Thesis (M. Sc.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 190-202). Also available via the World Wide Web.

<p> The St. Cyr klippe hosts well preserved to variably retrogressed eclogites found as sub-meter to hundreds of meter scale lenses within quartzofeldspathic schists in the Yukon-Tanana terrane, Canadian Cordillera. The St. Cyr area consists of structurally imbricated, polydeformed, and polymetamorphosed units of continental arc and oceanic crust. The eclogite-bearing quartzofeldspathic schists form a 30 by 6 kilometer thick, northwest-striking, coherent package. The schists consist of metasediments and felsic intrusives that are intercalated on the tens of meter scale. The presence of phengite and Permian age zircon crystallized under eclogite facies metamorphic conditions indicates that the eclogite was metamorphosed <i>in situ</i> with its quartzofeldspathic host. </p><p> I investigated the metamorphic evolution of the eclogite-facies rocks in the St. Cyr klippe using isochemical phase equilibrium thermodynamic (pseudosection) modeling. I constructed <i>P-T</i> pseudosections in the system Na₂O-K₂O-CaO-FeO-O₂-MnO-MgO-Al₂O₃-SiO₂-TiO₂-H₂O for the bulk-rock composition of an eclogite and a host metatonalite. In combination with petrology and mineral compositions, St. Cyr eclogites followed a five-stage clockwise <i> P-T</i> path. Peak pressure conditions for the eclogites and metatonalites reached up to 3.2 GPa, well within the coesite stability field, indicating the eclogites reached ultrahigh-pressure conditions. Decompression during exhumation occurred with a corresponding temperature increase. </p><p> SHRIMP-RG zircon dating shows that the protolith of the eclogites formed within the Yukon-Tanana terrane during early, continental arc activity, between 364 and 380 Ma, while the metatonalite protolith formed at approximately 334 Ma, during the Little Salmon Cycle of the Klinkit phase of Yukon-Tanana arc activity. Both the eclogites and the metatonalites were then subducted to mantle depths and metamorphosed to ultrahigh-pressure conditions during the late Permian, between 266 and 271 Ma. The results of our study suggest portions of the Yukon-Tanana terrane were subducted to high-pressure and ultrahigh-pressure conditions. This is the first report of ultrahigh-pressure metamorphism in the accreted terranes of the North American Cordillera. Petrological, geochemical, geochronological, and structural relationships link the eclogites at St. Cyr to other eclogite localities in Yukon, indicating the high-pressure assemblages form a larger lithotectonic unit within the Yukon-Tanana terrane.</p>

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<p> The Davis-Schrimpf Seep Field is a cluster of about 50 transtension-related geothermal seeps in the Imperial Valley, southeastern California. Five temperature time-series were collected from four features and compared to one another, against prior time-series, and to local seismicity. Loggers placed in separate vents within one seep returned moderate anti-correlation. Vents may selectively clog and unclog. Clogging frequencies explaining the observed level of negative correlation were given. Loggers placed in the same vent produced 87-92% positive correlation. It is therefore likely that the vast majority of temperature data measured with loggers possesses meaningful accuracy. Loggers placed in separate seeps exhibited correlation close to or greater than the statistically significant 60% threshold. I propose two lineaments provide a hydraulic connection between these seeps. Two M_w>3.0 earthquake swarms, including one M_w>4.0 event, within 24 kilometers showed possible linkage with >5 degree Celsius temperature perturbations. Seepage warmed 14.5-36.8 degrees Celsius over 5-7 years.</p>

The collision of the Indian subcontinent with Asia beginning 40 million years ago produced the Himalayan orogenic belt, the largest continental collision belt active today. The foreland fold-and-thrust belt in northern Pakistan consists of the Salt Range-Potwar Plateau area. In this region the distance from the Main Boundary Thrust(MBT) to the front of the fold-and-thrust belt is very wide (100-150 km) because a thick evaporite sequence forms the zone of décollement. Recent studies have combined seismic reflection profiles, petroleum exploration wells, Bouguer gravity anomalies, and surface geology to construct cross sections in the eastern, central, and western Salt Range-Potwar Plateau areas. In this study the sections are compared with a previous model that considers the mechanics of a fold-and-thrust belt to be analogous to that of a wedge of snow or soil pushed in front of a bulldozer (Davis et al., 1983; Dahlen et al., 1984; Dahlen, 1984), and a later model (Davis and Engelder, 1985) which suggests that fold-and-thrust belts underlain by salt will have: a) narrow (< 1°) cross-sectional tapers, b) larger widths than areas not underlain by salt, c) symmetrical structures, and d) changes in deformational style at the edge of the salt basin. The section across the eastern Potwar Plateau most closely resembles this latter model, having: a) a taper of 0.8° ± 0.1°, b) a width of 100-150 km, c) thrust faults that verge both to the north and south, and d) structures rotated 30° counterclockwise with respect to the Salt Range. From the observed taper and pore fluid pressures of the eastern Potwar Plateau, estimates of the values for the yield strength of the evaporites (τ₀) and the coefficent of internal friction (μ) are calculated as τ₀ = 1.33-1.50 MPa and μ = 0.95-1.04, which are then applied to the other cross sections. In the central and western sections a basement uplift, the Sargodha High, interferes with the front of the fold-and-thrust belt. This feature causes the ramping of the Salt Range Thrust and produces a relatively steep basement slope (2°-4°) beneath the Potwar Plateau. This dip, together with the weak evaporite layer, allows the thrust wedge of the southern Potwar Plateau to be pushed over the décollement without undergoing internal deformation. In detail, the Salt Range ramping is caused by a large normal fault in the basement in the central section and the basement upwarp of the Sargodha High in the western section. The northern Potwar Plateau is strongly folded and faulted, yet the topographic slope remains flat. Although the deformation suggests that salt is not present there, the observed taper in the northern Potwar Plateau is best fitted by the model with salt at the décollement. Combining this with published paleomagnetic and geologic constraints, a model for the evolution of the northern Potwar Plateau suggests that the area deformed as a steeply tapered (3.5°-5.5°) thrust wedge until approximately 2 million years ago, when the décollement encountered the Salt Range formation. Between 2 m.y.a. and the present, the northern Potwar Plateau has been pushed along the salt décollement without deformation, and erosion has reduced its original steep topographic slope to a nearly level surface. The success of the mechanical model in predicting the observed features in the Salt Range-Potwar Plateau suggests that salt may lie beneath other fold-and-thrust belts in Pakistan. Two areas, the Sulaiman Lobe and the Karachi Arc, are possible candidates. Although published subsurface information is lacking in these areas, surface observations show that they both: a) extend far across the foreland, b) exhibit low topographic slopes, c) display symmetrical structures, and d) show a change in structural orientation along what is believed to be the edge of the salt basin. / Graduation date: 1987

Modern, powerful techniques for the residual analysis of spatial-temporal point process models are reviewed and their power under various null and alternative hypotheses is compared. Residual methods can be divided into two schemes: transformation-based and pixel-based methods. Rescaling, thinning and superposition are useful transformation-based methods for the residual analysis of spatial-temporal point processes. These techniques involve transforming the original point process into a new process that should be a homogeneous Poisson process if and only if the fitted model is correct, so that one may inspect the residual process for homogeneity using standard tests for homogeneity as a means of assessing the goodness-of-fit of the model. Unfortunately, tests of homogeneity performed on residuals based on these three residual methods tend to have low power when the modeled conditional intensity of the original process is volatile. For such purposes, we propose the method of super-thinning, which combines thinned residuals and superposition. This technique involves the use of a tuning parameter, k, which controls how much thinning and superposition are performed to homogenize the process. The method is applied to the assessment of a parametric space-time point process model for the origin times and epicentral locations of recent major California earthquakes. / These residual methods are then applied to California earthquake forecast models used in the Collaboratory for the Study of Earthquake Predictability (CSEP). Assessments of these earthquake forecasting models have previously been performed using simple, low-power means such as the L-test and N-test. We instead propose using the transformation residual methods for model assessment, and the pixel-based methods, such as Pearson and deviance residuals, to compare competing models. The different residual analysis techniques are demonstrated using the CSEP models and are used to highlight certain deficiencies in the models. / Both pixel-based and transformation methods are evaluated through a simulation study by applying each method to a group of Hawkes processes that contain different degrees of clustering and inhibition. Pixel-based methods, such as raw, Pearson, inverse, deviance, and tessellation residuals appear to be generally weaker than transformed residuals at detecting insufficient or excessive local clustering in the model. The transformation method of super-thinning is shown to have relatively high power when the value of the tuning parameter, k, is carefully chosen. / Finally, we introduce the R package stppResid, which implements both transformation and pixel-based residual analysis for space-time point process models. We illustrate the use of each of these residual tools by applying them to a well known space-time point process model fitted to a red banana data set.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.