Graduate Student Posters

Paleontological, Geochemical, and Petrographic Characterizations of the Late Neoproterozoic Pocatello and Perry Canyon Formations, Northern Utah and Southern Idaho

Robin Nagy — Fri, 12 Apr 2013 14:39:54 PDT

Mid- to Late-Neoproterozoic (ca. 680 - 665 Ma) sedimentary rocks of northern Utah and southern Idaho provide a record of the Earth system during and immediately following “Snowball Earth” glaciations.

Strata in this structurally complex region are not clearly correlated. Although a geochronologic framework is currently emerging, the stratigraphic context of these units is not clear.

What was the nature of the biosphere during this time? What was the state of primary productivity? What did these paleoecosystems look like?

Are there syn-glacial carbonates preserved in this region? What can they tell us about global climate or depositional environment?

How do regional datasets fit into the global picture?

A Glimpse of the Syn- and Post-Glacial Biosphere Recorded in the Late Neoproterozoic Pocatello and Perry Maple Canyon Formations, Southeastern Idaho and Northern Utah, USA

Robin Nagy et al. — Fri, 12 Apr 2013 14:39:53 PDT

Fracture behavior across interfaces in seal lithologies

Elizabeth S. Petrie et al. — Mon, 25 Mar 2013 09:12:00 PDT

Faults and fracture networks at depth are important fluid pathways, especially in fine-grained, low permeability seal lithologies. Discontinues in sealing lithologies can create seal bypass systems, leading to the failure of CO₂ geosequestration sites or hydrocarbon traps. We characterize the occurrence of and changes in discontinuity patterns and the associated changes in elastic moduli across sedimentologic interfaces to document the importance of these discontinuities for fluid management in the subsurface and potential for re-activation in high-pressure injection scenarios. We evaluate well-exposed, fine-grained, low-permeability Mesozoic and Paleozoic units that are seals of potential CO₂ repositories on the Colorado Plateau and show evidence for open fractures and fluid flow in the subsurface. Field observations document changes in fracture distributions across lithologic boundaries allowing us to identify mechano-stratigraphic units and focus on the effect of lithologic interfaces on fracture distribution. An interface marks the boundary between facies in a seal and in this study the fractures are shown to deflect or arrest at the interface. In outcrop fracture intensity varies in from 1 to 18 fractures per meter and fracture apertures range from mm to cm. The mineralized fractures often have associated alteration halos along their boundaries; their general orientation follows that of discontinuities within the underlying reservoir facies or adjacent faults. The recognition of these changes in fracture distribution is important for forward modeling of fluid flow and risk management. Studying the occurrence of and changes in fracture patterns from outcrops and scaling it up for use in modeling at a field scale is difficult due to the lack of direct correlation between outcrop observations and subsurface data. Due to the size and amount of data needed to model fluid flow at the field scale the meso-scale (cm to m) variability of rock properties is often neglected. We evaluate this meso-scale variability in elastic moduli, where possible. We combine mechano-stratigraphic outcrop observations with elastic moduli calculated from publically available wire line log data to evaluate the variability in rock strength within the heterolithic top seal. Relationships between changes in Young’s modulus to resulting fracture distribution can then be observed. The outcome of this analysis can be used for modeling the effectiveness of seal for storage of CO₂ in the underlying reservoirs. Digitized publically available wire line well log data were used to calculate Poisson’s ratio and Young’s modulus over the Carmel Formation and upper most 3 m of the underlying Navajo Sandstone. Our calculations show that Young’s Modulus can range between 15 to 34 GPa across 60 cm of the intra-seal interfaces, and an average difference of 5 GPa across the reservoir seal interface. These variations will affect fracture distributions and fluid behavior in the subsurface. These data provide a means to closely tie outcrop observations to derived estimates of subsurface rock strength. The characterization of rock strength variability is especially important for modeling the response of seals to increased pressure, due to CO₂injection, and will allow for better site screening and fluid management once injection projects are underway.

Use of wire line logs for estimation of strength variability in cap-‐rock lithologies

Elizabeth S. Petrie et al. — Mon, 25 Mar 2013 09:11:59 PDT

The characterization of cap-rock, low permeability and high capillary entry pressure lithologies is important for modeling the response of cap-rocks to increased pressures due to CO2 injection. We evaluate the use of publically available wireline log data to provide empirical estimate of rock strength in order to determine the strength of top seal over a range of scales. This method is being used to characterize cap-rock lithologies in systems proposed for CO2 geosequestration, these data will be combined with outcrop fracture density observations, petrology, lithologic stacking patterns and mineralogy to predict the potential for bypass.

Analysis to date includes wells with monopole and dipole sonic logs for comparison of the relationships established empirically by other workers and used in this study to estimate the dynamic values for Poisson’s Ratio and Young’s Modulus from publically available vintage well log data in Utah. This study focuses specifically on the Jurassic Carmel Formation, which is a cap-rock to the underlying proposed CO2 injection reservoir, the Navajo Sandstone. This study compliments the well data with outcrop characterization of the Carmel Formation, which we split into 3 mechanical units based on lithologic stacking patterns, fracture density, and relationships observed between the percent shale and fracture spacing ratio.

Results obtained from the well log analysis fall within the published ranges for these rock types, however the data show a variability which is being evaluated further to understand if these observations are related to geology or artifacts associated with the wireline data. In future the use of these empirical estimates will provide a lower estimate for subsurface rock strength, as well as provide a means to closely tie outcrop observations to those made from subsurface data.

Grand Canyon as a Universally Accessible Virtual Field Trip for Intro Geoscience Classes Using Geo-Referenced Mobile Game Technology

Natalie Bursztyn et al. — Mon, 25 Mar 2013 09:11:54 PDT

There is a well-documented and nationally reported trend of declining interest, poor preparedness, and lack of diversity within U.S. students pursuing geoscience and other STEM disciplines. We suggest that a primary contributing factor to this problem is that introductory geoscience courses simply fail to inspire (i.e. they are boring). Our experience leads us to believe that the hands-on, contextualized learning of field excursions are often the most impactful component of lower division geoscience classes. However, field trips are becoming increasingly more difficult to run due to logistics and liability, high-enrollments, decreasing financial and administrative support, and exclusivity of the physically disabled. Recent research suggests that virtual field trips can be used to simulate this contextualized physical learning through the use of mobile devices – technology that exists in most students’ hands already. Our overarching goal is to enhance interest in introductory geoscience courses by providing the kinetic and physical learning experience of field trips through geo-referenced educational mobile games and test the hypothesis that these experiences can be effectively simulated through virtual field trips. We are doing this by developing “serious”ù games for mobile devices that deliver introductory geology material in a fun and interactive manner. Our new teaching strategy will enhance undergraduate student learning in the geosciences, be accessible to students of diverse backgrounds and physical abilities, and be easily incorporated into higher education programs and curricula at institutions globally. Our prototype involves students virtually navigating downstream along a scaled down Colorado River through Grand Canyon – physically moving around their campus quad, football field or other real location, using their smart phone or a tablet. As students reach the next designated location, a photo or video in Grand Canyon appears along with a geological question. The students must answer each question correctly in order to proceed to the next location and accrue points in the game and multiple attempts reduce the number of points earned when the correct answer is found. The questions are either multiple choice or involve touch-screen interaction to identify a specific geologic feature. Initial testing of the prototype game in Historical and Physical geology courses at Utah State University indicate that students enjoy the mobile “exploration”ù nature of the game as well as experiencing photographs of geologic features rather than traditional cartoons. Qualitative evaluation using anonymous surveys was conducted to help determine the usability of the game and the potential effectiveness of this technology-based approach. Students were asked about the degree of fun and difficulty of the game, content learned, and their overall response to features they liked/disliked about it. The results of these early assessments are positive, both in regard to the improvement of students’ understanding of key geology concepts and their enjoyment of learning with the technology in a mobile orienteering manner. This is a positive first step in an innovative teaching tool with the power to overcome the pervasive problem of the boring first year STEM course and make world-class field trips accessible to all.

Comparison of Mechanical and Fracture Stratigraphy between Failed Seal Analouges

Elizabeth S. Petrie et al. — Wed, 20 Mar 2013 14:15:25 PDT

A cap rock, or seal, provides a barrier to the migration of fluid or gas out of intended trap due to its low permeability, high capillary-entry pressure nature. The presence of discontinuities in seal lithologies affects both their mechanical and hydrogeologic properties; migration of fluids or gas through mm- to cm-scale discontinuity networks can lead to the failure of hydrocarbon traps or waste repositories. We examine the mechanical and fracture stratigraphy of Paleozoic and Mesozoic analogues of failed seals exposed in central and south-east Utah to understand the nature and distribution of fluid flow pathways in various sealing lithologies. We use outcrop surveys of stratigraphic changes and discontinuity distributions to identify the relationships between depositional composition, diagenesis and loading history, and to describe fluid-flow pathways across four seal types. Each seal type has experienced a varied depositional and tectonic history and all show evidence for fracture propagation and fluid flow at depth. Characterizing the distribution and morphologies of open mode fractures (mode I/II), with changes in lithology (which include depositional and structural variations), provides data for accurate quantitative subsurface geomechanical and fluid flow models.

Use of wireline logs to estimate strength of cap-rock lithologies

Elizabeth S. Petrie et al. — Wed, 20 Mar 2013 14:15:23 PDT

The characterization of rock strength for cap rock, low-permeability and high capillary entry pressure, lithologies is important for modeling their response to increased fluid pressures in CO2 sequestration schemes and other geo-engineering operations such as waste disposal and recovery of fluids from plays with insufficient permeability. We investigate Mesozoic fine-grained sequences to evaluate the nature of sedimentological and structural processes that may control the nature of brittle deformation observed in these sequences. To characterize these fine-grained sequences we use a combination of data obtained from outcrop, including fracture orientation and density, lithologic stacking patterns, grain-size distributions and mineralogy to predict the potential for fluid bypass. In addition we also use publically available wireline log data to estimate the rock strength of these units in the subsurface. Outcrop observations of the mixed silisiclastic carbonate sequence of the Carmel Formation shows vertically continuous fractures crossing lithologic boundaries and analysis of scan-line and fracture orientation data indicate three discontinuity sets. Sets one and two are a conjugate pair of non-mineralized discontinuities which include faults and fractures, with a mean orientations of 323°/78° and 100°/76° respectively and discontinuity spacing ranging between 0.2-0.4 per meter. Set three is a near vertical, mineralized fracture set which is cross-cut by fractures of set one and two, with a mean orientation 31°/80 and a fracture spacing of 0.2 fractures per meter. Use of publically available wireline log data allows us to estimate rock strength over larger scales than those provided by the local outcrops. The wells selected for analysis are located within a 15-km radius from the outcrop location. Gamma ray, sonic, and density logs from 7 wells were digitized from scanned originals. The inverse of the sonic log data was taken to obtain a velocity value (Vp), no dipole sonic logs are available therefore shear velocity was calculated using empirical relationships established by other workers. Having both compression and shear velocity as well as bulk density values we are able to empirically determine Poisson’s Ratio and Young’s Modulus. Poisson’s Ratio values for these wells ranges between 0.18-0.48, and Young’s Modulus results range from 7GPa-50 GPa. Most of the results obtained by this data analysis fall within the published ranges for these rock types, but the data show variability, which must be further evaluated to understand if these are related to geology or artifacts associated with the wireline.

Meteoric ¹⁰Be, Fe_d, and Clay in Critical Zone Soils, Front Range, Colorado

Cianna E. Wyshnytzky et al. — Fri, 08 Mar 2013 10:55:15 PST

The critical zone is the zone within which meteoric water, atmospheric gases, soil, and bedrock interact, encompassing the zone of soil formation (Anderson et al., 2007). The concentrations of various pedogenic compounds at a given location indicate the degree of weathering that has taken place in the Critical Zone. Among the products of chemical weathering are secondary phyllosilicate minerals (clays) and iron (Birkeland, 1999). At stable sites, chronosequence studies have shown that the amount of pedogenic iron oxide and clay increase as soils become older (McFadden and Hendricks, 1985).

Meteoric ¹⁰Be is a cosmogenic nuclide produced from oxygen and nitrogen in the atmosphere. It reaches the surface in rain water and dust and then binds to soil particles. As a soil profile evolves, so does its meteoric ¹⁰Be inventory due to soil formation and mixing processes. Given a steady state hillslope, the peak concentration of meteoric ¹⁰Be is expected in one horizon (Jungers et al., 2009). Concentration then decreases with depth, and the inventory is expected to increase downslope, creating a profile with a bulge. Given a young and eroding hillslope profile, the highest concentration of meteoric ¹⁰Be will still be in a single layer but erosion prevents this concentration from moving to depths beyond near-surface (Graly et al., 2010). The geochemistry of soils provides useful insight into soil character and development, and when applied to steep, active hillslopes, aids in the analysis of evolving topography. The addition of meteoric ¹⁰Be to soil analysis, combined with well-constrained delivery rates, allows for the dating of evolving soils and calculation of downslope soil transport.

This study examined hillslopes in Gordon Gulch, a 2.75 km² catchment with locally exposed bedrock and one of three focus areas of the Boulder Creek Critical Zone Observatory. Gordon Gulch is located downslope and to the east of the modern alpine environment and late Pleistocene glacial limit and generally upslope and to the west of the deeply incised landscape that characterizes the lower portion of Front Range rivers. Gordon Gulch may be affected by both upstream-migrating rejuvenation from the lower portion of the range and/or alpine environmental processes (i.e. periglacial activity).

Updated glacial chronology of the South Fork Hoh River valley, Olympic Peninsula, Washington through detailed stratigraphy and OSL dating

Cianna E. Wyshnytzky et al. — Fri, 08 Mar 2013 10:55:14 PST

Four glacial advances are preserved and exposed in the stratigraphy of the South Fork Hoh River valley. The oldest of these advances extended beyond the South Fork valley into the Hoh River valley. The three younger advances are preserved in the stratigraphy cut bank exposures in the valley and geomorphically by moraines and outwash plains. One of these advances represents a re-advance to the same terminal position of the previous advance and has not previously been recognized in this valley or other glaciated valleys in the western Olympic Mountains. This finding advocates for a detailed sedimentologic and stratigraphic approach to glacial deposits and questions whether a similar advance is seen in other glaciated valleys of the region. If so, this may reveal information regarding climate influences on glacial advance not previously considered for this specific time period.

A Study of Bedrock Strength Controls on the Erosion of the Colorado Plateau

Natalie Bursztyn et al. — Fri, 08 Mar 2013 09:15:51 PST

There has been renewed debate over the mechanisms of uplift and erosion in the Colorado Plateau, and in order to understand the patterns of topography and process in this landscape a third factor of bedrock properties must be considered. Our goal is to compile a dataset of bedrock strength and explore it in the context of topographic metrics. To do so, a methodology problem must be addressed. Traditional rock-strength measures such as Schmidt hammer rebound, Selby rock-mass strength, or tensile strength ignore weak rock types. We hope to develop an indirect, topography-based method that reliably estimates the strength of mud-rocks that are too incompetent to test directly.

We will complete measurements of the characteristics of rock formations along the Colorado and Green rivers to allow erosional resistance to be quantified. The drainage in the Colorado Plateau can be broken up into 48 reaches underlain by a variety of bedrock compositions including quartzite, sandstone, shale, limestone, evaporites, and crystalline basement. Compressive strength data from most of the outcropping rock formations have been collected from all reaches, however tensile strength data for these rocks are incomplete, and there are no data from any incompetent rocks. Our existing data indicate there are strong relations between rock strength and channel/valley width and gradient and stream power. Documentation will be done to complete modified Selby rock mass strength evaluations, noting thickness and proportion of beds that are too weak to be tested. From these new data, we aim to back-calculate strength of “weak” beds using functional relations between measured channel widths and known rock strengths, similar to previous numerical modeling in the region.

Linkages of fluvial terrace formation and geometry to Milankovitch-scale climate change revealed by the chronostratigraphy of the Colorado River above Moab, UT, and regional correlations

Andrew P. Jochems et al. — Fri, 08 Mar 2013 09:15:49 PST

The Colorado River flows from its Rocky Mountain headwaters to the Gulf of California, draining most of the Colorado Plateau. Although the river’s hydrology is set in the Rockies, its sediment load is largely supplied by the plateau drylands of the lower drainage.

Terrace genesis at Milankovitch timescales
• Reflects changing dynamics between fluctuating hydrology and local sediment supply?
• Relations to major late Pleistocene climate shifts?
• Do study terraces correlate regionally? (i.e. are pulses of sedimentation transient or synchronous?)
• What controls the formation of fill vs. strath terraces?

Deformation of terraces
• Is there a detectable influence of salt tectonism on terrace form and type?

Our goal is to address these questions through detailed chronostratigraphy, correlation, surveying, and long-profile analysis.

Electrostatic Discharge Properties of Fused Silica Coatings

Allen Andersen et al. — Tue, 20 Nov 2012 13:24:58 PST

The electric field value at which electrostatic discharge (ESD) occurs was studied for thin coatings of fused silica (highly disordered SiO2/SiOx) on conductive substrates, such as those encountered as optical coatings and in Si microfabrication. The electrostatic breakdown field was determined using an increasing voltage, while monitoring the leakage current. A simple parallel-plate capacitor geometry was used, under medium vacuum and at temperatures down to ~150 K using a liquid N2 reservoir. The breakdown field, pre-breakdown arcing and I-V curves for fused silica samples are compared for ~60 nm and ~80 μm thick, room and low temperature, and untreated and irradiated samples. Unlike typical I-V results for polymeric insulators, the thin film silica samples did not exhibit pre-breakdown arcing, displayed transitional resistivity after initial breakdown, and in many cases showed evidence of a second discontinuity in the I-V curves. This diversity of observed discharge phenomena is discussed in terms of breakdown modes and defect generation on a microscopic scale.

Characterization of Pollen Particles Using LIDAR

Leda Sox — Tue, 30 Oct 2012 15:00:19 PDT

We have observed pollen in the local troposphere using the depolarization capabilities of a LIDAR (Light Detection and Ranging) system. The polarization characteristics of the received LIDAR signal, along with supplemental pollen forecast data, allowed me to characterize the shape of the pollen particles.

Upgraded ALO Rayleigh Lidar System and Its Improved Gravity Wave Measurements

Leda Sox et al. — Tue, 30 Oct 2012 15:00:17 PDT

The Rayleigh-Scatter lidar system at the Atmospheric Lidar Observatory (ALO) on the Utah State campus is currently going through a series of upgrades to significantly improve its observational abilities. A specific objective of these upgrades is to expand the altitude range over which backscattered photons can be collected. A second objective is to increase the sensitivity of the instrument to be able to analyze the raw data at finer temporal and/or spatial resolutions. By measuring relative densities, the system will be able to produce absolute temperatures and relative density perturbations, which illustrate gravity wave structures. Gravity wave studies will significantly benefit from the improved system due to the waves’ propagation throughout the atmosphere and their evolving structures on various spatial and temporal scales during propagation. Preliminary data will be shown and its relevance to further gravity wave studies will be explained.

Observations with the Most Sensitive Rayleigh-Scatter Lidar

Leda Sox et al. — Tue, 30 Oct 2012 15:00:15 PDT

The mesosphere is the most unexplored region of the atmosphere. Its altitude range of 50-85 km lies in between the reaches of data collecting instruments like weather balloons and satellites. For this reason, remote sensing systems, such as lidar, which are able to employ ground-based instruments to make extensive measurements in this difficult to detect region. The Rayleigh-scatter lidar at USU is currently being redeveloped to be the most powerful and sensitive of its kind. This type of lidar exploits light and particle interactions, like those that account for the blue color of the sky, to make relative density and absolute temperature measurements. In turn, the variation in these densities and temperatures can be analyzed to further explore atmospheric phenomena that are either the cause of or caused by these variations. By increasing the power output and measurement sensitivity, this lidar system will be unique in its expansive altitude range and in its capabilities of measuring small spatial and time scale atmospheric phenomena. Atmospheric gravity waves are one form of such phenomena that will be studied, as they are an important component of atmospheric dynamics.