised valleys backfilled by lowstand and transgressive
- Overview
Project objectives are to (1) develop innovative analytical techniques for isotope geochemistry and U-Pb geochronology using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and (2) apply these techniques to collaborative research projects of high priority to the Mineral Resources Program, including studies related to the formation of "critical mineral" deposits, and studies related to Alaska and U.S. midcontinent regions.
The major instrumentation in the Plasma Lab that is used for U-Pb dating of accessory and ore minerals, and trace element analyses of geological materials by laser ablation ICPMS. (Credit: Kate Souders, USGS. Public domain.) Scientific Issue and Relevance
The Plasma Laboratory houses a new double-focusing multiple-collector plasma ionization mass spectrometer (MC-ICPMS), a Nu Plasma II, and a new 193 nm laser ablation system (RESOlution-SE). This LA-MC-ICPMS is designed to perform in-situ high-precision measurements of radiogenic and stable isotopes of trace elements. The other instrumentation in the Plasma Laboratory includes double-focusing single-collector lasma ionization mass spectrometer (SC-ICPMS), a Nu AttoM ES, and a new Agilent 7900 quadruple (Q) ICPMS. The latter two instruments are primarily used to perform rapid in situ measurements of Pb isotope ratios (i.e., common Pb for tracer studies or radiogenic Pb for U-Pb dating) and trace element abundances.
This project will allow us to (1) develop innovative in-situ analytical techniques for isotope geochemistry and U-Pb geochronology using plasma ionization mass spectrometry and (2) apply our new analytical techniques to collaborative research projects of high priority to the
Mineral Resources Program (MRP), including studies related to the U.S. midcontinent region and Alaska, and/or processes related to the formation of critical mineral deposits.Sources/Usage: Public Domain. Visit Media to see details.Scanning electron microscope (SEM) image of typical laser ablation craters in cassiterite after the LA-ICPMS runs. (Credit: Denver Microbeam Laboratory, USGS. Public domain.) Methods to Address Issue
Our next major tasks are to refine our existing techniques and establish a series of new methods for isotopic and geochronological research using a philosophy of innovation through collaboration.
Innovation: Our goal is to improve the precision and accuracy of each technique to reach or surpass the cutting edge, while increasing efficiency (i.e., reducing the time and cost per analysis). We are following a phased approach of establishing or refining the analytical techniques from the basics (e.g., in situ U-Pb dating of zircon, apatite, titanite, and rutile, Hf isotopes in zircon; Nd isotopes in monazite) to those with higher risk and greater impact (e.g., St isotopes in apatite, feldspars, carbonates, and barite; Pb isotopes in feldspar and tourmaline; Li isotopes in tourmaline; Nd isotopes in bastnaesite or scheelite; Sn isotopes in cassiterite, or in situ U-Pb dating of ore-related minerals, such as bastnaesite, columbite, cassiterite, or scheelite).
Collaboration: The closely related fields of isotope geochemistry and geochronology are the power tools in the Geologist's tool chest. A major goal of this project is to increase the usage of these tools within the USGS through collaboration with other scientists on current and future MRP projects. We will involve USGS scientists in research with isotopes through a series of case studies related to high-priority Mineral Resources Program projects.
Project tasks are focused on the following activities:
- In-situ Isotope analysis of critical mineral isotope systems for geologic applications
- In-situ U-Pb geochronology of ore-forming and ore-related minerals applied to geologic processes
- In-situ U-Pb geochronology and trace element geochemistry of ore minerals and ore-forming processes
Metal-free fume hoods in the Clean Lab. Tera-Wasserburg Concordia diagram for combined cassiterite samples Llallagua and Siglo XX, Llallagua tin deposit, Bolivia. A cathodoluminescence (CL) image of an analyzed crystal fragment is shown as an insert here and in the following figures. Laser spot diameter is 135 μm. (Public domain.) Class-10 drying stations in the Clean Lab, Denver, CO. (Credit: Aaron Pietruszka, USGS. Public domain.) Modular workstations for ion-exchange chromatographic separations of single elements from geological materials in the Clean Lab, Denver, CO. Return to: Mineral Resources Program | Geology, Geophysics, and Geochemistry Science Center
- Science
Below are other science projects associated with this project.
Filter Total Items: 17Analytical Chemistry
The USGS Mineral Resources Program and other USGS scientists need specialized routine analysis in order to conduct their research. The Analytical Chemistry project facilitates the ability of USGS scientists to obtain needed analyses.Uranium Mineral Systems
To assure adequate uranium to supply electricity from nuclear power, the US Geological Survey is working to better understand the genetic controls, distribution, and quantities of domestic uranium. Because of the heavy reliance on imported uranium, scientists also lead international groups of uranium resource experts to monitor world uranium supply. This research benefits the mining industry...Geophysics of the Midcontinent Rift Region
The Midcontinent Rift system and surrounding Precambrian rocks are known to host highly significant mineral resources. Our project objectives are to increase understanding of this system through the integration of new and legacy geophysical data with geochemical and borehole data, map the lithology and structure of PreCambrian rocks, and develop an integrated 3D geologic model of the region.Geologic Framework of the Intermountain West
The Geologic Framework of the Intermountain West project was launched with the goal of producing a new digital geologic map database and 3D geologic model of a transect from the Rio Grande rift to the Basin and Range, based on a synthesis of existing geologic maps with new targeted new mapping, subsurface data, and other data sets. This database will integrate disparate map data, resolve...Alaska Earth Mapping Resources Initiative (Earth MRI)
Our objective is to provide a strategic framework for planning, coordination, and execution of the USGS Earth Mapping Resources Initiative (Earth MRI) in Alaska. Earth MRI aims to improve knowledge of the U.S. geologic framework through new geological and geophysical mapping and to identify areas that have the potential to contain undiscovered critical mineral resources.Gulf Coast Geologic Energy Research
The Gulf Coast Geologic Energy Assessments and Research (GEAR) project also conducts research on the properties and processes relevant to the Gulf Coast Jurassic-Cretaceous-Tertiary composite total petroleum system (TPS). This research aims to improve ongoing and future undiscovered, technically recoverable hydrocarbon resources assessments on the onshore and State waters portion of the Gulf Coast...Iron Oxide-Copper-Cobalt-Gold-Rare Earth Element Deposits of Southeast Missouri—From the Ore Deposit Scale to a Global Deposit Model
The project main objectives are to: 1) geologically, characterize the setting and origin of the iron-copper-cobalt-gold-rare earth element deposits, and advance the knowledge of rare earth element and Co potential within iron oxide-copper-gold (IOCG) deposits of southeast Missouri, and 2) geophysically delineate and characterize the subsurface Precambrian geology using existing ground and new...Antimony In and Around the Yellow Pine Deposit, Central Idaho
Project objectives are to document the origin of the Yellow Pine gold-antimony deposit and, by extension, the origin of this deposit type. Our goal is to understand the structural, tectonic, and magmatic setting of the deposit, the character of the ore-transporting fluids, the conditions of ore deposition, and the regional stratigraphic framework and geochemical ore controls of metasedimentary...Mineville, Eastern Adirondacks – Geophysical and Geologic Studies
The USGS is using a set of advanced imaging and analysis tools to study the rocks within the eastern Adirondacks of upstate New York. The goal of these studies is to gain a better understanding of the geology and mineral resources in the area.Macro and Micro Analytical Methods Development
The Macro and Micro Analytical Methods Development Project (MMAMD) provides access to the expertise of highly experienced research scientists and state of the art analytical instrumentation to develop new and unique analytical capabilities to solve complex problems beyond routine analysis.Tectonic and Metallogenic Evolution of the Yukon-Tanana Upland, Alaska
The Yukon-Tanana upland in eastern interior Alaska is a geologically complex block containing deposits of base-metal, platinum-group-element, and gold-silver-copper mineralization. It also hosts numerous mineral systems that are known or suspected to contain critical minerals.Petrology, Tectonic Setting, and Potential for Concentration of Rare Earth Elements (REE) and High Field Strength Elements (HFSE) in the High-K Darby and Kachauik Plutons, Seward Peninsula, Alaska
One of the geologic environments that host rare earth and other critical and strategic element deposits are alkaline intrusive rocks. - Data
Below are data releases associated with this project.
U-Pb zircon data for: Upper Triassic and Jurassic sedimentary rocks from Sonora, MX
This laser ablation ICPMS U-Pb zircon data set supports stratigraphic, biostratigraphic and age interpretations of the of the fossil-plant-bearing El Game?o 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) foPb-Pb and U-Pb data of Proterozoic to Phanerozoic cassiterite deposits in Russia
Cassiterite (SnO2), a main ore mineral in tin deposits, was collected by multiple Russian geologists or obtained from museum collections in both the USA and Russia and dated at the U.S. Geological Survey. The dated samples represent four different mining districts spanning the entire country from the village of Pitkaranta in the west (31 degrees E Longitude) to the Merekskoe Deposit in the RussianIn situ U-Pb dating of apatite and rutile from St. Francois Mountains IOA and IOCG deposits, southeast Missouri
Apatite (Ca5(PO4)3(Cl/F/OH)) and rutile (TiO2) samples were collected by the U.S. Geological Survey (USGS) from the iron oxide-apatite-rare earth element (IOA-REE) and iron oxide-copper-gold (IOCG) deposits hosted by the Mesoproterozoic, St. Francois Mountains terrane, southeast Missouri. Samples were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass sU-Pb data for the Coles Hill uranium deposit, Virginia
Apatite [Ca5(PO4)3F], titanite [CaTiSiO5], and rutile [TiO2] samples were collected by the U.S. Geological Survey (USGS) from the Coles Hill uranium deposit, Virginia. The samples (in the form of polished thin sections) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the USGS in Denver, Colorado from August 2017U-Pb data for inherited cassiterite in "Tin Granites", an example from the Yazov Granite, Eastern Siberia
Zircon (ZrSiO4) and cassiterite (SnO2) samples were collected by the U.S. Geological Survey (USGS) from the Yazov Granite, Transbaikalia region, Eastern Siberia, Russia. Samples (in the form of mounted loose grains) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA?ICPMS) system at the USGS in Denver, Colorado from February 2017 tU-Pb zircon data for: Cretaceous plutonic rocks of western Glacier Bay National Park and Preserve
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 GU-Pb data for Origin of Tin Mineralization in the Sullivan Pb-Zn-Ag Deposit, British Columbia: Constraints from Textures, Geochemistry, and LA-ICP-MS U-Pb Geochronology of Cassiterite
Cassiterite (SnO2) samples were collected throughout the underground Sullivan Mine near Kimberley, British Columbia. Samples (in the form of mounted loose grains, polished thin sections, and rock mounts) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the U.S. Geological Survey in Denver, Colorado in February anU-Pb data for: Monazite and cassiterite U-Pb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian Shield
Cassiterite (SnO2) samples were collected from alluvial ore concentrate from the Abu Dabbab Granite in eastern Egypt. Samples (in the form of mounted loose grains) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the U.S. Geological Survey in Denver, Colorado in February 2019. This data release accompanies the puU-Pb detrital zircon data for: lower Paleozoic sedimentary rocks near Silverton, CO USA
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 CamU-Pb data for: U-Pb geochronology of tin deposits associated with the Cornubian Batholith of southwest England: Direct dating of cassiterite by in situ LA-ICPMS
Cassiterite (SnO2) samples were collected throughout Devon and Cornwall Counties in southwest England, United Kingdom. Samples were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the U.S. Geological Survey in Denver, Colorado in February and April 2018. This data release accompanies the publication, 'U-Pb geochronolU-Pb data for: In situ LA-ICPMS U-Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to Tertiary
This dataset accompanies the publication, 'In situ LA-ICPMS U-Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to Tertiary', published in Chemical Geology (https://doi.org/10.1016/j.chemgeo.2018.03.008), which reports a LA-ICPMS analytical procedure for dating cassiterite, a main ore mineral in tin deposit - Publications
Below are publications associated with this project.
Filter Total Items: 21Provenance of Devonian-Carboniferous strata of Colorado: The influence of the Cambrian and the Proterozoic
We report new LA-ICPMS U-Pb detrital zircon ages and sedimentary petrology of silty to sandy limestones and dolostones, as well as calcareous to dolomitic sandstones of the Devonian-Carboniferous (Mississippian) Chaffee Group, as well as detrital zircon ages from the Late Cambrian Sawatch Quartzite and a U-Pb zircon crystallization age on a late Mesoproterozoic (1087.9 13.5 Ma) granitoid of underAuthorsChristopher Holm-Denoma, William A. Matthews, Linda Soar, Mark W. Longman, James W. HagadornThe Coles Hill uranium deposit, Virginia, USA: Geology, geochemistry, geochronology, and genetic model
The Coles Hill uranium deposit with an indicated resource of about 130 million lbs. of U3O8 is the largest unmined uranium deposit in the United States. The deposit is hosted in the Taconian (approximately 480 – 450 Ma) Martinsville igneous complex, which consists of the Ordovician Leatherwood Granite (granodiorite) and Silurian Rich Acres Formation (diorite). The host rock was metamorphosed to orAuthorsSusan M. Hall, J.S. Beard, Christopher J. Potter, R.J. Bodnar, Leonid A. Neymark, James B. Paces, Craig A. Johnson, G.N. Breit, Robert A. Zielinski, G. J. AylorMajor reorganization of the Snake River modulated by passage of the Yellowstone Hotspot
The details and mechanisms for Neogene river reorganization in the U.S. Pacific Northwest and northern Rocky Mountains have been debated for over a century with key implications for how tectonic and volcanic systems modulate topographic development. To evaluate paleo-drainage networks, we produced an expansive data set and provenance analysis of detrital zircon U-Pb ages from Miocene to PleistocenAuthorsLydia M. Staisch, Jim E. O'Connor, Charles M. Cannon, Christopher Holm-Denoma, Paul K. Link, John Lasher, Jeremy A. AlexanderPb-Pb and U-Pb dating of cassiterite by in situ LA-ICPMS: Examples spanning ~1.85 Ga to ~100 Ma in Russia and implications for dating Proterozoic to Phanerozoic tin deposits.
This paper investigates applicability of cassiterite to dating ore deposits in a wide age range. We report in situ LA-ICPMS U-Pb and Pb-Pb dating results (n = 15) of cassiterite from six ore deposits in Russia ranging in age from ~1.85 Ga to 93 Ma. The two oldest deposits dated at ~1.83–1.86 Ga are rare metal Vishnyakovskoe located in the East Sayan pegmatite belt and tin deposits within the TuyukAuthorsLeonid A. Neymark, Anatoly M. Larin, Richard J. MoscatiPostcaldera intrusive magmatism at the Platoro caldera complex, Southern Rocky Mountain volcanic field, Colorado, USA
The Oligocene Platoro caldera complex of the San Juan volcanic locus in Colorado (USA) features numerous exposed plutons both within the caldera and outside its margins, enabling investigation of the timing and evolution of postcaldera magmatism. Intrusion whole-rock geochemistry and phenocryst and/or mineral trace element compositions coupled with new zircon U-Pb geo-chronology and zircon in situAuthorsAmy K. Gilmer, Ren A. Thompson, Peter W. Lipman, Jorge A. Vazquez, Amanda (Kate) SoudersPetrology and geochronology of 1.48 to 1.45 Ga igneous rocks in the St. Francois Mountains terrane, southeast Missouri
The igneous geology of the St. Francois Mountains terrane in southeast Missouri is dominated by the products of 1.48 to 1.45 billion year old volcanic and plutonic magmatism but also includes volumetrically minor, compositionally bimodal contributions added during plutonism between 1.34 and 1.27 billion years ago. The 1.48 to 1.45 billion year old igneous rocks in the St. Francois Mountains terranAuthorsEdward A. du Bray, John N. Aleinikoff, Warren C. Day, Leonid A. Neymark, Seth D. BurgessLA-ICPMS U-Pb dating reveals cassiterite inheritance in the Yazov granite, Eastern Siberia: Implications for tin mineralization
U-Pb dating of cassiterite and zircon from the Yazov granite (Transbaikalia region, Eastern Siberia, Russia) and cassiterite from spatially associated tin mineralization in the Tuyukan ore district in the Tonod uplift was conducted using in situ laser ablation inductively coupled plasma mass spectrometry. These analyses allow comparison of isotopic systematics for both minerals, especially relatedAuthorsLeonid A. Neymark, Christopher S. Holm-Denoma, Anatoly Larin, Richard J. Moscati, Yulia PlotkinaEvidence for a concealed Midcontinent Rift-related northeast Iowa intrusive complex
Large amplitude aeromagnetic and gravity anomalies over a ~9500 km2 area of northeast Iowa and southeast Minnesota have been interpreted to reflect the northeast Iowa intrusive complex (NEIIC), a buried intrusive igneous complex composed of mafic/ultramafic rocks in the Yavapai Province (1.8–1.7 Ga). Hundreds of meters of Paleozoic sedimentary cover and a paucity of basement drilling have preventeAuthorsBenjamin J. Drenth, A. Kate Souders, Klaus J. Schulz, Joshua M. Feinberg, Raymond R. Anderson, Val W. Chandler, William F. Cannon, Ryan ClarkMonazite and cassiterite Usingle bondPb dating of the Abu Dabbab rare-metal granite, Egypt: Late Cryogenian metalliferous granite magmatism in the Arabian-Nubian Shield
The Abu Dabbab rare-metal granite in the Eastern Desert of Egypt is a highly-evolved alkali-feldspar granite with transitional magmatic-hydrothermal features. Extreme geochemical fractionation and the associated significant TaSn resource make the Abu Dabbab intrusion an important feature in the metallogenic evolution of the Arabian-Nubian Shield. UPb dating by laser ablation sector field (SF)-ICPMAuthorsBernd Lehmann, Basem Zoheir, Leonid A. Neymark, Armin Zeh, Ashraf Emam, Abdelhady Radwan, Rongqing Zhang, Richard J. MoscatiGeochronologic age constraints on tectonostratigraphic units of the central Virginia Piedmont, USA
New geologic mapping coupled with uranium-lead (U-Pb) zircon geochronology (sensitive high-resolution ion microprobe-reverse geometry [SHRIMP-RG] and laser ablation-inductively coupled plasma-mass spectrometry [LA-ICP-MS]) analyses of 10 samples, provides new constraints on the tectonostratigraphic framework of the central Virginia Piedmont. Detrital zircon analysis confirms that the Silurian-Devo
AuthorsMark W. Carter, Ryan J. McAleer, Christopher S. Holm-Denoma, David B. Spears, Sean P. Regan, William C. Burton, Nick H. EvansA new stratigraphic framework and constraints for the position of the Paleocene-Eocene boundary in the rapidly subsiding Hanna Basin, Wyoming
The Paleocene–Eocene strata of the rapidly subsiding Hanna Basin give insights in sedimentation patterns and regional paleogeography during the Laramide orogeny and across the climatic event at the Paleocene–Eocene Thermal Maximum (PETM). Abundant coalbeds and carbonaceous shales of the fluvial, paludal, and lacustrine strata of the Hanna Formation offer a different depositional setting than PETMAuthorsMarieke Dechesne, Ellen D Currano, Regan E Dunn, Pennilyn Higgins, Joseph Hartman, Kevin R Chamberlain, Christopher S. Holm-DenomaRecognition and significance of Late Devonian fluvial, estuarine, and mixed siliciclastic-carbonate nearshore marine environments in the San Juan Mountains (southwestern Colorado, U.S.A.): Multiple incised valleys backfilled by lowstand and transgressive
The Upper Devonian Ignacio Formation (as stratigraphically revised) comprises a transgressive, tide-dominated estuarine depositional system in the San Juan Mountains (Colorado, USA). The unit backfills at least three bedrock paleovalleys (10–30 km wide and ≥42 m deep) with a consistent stratigraphy of tidally influenced fluvial, bayhead-delta, central estuarine-basin, mixed tidal-flat, and estuariAuthorsJames E. Evans, Joshua T Maurer, Christopher S. Holm-Denoma