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Articles 6751 - 6780 of 29939

Full-Text Articles in Geology

Mgrre_Thinsections_Mgrre-122_14, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-122_14, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-123_1, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-123_1, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Moc-15_2, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_2, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Moc-15_10, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_10, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Moc-15_14, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_14, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Moc-15_18, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_18, Mgrre

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No abstract provided.


Mgrre_Thinsections_Moc-15_24, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_24, Mgrre

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No abstract provided.


Mgrre_Thinsections_Moc-15_25, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_25, Mgrre

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No abstract provided.


Mgrre_Thinsections_Moc-15_29, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_29, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-83_10, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-83_10, Mgrre

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No abstract provided.


Mgrre_Thinsections_Moc-15_12, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_12, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-86_9, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-86_9, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-122_1, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-122_1, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-122_10, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-122_10, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Moc-15_20, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_20, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-83_6, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-83_6, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-84_11, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-84_11, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-85_20, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-85_20, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-122_13, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-122_13, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-124_3, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-124_3, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-124_18, Mgrre Feb 2022

Mgrre_Thinsections_Mgrre-124_18, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Moc-15_13, Mgrre Feb 2022

Mgrre_Thinsections_Moc-15_13, Mgrre

Thin Sections

No abstract provided.


Fluids And Melts At The Magmatic-Hydrothermal Transition, Recorded By Unidirectional Solidification Textures At Saginaw Hill, Arizona, Usa, Wyatt M. Bain, Pilar Lecumberri-Sanchez, Erin E. Marsh, Matthew Steele-Macinnis Feb 2022

Fluids And Melts At The Magmatic-Hydrothermal Transition, Recorded By Unidirectional Solidification Textures At Saginaw Hill, Arizona, Usa, Wyatt M. Bain, Pilar Lecumberri-Sanchez, Erin E. Marsh, Matthew Steele-Macinnis

United States Geological Survey: Staff Publications

Fluid exsolution and melt evolution at the magmatic-hydrothermal transition are critical processes driving the metal enrichment of porphyry systems. Coeval fluid and melt inclusion assemblages in unidirectional solidification textures (USTs) at Saginaw Hill—a small, porphyry Cu system in southwestern Arizona—record a dynamic and repetitious process of fluid accumulation and release. The cores of quartz crystals throughout the UST bands host coeval silicate melt and brine inclusions but lack vapor-rich inclusions. This could indicate preferential expulsion of vapor and trapping of high-density brine during episodes of fracturing or the direct exsolution of single-phase high-salinity brine from the silicate melt. In contrast, …


The Castle Rock And Ironside Mountain Calderas, Eastern Oregon, Usa: Adjacent Venting Sites Of Two Dinner Creek Tuff Units—The Most Widespread Tuffs Associated With Columbia River Flood Basalt Volcanism, Matthew Cruz, Martin J. Streck Feb 2022

The Castle Rock And Ironside Mountain Calderas, Eastern Oregon, Usa: Adjacent Venting Sites Of Two Dinner Creek Tuff Units—The Most Widespread Tuffs Associated With Columbia River Flood Basalt Volcanism, Matthew Cruz, Martin J. Streck

Geology Faculty Publications and Presentations

The Dinner Creek Tuff is an important unit of mid-Miocene rhyolite volcanism contemporaneous to flood basalts of the Columbia River magmatic province. Field mapping along with analytical data of tuff samples identify two calderas, the Castle Rock and Ironside Mountain calderas, as the venting sites of two widespread ignimbrites of the Dinner Creek Tuff. Both calderas lie within the area of the proposed general storage sites of main-phase Columbia River Basalt magmas. The Castle Rock caldera formed during the eruption of the 16.16 Ma Dinner Creek Tuff unit 1. The northwestern boundary of the caldera is roughly defined by the …


Automatic Segmentation Of Sinkholes Using A Convolutional Neural Network, Muhammad Usman Rafique, Junfeng Zhu, Nathan Jacobs Feb 2022

Automatic Segmentation Of Sinkholes Using A Convolutional Neural Network, Muhammad Usman Rafique, Junfeng Zhu, Nathan Jacobs

Faculty, Staff, and Affiliated Publications--KGS

Sinkholes are the most abundant surface features in karst areas worldwide. Understanding sinkhole occurrences and characteristics is critical for studying karst aquifers and mitigating sinkhole-related hazards. Most sinkholes appear on the land surface as depressions or cover collapses and are commonly mapped from elevation data, such as digital elevation models (DEMs). Existing methods for identifying sinkholes from DEMs often require two steps: locating surface depressions and separating sinkholes from non-sinkhole depressions. In this study, we explored deep learning to directly identify sinkholes from DEM data and aerial imagery. A key contribution of our study is an evaluation of various ways …


The Shepherd Mountain Iron Ore Deposit In Southeast Missouri, Usa -- An Extension Of The Pilot Knob Magmatic-Hydrothermal Ore System: Evidence From Iron Oxide Chemistry, Bolorchimeg N. Tunnell, Marek Locmelis, Cheryl Seeger, Marilena Moroni, Sarah Dare, Ryan Mathur, Brandon Sullivan Feb 2022

The Shepherd Mountain Iron Ore Deposit In Southeast Missouri, Usa -- An Extension Of The Pilot Knob Magmatic-Hydrothermal Ore System: Evidence From Iron Oxide Chemistry, Bolorchimeg N. Tunnell, Marek Locmelis, Cheryl Seeger, Marilena Moroni, Sarah Dare, Ryan Mathur, Brandon Sullivan

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Southeast Missouri Iron Metallogenic Province in the Midcontinent USA contains seven major and several minor IOA/IOCG-type deposits and a series of shallow vein-type deposits/prospects, all of which are spatially and temporally associated with early Mesoproterozoic (1500–1440 Ma) magmatism in the St. Francois Mountains terrane. One of the vein-type deposits is the Shepherd Mountain deposit, which consists of two northeast-trending ore veins dominated by magnetite and lesser amounts of hematite. Here we report the findings of a study that investigates the origin of the Shepherd Mountain deposit and a possible genetic link to the nearby (i.e., < 5 km away) magmatic to magmatic-hydrothermal Pilot Knob ore system that comprises the massive-to-disseminated Pilot Knob Magnetite deposit and the overlying bedded and brecciated Pilot Knob Hematite deposit. Petrographic observations, whole-rock data and the trace element and Fe isotope composition of magnetite and hematite show that the Shepherd Mountain deposit formed from at least five pulses of magmatic-hydrothermal fluids with different compositions and physicochemical parameters. Integration of the data for the Shepherd Mountain deposit with new and published data from the Pilot Knob Magnetite and Pilot Knob Hematite deposits shows that the three deposits are genetically linked through two local faults. The Ironton and Pilot Knob faults provided fluid pathways that connected the Pilot Knob Magnetite deposit to the shallower Shepherd Mountain and Pilot Knob Hematite deposits. Consequently, we argue that the Shepherd Mountain and Pilot Knob Hematite deposits are near-surface extensions of the same magmatic to hydrothermal plumbing system that formed the Pilot Knob Magnetite deposit at depth.


The Role Of Slow Slip Events In The Cascadia Subduction Zone Earthquake Cycle, Juliette P. Saux, Elias G. Molitors Bergman, Eileen L. Evans, John P. Loveless Feb 2022

The Role Of Slow Slip Events In The Cascadia Subduction Zone Earthquake Cycle, Juliette P. Saux, Elias G. Molitors Bergman, Eileen L. Evans, John P. Loveless

Geosciences: Faculty Publications

Slow slip events (SSEs) detected on the Cascadia Subduction Zone interface at 30–50 km depth imply a release of accumulated strain. However, studies of interseismic deformation in Cascadia typically find coupling on the upper 30 km of the interface, which is generally accepted as defining the seismogenic zone. Estimates of coupling using net interseismic velocities (including SSE effects) and restricting coupling to the shallow interface may underestimate slip deficit accumulation at depths >30 km. Here, we detect reversals in GPS motion as indications of SSEs, then use SSE displacements to estimate cumulative slow slip from 2007 to 2021. We calculate …


Geologic Homogenization, Conditioning, & Reuse, University Of North Dakota. Energy And Environmental Research Center Feb 2022

Geologic Homogenization, Conditioning, & Reuse, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet about the Energy & Environmental Research Center project to evaluate the geologic homogenization, conditioning, and reuse (GHCR) concept of water management. Describes the GHCR concept and summarizes results of the multiyear project.


Mgrre_Thinsections_Mgrre-81_7, Mgrre Jan 2022

Mgrre_Thinsections_Mgrre-81_7, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-82_1, Mgrre Jan 2022

Mgrre_Thinsections_Mgrre-82_1, Mgrre

Thin Sections

No abstract provided.