Transverse zones cross strike of thrust-belt structures as large-scale alignments of cross-strike structures. The Transylvania fault zone is a set of discontinuous right-lateral transverse faults striking at about 270º across Appalachian thrust-belt structures along 40º N latitude in Pennsylvania. Near Everett, Pennsylvania, the Breezewood fault terminates with the Ashcom thrust fault. The Everett Gap fault terminates westward with the Hartley thrust fault. Farther west, the Bedford fault extends westward to terminate against the Wills Mountain thrust fault. The rocks, deformed during the Alleghanian orogeny, are semi-independently deformed on opposite sides of the transverse fault, indicating fault movement during folding and thrusting. Palinspastic restorations of cross sections on either side of the fault zone are used to compare transverse fault displacement. The difference in shortening corresponds to the amount of displacement on either side of the transverse fault. The palinspastic restoration indicates a difference in the amount of shortening that will balance farther to the west in the Appalachian Plateau province.

Thesis (M.A.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on June 12, 2006). Thesis advisor: Marilyn Kallet. Vita. Includes bibliographical references.

The St. Lawrence Platform (SLP) and Humber Zone (HZ) of the southern Quebec Appalachians has historically been explored as a potential hydrocarbon reservoir. Extensive vitrinite reflectance studies on the basin resolved the degree of thermal maturation yet the timing of the thermal maximum is not well undertood. Determining the timing of such low temperature events can allow for a better understanding of the shallow crustal processes that may have allowed for the generation and entrapment of oil and gas. We have employed apatite (AHe) and zircon (ZHe) (U-Th)/He thermochronmetry across a network of late Cambrian to late Ordovician siliciclastic and Grenvillian basement samples in order to resolve the history within the ~210-35°C window. Single crustal dates from individual samples show age dispersion by as much as 300 m.y. with a strong positive to negative correlation with increasing eU concentration. A similar positive correlation can be observed when significant intra-sample grain size variation is present. AHe and ZHe data in the southwestern portion of the basin, near Montreal, allow for thermal maxima of up to 200°C to occur either during the late Ordovician, as a result of the Taconic orogeny, or from the continued sedimentation into the Devonian as a result of the Acadian orogeny. Regional burial trends deduced from these thermal maxima along with local paleo-geothermal gradients indicate that if sedimentation continued after the late Ordovician there was no significant increase in burial in southwestern portion of the SLP as previously suggested. Maximum heating is followed by a protracted cooling through the ZHe partial retention zone (PRZ) into the late Jurassic and early Cretaceous where the cooling rate increases by an order of magnitude through the AHe PRZ until ca. 100 Ma. The timing of this accelerated cooling is coeval with the passage of the Great Meteor Hot Spot across the area; the cooling may be a result of increased erosion from thermal uplift. Within the HZ, both the external and internal sections experienced rapid cooling through the Silurian after the Taconic thermal maximum. The timing of relatively rapid cooling coincides with documented normal faulting and back-thrusting in the orogen, which is the likely cause of exhumation. The HZ witnessed protracted cooling through the late Jurassic, when there is a one order of magnitude increase in cooling rate until surface conditions are attained. Increased recognition of these low temperature events has augmented our understanding of the evolution of accretionary orogens and consequently reduces the risks associated with oil and gas exploration.

Hybridization in plants can be common, may lead to increased genetic variation, and in some instances the formation of new species. For endangered species, hybridization can introduce novel genetic variation and potentially increase genetic diversity. In contrast, hybridization can negatively affect an endangered species or population by introducing maladaptive alleles into locally adapted lineages or lead to the homogenization of once distinct lineages. We used microsatellites, AFLP markers, and morphological data to identify potential hybridization between the endangered Roan Mountain bluet (Houstonia purpurea var. montana) and its commonly occurring congener (H. purpurea var. purpurea). We used these data to clarify the taxonomic relationship of these varieties and to assess population structuring of the Roan Mountain bluet. The results showed that these lineages are distinct and few individuals exhibited admixture in several populations. Additionally, the results showed there is genetic population structure among the remaining populations of H. purpurea var. montana, which is consistent with other mountaintop species. Our results show that Roan Mountain bluet populations should be protected to maintain genetic diversity and monitored to assess future hybridization, and additional studies that comprise a greater population sampling would provide more information.

Neogene land-mammal localities are very rare in the northeastern U.S.; therefore, the late Miocene/early Pliocene Gray Fossil Site in eastern Tennessee can clarify paleoecological dynamics during a time of dramatic global change. In particular, the identification of ancient forests and past climate regimes will better our understanding of the environmental context of mammalian evolution during the late Cenozoic. Stable isotope analyses of bulk and serial samples of fossil tooth enamel from all ungulates present at the Gray site elucidate paleoecological reconstructions. The herbivorous megafauna include taxa of likely North American and Eurasian ancestry including: the tapir Tapirus polkensis, rhino Teleoceras cf. T. hicksi, camel cf. Megatylopus sp., peccary Tayassuidae, and proboscidean Gomphotheriidae. The tapir, rhino, camel, and peccary yield mean stable carbon isotope (δ13C) tooth enamel values of - 13.0‰, - 13.3‰, - 13.8‰, and - 13.1‰, respectively, suggesting forest-dwelling browsers. This range of δ13C values indicates the presence of a C3 dominated ancient local flora. Because δ13C values decline with increasing canopy density, the ancient temperate forests from the Gray site were moderately dense. The lack of significant C4 plant consumption (i.e., tooth enamel δ13C values < - 9‰) suggests the presence of forests large enough to independently support the continued browsing of sustainable populations of browsers from the Gray site. In contrast, bulk and serial δ13C values ranging from - 0.7‰ to 0.3‰ from a gomphothere tusk support a diet consisting of C4 grasses, suggesting the presence of C4 grasslands within the individuals home range. The rare earth element (REE) analyses of the gomphothere tusk and the teeth of Tapirus and Teleoceras indicates that these individuals shared similar depositional environments; thus, demonstrating the concurrent presence of C3 forests and C4 grasslands in the northeast. Stable carbon and oxygen serial sample variation of the tapir, rhino, peccary, and gomphothere is less than 1.5‰, suggesting minor differences in seasonal temperature and/or precipitation. These data support the possibility of a North American forest refugium in the southern Appalachians during a time typified by more open environments.

For the past 5 years we have been conducting a large-scale, multi-habitat inventory of the tardigrades in the Great Smoky Mountains National Park (U.S.A.) as part of the All Taxa Biodiversity Inventory (ATBI) (see www.dlia.org). In terrestrial habitats, we collected moss, lichen, and soil samples from 19 permanent ATBI plots, representing all major land cover types within the park. Each ATBI plot is 100 × 100 m. In each plot, when available, 16 moss samples, 16 lichen samples, and 4 soil samples were collected in paper bags and air dried in the laboratory. Specimens were isolated with LudoxAM centrifugation, and for each sample up to 50 adults plus eggs were individually mounted on microscope slides in Hoyer's medium and identified using phase contrast and DIC microscopy. Additional collections were made in the limestone caves of the Cades Cove region of the park, bird nests, and 13 different streams. To date (1-Jun-06), 589 samples have been collected, and of these 401 have been analyzed, yielding a total of 8133 identifiable tardigrades or, in some cases, species groups. A total of 73 species have been found in the park, 14 of which we believe are new to science. Seven species richness estimators have been developed to predict total species richness (see EstimateS 7.5 software, viceroy.eeb.uconn.edu/ estimates), and these were evaluated by comparing predictions from half of our data to the actual numbers from the total database. The results of this comparison indicate that different estimators work best in different habitats. Using the best estimators in each habitat, EstimateS 7.5 indicates that a total of 96 species are likely to occur throughout the park. Thus, Great Smoky Mountains National Park tardigrade diversity represents 10% of the world's known tardigrade fauna.

No description available.

The timing, duration, and pressure-temperature (P-T) conditions of metamorphism provide a direct record of the physical and chemical evolution of the crust and inform our knowledge and understanding of plate tectonics. The characteristic timescales and length-scales of metamorphism vary by orders of magnitude, depending on the driving tectonic process. Two fundamental problems with the retrieval of this information from the metamorphic rock record are insufficient temporal resolution and processes that overprint or obscure the full record of metamorphism. Understanding what processes are recorded, and why they are recorded, is critical for accurate models of tectonics. This dissertation examines these processes in the metamorphic rock record in two settings: the central Appalachian orogen and the Western Alps fossil subduction zone. Chapters 2 and 3 focus on poly-metamorphic migmatites from the Smith River Allochthon (SRA) in the central Appalachians. A combination of petrography, thermodynamic modeling, and geochemistry is used to document and quantify the metamorphic evolution of the SRA and determine the petrologic processes that control metamorphic re-equilibration in high-temperature metamorphic systems. Chapter 2 presents new constraints for Silurian high-temperature (~750℃, 0.5 GPa) contact metamorphism in response to mafic magmatism and a cryptic Alleghanian metamorphism (~600℃, 0.8 GPa). A combination of extensive and highly variable melt loss followed by H2O-flux melting during contact metamorphism is shown to produce a range of modified bulk rock compositions and domains with variable fertilities for metamorphic re-equilibration during the Alleghanian. In chapter 3, monazite, allanite, and zircon laser ablation split-stream petrochronology are used to constrain the timing of poly-metamorphism and develop a tectonic model for the SRA. The SRA preserves evidence for at least three orogenic events, each with a relatively short duration (< 10 Myr.), likely due to repeated magmatic heating. The full record of this punctuated heating is obscured by dissolution-reprecipitation reactions that variably recrystallize monazite and decouple trace element chemistry from isotopic age and significantly restrict equilibrium length-scales. Chapters 4 and 5 examine the dynamic interplay between transient fluid flow, episodic metamorphism, and deformation in subduction zones. In chapter 4, diffusional speedometry is applied to eclogite breccias from the Monviso ophiolite to quantify the periodicity of transient deformation and metamorphism at eclogite facies P-T conditions. The maximum timescale for repeated fracturing is constrained to ~1 Myr., likely caused by cyclic variations in fluid pressure and strain rate (not necessarily seismicity). While difficult to preserve and detect in the rock record, this periodic metamorphism may play an important role in detachment and exhumation processes in subduction zones worldwide. Finally, in chapter 4 a combination of thermodynamic modeling and Sm-Nd garnet geochronology are used to construct a model for subduction and exhumation of the Voltri ophiolite. Garnet growth occurs rapidly and close to peak P-T conditions (~520℃, 2.4 GPa) across the ophiolite, with large (>10 km2) areas preserving near-identical ages, suggesting that the Voltri ophiolite was exhumed as several large coherent units, aided by the presence of buoyant serpentinites. / Doctor of Philosophy / Metamorphism provides a direct record of the physical and chemical evolution of Earth's crust and informs our knowledge and understanding of how plate tectonics works on Earth. Differences in the physical conditions (e.g. pressure, temperature) and timescales of metamorphism can provide clues for the operation of unique tectonic processes, such as the intrusion and cooling of magma deep underground or the collision of two tectonic plates and formation of a mountain range. The key is to correctly "read" the metamorphic rock record. One inherent difficulty in reading and interpreting metamorphic rocks is that few current methods are able to resolve very short timescale events (much less that 1 million years (Myr.) in duration), such as earthquakes, in the rock record. Moreover, metamorphic rocks experience numerous distinct 'events', which partly overprint one another and produce a complicated and near impossible puzzle for geologists to unravel. Solving this puzzle is critical to fully understand how plate tectonics works on Earth. This dissertation addresses these problems and examines metamorphism in two locations: the core of the ancient supercontinent Pangea (central Appalachians) and a fossil subduction zone (the Western Alps). Chapters 2 and 3 focus on the central Appalachians. Chemical and textural analysis of metamorphic rocks are used to understand the major heat sources that operated in the crust during the formation of the Appalachians and determine the processes that control metamorphic re-crystallization at extremely high temperatures. Chapter 2 presents new constraints for high-temperature (~750℃) metamorphism in response to magmatic heating and provides evidence for a younger metamorphic event that is cryptically recorded. A combination of compositional changes caused by earlier high-temperature metamorphism and the later addition of water along reactive grain boundaries are shown to be important factors in the cryptic record of the younger metamorphic event. In chapter 3, U-Pb geochronology is used to the determine the timing of metamorphism and construct a tectonic model for the central Appalachians, which preserves evidence for at least three tectonic events over ~200 Myr, but with each occurring over a relatively short duration (< 10 Myr.). These events are interpreted to represent repeated magmatic heating 'pulses' during the formation of Pangea. However, the full record of this punctuated heating is partly obscured by subsequent fluid alteration. Chapters 4 and 5 examine the dynamic interplay between transient fluid flow, earthquakes, and metamorphism deep in subduction zones. In chapter 4, fracture sets within metamorphic garnet crystals from the French Alps (Monviso) are used to determine the timescale of repeated fracturing and recrystallization during subduction. The fracture timescales are estimated to be much less than 1 Myr. and are interpreted to record repeated fluid "pulses" and possibly deep earthquakes. While difficult to preserve and detect in the rock record, this process may play an important role in bringing metamorphic rocks back from deep in subduction zones to Earth's surface. In chapter 4, a combination of mineral chemistry and geochronology are used to construct a tectonic model for the subduction and exhumation of a portion of the Italian Alps (Voltri). Metamorphic reactions occur synchronously and immediately before exhumation across a wide area (> 10 km2). This suggest that large (> 10 km2) pieces of oceanic crust can metamorphose, detach, and exhume deep in subduction zones.

The rocks of the Appalachian orogen are world-class examples of collisional and extensional tectonics, where multiple episodes of mountain building and rifting from the pre-Cambrian to the present are preserved in the geologic record. These orogenic events produced plutonic rocks, which can be used as probes of the thermal state of the source region. SIMS (secondary ion mass spectrometry) U/Pb ages of zircons were obtained for ten plutons (Leatherwood, Rich Acres, Melrose, Buckingham, Diana Mills, Columbia, Poore Creek, Green Springs, Lahore and Ellisville) within Virginia. These plutons are distinct chemically, isotopically, and show an age distribution where felsic rocks are approximately 440 Ma, and Mafic rocks are approximately 430 Ma. Initial strontium isotopic ratios and bulk geochemical analyses were also performed. These analyses show the bimodal nature of magmatism within this region. In order to facilitate management of geologic data, including radiometric ages, strontium isotope initial ratios and major element geochemistry, a GIS based approach has been developed. Geospatially references sample locations, and associated attribute data allow for analysis of the data, and an assessment of the accuracy of field locations of plutons at both regional and local scales. The GIS based assessment of plutons also allows for the incorporation of other multidisciplinary databases to enhance analysis of regional and local geologic processes. Extending such coverage to the central Appalachians (distribution of lithotectonic belts, plutons, and their ages and compositions) will enable a rapid assessment of tectonic models. / Master of Science

Interest in transport of dissolved nitrogen (N) and carbon (C) in forested ecosystems is growing because of potential effects of these solutes on streamwater quality and implications for C sequestration. Additional research will further the understanding about the dynamics of these soil solutes, particularly in response to harvesting of forests. Also, the purported role of riparian buffers, where logging is restricted along stream channels, in retaining soil solutes is not well studied in the steeply sloping terrain of the southern Appalachian Mountains. I examined solute transport in a first-order watershed in the Nantahala National Forest in North Carolina that was harvested in February 2006 with retention of a 10-m riparian buffer. To quantify the movement of dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), and dissolved organic carbon (DOC), four transects of lysimeters, approximately 30 m apart, were installed perpendicular to the stream on one hillslope. Porous ceramic cup (2-bar) lysimeters were installed in each transect 1, 4, 10, 16, 30, and 50 m from the stream in the A horizon and B horizon, and 4, 16, and 50 m from the stream in the saprolite layer. Samples were removed from the lysimeters 24 hr after 50 centibars of tension were placed on them, and riparian groundwater well and stream samples were collected at the same time as lysimeter samples. Collection of samples from the lysimeters, wells, and stream occurred every four to six weeks for one calendar year beginning March 2007. A 16-wk laboratory N mineralization study was conducted on A horizon soils. Mean nitrate values in the soil solution of the A horizon in the spring were 1.53mg-N/L and decreased through the growing season to 0.030mg-N/L. Mean soil solution nitrate values in the B horizon and saprolite layer were 0.40mg-N/L in the spring and summer and decreased to 0.031mg-N/L in the winter. Mean soil solution ammonium concentrations were higher in the A horizon (0.090mg-N/L) than the B horizon and saprolite layer (0.034mg-N/L) and were lowest during the summer and fall. Dissolved organic C was significantly higher in the A horizon, with values ranging from 2.3mg/L to 599mg/L, than in the relatively stable B horizon and saprolite (1.9mg/L to 36.6mg/L). Dissolved organic C was logarithmically correlated to DON (r2 = 0.64), and DON values were highest in the A horizon (0.70mg/L). Cumulative N mineralization potential ranged from 48.1mg-N/kg to 75.6mg-N/kg and was not a useful predictor for nitrate soil solution values. Nitrate leached vertically, and a large percentage of nitrate was stored in the B horizon and saprolite. Ammonium, DON, and DOC did not appear to leach vertically because they did not increase in the B horizon or saprolite layer. Ammonium, DON, and DOC are less mobile in soil solution than nitrate. The 10-m riparian zone had little impact on nitrate, ammonium, DON, and DOC removal. Nitrate remaining in the A horizon was likely removed through plant uptake in the harvested area before reaching the riparian zone. There was no detectable difference between ammonium concentrations in the harvested area and riparian zone likely because of limited mobility. The riparian zone did not remove excess DON or DOC, and in some transects was a source of DON and DOC. Nitrate and DOC concentrations were highly variable among transects and locations within transects. This may be caused by sensitivity of these solutes to site heterogeneity. This suggests that a large number of lysimeters should be used to account for this variability in future studies to ensure accuracy. This study observed limited vertical leaching of ammonium, DON, and DOC through the profile. However, excess nitrate was observed moving from the A horizon into the B horizon and saprolite layer, suggesting the potential for delivery to the stream via subsurface transport and the need for attenuation of nitrate by the riparian zone. Because of low concentrations of nitrate entering the riparian zone during this study, the capacity for riparian attenuation of nitrate was not demonstrated. / Master of Science