Physical Sciences and Mathematics Commons^™

Energy‐Constrained Open‐System Magmatic Processes 3. Energy‐Constrained Recharge, Assimilation, And Fractional Crystallization (Ec‐Rafc), Frank J. Spera, Wendy A. Bohrson

All Faculty Scholarship for the College of the Sciences

Geochemical data for igneous rock suites provide conclusive evidence for the occurrence of open‐system processes within thermally and compositionally evolving magma bodies. The most significant processes include magma Recharge (with possible enclave formation and magma mixing), Assimilation of anatectic melt derived from wallrock partial melting and formation of cumulates by Fractional Crystallization (RAFC). In this study, we extend the Energetically Constrained Assimilation and Fractional Crystallization (EC‐AFC) model [Spera and Bohrson, 2001; Bohrson and Spera, 2001] to include the addition of compositionally and thermally distinct recharge melt during simultaneous assimilation and fractional crystallization. Energy‐Constrained Recharge, Assimilation, and Fractional …

Rapid Postseismic Transients In Subduction Zones From Continuous Gps, Timothy I. Melbourne, Frank H. Webb, Joann M. Stock, Christoph Reigber

All Faculty Scholarship for the College of the Sciences

Continuous GPS time series from three of four recently measured, large subduction earthquakes document triggered rapid postseismic fault creep, representing an additional moment release upward of 25% over the weeks following their main shocks. Data from two M_w = 8.0 and M_w = 8.4 events constrain the postseismic centroids to lie down dip from the lower limit of coseismic faulting, and show that afterslip along the primary coseismic asperities is significantly less important than triggered deep creep. Time series for another M_w = 7.7 event show 30% postseismic energy release, but here we cannot differentiate between afterslip …

Seismic Cycle And Rheological Effects On Estimation Of Present-Day Slip Rates For The Agua Blanca And San Miguel-Vallecitos Faults, Northern Baja California, Mexico, Timothy H. Dixon, Julien Decaix, Fred Farina, Kevin Furlong, Rocco Malservisi, Richard Bennett, Francisco Suarez-Vidal, John Fletcher, Jeffrey Lee

All Faculty Scholarship for the College of the Sciences

Geodesy can be used to infer long-term fault slip rates, assuming a model for crust and upper mantle rheology. We examine the sensitivity of fault slip rate estimates to assumed rheology for the Agua Blanca and San Miguel-Vallecitos faults in northern Baja California, Mexico, part of the Pacific–North America plate boundary zone. The Agua Blanca fault is seismically quiet, but offset alluvial fans indicate young activity. Current seismicity is confined to the nearby San Miguel-Vallecitos fault, a small offset fault better aligned with plate motion. GPS measurements between 1993 and 1998 suggest that both faults are active, with a combined …

Late Quaternary Slip Rates Across The Central Tien Shan, Kyrgyzstan, Central Asia, Stephen C. Thompson, Ray J. Weldon, Charles M. Rubin, Kanatbek Abdrakhmatov, Peter Molnar, Glenn W. Berger

All Faculty Scholarship for the College of the Sciences

Slip rates across active faults and folds show that late Quaternary faulting is distributed across the central Tien Shan, not concentrated at its margins. Nearly every intermontane basin contains Neogene and Quaternary syntectonic strata deformed by Holocene north‐south shortening on thrust or reverse faults. In a region that spans two thirds of the north‐south width of the central Tien Shan, slip rates on eight faults in five basins range from ∼0.1 to ∼3 mm/yr. Fault slip rates are derived from faulted and folded river terraces and from trenches. Radiocarbon, optically stimulated luminescence, and thermoluminescence ages limit ages of terraces and …

Field Trip Guide (For The Nebraska Well Drillers Association) Central Nebraska Geology, James W. Goeke, Robert F. Diffendal Jr., Duane A. Eversoll

Conservation and Survey Division

Field trip guide, for the Nebraska Well Drillers Association, covering Central Nebraska Geology from September 2002.

Field Guide To The Geology Of The Harlan County Lake Area, Harlan County, Nebraska, With A History Of Events Leading To Construction Of Harlan County Dam, Robert F. Diffendal Jr., Duane R. Mohlman, R. George Corner, F. Edwin Harvey, K. J. Warren, Scott Summerside, Roger K. Pabian, Duane A. Eversoll

School of Natural Resources: Faculty Publications

The year 2002 will mark the fiftieth anniversary of completion of the Harlan County Dam and Multi-Purpose Reservoir. This seems a good time to write about the history of and reasons for building the dam, the effects of the dam and reservoir on the Republican River valley, and the geologic features seen along the shores of the lake and areas nearby. As many junior authors helped produced this educational circular, they are listed in the table of contents. All other sections were written by the senior author.

Includes July 2016 update: Addendum of photographs showing fault traces on drought-exposed lake …

Karst Aquifers As Atmospheric Carbon Sinks: An Evolving Global Network Of Research Sites, Chris Groves, Joe Meiman, Joel Despain, Liu Zaihua, Daoxin Yuan

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Karst flow systems formed in carbonate rocks have been recognized as a sink for atmospheric carbon that originates as gaseous carbon dioxide and ends up as dissolved aqueous carbon, primarily as bicarbonate. While measurements of the magnitude of the sink associated with carbonate rock dissolution have assumed that half of the dissolved inorganic carbon leaving a given catchment comes from the mineral and half from the atmosphere, consideration of the kinetics of carbonate mineral dissolution in acid solutions suggests that the ratio is enriched in mineral-source carbon to an extent that depends on the geochemical environment of mineral/fluid contact. After …

Karst Aquifers As Atmospheric Carbon Sinks: An Evolving Global Network Of Research Sites, Chris Groves, Joe Meiman, Joel Despain, Liu Zaihua, Daoxin Yuan

Chris Groves

Karst flow systems formed in carbonate rocks have been recognized as a sink for atmospheric carbon that originates as gaseous carbon dioxide and ends up as dissolved aqueous carbon, primarily as bicarbonate. While measurements of the magnitude of the sink associated with carbonate rock dissolution have assumed that half of the dissolved inorganic carbon leaving a given catchment comes from the mineral and half from the atmosphere, consideration of the kinetics of carbonate mineral dissolution in acid solutions suggests that the ratio is enriched in mineral-source carbon to an extent that depends on the geochemical environment of mineral/fluid contact. After …

Medusae Fossae Formation: New Perspectives From Mars Global Surveyor, Bethany Bradley, S. E.H Sakimoto, H. Frey, J. R. Zimbelman

Bethany Bradley

The nature and origin of the Medusae Fossae Formation (MFF) on Mars has been debated since the return of the first Viking images. The MFF's young age, distinctive surface texture, and lack of obvious source have prompted multiple hypotheses for its origin. This study uses data from the Mars Global Surveyor (MGS) mission to examine the MFF at all available scales. We discuss and quantify observations from Mars Orbiter Laser Altimeter (MOLA) topography and Mars Orbiter Camera (MOC) images to better constrain the origin of the MFF. Topographic grid estimates yield a present extent of 2.1 × 106 km2 and …

Relationships Between Stream Geomorphology And Fish Community Structure And Diversity In Maine, Emily Gaenzle

Electronic Theses and Dissertations

Predicting patterns in species distribution and abundance for resource management and conservation is a major focus of applied ecology. The primary objective of this study was to determine if there is a predictable relationship between stream geomorphology and fish community structure, native species richness, and native salmonid abundance in Maine. Specifically, I examined relationships between fish assemblages and geomorphic stream types, as delineated by the Rosgen classification system (Rosgen 1996). Fifty-three stream reaches in Maine were classified, and fish communities within the reaches were characterized using backpack electrofishing. Species richness was lowest in A-type streams (i.e., steep, entrenched, confined), which …

Genesis And Morphology Of Soil Pendants In Quaternary Landforms Of Pahranagat Valley, Nevada, Amy Lynn Brock

UNLV Theses, Dissertations, Professional Papers, and Capstones

Five geomorphic surfaces present in the northern Pahranagat Valley, Lincoln County, Nevada range in age from Early Pleistocene to Recent (Q1-Q5) and vary in clast lithology from dolomite to volcanic tephras. Two chronosequences and 5 lithosequences were compared to evaluate micro and macromorphic characteristics and development of soil pendants. This study presents a new interpretation for soil pendant development. Key features observed in the Pahranagat Valley pendants provide evidence for precipitation at the clast-pendant contact suggesting that newer deposits are not always found at the pendant terminus as other studies have assumed. These features include a void at the clast-pendant …

Field Trip Guide (For The Nebraska Well Drillers Association) Southwestern Nebraska Geology, Duane Eversoll, Jim Goeke

Conservation and Survey Division

No abstract provided.

Structural And Geomorphological Evolution Of Huangshan (Yellow Mountain), Anhui Province, China, Pei-Hua Huang, Robert F. Diffendal Jr., Ming-Qing Yang

School of Natural Resources: Faculty Publications

Huangshan (Yellow Mountain) is an 1864-m granite massif situated at 30° 10′ N and 118° 11′ E, south of the lower reaches of the Yangtze River. The granite formed during the Early Cretaceous and was subsequently uplifted several times along faults. After the initial uplift, about 54 Ma, erosion proceeded to wear away the mountain for the next 30 Ma. By 24 Ma the Bright Summit Peneplain had formed. Renewed uplift in the Miocene along the same fault systems produced a mountain in the same place as the original one. This mountain was eroded to produce a second mature denudational …

Physical And Chemical Heterogeneity In The Subsurface: Spatial Distribution Of Transport Parameters And Their Relation To Depositional Processes, Dana Divine

Conservation and Survey Division

This thesis consists of two parts. The goal of first section is to better understand the influence of heterogeneity on contaminant transport. This objective is approached by quantifying the heterogeneity that may have affected transport of the Stanford-Waterloo tetrachloroethene (PCE) plume. Specifically, I determine the statistical distribution of the PCE sorption distribution coefficient (K_d) at Canadian Forces Base Borden, identify the spatial distribution of K_d, and determine the cross-correlation structure between PCE Kd and permeability (k). The results show that K_d is not lognormally distributed, and that variance is insufficient to …

Transition From Contraction To Extension In The Northeastern Basin And Range: New Evidence From The Copper Mountains, Nevada, Jeffrey M. Rahl, Allen J. Mcgrew, Kenneth A. Foland

Geology Faculty Publications

New mapping, structural analysis, and 40Ar/39Ar dating reveal an unusually well‐constrained history of Late Eocene extension in the Copper Mountains of the northern Basin and Range province. In this area, the northeast‐trending Copper Creek normal fault juxtaposes a distinctive sequence of metacarbonate and granitoid rocks against a footwall of Upper Precambrian to Lower Cambrian quartzite and phyllite. Correlation of the hanging wall with footwall rocks to the northwest provides an approximate piercing point that requires 8–12 km displacement in an ESE direction. This displaced fault slice is itself bounded above by another normal fault (the Meadow Fork Fault), which brings …

The Use Of A Synthetic Binary Solid Solution To Model Igneous Textural Evolution, Elizabeth Scott

Geology Theses and Dissertations

Crystallization experiments using a synthetic igneous analog have shown that grain boundary migration can take place in melt-present environments (Means and Park, 1994). In order to evaluate the importance of metamorphic processes during the textural evolution of a crystal mush, microstructural evidence is needed to link them with final igneous textures. In natural magmatic systems, plagioclase may provide a microstructural link; plagioclase solid solution enables the process of chemical zoning and preserves a record of crystal morphology (and chemistry) during growth. If metamorphic processes are common, they should affect the zoning patterns of plagioclase crystals.
A petrographic stage heater apparatus …

Geomorphology’S Role In The Study Of Weathering Of Cultural Stone, Gregpry A. Pope, Thomas R. Paradise, Thomas Meierding

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Great monumental places—Petra, Giza, Angkor, Stonehenge, Tikal, Macchu Picchu, Rapa Nui, to name a few—are links to our cultural past. They evoke a sense of wonderment for their aesthetic fascination if not for their seeming permanence over both cultural and physical landscapes. However, as with natural landforms, human constructs are subject to weathering and erosion. Indeed, many of our cultural resources suffer from serious deterioration, some natural, some enhanced by human impact. Groups from the United Nations to local civic and tourism assemblies are deeply interested in maintaining and preserving such cultural resources, from simple rock art to great temples. …

Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith

Conservation and Survey Division

No abstract provided.

Creep Critters From Nebraska's Past, Roger K. Pabian

Conservation and Survey Division

No abstract provided.

Surficial Geology And Geomorphology Of The Western Olympus Range, Antarctica: Implications For Ice-Sheet History, Brett Vandenheuvel

Electronic Theses and Dissertations

A widespread erosion surface passes across bedrock and sedimentary deposits in the western Dry Valleys sector of the Transantarctic Mountains (TAM), southern Victoria Land, Antarctica. The surface includes stoss-and-lee slopes, channels, potholes, scoured basins, and corrugated bedrock. These features have been taken to represent subglacial meltwater erosion beneath a greatly expanded East Antarctic Ice Sheet (EAIS) in the mid-Miocene (Denton et al. 1984, Marchant et al. 1993a). Sedimentary deposits that are typically associated with ice-sheet wastage, such as outwash, are not present on the erosion surface. The lack of these deposits indicates that the expanded ice-sheet postulated to be responsible …

Development Of A Circa 2000 Landcover Database For The United States, Collin Homer, Chengquan Huang, Limin Yang, Bruce K. Wylie

Publications of the US Geological Survey

Multi-Resolution Land Characterization 2000 (MRLC 2000) is a second-generation federal consortium to create an updated pool of nation-wide Landsat 7 imagery, and derive a second-generation National Land Cover Database (NLCD 2000). This multi-layer, multisource database will include a suite of 30-meter resolution data that will serve as standardized ingredients for the production of land cover – both nationally and locally. This database will also provide the framework to allow flexibility in developing and applying suites of independent data layers. These nationally standardized independent data layers or components, will be useful not only within the land-cover classification but as data themes …

Derivation Of A Tasseled Cap Transformation Based On Landsat 7 At-Satellite Reflectance, C. Huang, Bruce K. Wylie, Limin Yang, Collin Homer, Gregory Zylstra

Publications of the US Geological Survey

A new tasseled cap transformation based on Landsat 7 at-satellite reflectance was developed. This transformation is most appropriate for regional applications where atmospheric correction is not feasible. The brightness, greenness and wetness of the derived transformation collectively explained over 97% of the spectral variance of the individual scenes used in this study.

Assessment Of Elemental Concentrations In Streams Of The New Lead Belt In Southeastern Missouri, 2002–05, William G. Brumbaugh, Thomas W. May, John M. Besser, Ann L. Allert, Christopher J. Schmitt

Publications of the US Geological Survey

Concerns about possible effects of lead-mining activities on the water quality of federally protected streams located in southeastern Missouri prompted a suite of multidisciplinary studies to be conducted by the U.S. Geological Survey. As part of this investigation, a series of biological studies were initiated in 2001 for streams in the current mining region and the prospecting area. In this report, results are examined for trace elements and other selected chemical measurements in sediment, surface water, and sediment interstitial (pore) water sampled between 2002 and 2005 in association with these biological studies. Compared to reference sites, fine sediments collected downstream …

Field Trip Guide (For The Nebraska Well Drillers Association) Southwestern Nebraska Geology, D. Eversoll

Conservation and Survey Division

No abstract provided.

Morrill County Test Hole Logs, Vernon L. Souders, James B. Swinehart

Conservation and Survey Division

No abstract provided.

Groundwater-Level Changes In Nebraska-Spring 2000 To Spring 2001/Groundwater-Level Changes In Nebraska-Predevelopment To Spring 2001, Conservation Survey Division

Conservation and Survey Division

No abstract provided.

Field Trip Guide (For The Nebraska Well Drillers Association) Central Nebraska Geology, James W. Goeke, Robert F. Diffendal Jr., Duane A. Eversoll

Conservation and Survey Division

Field trip guide for the Nebraska Well Drillers Association covering central Nebraska geology from 2002.

Dune Morphology Response To Water Level Change, Pinery Provincial Park, Ontario, Canada, Michael C.A. Bitton

Theses and Dissertations (Comprehensive)

This thesis describes the geomorphological changes to a trough blowout in Pinery Provincial Park's sand dunes. The Park is located on Lake Huron’s southeastern shore where, due to rapid changes in Lake Huron water levels, a study could be completed examining the changes to blowout morphology based on the change in beach sediment supply. The study took place during relative low Lake Huron levels (1999-2000) and was compared to data collected during a period of relative high Lake Huron levels (1994-1995). Field research included erosion pin measurement to monitor and verify morphological change through the throat of the blowout, aeolian …

Banner County Test Hole Logs, Frank A. Smith

Conservation and Survey Division

No abstract provided.

Strontium Isotopic Signatures Of The Streams And Lakes Of Taylor Valley, Southern Victoria Land, Antarctica: Chemical Weathering In A Polar Climate, W. B. Lyons, Carmen A. Nezat, Larry V. Benson, Thomas D. Bullen, Elizabeth Y. Graham, Jesicca Kidd, Kathleen A. Welch, James M. Thomas

United States Geological Survey: Staff Publications

We have collected and analyzed a series of water samples from three closed-basin lakes (Lakes Bonney, Fryxell, and Hoare) in Taylor Valley, Antarctica, and the streams that flow into them. In all three lakes, the hypolimnetic waters have different ⁸⁷Sr/⁸⁶Sr ratios than the surface waters, with the deep water of Lakes Fryxell and Hoare being less radiogenic than the surface waters. The opposite occurs in Lake Bonney. The Lake Fryxell isotopic ratios are lower than modern-day ocean water and most of the whole-rock ratios of the surrounding geologic materials. A conceivable source of Sr to the system …