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Ian Hillenbrand

Ian Hillenbrand is a Geologist with the Geosciences and Environmental Change Science Center

Science and Products

Close up view of metagreywacke

Igneous and Metamorphic Working Group

The Igneous and Metamorphic Working Group supports the Geologic Framework of the Intermountain West (IMW) Project by conducting geologic mapping in igneous terranes and research focused on understanding the magmatic and metamorphic processes that shaped the Intermountain West region and their implications for mineral resource exploration and tectonic history. This research provides a process-based...
By
Geosciences and Environmental Change Science Center
Igneous and Metamorphic Working Group

Igneous and Metamorphic Working Group

The Igneous and Metamorphic Working Group supports the Geologic Framework of the Intermountain West (IMW) Project by conducting geologic mapping in igneous terranes and research focused on understanding the magmatic and metamorphic processes that shaped the Intermountain West region and their implications for mineral resource exploration and tectonic history. This research provides a process-based...
Learn More
Decorative banner image of Color cathodoluminescence (CL) image of zircons

USGS Geochron: A database of USGS geochronological and thermochronological data

The U.S. Geological Survey (USGS) has developed an updated geochronology database (USGS Geochron) to include geochronology summary and analytical data created or funded by the USGS.
By
Geosciences and Environmental Change Science Center
USGS Geochron: A database of USGS geochronological and thermochronological data

USGS Geochron: A database of USGS geochronological and thermochronological data

The U.S. Geological Survey (USGS) has developed an updated geochronology database (USGS Geochron) to include geochronology summary and analytical data created or funded by the USGS.
Learn More
Mt. Ouray, Colorado with aspen colors

Geologic Framework of the Intermountain West

The Geologic Framework of the Intermountain West (IMW) Project conducts 1:24,000- to 1:100,000-scale geologic mapping to support framework geologic investigations. The IMW project is prioritizing development of a seamless, integrated geologic map database in targeted areas of the Intermountain West region of the United States that host substantial mineral, energy, water, and industrial material...
By
Geosciences and Environmental Change Science Center
Geologic Framework of the Intermountain West

Geologic Framework of the Intermountain West

The Geologic Framework of the Intermountain West (IMW) Project conducts 1:24,000- to 1:100,000-scale geologic mapping to support framework geologic investigations. The IMW project is prioritizing development of a seamless, integrated geologic map database in targeted areas of the Intermountain West region of the United States that host substantial mineral, energy, water, and industrial material...
Learn More
NGMDB Icon

The National Geologic Map Database (NGMDB)

The National Geologic Map Database (NGMDB) is a distributed archive of geoscience information for the Nation. It was mandated by the Geologic Mapping Act of 1992 and is cooperatively built and maintained by the USGS and State Geological Surveys. We welcome you to explore the archive, view the maps, and help us to improve this resource.
By
Geology, Energy, and Minerals Mission Area, National Cooperative Geologic Mapping Program
The National Geologic Map Database (NGMDB)

The National Geologic Map Database (NGMDB)

The National Geologic Map Database (NGMDB) is a distributed archive of geoscience information for the Nation. It was mandated by the Geologic Mapping Act of 1992 and is cooperatively built and maintained by the USGS and State Geological Surveys. We welcome you to explore the archive, view the maps, and help us to improve this resource.
Learn More

Data release of isotope geochemistry, mineral chemistry, and geochronology for a Proterozoic paragneiss sampled from drill core from North Dakota Data release of isotope geochemistry, mineral chemistry, and geochronology for a Proterozoic paragneiss sampled from drill core from North Dakota

This U.S. Geological Survey (USGS) data release provides whole rock isotope geochemistry, zircon hafnium isotope geochemistry, feldspar mineral chemistry, and zircon, monazite, and xenotime geochronology for a paragneiss sampled from a drill core from North Dakota. The sample was collected from the 9-11R E-M Larson well in order to constrain the depositional age, provenance, metamorphic...
By
Geology, Minerals, Energy, and Geophysics Science Center

Zircon U-Pb data for Proterozoic rocks in southwestern Colorado and rocks from drill core from Wyoming, Montana, and Nebraska Zircon U-Pb data for Proterozoic rocks in southwestern Colorado and rocks from drill core from Wyoming, Montana, and Nebraska

This U.S. Geological Survey (USGS) data release provides U-Pb zircon data and geochronology for Proterozoic rocks in the Needle Mountains of southwestern Colorado and for Proterozoic rocks sampled from drill cores from Wyoming, Montana, and Nebraska. Samples from the Needle Mountains were collected in order to constrain the polyphase tectonic evolution of the area. Drill core samples are...
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center

Data release of geochemistry and geochronology for Proterozoic rocks in southwestern Colorado and rocks from drill core from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska Data release of geochemistry and geochronology for Proterozoic rocks in southwestern Colorado and rocks from drill core from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska

This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data, mineral chemistry, and monazite and xenotime geochronology for Proterozoic rocks in the Needle Mountains of southwestern Colorado and for Proterozoic rocks sampled from drill cores from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska. Samples from the...
By
Geosciences and Environmental Change Science Center

USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025) USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025)

USGS Geochron is a database of geochronological and thermochronological dates and data. The data set contains published ages, dates, analytical information, sample metadata including location, and source citations. The following analytical techniques are represented in the data set: 40Ar/39Ar, K-Ar, U-Th-Pb, Sm-Nd, Rb-Sr, Lu-Hf, fission track, luminescence, U-series, (U-Th)/He, Re-Os...
By
Community for Data Integration (CDI), Geosciences and Environmental Change Science Center
Filter Total Items: 15

Zircon as a pathfinder to REE mineralization Zircon as a pathfinder to REE mineralization

Carbonatites and alkaline silicate rocks are major primary sources of the rare earth elements (REE) and other critical metals, such as Nb. Despite the economic significance of these rocks, their formation and the processes of REE enrichment are poorly understood. Here, statistical analysis of a global dataset demonstrates that zircon geochemistry is a powerful recorder of REE...
Authors
Ian William Hillenbrand
By
Geosciences and Environmental Change Science Center

Alteration mapping in granitic gneiss using handheld geophysical and geochemical instruments: Implications for iron oxide-apatite and rare earth elements exploration Alteration mapping in granitic gneiss using handheld geophysical and geochemical instruments: Implications for iron oxide-apatite and rare earth elements exploration

The Adirondack Mountains of New York, U.S.A. contain iron oxide-apatite (IOA) mineral deposits with variable concentrations of rare earth elements (REE). The IOA mineral deposits are typically hosted in the Lyon Mountain Granite Gneiss and are spatially correlated with extensive Na metasomatism (albitization) of the surrounding country rocks, although some mineral deposits also occur in...
Authors
Kaitlyn A. Suarez, Michael L. Williams, Gregory J. Walsh, Daniel E. Harlov, Michael J. Jercinovic, Daniel J. Tjapkes, Ian William Hillenbrand
By
Florence Bascom Geoscience Center

Enhancing mineral systems exploration through geochronology, thermochronology, and isotope analysis: USGS Geochron and USGS Isotope databases Enhancing mineral systems exploration through geochronology, thermochronology, and isotope analysis: USGS Geochron and USGS Isotope databases

A mineral systems approach to mineral exploration provides a comprehensive framework for understanding ore deposit formation by examining the geodynamic, magmatic, hydrothermal, and sedimentary processes responsible for mineralization, alteration, and remobilization of economic mineral deposits. Temporal and thermal constraints on ore genesis are crucial for refining mineral system...
Authors
Kelly David Thomson, Ian William Hillenbrand, Amy K. Gilmer, Leah E. Morgan, Zachary T. Engle, Anna T. Miller
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center

Multi-stage crustal thickening, surface uplift, and collision in the western Himalaya-Karakoram-Tibet orogen revealed by chemical mohometry Multi-stage crustal thickening, surface uplift, and collision in the western Himalaya-Karakoram-Tibet orogen revealed by chemical mohometry

The Himalaya-Karakoram-Tibet (HKT) orogen provides an unrivaled opportunity to study the dynamic linkages between deep and surface processes during collisional orogenesis. However, these efforts are hindered by conflicting interpretations on the number and timing of collisional events, and the timing of crustal thickening and associated surface uplift. Here, we resolve this with...
Authors
Ian William Hillenbrand, Victor E. Guevara
By
Geosciences and Environmental Change Science Center

Finding the hidden orogeny – The Proterozoic polymetamorphic history of northern New Mexico Finding the hidden orogeny – The Proterozoic polymetamorphic history of northern New Mexico

Pressure–temperature–time-deformation histories provide key constraints on orogenic processes but can be affected by later overprinting. This is exemplified in the Proterozoic orogenic belts of southwestern Laurentia where competing tectonic models involve either a single progressive Mesoproterozoic event, the Picuris orogeny, or a polyorogenic history that also includes the ~1.65 Ga...
Authors
Ian William Hillenbrand, Michael L Williams, Amy K. Gilmer, Karl E. Karlstrom, Michael J. Jercinovic, Daniel J Young
By
Geosciences and Environmental Change Science Center

Anatectic origin of Mississippian spodumene-bearing pegmatites in western Maine during orogenic plateau collapse Anatectic origin of Mississippian spodumene-bearing pegmatites in western Maine during orogenic plateau collapse

Spodumene pegmatites are an important lithium source, but the processes and tectonic settings in which they form are poorly understood. The Rumford pegmatite district surrounding Plumbago Mountain, western Maine, is host to numerous spodumene pegmatites, including the Plumbago North pegmatite (a world-class spodumene resource). Competing petrogenetic models for these spodumene pegmatites...
Authors
Myles M Felch, Ian William Hillenbrand, J. Dykstra Eusden, Christopher S. Holm-Denoma, Dwight C. Bradley, Amber T.H. Whittaker, Michael J. Jercinovic, Michael L. Williams, Laura Pianowski
By
Geosciences and Environmental Change Science Center

Geochemistry and radiogenic isotopes constrain the mantle source region of the Mountain Pass Intrusive Suite, California Geochemistry and radiogenic isotopes constrain the mantle source region of the Mountain Pass Intrusive Suite, California

The Mountain Pass carbonatite stock is the largest rare earth element (REE) deposit and only active REE mine in the United States. The carbonatite intrusion and spatially associated alkaline silicate intrusions constitute the Mountain Pass Intrusive Suite, which is located within the Mojave Province in California. Both the carbonatite and the alkaline silicate rocks are enriched in large...
Authors
Erin Kay Benson, Kathryn E. Watts, Ian William Hillenbrand
By
Geology, Minerals, Energy, and Geophysics Science Center

Re-evaluating the tectonic affinity of Proterozoic crustal provinces in the Southwest USA: Detrital zircon evidence for a Laurentian source for the Yavapai and Mojave Provinces Re-evaluating the tectonic affinity of Proterozoic crustal provinces in the Southwest USA: Detrital zircon evidence for a Laurentian source for the Yavapai and Mojave Provinces

Models for crustal growth commonly involve the accretion of dominantly juvenile crust to continental margins. However, tracking the provenance and tectonic affinity of dominantly juvenile crustal provinces is challenging. This difficulty is highlighted by uncertainty over whether the Yavapai and Mojave Provinces, part of the >1300-km-wide system of Proterozoic orogens in southwestern...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Wayne R. Premo, Michael L. Williams, Michael J. Jercinovic
By
Geosciences and Environmental Change Science Center

Lead isotopes constrain Precambrian crustal architecture, thermal history, and lithospheric foundering in Laurentia Lead isotopes constrain Precambrian crustal architecture, thermal history, and lithospheric foundering in Laurentia

Laurentia (ancestral North America) records nearly 4 billion years of crustal evolution. Here, a newly compiled continental-scale Pb isotopic database is used to evaluate the Precambrian crustal evolution of Laurentia. Pb model ages yield a 2.7 Ga peak, a 2.5–1.8 Ga minimum and 1.8–0.9 Ga continuum. Pb model ages yield thermochronometric data and track crustal growth via arc-related...
Authors
Ian William Hillenbrand
By
Geosciences and Environmental Change Science Center

Geochemical and geochronologic evidence for a contiguous northeastern Wyoming Province Geochemical and geochronologic evidence for a contiguous northeastern Wyoming Province

The extent and nature of the Wyoming Province, an Archean craton in southwestern Laurentia, are poorly understood due to limited exposure between spatially isolated basement-cored uplifts. This lack of exposure has led to debate about whether the northeastern Wyoming Province is underlain by contiguous Archean crust or Proterozoic rocks and suture zone associated with the Trans-Hudson...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Amanda Souders, Ilya N. Bindeman
By
Geosciences and Environmental Change Science Center

Paleoproterozoic reworking of Archean crust and extreme back-arc metamorphism in the enigmatic southern Trans-Hudson orogen Paleoproterozoic reworking of Archean crust and extreme back-arc metamorphism in the enigmatic southern Trans-Hudson orogen

The crustal evolution of the southernmost ∼2000–1800 Ma Trans-Hudson orogen (THO) is enigmatic due to burial by Phanerozoic sediments. We provide new insights through petrochronologic analysis of a paragneiss drill core sample. Detrital zircon age peaks at 2625, 2340, and 1880 Ma and Hf isotopes suggest Paleoproterozoic arc development proximal to Archean source(s). Phase equilibria...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Michael L. Williams, Amanda Souders, Michael J. Jercinovic, Heather A. Lowers, Jorge A. Vazquez
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center, Denver Microbeam Laboratory

Heterogeneous multi-stage accretionary orogenesis — Evidence from the Gunnison block in the Yavapai Province, southwest USA Heterogeneous multi-stage accretionary orogenesis — Evidence from the Gunnison block in the Yavapai Province, southwest USA

Proterozoic rocks exposed in the southwestern U.S.A. represent one of the best examples of crustal growth by arc-related magmatism and accretionary orogenesis. Within the Southwest the 1.8–1.7 Ga Yavapai Province is widely regarded as a classic example of juvenile arc crust, however 1.8–2.5 Ga inherited zircon and Nd and Hf model ages have been recognized near Gunnison in central...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Michael L. Williams, Karl E. Karlstrom, Amanda Souders, Jorge A. Vazquez, Wayne R. Premo
By
Geosciences and Environmental Change Science Center

Science and Products

Close up view of metagreywacke

Igneous and Metamorphic Working Group

The Igneous and Metamorphic Working Group supports the Geologic Framework of the Intermountain West (IMW) Project by conducting geologic mapping in igneous terranes and research focused on understanding the magmatic and metamorphic processes that shaped the Intermountain West region and their implications for mineral resource exploration and tectonic history. This research provides a process-based...
By
Geosciences and Environmental Change Science Center
Igneous and Metamorphic Working Group

Igneous and Metamorphic Working Group

The Igneous and Metamorphic Working Group supports the Geologic Framework of the Intermountain West (IMW) Project by conducting geologic mapping in igneous terranes and research focused on understanding the magmatic and metamorphic processes that shaped the Intermountain West region and their implications for mineral resource exploration and tectonic history. This research provides a process-based...
Learn More
Decorative banner image of Color cathodoluminescence (CL) image of zircons

USGS Geochron: A database of USGS geochronological and thermochronological data

The U.S. Geological Survey (USGS) has developed an updated geochronology database (USGS Geochron) to include geochronology summary and analytical data created or funded by the USGS.
By
Geosciences and Environmental Change Science Center
USGS Geochron: A database of USGS geochronological and thermochronological data

USGS Geochron: A database of USGS geochronological and thermochronological data

The U.S. Geological Survey (USGS) has developed an updated geochronology database (USGS Geochron) to include geochronology summary and analytical data created or funded by the USGS.
Learn More
Mt. Ouray, Colorado with aspen colors

Geologic Framework of the Intermountain West

The Geologic Framework of the Intermountain West (IMW) Project conducts 1:24,000- to 1:100,000-scale geologic mapping to support framework geologic investigations. The IMW project is prioritizing development of a seamless, integrated geologic map database in targeted areas of the Intermountain West region of the United States that host substantial mineral, energy, water, and industrial material...
By
Geosciences and Environmental Change Science Center
Geologic Framework of the Intermountain West

Geologic Framework of the Intermountain West

The Geologic Framework of the Intermountain West (IMW) Project conducts 1:24,000- to 1:100,000-scale geologic mapping to support framework geologic investigations. The IMW project is prioritizing development of a seamless, integrated geologic map database in targeted areas of the Intermountain West region of the United States that host substantial mineral, energy, water, and industrial material...
Learn More
NGMDB Icon

The National Geologic Map Database (NGMDB)

The National Geologic Map Database (NGMDB) is a distributed archive of geoscience information for the Nation. It was mandated by the Geologic Mapping Act of 1992 and is cooperatively built and maintained by the USGS and State Geological Surveys. We welcome you to explore the archive, view the maps, and help us to improve this resource.
By
Geology, Energy, and Minerals Mission Area, National Cooperative Geologic Mapping Program
The National Geologic Map Database (NGMDB)

The National Geologic Map Database (NGMDB)

The National Geologic Map Database (NGMDB) is a distributed archive of geoscience information for the Nation. It was mandated by the Geologic Mapping Act of 1992 and is cooperatively built and maintained by the USGS and State Geological Surveys. We welcome you to explore the archive, view the maps, and help us to improve this resource.
Learn More

Data release of isotope geochemistry, mineral chemistry, and geochronology for a Proterozoic paragneiss sampled from drill core from North Dakota Data release of isotope geochemistry, mineral chemistry, and geochronology for a Proterozoic paragneiss sampled from drill core from North Dakota

This U.S. Geological Survey (USGS) data release provides whole rock isotope geochemistry, zircon hafnium isotope geochemistry, feldspar mineral chemistry, and zircon, monazite, and xenotime geochronology for a paragneiss sampled from a drill core from North Dakota. The sample was collected from the 9-11R E-M Larson well in order to constrain the depositional age, provenance, metamorphic...
By
Geology, Minerals, Energy, and Geophysics Science Center

Zircon U-Pb data for Proterozoic rocks in southwestern Colorado and rocks from drill core from Wyoming, Montana, and Nebraska Zircon U-Pb data for Proterozoic rocks in southwestern Colorado and rocks from drill core from Wyoming, Montana, and Nebraska

This U.S. Geological Survey (USGS) data release provides U-Pb zircon data and geochronology for Proterozoic rocks in the Needle Mountains of southwestern Colorado and for Proterozoic rocks sampled from drill cores from Wyoming, Montana, and Nebraska. Samples from the Needle Mountains were collected in order to constrain the polyphase tectonic evolution of the area. Drill core samples are...
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center

Data release of geochemistry and geochronology for Proterozoic rocks in southwestern Colorado and rocks from drill core from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska Data release of geochemistry and geochronology for Proterozoic rocks in southwestern Colorado and rocks from drill core from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska

This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data, mineral chemistry, and monazite and xenotime geochronology for Proterozoic rocks in the Needle Mountains of southwestern Colorado and for Proterozoic rocks sampled from drill cores from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska. Samples from the...
By
Geosciences and Environmental Change Science Center

USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025) USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data (ver. 4.0, May 2025)

USGS Geochron is a database of geochronological and thermochronological dates and data. The data set contains published ages, dates, analytical information, sample metadata including location, and source citations. The following analytical techniques are represented in the data set: 40Ar/39Ar, K-Ar, U-Th-Pb, Sm-Nd, Rb-Sr, Lu-Hf, fission track, luminescence, U-series, (U-Th)/He, Re-Os...
By
Community for Data Integration (CDI), Geosciences and Environmental Change Science Center
Filter Total Items: 15

Zircon as a pathfinder to REE mineralization Zircon as a pathfinder to REE mineralization

Carbonatites and alkaline silicate rocks are major primary sources of the rare earth elements (REE) and other critical metals, such as Nb. Despite the economic significance of these rocks, their formation and the processes of REE enrichment are poorly understood. Here, statistical analysis of a global dataset demonstrates that zircon geochemistry is a powerful recorder of REE...
Authors
Ian William Hillenbrand
By
Geosciences and Environmental Change Science Center

Alteration mapping in granitic gneiss using handheld geophysical and geochemical instruments: Implications for iron oxide-apatite and rare earth elements exploration Alteration mapping in granitic gneiss using handheld geophysical and geochemical instruments: Implications for iron oxide-apatite and rare earth elements exploration

The Adirondack Mountains of New York, U.S.A. contain iron oxide-apatite (IOA) mineral deposits with variable concentrations of rare earth elements (REE). The IOA mineral deposits are typically hosted in the Lyon Mountain Granite Gneiss and are spatially correlated with extensive Na metasomatism (albitization) of the surrounding country rocks, although some mineral deposits also occur in...
Authors
Kaitlyn A. Suarez, Michael L. Williams, Gregory J. Walsh, Daniel E. Harlov, Michael J. Jercinovic, Daniel J. Tjapkes, Ian William Hillenbrand
By
Florence Bascom Geoscience Center

Enhancing mineral systems exploration through geochronology, thermochronology, and isotope analysis: USGS Geochron and USGS Isotope databases Enhancing mineral systems exploration through geochronology, thermochronology, and isotope analysis: USGS Geochron and USGS Isotope databases

A mineral systems approach to mineral exploration provides a comprehensive framework for understanding ore deposit formation by examining the geodynamic, magmatic, hydrothermal, and sedimentary processes responsible for mineralization, alteration, and remobilization of economic mineral deposits. Temporal and thermal constraints on ore genesis are crucial for refining mineral system...
Authors
Kelly David Thomson, Ian William Hillenbrand, Amy K. Gilmer, Leah E. Morgan, Zachary T. Engle, Anna T. Miller
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center

Multi-stage crustal thickening, surface uplift, and collision in the western Himalaya-Karakoram-Tibet orogen revealed by chemical mohometry Multi-stage crustal thickening, surface uplift, and collision in the western Himalaya-Karakoram-Tibet orogen revealed by chemical mohometry

The Himalaya-Karakoram-Tibet (HKT) orogen provides an unrivaled opportunity to study the dynamic linkages between deep and surface processes during collisional orogenesis. However, these efforts are hindered by conflicting interpretations on the number and timing of collisional events, and the timing of crustal thickening and associated surface uplift. Here, we resolve this with...
Authors
Ian William Hillenbrand, Victor E. Guevara
By
Geosciences and Environmental Change Science Center

Finding the hidden orogeny – The Proterozoic polymetamorphic history of northern New Mexico Finding the hidden orogeny – The Proterozoic polymetamorphic history of northern New Mexico

Pressure–temperature–time-deformation histories provide key constraints on orogenic processes but can be affected by later overprinting. This is exemplified in the Proterozoic orogenic belts of southwestern Laurentia where competing tectonic models involve either a single progressive Mesoproterozoic event, the Picuris orogeny, or a polyorogenic history that also includes the ~1.65 Ga...
Authors
Ian William Hillenbrand, Michael L Williams, Amy K. Gilmer, Karl E. Karlstrom, Michael J. Jercinovic, Daniel J Young
By
Geosciences and Environmental Change Science Center

Anatectic origin of Mississippian spodumene-bearing pegmatites in western Maine during orogenic plateau collapse Anatectic origin of Mississippian spodumene-bearing pegmatites in western Maine during orogenic plateau collapse

Spodumene pegmatites are an important lithium source, but the processes and tectonic settings in which they form are poorly understood. The Rumford pegmatite district surrounding Plumbago Mountain, western Maine, is host to numerous spodumene pegmatites, including the Plumbago North pegmatite (a world-class spodumene resource). Competing petrogenetic models for these spodumene pegmatites...
Authors
Myles M Felch, Ian William Hillenbrand, J. Dykstra Eusden, Christopher S. Holm-Denoma, Dwight C. Bradley, Amber T.H. Whittaker, Michael J. Jercinovic, Michael L. Williams, Laura Pianowski
By
Geosciences and Environmental Change Science Center

Geochemistry and radiogenic isotopes constrain the mantle source region of the Mountain Pass Intrusive Suite, California Geochemistry and radiogenic isotopes constrain the mantle source region of the Mountain Pass Intrusive Suite, California

The Mountain Pass carbonatite stock is the largest rare earth element (REE) deposit and only active REE mine in the United States. The carbonatite intrusion and spatially associated alkaline silicate intrusions constitute the Mountain Pass Intrusive Suite, which is located within the Mojave Province in California. Both the carbonatite and the alkaline silicate rocks are enriched in large...
Authors
Erin Kay Benson, Kathryn E. Watts, Ian William Hillenbrand
By
Geology, Minerals, Energy, and Geophysics Science Center

Re-evaluating the tectonic affinity of Proterozoic crustal provinces in the Southwest USA: Detrital zircon evidence for a Laurentian source for the Yavapai and Mojave Provinces Re-evaluating the tectonic affinity of Proterozoic crustal provinces in the Southwest USA: Detrital zircon evidence for a Laurentian source for the Yavapai and Mojave Provinces

Models for crustal growth commonly involve the accretion of dominantly juvenile crust to continental margins. However, tracking the provenance and tectonic affinity of dominantly juvenile crustal provinces is challenging. This difficulty is highlighted by uncertainty over whether the Yavapai and Mojave Provinces, part of the >1300-km-wide system of Proterozoic orogens in southwestern...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Wayne R. Premo, Michael L. Williams, Michael J. Jercinovic
By
Geosciences and Environmental Change Science Center

Lead isotopes constrain Precambrian crustal architecture, thermal history, and lithospheric foundering in Laurentia Lead isotopes constrain Precambrian crustal architecture, thermal history, and lithospheric foundering in Laurentia

Laurentia (ancestral North America) records nearly 4 billion years of crustal evolution. Here, a newly compiled continental-scale Pb isotopic database is used to evaluate the Precambrian crustal evolution of Laurentia. Pb model ages yield a 2.7 Ga peak, a 2.5–1.8 Ga minimum and 1.8–0.9 Ga continuum. Pb model ages yield thermochronometric data and track crustal growth via arc-related...
Authors
Ian William Hillenbrand
By
Geosciences and Environmental Change Science Center

Geochemical and geochronologic evidence for a contiguous northeastern Wyoming Province Geochemical and geochronologic evidence for a contiguous northeastern Wyoming Province

The extent and nature of the Wyoming Province, an Archean craton in southwestern Laurentia, are poorly understood due to limited exposure between spatially isolated basement-cored uplifts. This lack of exposure has led to debate about whether the northeastern Wyoming Province is underlain by contiguous Archean crust or Proterozoic rocks and suture zone associated with the Trans-Hudson...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Amanda Souders, Ilya N. Bindeman
By
Geosciences and Environmental Change Science Center

Paleoproterozoic reworking of Archean crust and extreme back-arc metamorphism in the enigmatic southern Trans-Hudson orogen Paleoproterozoic reworking of Archean crust and extreme back-arc metamorphism in the enigmatic southern Trans-Hudson orogen

The crustal evolution of the southernmost ∼2000–1800 Ma Trans-Hudson orogen (THO) is enigmatic due to burial by Phanerozoic sediments. We provide new insights through petrochronologic analysis of a paragneiss drill core sample. Detrital zircon age peaks at 2625, 2340, and 1880 Ma and Hf isotopes suggest Paleoproterozoic arc development proximal to Archean source(s). Phase equilibria...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Michael L. Williams, Amanda Souders, Michael J. Jercinovic, Heather A. Lowers, Jorge A. Vazquez
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center, Denver Microbeam Laboratory

Heterogeneous multi-stage accretionary orogenesis — Evidence from the Gunnison block in the Yavapai Province, southwest USA Heterogeneous multi-stage accretionary orogenesis — Evidence from the Gunnison block in the Yavapai Province, southwest USA

Proterozoic rocks exposed in the southwestern U.S.A. represent one of the best examples of crustal growth by arc-related magmatism and accretionary orogenesis. Within the Southwest the 1.8–1.7 Ga Yavapai Province is widely regarded as a classic example of juvenile arc crust, however 1.8–2.5 Ga inherited zircon and Nd and Hf model ages have been recognized near Gunnison in central...
Authors
Ian William Hillenbrand, Amy K. Gilmer, Michael L. Williams, Karl E. Karlstrom, Amanda Souders, Jorge A. Vazquez, Wayne R. Premo
By
Geosciences and Environmental Change Science Center
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