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Jeremiah Workman

Jeremy Workman is a Geologist with the Geosciences and Environmental Change Science Center

Science and Products

Rippling marine deposits with hammer shown for scale

Sedimentology and Structure Working Group

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

Sedimentology and Structure Working Group

The Sedimentology and Structure Working Group supports the Geologic Framework of the Intermountain West (IMW) Project by conducting geologic mapping and research focused on the structural and sedimentary processes that shaped the Intermountain West region and their implications for resource exploration and tectonic history. This research provides a process-based framework for understanding mineral...
Learn More
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
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

Bedrock geologic map database for the Aztec 1-degree x 2-degree quadrangle, northern New Mexico and southern Colorado Bedrock geologic map database for the Aztec 1-degree x 2-degree quadrangle, northern New Mexico and southern Colorado

This data release presents geologic map data for the bedrock geology of the Aztec 1-degree by 2-degree quadrangle, New Mexico. Geologic mapping incorporates new interpretive contributions and compilation from published geologic map data sources primarily ranging from 1:24,000 to 1:50,000 scale. Much of the geology incorporated from published geologic maps is adjusted based on digital...
By
Geosciences and Environmental Change Science Center

Bedrock geologic map database for the Blanca Peak, Walsenburg, Trinidad, and Alamosa 30' x 60' quadrangles, Colorado Bedrock geologic map database for the Blanca Peak, Walsenburg, Trinidad, and Alamosa 30' x 60' quadrangles, Colorado

This data release presents geologic map data for the bedrock geology of the Blanca Peak, Walsenburg, Trinidad, and Alamosa 30' x 60' quadrangles, Colorado. Geologic mapping incorporates new interpretive contributions and compilation from published geologic map data sources primarily ranging from 1:24,000 to 1:50,000 scale. Much of the geology incorporated from published geologic maps is...
By
Geosciences and Environmental Change Science Center

Bedrock geologic map database for the Durango 1-degree x 2-degree quadrangle, southern Colorado: Contributions to the National Geologic Map (ver. 2.0, June 2024) Bedrock geologic map database for the Durango 1-degree x 2-degree quadrangle, southern Colorado: Contributions to the National Geologic Map (ver. 2.0, June 2024)

This data release presents geologic map data for the bedrock geology of the Durango 1-degree by 2-degree quadrangle. Geologic mapping incorporates new interpretive contributions and compilation from published geologic map data sources primarily ranging from 1:24,000 to 1:50,000 scale. Much of the geology incorporated from published geologic maps is adjusted based on digital elevation...
By
Geosciences and Environmental Change Science Center

Data Release for Geologic Map of the Fort Collins 30' x 60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming Data Release for Geologic Map of the Fort Collins 30' x 60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming

This geologic map provides new and compiled geologic mapping at 1:100,000-scale in the Fort Collins 30' x 60' quadrangle covering the northern Front Range and adjacent areas of Colorado.
By
National Cooperative Geologic Mapping Program, Geosciences and Environmental Change Science Center, Denver Radiogenic Isotope Lab

Geologic map of the Fort Collins 30'×60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming Geologic map of the Fort Collins 30'×60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming

The rocks and landforms of the Fort Collins 30 ′ × 60 ′ 1:100,000-scale U.S. Geological Survey quadrangle reveals a particularly complete record of geologic history in the northern Front Range of Colorado. The Proterozoic basement rocks exposed in the core of the range preserve evidence of Paleoproterozoic marine sedimentation, volcanism, and regional soft-sediment deformation, followed...
By
Energy Resources Program, Mineral Resources Program, National Cooperative Geologic Mapping Program, National Laboratories Program, Science and Decisions Center, Geosciences and Environmental Change Science Center

Geologic map of the Sand Creek Pass quadrangle, Larimer County, Colorado, and Albany County, Wyoming Geologic map of the Sand Creek Pass quadrangle, Larimer County, Colorado, and Albany County, Wyoming

New geologic mapping within the Sand Creek Pass 7.5 minute quadrangle defines geologic relationships within the northern Front Range of Colorado along the Wyoming border approximately 35 km south of Laramie, Wyo. Previous mapping within the quadrangle was limited to regional reconnaissance mapping; Eaton Reservoir 7.5 minute quadrangle to the east (2008), granite of the Rawah batholith...
By
Ecosystems Mission Area, Geosciences and Environmental Change Science Center

Geologic map of the Hidden Hills Ranch Quadrangle, Clark County, Nevada Geologic map of the Hidden Hills Ranch Quadrangle, Clark County, Nevada

The prominent structural feature in the Pahrump Valley is the right-lateral Pahrump-Stewart Valley fault system (PSV) (Anderson and others, 1995b), which is the central segment of the State Line fault system as defined by Blakely and others (1998). The main trace of this fault system, as shown in figure 1A, strikes northwest along the California-Nevada state line through Pahrump and...
By
Geosciences and Environmental Change Science Center

Geologic Map of the Eaton Reservoir Quadrangle, Larimer County, Colorado and Albany County, Wyoming Geologic Map of the Eaton Reservoir Quadrangle, Larimer County, Colorado and Albany County, Wyoming

New geologic mapping of the Eaton Reservoir 7.5' quadrangle defines geologic relationships in the northern Front Range along the Colorado/Wyoming border approximately 35 km south of Laramie, Wyo. Previous mapping within the quadrangle was limited to regional reconnaissance mapping (Tweto, 1979; Camp, 1979; Burch, 1983) and some minor site-specific studies (Carlson and Marsh, 1986; W...
By
Geosciences and Environmental Change Science Center

Geologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California Geologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California

Las Vegas and Pahrump are two of the fastest growing cities in the US, and the shortage of water looms as among the greatest future problems for these cities. These new maps of the Las Vegas 30 x 60-minute quadrangle provide a geologic and geophysical framework and fundamental earth science database needed to address societal issues such as ground water supply and contamination, surface...
By
Geosciences and Environmental Change Science Center

Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California

The Mound Spring quadrangle, the southwestern-most 7.5' quadrangle of the area of the Las Vegas 1:100,000-scale quadrangle, is entirely within the Pahrump Valley, spanning the Nevada/California State line. New geologic mapping of the predominantly Quaternary materials is combined with new studies of gravity and geochronology in this quadrangle. Eleven predominantly fine-grained units are

Seamless Geologic Map Database for the Intermountain West, United States: A foundational dataset for mineral systems analysis Seamless Geologic Map Database for the Intermountain West, United States: A foundational dataset for mineral systems analysis

The Intermountain West has a complex geologic history, resulting in the formation of a diverse array of mineral deposits. Effective mineral exploration requires understanding the spatial and temporal relationships among geologic processes and events, a key focus of the mineral systems approach to exploration. This paper presents the Intermountain West Seamless Geologic Map Database, a...
Authors
Amy K. Gilmer, Kenzie J. Turner, Jeremiah B. Workman, Ren A. Thompson, Theresa Maude Schwartz, Chester A. Ruleman
By
Geosciences and Environmental Change Science Center

Paleogene sedimentary basin development in southern Nevada, USA Paleogene sedimentary basin development in southern Nevada, USA

The cause of the transition from Mesozoic and early Cenozoic crustal shortening to later extension in the western United States is debated. In many parts of the extant Sevier hinterland, now the Basin and Range Province, the sedimentary sections that provide the most direct record of that transition remain poorly studied and lack meaningful age control. In this paper, we present field
Authors
Jens-Erik Lundstern, Theresa Maude Schwartz, Cameron Mark Mercer, Joseph P. Colgan, Jeremiah B. Workman, Leah E. Morgan
By
Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center

The Seamless Integrated Geologic Mapping (SIGMa) extension to the Geologic Map Schema (GeMS) The Seamless Integrated Geologic Mapping (SIGMa) extension to the Geologic Map Schema (GeMS)

Geologic maps are the fundamental building blocks of surface and subsurface three-dimensional geologic framework models of the Earth’s crust. However, as the production and availability of geologic map databases continues to increase, inconsistent data models and the lack of synthesized, national geologic map data at scales appropriate for informed decision making negatively affect the...
Authors
Kenzie J. Turner, Jeremiah B. Workman, Joseph P. Colgan, Amy K. Gilmer, Margaret E. Berry, Samuel Johnstone, Kathleen F. Warrell, Marieke Dechesne, D. Paco VanSistine, Ren A. Thompson, Adam M. Hudson, Kristine L. Zellman, Donald S. Sweetkind, Chester A. Ruleman
By
Geosciences and Environmental Change Science Center

A cosmopolitan late Ediacaran biotic assemblage: new fossils from Nevada and Namibia support a global biostratigraphic link A cosmopolitan late Ediacaran biotic assemblage: new fossils from Nevada and Namibia support a global biostratigraphic link

Owing to the lack of temporally well-constrained Ediacaran fossil localities containing overlapping biotic assemblages, it has remained uncertain if the latest Ediacaran (ca 550–541 Ma) assemblages reflect systematic biological turnover or environmental, taphonomic or biogeographic biases. Here, we report new latest Ediacaran fossil discoveries from the lower member of the Wood Canyon...
Authors
E. F. Smith, L. L. Nelson, S. M. Tweedt, H. Zeng, Jeremiah B. Workman
By
Groundwater and Streamflow Information Program, Geosciences and Environmental Change Science Center

Integration of tectonic, sedimentary, and geohydrologic processes leading to a small-scale extension model for the Mormon Mountains area north of Lake Mead, Lincoln County, Nevada Integration of tectonic, sedimentary, and geohydrologic processes leading to a small-scale extension model for the Mormon Mountains area north of Lake Mead, Lincoln County, Nevada

Scattered remnants of highly diverse stratigraphic sections of Tertiary lacustrine limestone, andesite flows, and 23.8–18.2 Ma regional ash-flow tuffs on the north flank of the Mormon Mountains record previously unrecognized deformation, which we interpret as pre–17 Ma uplift and possibly weak extension on the north flank of a growing dome. Directly to the north of the Mormon dome, 17–14...
Authors
R. Ernest Anderson, Tracey J. Felger, Sharon F. Diehl, William R. Page, Jeremiah B. Workman
By
Geology, Minerals, Energy, and Geophysics Science Center

Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado

This field trip highlights recent research into the Laramide uplift, erosion, and sedimentation on the western side of the northern Colorado Front Range. The Laramide history of the North Park-Middle Park basin (designated the Colorado Headwaters Basin in this paper) is distinctly different from that of the Denver basin on the eastern flank of the range. The Denver basin stratigraphy...
Authors
James C. Cole, James H. Trexler, Patricia H. Cashman, Ian M. Miller, Ralph R. Shroba, Michael A. Cosca, Jeremiah B. Workman
By
Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center

Science and Products

Rippling marine deposits with hammer shown for scale

Sedimentology and Structure Working Group

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

Sedimentology and Structure Working Group

The Sedimentology and Structure Working Group supports the Geologic Framework of the Intermountain West (IMW) Project by conducting geologic mapping and research focused on the structural and sedimentary processes that shaped the Intermountain West region and their implications for resource exploration and tectonic history. This research provides a process-based framework for understanding mineral...
Learn More
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
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

Bedrock geologic map database for the Aztec 1-degree x 2-degree quadrangle, northern New Mexico and southern Colorado Bedrock geologic map database for the Aztec 1-degree x 2-degree quadrangle, northern New Mexico and southern Colorado

This data release presents geologic map data for the bedrock geology of the Aztec 1-degree by 2-degree quadrangle, New Mexico. Geologic mapping incorporates new interpretive contributions and compilation from published geologic map data sources primarily ranging from 1:24,000 to 1:50,000 scale. Much of the geology incorporated from published geologic maps is adjusted based on digital...
By
Geosciences and Environmental Change Science Center

Bedrock geologic map database for the Blanca Peak, Walsenburg, Trinidad, and Alamosa 30' x 60' quadrangles, Colorado Bedrock geologic map database for the Blanca Peak, Walsenburg, Trinidad, and Alamosa 30' x 60' quadrangles, Colorado

This data release presents geologic map data for the bedrock geology of the Blanca Peak, Walsenburg, Trinidad, and Alamosa 30' x 60' quadrangles, Colorado. Geologic mapping incorporates new interpretive contributions and compilation from published geologic map data sources primarily ranging from 1:24,000 to 1:50,000 scale. Much of the geology incorporated from published geologic maps is...
By
Geosciences and Environmental Change Science Center

Bedrock geologic map database for the Durango 1-degree x 2-degree quadrangle, southern Colorado: Contributions to the National Geologic Map (ver. 2.0, June 2024) Bedrock geologic map database for the Durango 1-degree x 2-degree quadrangle, southern Colorado: Contributions to the National Geologic Map (ver. 2.0, June 2024)

This data release presents geologic map data for the bedrock geology of the Durango 1-degree by 2-degree quadrangle. Geologic mapping incorporates new interpretive contributions and compilation from published geologic map data sources primarily ranging from 1:24,000 to 1:50,000 scale. Much of the geology incorporated from published geologic maps is adjusted based on digital elevation...
By
Geosciences and Environmental Change Science Center

Data Release for Geologic Map of the Fort Collins 30' x 60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming Data Release for Geologic Map of the Fort Collins 30' x 60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming

This geologic map provides new and compiled geologic mapping at 1:100,000-scale in the Fort Collins 30' x 60' quadrangle covering the northern Front Range and adjacent areas of Colorado.
By
National Cooperative Geologic Mapping Program, Geosciences and Environmental Change Science Center, Denver Radiogenic Isotope Lab

Geologic map of the Fort Collins 30'×60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming Geologic map of the Fort Collins 30'×60' quadrangle, Larimer and Jackson Counties, Colorado, and Albany and Laramie Counties, Wyoming

The rocks and landforms of the Fort Collins 30 ′ × 60 ′ 1:100,000-scale U.S. Geological Survey quadrangle reveals a particularly complete record of geologic history in the northern Front Range of Colorado. The Proterozoic basement rocks exposed in the core of the range preserve evidence of Paleoproterozoic marine sedimentation, volcanism, and regional soft-sediment deformation, followed...
By
Energy Resources Program, Mineral Resources Program, National Cooperative Geologic Mapping Program, National Laboratories Program, Science and Decisions Center, Geosciences and Environmental Change Science Center

Geologic map of the Sand Creek Pass quadrangle, Larimer County, Colorado, and Albany County, Wyoming Geologic map of the Sand Creek Pass quadrangle, Larimer County, Colorado, and Albany County, Wyoming

New geologic mapping within the Sand Creek Pass 7.5 minute quadrangle defines geologic relationships within the northern Front Range of Colorado along the Wyoming border approximately 35 km south of Laramie, Wyo. Previous mapping within the quadrangle was limited to regional reconnaissance mapping; Eaton Reservoir 7.5 minute quadrangle to the east (2008), granite of the Rawah batholith...
By
Ecosystems Mission Area, Geosciences and Environmental Change Science Center

Geologic map of the Hidden Hills Ranch Quadrangle, Clark County, Nevada Geologic map of the Hidden Hills Ranch Quadrangle, Clark County, Nevada

The prominent structural feature in the Pahrump Valley is the right-lateral Pahrump-Stewart Valley fault system (PSV) (Anderson and others, 1995b), which is the central segment of the State Line fault system as defined by Blakely and others (1998). The main trace of this fault system, as shown in figure 1A, strikes northwest along the California-Nevada state line through Pahrump and...
By
Geosciences and Environmental Change Science Center

Geologic Map of the Eaton Reservoir Quadrangle, Larimer County, Colorado and Albany County, Wyoming Geologic Map of the Eaton Reservoir Quadrangle, Larimer County, Colorado and Albany County, Wyoming

New geologic mapping of the Eaton Reservoir 7.5' quadrangle defines geologic relationships in the northern Front Range along the Colorado/Wyoming border approximately 35 km south of Laramie, Wyo. Previous mapping within the quadrangle was limited to regional reconnaissance mapping (Tweto, 1979; Camp, 1979; Burch, 1983) and some minor site-specific studies (Carlson and Marsh, 1986; W...
By
Geosciences and Environmental Change Science Center

Geologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California Geologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California

Las Vegas and Pahrump are two of the fastest growing cities in the US, and the shortage of water looms as among the greatest future problems for these cities. These new maps of the Las Vegas 30 x 60-minute quadrangle provide a geologic and geophysical framework and fundamental earth science database needed to address societal issues such as ground water supply and contamination, surface...
By
Geosciences and Environmental Change Science Center

Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California

The Mound Spring quadrangle, the southwestern-most 7.5' quadrangle of the area of the Las Vegas 1:100,000-scale quadrangle, is entirely within the Pahrump Valley, spanning the Nevada/California State line. New geologic mapping of the predominantly Quaternary materials is combined with new studies of gravity and geochronology in this quadrangle. Eleven predominantly fine-grained units are

Seamless Geologic Map Database for the Intermountain West, United States: A foundational dataset for mineral systems analysis Seamless Geologic Map Database for the Intermountain West, United States: A foundational dataset for mineral systems analysis

The Intermountain West has a complex geologic history, resulting in the formation of a diverse array of mineral deposits. Effective mineral exploration requires understanding the spatial and temporal relationships among geologic processes and events, a key focus of the mineral systems approach to exploration. This paper presents the Intermountain West Seamless Geologic Map Database, a...
Authors
Amy K. Gilmer, Kenzie J. Turner, Jeremiah B. Workman, Ren A. Thompson, Theresa Maude Schwartz, Chester A. Ruleman
By
Geosciences and Environmental Change Science Center

Paleogene sedimentary basin development in southern Nevada, USA Paleogene sedimentary basin development in southern Nevada, USA

The cause of the transition from Mesozoic and early Cenozoic crustal shortening to later extension in the western United States is debated. In many parts of the extant Sevier hinterland, now the Basin and Range Province, the sedimentary sections that provide the most direct record of that transition remain poorly studied and lack meaningful age control. In this paper, we present field
Authors
Jens-Erik Lundstern, Theresa Maude Schwartz, Cameron Mark Mercer, Joseph P. Colgan, Jeremiah B. Workman, Leah E. Morgan
By
Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center

The Seamless Integrated Geologic Mapping (SIGMa) extension to the Geologic Map Schema (GeMS) The Seamless Integrated Geologic Mapping (SIGMa) extension to the Geologic Map Schema (GeMS)

Geologic maps are the fundamental building blocks of surface and subsurface three-dimensional geologic framework models of the Earth’s crust. However, as the production and availability of geologic map databases continues to increase, inconsistent data models and the lack of synthesized, national geologic map data at scales appropriate for informed decision making negatively affect the...
Authors
Kenzie J. Turner, Jeremiah B. Workman, Joseph P. Colgan, Amy K. Gilmer, Margaret E. Berry, Samuel Johnstone, Kathleen F. Warrell, Marieke Dechesne, D. Paco VanSistine, Ren A. Thompson, Adam M. Hudson, Kristine L. Zellman, Donald S. Sweetkind, Chester A. Ruleman
By
Geosciences and Environmental Change Science Center

A cosmopolitan late Ediacaran biotic assemblage: new fossils from Nevada and Namibia support a global biostratigraphic link A cosmopolitan late Ediacaran biotic assemblage: new fossils from Nevada and Namibia support a global biostratigraphic link

Owing to the lack of temporally well-constrained Ediacaran fossil localities containing overlapping biotic assemblages, it has remained uncertain if the latest Ediacaran (ca 550–541 Ma) assemblages reflect systematic biological turnover or environmental, taphonomic or biogeographic biases. Here, we report new latest Ediacaran fossil discoveries from the lower member of the Wood Canyon...
Authors
E. F. Smith, L. L. Nelson, S. M. Tweedt, H. Zeng, Jeremiah B. Workman
By
Groundwater and Streamflow Information Program, Geosciences and Environmental Change Science Center

Integration of tectonic, sedimentary, and geohydrologic processes leading to a small-scale extension model for the Mormon Mountains area north of Lake Mead, Lincoln County, Nevada Integration of tectonic, sedimentary, and geohydrologic processes leading to a small-scale extension model for the Mormon Mountains area north of Lake Mead, Lincoln County, Nevada

Scattered remnants of highly diverse stratigraphic sections of Tertiary lacustrine limestone, andesite flows, and 23.8–18.2 Ma regional ash-flow tuffs on the north flank of the Mormon Mountains record previously unrecognized deformation, which we interpret as pre–17 Ma uplift and possibly weak extension on the north flank of a growing dome. Directly to the north of the Mormon dome, 17–14...
Authors
R. Ernest Anderson, Tracey J. Felger, Sharon F. Diehl, William R. Page, Jeremiah B. Workman
By
Geology, Minerals, Energy, and Geophysics Science Center

Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado

This field trip highlights recent research into the Laramide uplift, erosion, and sedimentation on the western side of the northern Colorado Front Range. The Laramide history of the North Park-Middle Park basin (designated the Colorado Headwaters Basin in this paper) is distinctly different from that of the Denver basin on the eastern flank of the range. The Denver basin stratigraphy...
Authors
James C. Cole, James H. Trexler, Patricia H. Cashman, Ian M. Miller, Ralph R. Shroba, Michael A. Cosca, Jeremiah B. Workman
By
Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center
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