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Articles 61 - 90 of 346
Full-Text Articles in Geophysics and Seismology
Causes, Responses, And Implications Of Anthropogenic Versus Natural Flow Intermittence In River Networks, Kendra E. Kaiser
Causes, Responses, And Implications Of Anthropogenic Versus Natural Flow Intermittence In River Networks, Kendra E. Kaiser
Geosciences Faculty Publications and Presentations
Rivers that do not flow year-round are the predominant type of running waters on Earth. Despite a burgeoning literature on natural flow intermittence (NFI), knowledge about the hydrological causes and ecological effects of human-induced, anthropogenic flow intermittence (AFI) remains limited. NFI and AFI could generate contrasting hydrological and biological responses in rivers because of distinct underlying causes of drying and evolutionary adaptations of their biota. We first review the causes of AFI and show how different anthropogenic drivers alter the timing, frequency and duration of drying, compared with NFI. Second, we evaluate the possible differences in biodiversity responses, ecological functions, …
Uncertainty Of Icesat-2 Atl06- And Atl08-Derived Snow Depths For Glacierized And Vegetated Mountain Regions, Ellyn M. Enderlin, Colten M. Elkin, Madeline Gendreau, H.P. Marshall, Shad O'Neel, Christopher Mcneil, Caitlyn Florentine, Louis Sass
Uncertainty Of Icesat-2 Atl06- And Atl08-Derived Snow Depths For Glacierized And Vegetated Mountain Regions, Ellyn M. Enderlin, Colten M. Elkin, Madeline Gendreau, H.P. Marshall, Shad O'Neel, Christopher Mcneil, Caitlyn Florentine, Louis Sass
Geosciences Faculty Publications and Presentations
Seasonal snow melt dominates the hydrologic budget across a large portion of the globe. Snow accumulation and melt vary over a broad range of spatial scales, preventing accurate extrapolation of sparse in situ observations to watershed scales. The lidar onboard the Ice, Cloud, and land Elevation, Satellite (ICESat-2) was designed for precise mapping of ice sheets and sea ice, and here we assess the feasibility of snow depth-mapping using ICESat-2 data in more complex and rugged mountain landscapes. We explore the utility of ATL08 Land and Vegetation Height and ATL06 Land Ice Height differencing from reference elevation datasets in two …
Predictions And Drivers Of Sub-Reach-Scale Annual Streamflow Permanence For The Upper Missouri River Basin: 1989–2018, Kendra E. Kaiser
Predictions And Drivers Of Sub-Reach-Scale Annual Streamflow Permanence For The Upper Missouri River Basin: 1989–2018, Kendra E. Kaiser
Geosciences Faculty Publications and Presentations
The presence of year-round surface water in streams (i.e., streamflow permanence) is an important factor for identifying aquatic habitat availability, determining the regulatory status of streams, managing land use change, allocating water resources, and designing scientific studies. However, accurate, high resolution, and dynamic prediction of streamflow permanence that accounts for year-to-year variability at a regional extent is a major gap in modeling capability. Herein, we expand and adapt the U.S. Geological Survey (USGS) PRObability of Streamflow PERmanence (PROSPER) model from its original implementation in the Pacific Northwest (PROSPERPNW) to the upper Missouri River basin (PROSPERUM), a …
The Formation Of The 8˚20’ N Seamount Chain, East Pacific Rise, Dorsey Wanless
The Formation Of The 8˚20’ N Seamount Chain, East Pacific Rise, Dorsey Wanless
Geosciences Faculty Publications and Presentations
Near-axis seamounts provide a unique setting to investigate three-dimensional mantle processes associated with the formation of new oceanic crust and lithosphere. Here, we investigate the characteristics and evolution of the 8˚20’N Seamount Chain, a lineament of seamounts that extends ~ 175 km west of the East Pacific Rise (EPR) axis, just north of the fracture zone of the Siqueiros Transform Fault. Shipboard gravity, magnetic, and bathymetric data acquired in 2016 are utilized to constrain models of seamount emplacement and evolution. Geophysical observations indicate that these seamounts formed during four distinct episodes of volcanism coinciding with changes in regional plate motion …
Statistical Analysis Of Aquifer Hydraulic Properties By A Continuous Pumping Tomography Test: Application To The Boise Hydrogeophysical Research Site, Kan Bun Cheng, Gedeon Dagan, Warren Barrash, Michael Cardiff, Avinoam Rabinovich
Statistical Analysis Of Aquifer Hydraulic Properties By A Continuous Pumping Tomography Test: Application To The Boise Hydrogeophysical Research Site, Kan Bun Cheng, Gedeon Dagan, Warren Barrash, Michael Cardiff, Avinoam Rabinovich
Geosciences Faculty Publications and Presentations
Characterizing aquifer heterogeneity is paramount for accurate flow and transport modeling. In this work, we present a new approach for statistical analysis of hydraulic properties in continuous pumping tomography tests of a phreatic aquifer. The method entails determining equivalent hydraulic conductivity (Keq), specific storage (Ss,eq), and specific yield (Sy,eq) at many locations in the field and then calculating statistical moments of the equivalent properties, assuming they are random space variables. Equivalent properties are defined as the ones pertinent to a homogeneous aquifer for which the head time …
Emplacement Of The Franklin Large Igneous Province And Initiation Of The Sturtian Snowball Earth, Mark D. Schmitz
Emplacement Of The Franklin Large Igneous Province And Initiation Of The Sturtian Snowball Earth, Mark D. Schmitz
Geosciences Faculty Publications and Presentations
During the Cryogenian (720 to 635 Ma ago) Snowball Earth glaciations, ice extended to sea level near the equator. The cause of this catastrophic failure of Earth’s thermostat has been unclear, but previous geochronology has suggested a rough coincidence of glacial onset with one of the largest magmatic episodes in the geological record, the Franklin large igneous province. U-Pb geochronology on zircon and baddeleyite from sills associated with the paleo-equatorial Franklin large igneous province in Arctic Canada record rapid emplacement between 719.86 ± 0.21 and 718.61 ± 0.30 Ma ago, 0.9 to 1.6 Ma before the onset of widespread glaciation. …
Infrasonic Gliding Reflects A Rising Magma Column At Mount Etna (Italy), Mariangela Sciotto, Leighton M. Watson, Andrea Cannata, Massimo Cantarero, Emanuela De Beni, Jeffrey B. Johnson
Infrasonic Gliding Reflects A Rising Magma Column At Mount Etna (Italy), Mariangela Sciotto, Leighton M. Watson, Andrea Cannata, Massimo Cantarero, Emanuela De Beni, Jeffrey B. Johnson
Geosciences Faculty Publications and Presentations
Infrasound is increasing applied as a tool to investigate magma dynamics at active volcanoes, especially at open-vent volcanoes, such as Mt. Etna (Italy), which are prodigious sources of infrasound. Harmonic infrasound signals have been used to constrain crater dimensions and track the movement of magma within the shallow plumbing system. This study interprets the remarkable systematic change in monotonic infrasound signals preceding a lava fountaining episode at Mt. Etna on 20 February 2021. We model the changing tones (0.7 to 3 Hz fundamental frequency) as a rise in the magma column from 172 ± 25 m below the crater rim …
Improving Moisture Content Estimation From Field Resistivity Measurements With Subsurface Structure Information, Hang Chen, Qifei Niu
Improving Moisture Content Estimation From Field Resistivity Measurements With Subsurface Structure Information, Hang Chen, Qifei Niu
Geosciences Faculty Publications and Presentations
In Earth sciences, the measurement of soil and rock moisture content is essential in improving our understanding of various hydrologic processes. Recently, the electrical resistivity method has been frequently used to estimate the moisture content in the field. The uncertainty associated with resistivity-estimated moisture content is mainly from two sources: regularized inversion and petrophysical interpretation. In this study, to reduce the uncertainty, we propose (1) to use subsurface structural information from seismic refraction measurements to relax the smoothness-based regularization at structural boundaries and (2) to use structural unit-specific petrophysical relationships to translate resistivity into moisture content. The proposed methods are …
Upper-Plate Structure And Tsunamigenic Faults Near The Kodiak Islands, Alaska, Usa, Marlon D. Ramos, Lee M. Liberty, Peter J. Haeussler, Robert Humphreys
Upper-Plate Structure And Tsunamigenic Faults Near The Kodiak Islands, Alaska, Usa, Marlon D. Ramos, Lee M. Liberty, Peter J. Haeussler, Robert Humphreys
Geosciences Faculty Publications and Presentations
The Kodiak Islands lie near the southern terminus of the 1964 Great Alaska earthquake rupture area and within the Kodiak subduction zone segment. Both local and trans-Pacific tsunamis were generated during this devastating megathrust event, but the local tsunami source region and the causative faults are poorly understood. We provide an updated view of the tsunami and earthquake hazard for the Kodiak Islands region through tsunami modeling and geophysical data analysis. Using seismic and bathymetric data, we characterize a regionally extensive seafloor lineament related to the Kodiak shelf fault zone, with focused uplift along a 50-km-long portion of the newly …
Review Article: Global Monitoring Of Snow Water Equivalent Using High-Frequency Radar Remote Sensing, Hans-Peter Marshall
Review Article: Global Monitoring Of Snow Water Equivalent Using High-Frequency Radar Remote Sensing, Hans-Peter Marshall
Geosciences Faculty Publications and Presentations
Seasonal snow cover is the largest single component of the cryosphere in areal extent, covering an average of 46 × 106 km2 of Earth's surface (31 % of the land area) each year, and is thus an important expression and driver of the Earth's climate. In recent years, Northern Hemisphere spring snow cover has been declining at about the same rate (∼ −13 % per decade) as Arctic summer sea ice. More than one-sixth of the world's population relies on seasonal snowpack and glaciers for a water supply that is likely to decrease this century. Snow is also …
Relative Timing Of Off-Axis Volcanism From Sediment Thickness Estimates On The 8°20’N Seamount Chain, East Pacific Rise, Andrea Fabbrizzi, Ross Parnell-Turner, Patricia M. Gregg, Daniel J. Fornari, Michael R. Perfit, V. Dorsey Wanless, Molly Anderson
Relative Timing Of Off-Axis Volcanism From Sediment Thickness Estimates On The 8°20’N Seamount Chain, East Pacific Rise, Andrea Fabbrizzi, Ross Parnell-Turner, Patricia M. Gregg, Daniel J. Fornari, Michael R. Perfit, V. Dorsey Wanless, Molly Anderson
Geosciences Faculty Publications and Presentations
Volcanic seamount chains on the flanks of mid-ocean ridges record variability in magmatic processes associated with mantle melting over several millions of years. However, the relative timing of magmatism on individual seamounts along a chain can be difficult to estimate without in situ sampling and is further hampered by Ar40/Ar39 dating limitations. The 8°20’N seamount chain extends ∼170 km west from the fast-spreading East Pacific Rise (EPR), north of and parallel to the western Siqueiros fracture zone. Here, we use multibeam bathymetric data to investigate relationships between abyssal hill formation and seamount volcanism, transform fault slip, and …
The Geochemical Evolution Of Santa Cruz Island, Galápagos Archipelago, E. L. Wilson, K. S. Harpp, D. M. Schwartz, R. Van Kirk
The Geochemical Evolution Of Santa Cruz Island, Galápagos Archipelago, E. L. Wilson, K. S. Harpp, D. M. Schwartz, R. Van Kirk
Geosciences Faculty Publications and Presentations
Understanding how ocean island volcanoes evolve provides important insight into the behavior of mantle plumes, how plumes interact with mid-ocean ridges, and potential risks posed to inhabitants as the islands age. In this field-based study of the Galápagos Islands, we use radiogenic isotope ratio, major element, and trace element analysis of >70 new lava samples to document the geochemical evolution of Santa Cruz Island over the past ∼2 million years, as it has been carried away from the plume. Currently, Santa Cruz is a dormant shield volcano in the central archipelago. Previous work indicates that exposed lavas preserve >1 million …
Airborne Snowsar Data At X And Ku Bands Over Boreal Forest, Alpine And Tundra Snow Cover, Hans-Peter Marshall
Airborne Snowsar Data At X And Ku Bands Over Boreal Forest, Alpine And Tundra Snow Cover, Hans-Peter Marshall
Geosciences Faculty Publications and Presentations
The European Space Agency SnowSAR instrument is a side-looking, dual-polarised (VV/VH), X/Ku band synthetic aperture radar (SAR), operable from various sizes of aircraft. Between 2010 and 2013, the instrument was deployed at several sites in Northern Finland, Austrian Alps and northern Canada. The purpose of the airborne campaigns was to measure the backscattering properties of snow-covered terrain to support the development of snow water equivalent retrieval techniques using SAR. SnowSAR was deployed in Sodankylä, Northern Finland, for a single flight mission in March 2011 and 12 missions at two sites (tundra and boreal forest) in the winter of 2011–2012. Over …
Diverse Magmatic Evolutionary Trends Of The Northern Andes Unraveled By Paleocene To Early Eocene Detrital Zircon Geochemistry, James L. Crowley
Diverse Magmatic Evolutionary Trends Of The Northern Andes Unraveled By Paleocene To Early Eocene Detrital Zircon Geochemistry, James L. Crowley
Geosciences Faculty Publications and Presentations
The Paleocene-early Eocene continental magmatic arc (PECMA) in the Northern Andes is an example of arc magmatism following a major collisional event. This arc formed after the arc-continent collision between the Caribbean Plate and the South American continental margin at ca. 72 Ma. We used detrital zircon LA-ICP-MS and CA-ID-TIMS geochronology and geochemistry to complement the limited plutonic record of the PECMA and better characterize the PECMA's magmatic evolution. Zircon geochronology and their respective trace element geochemistry were analyzed from Paleocene-early Eocene strata of the Bogotá Formation in the foreland region. Our results show that after the collision of the …
Nsf Supported Socio-Environmental Research: How Do Crosscutting Programs Affect Research Funding, Publication, And Citation Patterns?, Kendra E. Kaiser, Anna E. Braswell, Megan L. Fork
Nsf Supported Socio-Environmental Research: How Do Crosscutting Programs Affect Research Funding, Publication, And Citation Patterns?, Kendra E. Kaiser, Anna E. Braswell, Megan L. Fork
Geosciences Faculty Publications and Presentations
Recognizing the continued human domination of landscapes across the globe, social-ecological systems (SES) research has proliferated, necessitating interdisciplinary collaborations. Although interdisciplinary research started gaining traction in academic settings close to 50 years ago, formal frameworks for SES research did not develop until the late 1990s. The first National Science Foundation (NSF) funding mechanism specifically for interdisciplinary SES research began in 2001 and the SES-specific Coupled Natural Human (CNH) Systems program began in 2007. We used data on funded NSF projects from 2000 to 2015 to examine how SES research was funded, where the research is published, and the scholarly impact …
Low-Volume Magmatism Linked To Flank Deformation On Isla Santa Cruz, Galápagos Archipelago, Using Cosmogenic 3He Exposure And 40Ar/39Ar Dating Of Fault Scarps And Lavas, D. M. Schwartz, K. Harpp, M. D. Kurz, E. Wilson, R. Van Kirk
Low-Volume Magmatism Linked To Flank Deformation On Isla Santa Cruz, Galápagos Archipelago, Using Cosmogenic 3He Exposure And 40Ar/39Ar Dating Of Fault Scarps And Lavas, D. M. Schwartz, K. Harpp, M. D. Kurz, E. Wilson, R. Van Kirk
Geosciences Faculty Publications and Presentations
Isla Santa Cruz is a volcanic island located in the central Galápagos Archipelago. The island’s northern and southern flanks are deformed by E–W-trending normal faults not observed on the younger Galápagos shields, and Santa Cruz lacks the large summit calderas that characterize those structures. To construct a chronology of volcanism and deformation on Santa Cruz, we employ 40Ar/39Ar geochronology of lavas and 3He exposure dating of fault scarps from across the island. The combination of Ar–Ar dating with in situ-produced cosmogenic exposure age data provides a powerful tool to evaluate fault chronologies. The 40 …
Regolith And Host Rock Influences On Co2 Leakage: Active Source Seismic Profiling Across The Little Grand Wash Fault, Utah, Lee M. Liberty, Jonathan Yelton, Elin Skurtveit, Alvar Braathen, Ivar Midtkandal, James P. Evans
Regolith And Host Rock Influences On Co2 Leakage: Active Source Seismic Profiling Across The Little Grand Wash Fault, Utah, Lee M. Liberty, Jonathan Yelton, Elin Skurtveit, Alvar Braathen, Ivar Midtkandal, James P. Evans
Geosciences Faculty Publications and Presentations
Understanding carbon dioxide (CO2) reservoir to surface migration is crucial to successful carbon capture and sequestration approaches; especially fault/reservoir interactions under injection pressure. Through seismic imaging, we explore regolith and shallow stratigraphy across the Little Grand Wash fault. The presence of natural CO2 seeps, travertine and tufa deposits confirm modern and ancient fault-controlled CO2 leakage. We consider this an analogue for a long-failed sequestration site. We estimate bulk porosity and fracture density for host rock, regolith, and fault zone from petrophysical relationships. When combined with existing geochemical and geological data, we characterize a 60 m wide …
A Classification Framework To Assess Ecological, Biogeochemical, And Hydrologic Synchrony And Asynchrony, Kendra E. Kaiser
A Classification Framework To Assess Ecological, Biogeochemical, And Hydrologic Synchrony And Asynchrony, Kendra E. Kaiser
Geosciences Faculty Publications and Presentations
Ecosystems in the Anthropocene face pressures from multiple, interacting forms of environmental change. These pressures, resulting from land use change, altered hydrologic regimes, and climate change, will likely change the synchrony of ecosystem processes as distinct components of ecosystems are impacted in different ways. However, discipline-specific definitions and ad hoc methods for identifying synchrony and asynchrony have limited broader synthesis of this concept among studies and across disciplines. Drawing on concepts from ecology, hydrology, geomorphology, and biogeochemistry, we offer a unifying definition of synchrony for ecosystem science and propose a classification framework for synchrony and asynchrony of ecosystem processes. This …
A Typology For Characterizing Human Action In Multisector Dynamics Models, Kendra Kaiser
A Typology For Characterizing Human Action In Multisector Dynamics Models, Kendra Kaiser
Geosciences Faculty Publications and Presentations
The role of individual and collective human action is increasingly recognized as a prominent and arguably paramount determinant in shaping the behavior, trajectory, and vulnerability of multisector systems. This human influence operates at multiple scales: from short-term (hourly to daily) to long-term (annually to centennial) timescales, and from the local to the global, pushing systems toward either desirable or undesirable outcomes. However, the effort to represent human systems in multisector models has been fragmented across philosophical, methodological, and disciplinary lines. To cohere insights across diverse modeling approaches, we present a new typology for classifying how human actors are represented in …
Possible Bipolar Global Expression Of The P3 And P4 Glacial Events Of Eastern Australia In The Northern Hemisphere: Marine Diamictites And Glendonites From The Middle To Upper Permian In Southern Verkhoyanie, Siberia, V. I. Davydov
Geosciences Faculty Publications and Presentations
Three intervals of glaciomarine diamictites with extensive glendonites in middle to upper Permian sediments were found in the Kobyume River, southern Verkhoyanie, Russia. The successions are biostratigraphically constrained as middle to upper Permian. The middle Permian diamictite horizons extend over a large area with a lateral distance of >1000 km. The upper Permian diamictites developed only locally. The diamictites are interpreted as glaciomarine sediments containing ice-rafted debris. Two glacial episodes in Siberia temporally correspond to the P3 (middle Permian) and P4 (late Permian) glacial events of eastern Australia, strongly suggesting a global bipolar climate and well-developed climatic belts during the …
Interpreting Sentinel-1 Sar Backscatter Signals Of Snowpack Surface Melt/Freeze, Warming, And Ripening, Through Field Measurements And Physically-Based Snowmodel, Jewell Lund, Richard R. Forster, Elias J. Deeb, Glen E. Liston, S. Mckenzie Skiles, Hans-Peter Marshall
Interpreting Sentinel-1 Sar Backscatter Signals Of Snowpack Surface Melt/Freeze, Warming, And Ripening, Through Field Measurements And Physically-Based Snowmodel, Jewell Lund, Richard R. Forster, Elias J. Deeb, Glen E. Liston, S. Mckenzie Skiles, Hans-Peter Marshall
Geosciences Faculty Publications and Presentations
The transition of a cold winter snowpack to one that is ripe and contributing to runoff is crucial to gauge for water resource management, but is highly variable in space and time. Snow surface melt/freeze cycles, associated with diurnal fluctuations in radiative inputs, are hallmarks of this transition. C-band synthetic aperture radar (SAR) reliably detects meltwater in the snowpack. Sentinel-1 (S1) C-band SAR offers consistent acquisition patterns that allow for diurnal investigations of melting snow. We used over 50 snow pit observations from 2020 in Grand Mesa, Colorado, USA, to track temperature and wetness in the snowpack as a function …
High-Precision Ca-Id-Tims U-Pb Zircon Geochronology Of Felsic Rocks In The Finlayson Lake Vms District, Yukon: Linking Paleozoic Basin-Scale Accumulation Rates To The Occurrence Of Subseafloor Replacement-Style Mineralization, Matthew J. Manor, Stephen J. Piercey, Corey J. Wall, Nikola Denisová
High-Precision Ca-Id-Tims U-Pb Zircon Geochronology Of Felsic Rocks In The Finlayson Lake Vms District, Yukon: Linking Paleozoic Basin-Scale Accumulation Rates To The Occurrence Of Subseafloor Replacement-Style Mineralization, Matthew J. Manor, Stephen J. Piercey, Corey J. Wall, Nikola Denisová
Geosciences Faculty Publications and Presentations
Felsic igneous complexes and associated volcano-sedimentary rocks in continental back-arc environments host large-tonnage and/or high-grade volcanogenic massive sulfide (VMS) deposits. The emplacement mechanisms, style, and preservation of these deposits is thought to be partially dependent on depositional rates of the host lithofacies (i.e., discrete volcanic eruptions) relative to the setting of massive sulfide genesis on the seafloor as mounds and/or via subseafloor replacement of existing strata. The localization and occurrence of subseafloor replacement-style VMS deposits is therefore strongly influenced by the characteristics of the volcano-sedimentary facies in the hosting basin and the rates of their emplacement; the latter are poorly …
Synchronous Retreat Of Southeast Greenland's Peripheral Glaciers, Julia Liu, Ellyn Enderlin, Hans-Peter Marshall, Andre Khalil
Synchronous Retreat Of Southeast Greenland's Peripheral Glaciers, Julia Liu, Ellyn Enderlin, Hans-Peter Marshall, Andre Khalil
Geosciences Faculty Publications and Presentations
Recently, scientific attention has focused on estimating Greenland's dynamic mass loss through changes to flow speeds, thickness, and length on its marine outlet glaciers. For the ice sheet outlet glaciers, dynamic mass loss has been found to be highly sensitive to changes in climate and individual glacier geometry. For the ice-sheet-independent marine glaciers around Greenland's periphery, dynamic mass loss is presently overlooked. Here, we apply an open-source, automated method of measuring glacier length changes using satellite imagery, to produce highly detailed records of length changes for 135 peripheral marine glaciers in southeast Greenland. We find evidence for anomalous retreat across …
The Potential Of Citizen Science Data To Complement Satellite And Airborne Lidar Tree Height Measurements: Lessons From The Globe Program, Josh Enterkine, Brian A. Campbell, Holli Kohl, Nancy F. Glenn, Kristen Weaver, David Overoye, Deanna Danke
The Potential Of Citizen Science Data To Complement Satellite And Airborne Lidar Tree Height Measurements: Lessons From The Globe Program, Josh Enterkine, Brian A. Campbell, Holli Kohl, Nancy F. Glenn, Kristen Weaver, David Overoye, Deanna Danke
Geosciences Faculty Publications and Presentations
The Global Learning and Observations to Benefit the Environment (GLOBE) Program is an international science, citizen science, and education program through which volunteers in participating countries collect environmental data in support of Earth system science. Using the program's software application, GLOBE Observer (GO), volunteers measure tree height and optional tree circumference, which may support the interpretation of NASA and other space-based satellite data such as tree height data from the Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) and Global Ecosystem Dynamics Investigation instrument. This paper describes tree heights data collected through the GO application and identifies sources of error in …
From Soils To Streams: Connecting Terrestrial Carbon Transformation, Chemical Weathering, And Solute Export Across Hydrological Regimes, Alejandro Flores, Katie Murenbeeld
From Soils To Streams: Connecting Terrestrial Carbon Transformation, Chemical Weathering, And Solute Export Across Hydrological Regimes, Alejandro Flores, Katie Murenbeeld
Geosciences Faculty Publications and Presentations
Soil biota generates carbon that exports vertically to the atmosphere (CO2) and transports laterally to streams and rivers (dissolved organic and inorganic carbon, DOC and DIC). These processes, together with chemical weathering, vary with flow paths across hydrological regimes; yet an integrated understanding of these interactive processes is still lacking. Here we ask: How and to what extent do subsurface carbon transformation, chemical weathering, and solute export differ across hydrological and subsurface structure regimes? We address this question using a hillslope reactive transport model calibrated using soil CO2 and water chemistry data from Fitch, a temperate forest …
Effects Of Spatial And Temporal Variability In Surface Water Inputs On Streamflow Generation And Cessation In The Rain–Snow Transition Zone, Ernesto Trujillo
Effects Of Spatial And Temporal Variability In Surface Water Inputs On Streamflow Generation And Cessation In The Rain–Snow Transition Zone, Ernesto Trujillo
Geosciences Faculty Publications and Presentations
Climate change affects precipitation phase, which can propagate into changes in streamflow timing and magnitude. This study examines how the spatial and temporal distribution of rainfall and snowmelt affects discharge in rain–snow transition zones. These zones experience large year-to-year variations in precipitation phase, cover a significant area of mountain catchments globally, and might extend to higher elevations under future climate change. We used observations from 11 weather stations and snow depths measured from one aerial lidar survey to force a spatially distributed snowpack model (iSnobal/Automated Water Supply Model) in a semiarid, 1.8 km2 headwater catchment. We focused on surface …
Reconceptualizing The Hyporheic Zone For Nonperennial Rivers And Streams, Kendra E. Kaiser
Reconceptualizing The Hyporheic Zone For Nonperennial Rivers And Streams, Kendra E. Kaiser
Geosciences Faculty Publications and Presentations
Nonperennial streams dominate global river networks and are increasing in occurrence across space and time. When surface flow ceases or the surface water dries, flow or moisture can be retained in the subsurface sediments of the hyporheic zone, supporting aquatic communities and ecosystem processes. However, hydrological and ecological definitions of the hyporheic zone have been developed in perennial rivers and emphasize the mixing of water and organisms from both the surface stream and groundwater. The adaptation of such definitions to include both humid and dry unsaturated conditions could promote characterization of how hydrological and biogeochemical variability shape ecological communities within …
Final Inversion Of The Midcontinent Rift During The Rigolet Phase Of The Grenvillian Orogeny, Mark D. Schmitz
Final Inversion Of The Midcontinent Rift During The Rigolet Phase Of The Grenvillian Orogeny, Mark D. Schmitz
Geosciences Faculty Publications and Presentations
Despite being a prominent continental-scale feature, the late Mesoproterozoic North American Midcontinent Rift did not result in the break-up of Laurentia, and subsequently underwent structural inversion. The timing of inversion is critical for constraining far-field effects of orogenesis and processes associated with the rift's failure. The Keweenaw fault in northern Michigan (USA) is a major thrust structure associated with rift inversion; it places ca. 1093 Ma rift volcanic rocks atop the post-rift Jacobsville Formation, which is folded in its footwall. Previous detrital zircon (DZ) U-Pb geochronology conducted by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) assigned a ca. 950 Ma maximum …
Volcano Infrasound: Progress And Future Directions, Jacob F. Anderson, Jeffrey B. Johnson
Volcano Infrasound: Progress And Future Directions, Jacob F. Anderson, Jeffrey B. Johnson
Geosciences Faculty Publications and Presentations
Over the past two decades (2000–2020), volcano infrasound (acoustic waves with frequencies less than 20 Hz propagating in the atmosphere) has evolved from an area of academic research to a useful monitoring tool. As a result, infrasound is routinely used by volcano observatories around the world to detect, locate, and characterize volcanic activity. It is particularly useful in confirming subaerial activity and monitoring remote eruptions, and it has shown promise in forecasting paroxysmal activity at open-vent systems. Fundamental research on volcano infrasound is providing substantial new insights on eruption dynamics and volcanic processes and will continue to do so over …
A Robust Age Model For The Cryogenian Pocatello Formation Of Southeastern Idaho (Northwestern Usa) From Tandem In Situ And Isotope Dilution U-Pb Dating Of Volcanic Tuffs And Epiclastic Detrital Zircons, Vincent H. Isakson, Mark D. Schmitz, Carol M. Dehler, Francis A. Macdonald, W. Adolph Yonkee
A Robust Age Model For The Cryogenian Pocatello Formation Of Southeastern Idaho (Northwestern Usa) From Tandem In Situ And Isotope Dilution U-Pb Dating Of Volcanic Tuffs And Epiclastic Detrital Zircons, Vincent H. Isakson, Mark D. Schmitz, Carol M. Dehler, Francis A. Macdonald, W. Adolph Yonkee
Geosciences Faculty Publications and Presentations
Tandem in situ and isotope dilution U-Pb analysis of zircons from pyroclastic volcanic rocks and both glacial and non-glacial sedimentary strata of the Pocatello Formation (Idaho, northwestern USA) provides new age constraints on Cryogenian glaciation in the North American Cordillera. Two dacitic tuffs sampled within glacigenic strata of the lower diamictite interval of the Scout Mountain Member yield high-precision chemical abrasion isotope dilution U-Pb zircon eruption and depositional ages of 696.43 ± 0.21 and 695.17 ± 0.20 Ma. When supplemented by a new high-precision detrital zircon maximum depositional age of ≤ 670 Ma for shoreface and offshore sandstones unconformably overlying …