Groundwater flow through fractured karst conduit systems can be complex and difficult to diagnose. This project explores the role of geologic structures that influence the location of recharge points, flow paths, velocities, and discharge locations within Morrell Cave and at the resurgence of Morrell Spring, both of which are located near the city of Bluff City, TN. Understanding of the groundwater sources and flow paths in the Bluff City area will allow future researchers to more readily identify sources of pollution and better resolve local agricultural well drawdown conflicts among residents. The objectives of this project are to: 1) identify the active allogenic recharge sources of Morrell Spring, the largest known spring in the Bluff City area; 2) delineate a springshed for Morrell Spring and; 3) diagnose the structural controls for groundwater flow paths to Morrell Spring. It was found that surface streams flowing across the Sevier Shale on the northern slope of Holston Mountain enter the subsurface karst system through swallets along the Sevier shale and the Jonesboro Limestone contact. Once underground the water flows to the NW following 2 dominant joint sets until it reaches the NE/SW oriented fault line along which Morrell Cave has formed. Upon entering the cave the groundwater flows to the NE to Morrell Spring and into the South Fork Holston River.

Yes / The Mesolithic-to-Neolithic transition marked the time when a hunter-gatherer economy gave way to agriculture, coinciding with rising sea levels. Bouldnor Cliff, is a submarine archaeological site off the Isle of Wight in the United Kingdom that has a well-preserved Mesolithic paleosol dated to 8000 years before the present. We analyzed a core obtained from sealed sediments, combining evidence from microgeomorphology and microfossils with sedimentary ancient DNA (sedaDNA) analyses to reconstruct floral and faunal changes during the occupation of this site, before it was submerged. In agreement with palynological analyses, the sedaDNA sequences suggest a mixed habitat of oak forest and herbaceous plants. However, they also provide evidence of wheat 2000 years earlier than mainland Britain and 400 years earlier than proximate European sites. These results suggest that sophisticated social networks linked the Neolithic front in southern Europe to the Mesolithic peoples of northern Europe.

Scotland is one of the most valuable regions available for geologic study, as it has been a breeding ground for the discovery and development of many fundamental concepts from the earliest studies in the field through today. Scotland has traditionally been viewed, in a broad sense, as the amalgamation of two components: the eroded remnants of the Caledonide Orogen north of the Highland Boundary Fault (HBF), and the post-Caledonian Old Red Sandstone (ORS) to the south. Studies based in the Scottish Caledonides and the ORS have provided a host of concepts that we now deem fundamental, but much of that has been the byproduct of effort to understand how they were juxtaposed along the HBF. The metamorphosed strata of the Grampian Terrane (GT) lie against pillow basalts and minor sediments associated with the Highland Border Complex (HBC), and undeformed fluvial deposits of the ORS near the Highland Border. The incompatibility of lithologies, but also palaeontologic and radiometric ages, on either side of the fault was seemingly inexplicable, and coined the term “the Highland Border Paradox”. The Highland Border Paradox was used to describe the conflicting idea of continuity between the GT and HBC, despite incompatible lithologies and ages within the section. Several tectonic models have been suggested as a solution to the core of the issue, but a widely accepted solution has so far been elusive. The 40Ar/39Ar method is well-poised to investigate when the Scottish Caledonides were active, and when the ORS was deposited; each valuable in their own dimension but combined represent the best opportunity to understand the Highland Border Paradox to date. Two models exist: one which considers the Midland Valley Terrane (MVT; predominately ORS) to be relatively autochthonous relative to the northern terranes, and another that suggests the MVT is mostly allochthonous, or exotic. This dissertation is designed as a multi-pronged approach to offer an overarching understanding of the relationship between the Scottish Caledonides and the ORS, but with the intention that each chapter is a standalone contribution. We first investigate the relationship between the Grampian Terrane and the Old Red Sandstone by studying the contact that bounds them, which is along the Highland Boundary Fault. The base of the ORS is only reported to be exposed at five localities along the northern margin of the Midland Valley, but the basal unconformity is only found at Stonehaven. Outcrop exposure is not ideal in Scotland, such that the exposure of the contact between the GT and MVT is only exposed at those few localities, and physically tracing contacts between those localities is not possible. Chapter 1 is focused on exposure of the contact from the locality near Stonehaven, where we were surprised to find that no unconformity exists, and that the base of the ORS is a fault. A new age 40Ar/39Ar age of 438 Ma from biotite separated from a dike that crosscuts the Cowie Formation is over 20 Myr older than previous estimates, pushing the base of the ORS well into the Silurian. Fossils of Pneumodesmus Newmani found there, the earliest documented terrestrial and air-breathing fauna in the geologic record, must also be as old as 438 Ma. This pushes back both the timing of when air-breathing animals emerged from land, but also reinstates Stonehaven as the ideal locality to study the earliest life on land. This chapter was designed to be a manuscript for submission to Geology, or a similar journal, as it is a famous locality pertinent to a host of Caledonian studies, is commonly used for teaching, and has broad interest to the scientific community with respect to Pneumodesmus Newmani. Chapter 2 is focused on studying the physical contact between the GT and MVT at its other reported localities: Edzell (North Esk River), Callander, and Balmaha. Detailed field mapping and observations were made for each, also supplemented petrographic details from thin sections as needed. One of the most surprising findings is that, combined with observations from Stonehaven, the base of the ORS is either faulted or not exposed; there is effectively no evidence for a basal ORS unconformity. This releases the constraints that the ORS was deposited strictly after the Caledonian Orogeny, and that the ORS was deposited above the GT/HBC stack as we see it today. In addition, at each of these localities, we identify considerable evidence of faulting in the area between the GT and MVT; most affected is the intervening HBC. This is hard to reconcile with previous interpretations proposed for those localities by proponents of the autochthonous model, as it is based largely on proposed continuity at those localities. It is also difficult to reconcile with the suggestion, in that view, that the HBF only modestly displaces geology, and not responsible for the juxtaposition of the GT and MVT. Evidence at each locality for undeformed units directly juxtaposed with highly deformed rocks implies a significant amount of vertical displacement that has not previously been appreciated, in any previous account. A significant amount of vertical displacement is a characteristic of major strike-slip faults, yet previous strike-slip models for the HBF have invoked movements in a purely lateral sense. Chapter 3 aims to constraint when the GT, Northern Highland Terrane (NHT), and Hebridean Terrane (HT) were exhumed during the Caledonian Orogeny, with a particular focus on the southern region of the GT near the HBF. We employed single-step 40Ar/39Ar analysis of muscovite separated from bedrock exposed throughout the terranes north of the HBF, complementing a similar work by Dewey and Pankhurst (1970). Throughout all the terranes, these ages range from 500-420 Ma, with a concentration of ages ca. 470 Ma. Combined with previous data sets, the NHT appears to have had a younger exhumation, but if our dataset is considered alone that distinction is unclear. The second portion of Chapter 3 presents the results of step-heating 40Ar/39Ar analysis of muscovite separated from metamorphosed GT strata, sampled in transects spanning across the metamorphic zones of the GT. The purpose of the transects is to evaluate when the portion of the GT immediately against the MVT was active. The step-heating analyses range between 471-461 Ma at Stonehaven, 468-453 Ma at North Esk, and 459-447 Ma at Balmaha (combined with Callander). These ages indicate that the Caledonian Orogeny was active at least from ca. 471-447 Ma, whereas the Caledonian Orogeny was previously proposed to be unusually short (10 Myr). As these ages likely capture the latest stage of orogenesis, the actual duration is likely considerably longer, and this is also suggested by the wider range of single-step ages. It is also now difficult to envision a scenario in which the GT was a passive margin through Ordovician times, which is a widely accepted notion. Chapter 4 is designed to investigate the time at which the Midland Valley ORS was deposited, and where its sediments originated from. We obtained three ages from volcanic units interleaved throughout the ORS, including a result of 438 Ma near the base (from Stonehaven), a result of 431 Ma from the Lintrathen Porphyry near mid-section, and a result of 400 Ma at the top of the ORS near Oban. We sampled over ten volcanic units interleaved within the ORS, but most ultimately were unsuitable for age analysis. Despite only obtaining three ages, it is now clear that at least the onset of ORS sedimentation is significantly older than previous estimates, now as far back as 438 Ma, whereas it was previously considered to be mostly Devonian. Considering that the age from Lintrathen at midsection is only 6 Myr younger, and still Silurian, it is possible that a majority of the Midland Valley LORS is Silurian, and deposited within a much more narrow timeframe than previously suggested. The result of 399 Ma from Oban confirms the previous suspicion that the ORS near Oban is unrelated to the ORS in the Midland Valley. Detrital analyses from the Midland Valley ORS indicate a source that ranges in age from mainly 480-420 Ma, which effectively overlaps the Scottish source ages obtained in Chapter 3. This is at odds with a previous hypothesis that suggested the ORS was sourced from large river systems from Scandinavia (including the Western Gneiss Region), analogous to the Himalayan drainages today. In combination, the depositional ages (437 and 431 Ma) and range of detrital ages (480-420 Ma), suggest that the ORS was locally related to the Scottish Caledonides, rather than an exotic origin. So, while it is now clear that displacement along the HBF is more substantial than previously conceived, that displacement was not significant enough to isolate the ORS from a Scottish source.

The Sand Creek watershed, Choctaw County, Mississippi, constitutes a proposed site for a recreational and water management reservoir. Prior to the development of the site, the geology and hydrogeology of the watershed must be investigated to determine suitability for impoundment. Geological cross sections derived from geophysical logs and field exploration provides information regarding facies distributions within the proposed site area. Discharge characteristics of streams provide data concerning surface runoff that can then be related to the amount of water that is beneficial to the reservoir filling and remaining filled. All data collected and the characteristics of the reservoir are mapped using ArcGIS 9.1 software. The amount of sand located near the abutment of the levee and possible thin ridge with prospect of faulting to the southeast of the abutment is cause for concern. Analysis of the study area suggests that the proposed site is suitable for location of a reservoir.

No description available.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Impact processes, where a meteor strikes a planetary body’s surface, are ubiquitous in the Solar System. These highly energetic events require study by both computational methods and experimental investigation. An impact process of particular interest to our study is the impact plume, a collection of vaporized rock and superheated gases that is produced during an impact event. Tektites are silica rich (roughly rhyolitic), extremely dry, and often contain both lechatelierite inclusions (amorphous SiO2) and flow textures (schlieren) and are an impact product of particular interest to this study. Tektites likely form either very early in the impact process or within the impact plume itself as condensates, and therefore offer a unique insight into the early stages of the impact cratering process. Here, we present both the results of the statistical analysis of published tektite geochemistry and the geochemical analysis of a variety of glasses produced in an aerodynamic levitation laser furnace. The major findings of the statistical analysis are that the variance of tektite geochemistry is broadly controlled by MgO, CaO, K2O, and Na2O, that the Australasian strewn field (an extensive region of tektite distribution) is best subdivided into five geochemical subgroups, and that random forest classification models can predict the strewn field or geochemical subgroup of an unknown tektite with >94% accuracy. In terms of our heating experiments, in nearly all cases, Na2O and K2O are rapidly lost from the melt due to evaporation, while Al2O3, CaO, and TiO2 become progressively enriched. Volatility is far more dependent on peak heating temperature than on heating time. Additionally, the chemical constituents of basalts are less readily volatilized than those of rhyolites or loess, with few exceptions. We also find that the volatility of the chemical constituents of non-standard samples is far more variable than for standard samples and that oxygen fugacity has a strong influence over elemental volatility in the aerodynamic levitation laser furnace. Changes in oxygen fugacity can either result in variable, exaggerated, or even opposite volatility trends depending on the material and oxide in question.

Recent studies suggest that continental flood basalts may be suitable for geologic carbon sequestration due to fluid-rock reactions that mineralize injected CO₂ on relatively short time-scales. Flood basalts also possess a permeability structure favorable for injection, with alternating high-permeability (flow margin) and low-permeability (flow interior) layers. However, little information exists on the behavior of CO₂ as it leaks through fractures characteristic of the flow interior, particularly at conditions near the critical point for CO₂. In this study, a two-dimensional 5 × 5 m model of a fracture network is built based on high-resolution LiDAR scans of a Columbia River Basalt flow interior taken near Starbuck, WA. Three-phase CO₂ flow is simulated using TOUGH3 (beta) with equation of state ECO2M for 10 years simulation time. Initial conditions comprise a hydrostatic pressure profile corresponding to 750-755 m below ground surface and a constant temperature of 32° C. Under these conditions, the critical point for CO₂ occurs 1.5 meters above the bottom of the domain. Matrix permeability is assumed to be constant, based on literature values for the Columbia River Basalt. Fracture permeability is assigned based on a lognormal distribution of random values with mean and standard deviation based on measured fracture aperture values and in situ permeability values from literature. In order to account for fracture permeability uncertainty, CO₂ leakage is simulated in 50 equally probable realizations of the same fracture network with spatially random permeability constrained by the lognormal permeability distribution. Results suggest that fracture permeability uncertainty has some effect on the distribution of CO₂ within the fractures, but network geometry is the primary control in determining flow paths. Fracture permeability uncertainty has a larger influence on fluid pressure, and can affect the location of the critical point within ~1.5 m. Uncertainty in fluid pressure was found to be highest along major flow paths below channel constrictions, indicating permeability at a few key points can have a large influence on fluid pressure distribution. / Master of Science

Petrologic and thermobarometric studies, coupled with geologic mapping and structural analysis, provide critical evaluation of several different models for Acadian (Late Silurian to Middle Devonian) dome evolution in southern Vermont. Previous models considered diapiric uprise and composite nappe-stage crustal thickening and subsequent diapirism as likely causes of dome formation. Both of these previous models result in symmetrical distribution of P-T values about the dome structures with corresponding coreward increases in temperature, and typically, coreward decrease in associated pressures. Thermobarometric calculations made during this study demonstrate that both P and T increase eastward across the entire region and are not symmetrically distributed about dome axes. The P-T data coupled with petrographically derived relative age relationships and available geochronology also suggest that attainment of peak metamorphic conditions and concurrent dome-stage deformation are diachronous and young from west to east. These relationships are consistent with new geologic mapping and structural analysis which show that all of the domes in southern Vermont are low-amplitude fold interference structures. A current tectonic model indicates that Acadian Barrovian metamorphism in this region was a consequence of west-directed crustal thickening of an eastward dipping tectonic wedge, presumably from the Bronson Hill Terrane; an Ordovician arc sequence. The basal surface of this allochthonous mass projects above the present land surface within this area. Accretion of lower-plate rocks (of this study) into the thrust complex and continued west-directed thrusting of the accreted package over a seismically recognizable east dipping ramp structure provided the necessary geometry and mechanism for dome-stage fabric development, calculated uplift rates (1.2 to 1.7 km/m.y. and west to east younging of Acadian structural and metamorphic evolution. Thermobarometric and geochronologic estimates of metamorphic pressure - temperature (P-T) conditions and metamorphic cooling ages were used to constrain the required thermal and tectonic input parameters for use in one-dimensional thermal modeling of an Acadian (Silurian-Devonian} tectonotherma! regime within the pre-Silurian Taconide zone of southern Vermont. This regime includes: 1) garnet-grade rocks from the eastern flank of an Acadian composite dome structure (Sadawga Dome; the western domain); 2) staurolite/kyanite-grade rocks from the western flank of a second composite structure, the Athens dome (eastern domain). Results from thermal modeling include development of P-T paths, temperature-time (T-t) and pressure-time (P-t) curves, related values of maximum temperature and pressure, pressure conditions at maximum temperature, predicted closure ages for radiogenic phases, and integrated uplift and cooling rates. Thermal modeling results are remarkably similar to independently obtained data for Acadian regional metamorphism in western New England, and provide some important constraints on regional thermal evolution: 1) pressure values contemporaneous with peak temperature on P-T paths may be substantially lower than actual maximum pressure (> 2.5 kbars); 2) differences in peak temperature for rocks initially loaded to similar crustal depths (garnetgrade vs. staurolite-grade), differences in calculated uplift rates, and differences in Ar closure ages, are consequences of variations in durations of isobaric heating events (or "residence periods"), and differences in actual tectonic uplift rates. These modeling results are internally consistent with structural model that suggests west to east younging of specific Acadian deformations and resultant diachroneity of peak metamorphic and Ar closure ages. Regional variations in timing and conditions of metamorphism may be controlled by diachronous deformational events coupled with variations in crustal levels to which rocks were initially loaded during the ca. 400 Ma onset of Acadian orogenesis in western New England. / Ph. D.

Analysis of synthetic data was performed to determine the most cost-effective tomographic monitoring system for a geologic carbon sequestration injection site. Artificial velocity models were created that accounted for the expected velocity decrease due to the existence of a CO₂ plume after underground injection into a depleted petroleum reservoir. Seismic events were created to represent induced seismicity from injection, and five different geophone arrays were created to monitor this artificial seismicity. Double-difference tomographic inversion was performed on 125 synthetic data sets: five stages of CO₂ plume growth, five seismic event regions, and five geophone arrays. Each resulting velocity model from tomoDD—the double-difference tomography program used for inversion—was compared quantitatively to its respective synthetic velocity model to determine an accuracy value. The quantitative results were examined in an attempt to determine a relationship between cost and accuracy in monitoring, verification, and accounting applications using double-difference tomography. While all scenarios resulted in little error, no such relationship could be found. The lack of a relationship between cost and error is most likely due to error inherent to the travel time calculation algorithm used. / Master of Science