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Active seismicity and volcanism north of Washington state’s Mount St. Helens provide key ingredients for hydrothermal circulation at depth. This broad zone of seismicity defines the St. Helens Seismic Zone, which extends well north of the volcanic edifice below where several faults and associated fractures in outcrop record repeated slip, dilation, and alteration indicative of localized fluid flow. Candidate reservoir rocks for a geothermal system include marine metasediments overlain by extrusive volcanics. The colocation of elements comprising a geothermal system at this location is tested here by analysis of the structures potentially hosting a reservoir, their relationship to the modern stress state, and temperature logs to a depth of 250 m. Outcrop mapping and borehole image log analysis down to 244 m document highly fractured volcaniclastic deposits and basalt flows. Intervening ash layers truncate the vertical extent of most structures. However, large strike slip faults with well-developed fault cores and associated high fracture density cross ash layers; vein filling and alternation of the adjacent host rock in these faults suggest they act as vertically extensive flow paths. These faults and associated fractures record repeated slip, dilation, and healing by various dolomite, quartz, and hematite, as well as clay alteration, indicative of long-lived, localized fluid flow. In addition, where these rocks are altered by igneous intrusion, they host high fracture density that facilitated heat transfer evidenced by associated hydrothermal alteration. Breakouts in image logs indicate the azimuth of SHmax in the shear zone is broadly consistent with both the GPS plate convergence velocity field as well as seismically active strike slip faults and strike-slip faults mapped in outcrop and borehole image logs. However, the local orientation of SHmax varies by position relative to the edifice and in some cases with depth along the borehole making a simple regional average SHmax azimuth misleading. Boreholes within the seismic zone display a wider variety of fracture attitudes than those outside the shear zone, potentially promoting permeability. Temperature profiles in these wells all indicate isothermal conditions at average groundwater temperatures, consistent with rapidly flowing water localized within fractures. Together, these results indicate that the area north of Mount Saint Helens generates and maintains porosity and permeability suggesting that conditions necessary for a geothermal system are present, although as yet no modern heat source or hydrothermal circulation was detected at shallow depth. / Geology

The original document does not provide an abstract. McMaster Digitization Centre, 14 March 2019. / Thesis / Master of Arts (MA)

There is a definite lack of information on treponemal infections in Canada. This thesis attempts to add to the knowledge on treponemal infections from studying outbreaks of the disease from smaller geographic regions of Canada. The purpose of this thesis is to study an alleged outbreak of syphilis, known as St. Paul's Bay Disease (SPBD) and to learn as much as possible about this disease, including its clinical and epidemiological characteristics, diagnosis and origins. This thesis provides evidence to support the contention that this 18th century outbreak of SPBD was not venereal syphilis, but rather endemic syphilis. The findings of this study were drawn from multiple lines of qualitative and quantitative evidence. The descriptions of SPBD by the medical practitioners of that time period reflect a high degree of similarity between SPBD and endemic syphilis. These descriptions contain information on the symptoms, method of treatment, method of transmission and diagnosis of SPBD. Furthermore, when SPBD was compared to the Sibbens of Scotland (a confirmed outbreak of endemic syphilis) they were found to be almost indistinguishable. Lastly, the distribution and prevalence of SPBD among the affected populations were found to be more characteristic of endemic syphilis. It is suggested that future research be carried out in three major areas: the ethnohistory of the various towns in Lower Canada, the origins of SPBD, and lastly, why the disease 'suddenly' disappeared. All of which will bring us one step closer to both understanding this outbreak and the history of treponemal infections in general. / Thesis / Master of Arts (MA)

High arsenic concentrations (>100 ppb) have been measured in wells completed in the Ordovician St. Peter sandstone aquifer of eastern Wisconsin. The primary source of arsenic is As-bearing sulfide minerals within the aquifer. There is concern that periodic disinfection of wells by chlorination may facilitate arsenic release to groundwater by increasing the rate of sulfide mineral oxidation. Current guidance from the Wisconsin Department of Natural Resources recommends a "low-dose" treatment of 20% of the chlorine strength and 10% of the of the contact time of chlorine treatments used in non-arsenic impacted wells for well disinfection and biofilm removal. In order to provide information pertaining to WDNR's recommendations, St. Peter sulfide minerals were reacted with a range of chlorine "shock-treatments" similar to those occurring in wells. This study focuses on abiotic processes that mobilize arsenic from the solid phase during controlled exposure to chlorinated solutions. Thin sections were made from aquifer material collected at Leonard's Michael quarry, located in Winnebago County, Wisconsin. Bulk arsenic content of this material was measured as 674 ppm. Quantitative EPMA analysis shows As zoning in pyrite grains with concentrations up to 1 wt. % As. After mineral characterization, the thin sections were exposed to solutions of 60 mg/L "free chlorine," 1200 mg/L "free chlorine," and nanopure water (control) at pH 7.0 and pH 8.5 for 24 hours. Thin sections were then analyzed to measure changes in the pyrite surfaces. For solution experiments, aquifer material was crushed to between 250 μm and 355 μm mesh sizes (S.A. ~ 50 cm2/g – 60 cm2/g, Foust et al. 1980) and reacted under the same conditions as the thin sections in a batch reactor. Solution samples were collected periodically during the 24 hour exposure and analyzed for arsenic, iron, and sulfate ion. Pyrite oxidation is shown to dramatically increase with increasing chlorine concentrations as shown by measurements of released sulfate ion, used here as the reaction progress variable. EPMA maps also reveal complete oxidation of pyrite cements to Fe-oxyhydroxides at 1200 mg/L "free chlorine" and pH 7.0. This behavior does not occur at lower concentrations or higher pH. Arsenic release to solution does not appear to be directly correlated to increasing chlorine concentrations, but is governed by Fe-oxyhydroxide nucleation, which inhibits the release of dissolved arsenic at higher concentrations of chlorine. / Master of Science