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Campi Flegrei is a large volcanic complex located west of the city of Naples, Italy. The area has been the site of volcanic activity for more than 60 ka and represents a potential volcanic hazard owing to the large local population. In this study, the geochemistry of the magma associated with two different eruptions at Campi Flegrei has been characterized, with the aim to identify geochemical trends that may help to predict the style and nature of future eruptions. Two eruptions of different age and eruptive style have been selected for study, Fondo Riccio (9.5 ka) and Minopoli 1 (11.1 ka). A scoria (CF-FR-C1) and a bomb (CF-FR-C2) were collected from the Fondo Riccio eruption, and two scoria samples were collected from Minopoli 1 (CF-Mi1-C1 and C2) eruption. The pre-eruptive volatile content of magma plays an important role in the style of eruption and can be assessed from studies of melt inclusions (MI) contained in phenocrysts. Major and trace elements in Fondo Riccio MI show a wider variation compared to those in Minopoli 1 MI suggesting that the Fondo Riccio magma residence time was longer compared to the Minopoli 1 magma. Analyses of volatile contents in MI suggest that Fondo Riccio magma may have been more water-rich than Minopoli 1 magma, consistent with the more explosive character of this eruption compared to Minopoli 1. Trace element data suggest a combination of arc volcanic and upper continental crust magma as the source for the Fondo Riccio and Minopoli 1 eruptions. / Master of Science

Disotopic dating of zircons from the Flat River Complex in the Carolina "slate" belt north of Durham, N.C. shows this intrusive complex to be 650 ± m.y. old. Modal analyses of granophyric groundmass compared to experimental data, the presence of vent breccias and related pyroclastic deposits, and consideration of age relations between the intrusive and extrusive rocks indicate that the Flat River was emplaced at very shallow levels (< l km) and acted as the source for most of the volcanic material surrounding the complex. The age determined for the Flat River Complex indicates that deposition of the volcanic rocks began prior to 650 m.y. ago and extends the slate belt volcanicity interval to 130 m.y. (520 to 650 m.y. b.p.) Both subareal and marine depositional environments are represented in the stratigraphic sequence. / Master of Science

Six pedons derived from volcanic cinders from the San Francisco Volcanic Field near Flagstaff, Arizona, were studied to evaluate their physical, chemical, and mineralogical properties for inclusion in the proposed soil order Andisol. All the pedons meet the requirements for the Andic soil properties and they are thus classified as either Typic Ustivitrand or Melanic Ustivitrand Subgroups of Andisol Order. The proposed classification is discussed with respect to the guidelines presented in the ninth International Committee of Classification on Andisols (ICOMAND) letter.

The West Elk Breccia has been studied since the late 1800’s with many interpretations regarding its origin. One unrecognized possibility is that parts of it are debris-avalanche deposits. This study has recognized evidence for this interpretation at three scales: volcano scale, outcrop scale, and intra-outcrop scale. At the volcano scale, a scarp in the old volcano reveals underlying Mesozoic bedrock, suggesting sector collapse. At the outcrop scale, megablocks of the original edifice, up to hundreds of meters in length, have atypical orientations and are surrounded by a gravel matrix. At the intra-outcrop scale, jigsaw-fit fracturing and rip-up clasts are common in distal deposits, which are documented in analogous debris-avalanche deposits. Similar to the debris-avalanche deposit at Mt. Shasta, medial-to-distal-matrix volcaniclast content decreases by 23%; Paleozoic and Mesozoic clasts increase by 5%; and the size of megablocks decreases. The geochemical and petrographic signatures reveal breccia blocks composed of pyroxene-andesite, a more silicic matrix facies, and the andesitic-to-dacitic East Elk Creek Tuff, all compositions that corroborate previous work on this northern extension of the San Juan volcanic field. Measured sections in the 100-km² study area allow for an estimation of total formation volume of approximately 8.5 km3.

Ash-flow tuff (ignimbrite) is a general term indicating consolidated deposits of volcanic ash flow; a flow of a mixture of gas and pyroclastic materials as products of explosive volcano eruptions (Smith, 1960). Two different ash-flow tuffs are studied in this research: 1. Topopah Spring Tuff at Yucca Mountain, Nevada and 2. the Bandelier Tuff at Pajarito Plateau, New Mexico. Various dynamic test parameters (e.g. confining pressure, shearing strain, etc) were studied with two existing devices: (1) the combined resonant column and torsional shear (RCTS) device, and (2) the free-free, unconfined, resonant column (URC) device. The effects of these parameters are evaluated for two different types of ash-flow tuffs. In addition, a Large Resonant Column (LgRC) device was developed and used to test the some tuffs from Yucca Mountain at larger strain amplitudes than possible with the RCTS and URC devices. Relationships between the linear and nonlinear dynamic properties and lithostratigraphic features were further investigated. Finally, potential problems related to sample disturbance and specimen size are considered based on comparisons of small-strain shear wave velocity (VS) values measured in the laboratory and in the field. / text

A three-dimensional stochastic numerical inverse model has been developed for characterizing the properties of unsaturated fractured medium through analysis of singleand cross-hole pneumatic tests. Over 270 single-hole [Guzman et al., 1996] and 44 cross-hole pneumatic tests [Illman et al., 1998; Inman, 1999] were conducted in 16 shallow vertical and slanted boreholes in unsaturated fractured tuffs at the Apache Leap Research Site (ALRS), Arizona. The single-hole tests were interpreted through steady-state [Guzman et al., 1996] and transient [Illman and Neuman, 2000b] analytical methods. The cross-hole tests were interpreted by analytical type-curves [Illman and Neuman, 2000a]. I describe a geostatistical analysis of the steady-state single-hole data, and numerical inversion of transient single-hole and cross-hole data. The geostatistical analysis of single-hole steady-state data yields information about the spatial structure of air permeabilities on a nominal scale of 1 m. The numerical inverse analysis of transient pneumatic test data is based on the assumption of isothermal single-phase airflow through a locally isotropic, uniform or non-uniform continuum. The stochastic inverse model is based on the geostatistical pilot point method of parameterization [de Marsily, 1978], coupled with a maximum likelihood definition of the inverse problem [Carrera and Neuman, 1986a]. The model combines a finite-volume flow simulator, FEHM [Zyvoloski et al., 1997], an automatic mesh generator, X3D [Trease et al., 1996], a parallelized version of an automatic parameter estimator, PEST [Doherty et al., 1994], and a geostatistical code, GSTAT [Pebesma and Wesseling, 1998]. The model accounts directly for the ability of all borehole intervals to store and conduct air through the system; solves the airflow equations in their original nonlinear form accounting for the dependence of air compressibility on absolute air pressure; can, in principle, account for atmospheric pressure fluctuations at the soil surface; provides kriged estimates of spatial variations in air permeability and air-filled porosity throughout the tested fractured rock volume; and is applied simultaneously to pressure data from multiple borehole intervals as well as to multiple cross-hole tests. The latter amounts to three-dimensional stochastic imaging, or pneumatic tomography, of the rock as proposed by Neuman [1987] in connection with cross-hole hydraulic tests in fractured crystalline rocks near Oracle, Arizona. The model is run in parallel on a supercomputer using 32 processors. Numerical inversion of single-hole pneumatic tests allows interpreting multiple injection-step and recovery data simultaneously, and yields information about air permeability, air-filled porosity, and dimensionless borehole storage coefficient. Some of this cannot be accomplished with type-curves [Inman and Neuman, 2000b]. Air permeability values obtained by my inverse method agree well with those obtained by steady-state and type-curve analyses. Both stochastic inverse analysis of cross-hole data and geostatistical analysis of single-hole data, yield similar geometric mean and similar spatial pattern of air permeability. However, I observe a scale effect in both air permeability and air-filled porosity when I analyze cross-hole pressure records from individual monitoring intervals one by one, while treating the medium as being uniform; both pneumatic parameters have a geometric mean that is larger, and a variance that is smaller, than those obtained by simultaneous stochastic analysis of multiple pressure records. Overall, my analysis suggests that (a) pneumatic pressure behavior of unsaturated fractured tuffs at the ALRS can be interpreted by treating the rock as a continuum on scales ranging from meters to tens of meters; (b) this continuum is representative primarily of interconnected fractures; (c) its pneumatic properties nevertheless correlate poorly with fracture density; and (d) air permeability and air-filled porosity exhibit multiscale random variations in space.

The Lyttelton Volcanic Complex, north-western Banks Peninsula, New Zealand, is comprised of five overlapping volcanic cones. Two magma systems are postulated to have fed Banks Peninsula’s basaltic intraplate volcanism, with simultaneous volcanism occurring in both the north-western and south-eastern regions of Banks Peninsula, to form Lyttelton and Akaroa Volcanic Complexes respectively. The elongate form of Banks Peninsula is postulated to relate to the upward constraining of magmatism in a north-west / south-east fault bounded zone. The Lyttelton Volcanic Complex resulted from the development of a pull-apart basin, with a number of releasing bend faults, controlling the location of eruptive sites. Cone structure further influenced the pathway magma propagated, with new eruptive sites developing on the un-buttressed flanks, resulting in the eruption and formation of a new cone, or as further cone growth recorded as an eruptive package. Each cone formed through constructional or eruptive phases, termed an eruptive package. Eruptive packages commonly terminate with a rubbly a’a to blocky lava flow, identified through stratigraphic relationships, lava flow trends and flow types, a related dyking regime, and radial erosional features (i.e. ridges and valleys). Within the overall evolving geochemical trend of the Lyttelton Volcanic Complex, are cyclic eruptive phases, intrinsically linked to eruptive packages. Within an eruptive package, crystal content fluctuates, but there is a common trend of increasing feldspar content, with peak levels corresponding to a blocky lava flow horizon, indicating the role of increased crystalinity and lava flow rheology. Cyclic eruptive phases relate to discreet magma batches within the higher levels of the edifice, with crystal content increasing as each magma batch evolves, limiting the ability of the volcanic system, over time, to erupt. Evolving magmas resulted in explosive eruptions following effusive eruptives, and / or result in the intrusion of hypabyssal features such as dykes and domes, of more evolved compositions (i.e. trachyte). Each eruptive package hosts a radial dyke swarm, reflecting the stress state of a shallow level magma chamber or a newly developed stress field due to gravitational relaxation in the newly constructed edifice, at the time of emplacement. Two distinct erosional structures are modelled; radial valleys and cone-controlled valleys. Radial valleys reflect radial erosion about a cone’s summit, while cone-controlled valleys are regions where eruptive packages and cones from different centres meet, allowing stream development. Interbedded epiclastic deposits within the Lyttelton lava flow sequences indicate volcanic degradation during volcanic activity. As degradation of the volcanic complex progressed, summit regions coalesced, later becoming unidirectional breached, increasing the area of the drainage basin and thus the potential to erode and transport extensive amounts of material away, ultimately forming Lyttelton Harbour, Gebbies Pass, and the infilled Mt Herbert region. Epiclastic deposits on the south-eastern side of Lyttelton Harbour indicate a paleo-valley system (paleo-Lyttelton Harbour) existed prior to 8.1 Ma, while the morphology of the Lyttelton Volcanic Complex directed the eruptive sites, style and resultant morphology of the proceeding volcanic groups.

Includes appendix on CD-ROM (p. 157). / Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 158-175). / Also available by subscription via World Wide Web / xiv, 175 leaves, bound ill. (some col., one folded), maps (some col.) 29 cm. +

Thesis (doctoral)--Freie Universität Berlin, 2004. / Title from cover. Vita. "April 2005"--P. [2] of cover. Includes bibliographical references (p. 115-126). Also available via the World Wide Web.