The Early Cretaceous Eumeralla Formation is regarded as an ineffective regional top seal in the Otway Basin, largely due to sand interbeds providing preferential hydrocarbon migration pathways. A deeper water lacustrine facies consisting of interbedded siltstones and claystones and massive claystones is developed at the base of the Eumeralla Formation in some wells. This interval ( Unit VI ) was deposited within a transgressive to early highstand systems tract and has better sealing properties than the other overlying Eumeralla Formation intervals. Theoretical gas column heights that the various Eumeralla Formation facies can support were calculated from mercury injection capillary pressure ( MICP ) analysis. Results range from 4 meters to 812 meters, and indicate that the fine-grained, lower Eumeralla Formation intervals have a higher seal capacity than the sand rich upper Eumeralla facies. However, the floodplain-dominated sediments commonly developed within the lower Eumeralla Formation are coal-rich and therefore associated with a high risk of brittle failure. Shallow lacustrine sediments have higher seal integrity, but are lithologically variable with extensive secondary porosity developed from dissolution of feldspar. The deeper lacustrine Unit VI provides the best Eumeralla seal for potential Katnook Sandstone and Windermere Sandstone Member reservoirs. Unfortunately, Unit VI is the only Eumeralla facies that is not developed entirely throughout the South Australian Otway Basin. The gamma ray log is generally unable to identify Eumeralla sandstone interbeds due to the sand's high volcanoclastic content. An integration of log data with seismic data, palynology, conventional core, and sidewall core and cuttings descriptions has enabled the seal geometry of the Eumeralla Formation to be determined. The deeper lacustrine Unit VI is locally developed in the St Clair Trough and on the flank of the Merino High. It is absent in the central Penola Trough and the Robe Trough, but could potentially be developed within the undrilled southern Penola Trough and in the Tantanoola Trough. Unit VI occurs preferentially in basins formed on the hanging wall of half grabens during late rift to early sag. The risk of top seal fracturing is considered high in the Robe Trough, and the Eumeralla Formation is very sandy in the central Penola Trough. Good seals are likely to be developed in the southern, predominantly offshore Otway Basin where Eumeralla sediments are generally deeper, and therefore more affected by mechanical compaction and diagenesis. / Thesis (M.Sc.)--Australian School of Petroleum, 2004.

Thesis (M.S.)--Oregon State University, 1970. / Typescript. Mounted photographs. Includes bibliographical references (leaves 56-57). Also available online.

Artificial perturbations of borehole water levels, or slug tests, are a commonly employed means of characterizing the glacier hydrologic system. Results documenting the influence of slug testing on a field of boreholes and its change with time, however, are scarce. Slug tests were performed on Bench Glacier, AK in 21 boreholes over three field seasons during an annual late spring glacier speed up event. Fifty four slug tests were conducted, with water level monitoring in up to five boreholes adjacent to the slugged borehole. Seven of the slug tests were performed in conjunction with dye dispersion tests to identify water pathways within the slugged borehole following perturbation. Underdamped and overdamped slug test responses show a high degree of connectivity among boreholes connected via the glacier bed. The nature and degree of connectivity is temporally variable, suggesting that the drainage network at the bed is highly dynamic on time and space scales of hours and 10s of meters, respectively. The changes we document in slug test responses over time and space can be used to constrain explanations for the cause of the underdamped response. Examination of the underdamped response necessitates an understanding of the process(es) acting as the spring to produce the oscillatory water level behavior. We propose that coherent air packages are a likely means of producing the compliance needed to generate the underdamped slug test response, and that these air packages may exist within the glacier at the tips of subglacially propagated fractures. Synthesis of slug testing with other methods of study, such as video observation and dye tracing, helps lend insight into the governing processes at the glacier bed.

This thesis presents results from 1:24,000 scale surface mapping and related analysis of geology within the Rock Creek Lake 7.5 USGS Quadrangle in western Montana. The purpose of this study is to 1) document the Cenozoic structural evolution and sedimentary fill record associated with tectonic development of the northern Flint Creek Range and, in particular, the Anaconda metamorphic core complex and 2) determine the existence and extent of Pleistocene glacial deposition in the study area. Gneissic mylonitic granodiorite along the southeastern contact of the Royal Stock intrusion indicates the Anaconda metamorphic core complex detachment zone trends through the center of the map area but diminishes to the north. Synthetic top-to-the-east normal faults throughout the study area are interpreted as joining the main detachment at depth. Granitic and metamorphic rock fragments observed during provenance studies of sandstones and conglomerates indicate the initial opening of the Gold Creek basin was contemporaneous with the unroofing of the Anaconda metamorphic core complex. The upper Renova Formation observed in the study area is equivalent to the upper Renova Cabbage Patch beds best developed in the Flint Creek basin to the west and indicate primarily lacustrine, fluviatile, and palustrine depositional environments. Quaternary glacial deposits attributed to the Pinedale Glaciation consist of narrow, sharp-crested moraines (mean crest width of 5m) with high distal slope angles (average 30°) and primarily consist of relatively unweathered granitic boulders. Deposits interpreted as reflecting the Bull Lake Glaciation are characterized by wide, round-crested moraines (mean crest width of 50-100m) and low distal slope angles (average 10-20°), with little exposure of quartzite and weathered granite boulders at the surface. Formation of the Gold Creek basin was influenced by Cenozoic relaxation of Cretaceous thrust faults, extension from the Anaconda metamorphic core complex, and dextral transtension along the Lewis and Clark Lineament.

With the discovery of Na-sulfate minerals (thenardite, mirabilite) on Mars and Europa, recent studies using these minerals have focused on their ability to assist in the detection of biosignatures. On Earth, biotic and biotic processes can assist in the formation and deposition of these minerals. A primary objective of these studies is the detection of bio/organic compounds that may be associated with the mineral. These biosignatures would imply biological involvement during mineral formation. The following research presents a series of natural and synthetic investigations to determine if biological activity is associated with Na-sulfate mineralization, and if these minerals can assist in detecting bio/organic compounds. Evidence for biological activity associated with the formation of Na-sulfate deposits in the basaltic subsurface of Craters of the Moon National Monument, Idaho was examined by laser desorption Fourier transform mass spectrometry (LD-FTMS), infrared spectroscopy and sulfur isotopic fractionation. These experiments show that bio/organic compounds are likely associated with the secondary Na-sulfate minerals, suggesting biological involvement in the mineralization of these deposits. LD-FTMS results of the synthetic bio/organic-mineral combinations show the potential of Na-sulfate minerals to assist in the detection and identification of bio/organic compounds. These results prove the importance of Na-sulfate minerals for future exploration missions that are likely to use LDMS to search for signs of life in the solar system.

The discovery of jarosite on Mars in 2004 generated increased interest in the properties of the mineral related to the search for life on other planets. Several studies indicate that the formation of jarosite can be linked to biological activity on Earth and biomolecules such as amino acids have been found associated with terrestrial jarosite samples. A series of natural and synthetic investigations using different jarosite end-members has been conducted and is presented in this dissertation to investigate the possibility that jarosite can store biosignatures. Natural samples were analyzed by x-ray diffraction, elemental carbon analysis and laser-desorption Fourier transform mass spectrometry (LD-FTMS) and were found to contain the amino acid glycine. Synthetic experiments were conducted in which the different end-members were synthesized in the presence of glycine as well as the amino acid alanine and the amino acid breakdown product methylamine. These samples were analyzed by x-ray diffraction, neutron diffraction, LD-FTMS and thermogravimetric analysis (TGA) techniques. Results of these experiments show that the detection of the biosignature and the effect that biomolecule has on the jarosite minerals is dependent on the end-member and indicate that the jarosite minerals are an excellent target for detecting potential signs of past life on other planets.

Tertiary terrestrial sedimentary rocks of the Big Hole basin and Pioneer Mountains of southwestern Montana provide a record of regional extensional tectonism. Detailed observations of stratigraphy and sedimentology at widely scattered outcrops indicate the presence of paleosols, fine-grained debris flows, small alluvial channels, and rare fluvial deposits. U-Pb geochronology of detrital zircons and air-fall tuffs indicates the presence of Oligocene to Middle Miocene sedimentary rocks outcropping at the surface. Though the presence of detrital muscovite in several outcrops indicates derivation from the nearby 2-mica Chief Joseph pluton, a predicted ~75 Ma zircon population is not present: instead, a persistent peak of 70-72 Ma zircons is found throughout the basin, indicating the Chief Joseph pluton may have a younger emplacement age than is currently recognized. Simple physical models developed from Bouguer anomalies indicate the basin deepens and widens toward the south, which agrees with prior work suggesting Eocene initiation of extension in the Big Hole and places it in a class of extensional basins that formed in the early Tertiary. Late Cretaceous, Eocene, and Mesoproterozoic detrital zircon populations, along with consistently immature lithic sands, all indicate sediments were derived from local bedrock sources found around the rim of the modern Big Hole Valley. While these results indicate the Tertiary Big Hole basin resembled the modern basin, some later deformation may have cut off and reversed a paleodrainage flowing out of the southeastern portion of the basin, possibly leading to the modern configuration of the Big Hole River and the deep gorge it carves across the eastern Pioneer Mountains.

The sub-Middle Jurassic unconformity exhumed at Swift Reservoir, in the Rocky Mountain thrust belt of Montana, exposes structures that call for a re-evaluation of the deformation history at this locale. The unconformity separates Late Mississippian Madison Group carbonate (~340 Ma) from the transgressive basal sandstone of the Middle Jurassic (Bajocian-Bathonian) Sawtooth Formation (~170 Ma). Fieldwork established that northwest-trending, karst-widened fractures (grikes) are filled with cherty, phosphatic sandstone and conglomerate of the Sawtooth Formation and penetrate the Madison Group for 4 meters below the unconformity. Clam borings, filled with Sawtooth sandstone, pierce the unconformity surface, some of the fracture walls, and also perforate rounded clasts of Mississippian limestone that lie on the unconformity surface within basal Sawtooth conglomerate. Following deposition of the overlying foreland basin clastic-wedge, the grikes were stylolitized by layer-parallel shortening and buckled over fault-propagation anticlinal crests in the Late Cretaceous-Paleocene fold-and-thrust belt. The model proposes that the grikes record uplift and erosion followed by subsidence as the Rocky Mountain foreland experienced elastic flexure in response to tectonic loading at the plate boundary farther to the west during Early Jurassic; the forebulge opened strike-parallel fractures in the Madison Group that were karstified. The grike system contributes to the secondary porosity and permeability of the upper Madison Group; a major petroleum reservoir in the region. Grikes acted as fluid pathways during basin evolution as seen from the clay mineral assemblage and fluid inclusions contained within the grike fill. Mixed-layer illite-smectite (I/S) indicates that the grikes did not exceed 210∞ C (complete smectite-illite transition). The illite likely resulted from superstaturated fluids flushing through the foreland at the onset Laramide orogeny and may have been coincident with hydrocarbon migration. Hydrocarbon inclusions contained within the grike cements were trapped at temperatures ranging from 110∞-170∞ C; correlative with the clay temperature calculations. Recognition of the fractures as pre-middle Jurassic revises previous models, which related them to Cretaceous fracturing over the crests of fault-propagation folds, substantially changing the understanding of the hydrocarbon system.

The discovery of jarosite on Mars in 2004 generated increased interest in the properties of the mineral related to the search for life on other planets. Several studies indicate that the formation of jarosite can be linked to biological activity on Earth and biomolecules such as amino acids have been found associated with terrestrial jarosite samples. A series of natural and synthetic investigations using different jarosite end-members has been conducted and is presented in this dissertation to investigate the possibility that jarosite can store biosignatures. Natural samples were analyzed by X-ray diffraction, elemental carbon analysis and laser-desorption Fourier transform mass spectrometry (LD-FTMS) and were found to contain the amino acid glycine. Synthetic experiments were conducted in which the different end-members were synthesized in the presence of glycine as well as the amino acid alanine and the amino acid breakdown product methylamine. These samples were analyzed by X-ray diffraction, neutron diffraction, LD-FTMS and thermogravimetric analysis (TGA) techniques. Results of these experiments show that the detection of the biosignature and the effect that biomolecule has on the jarosite minerals is dependent on the end-member and indicate that the jarosite minerals are an excellent target for detecting potential signs of past life on other planets.

Thesis (M.S.)--Oregon State University, 1970. / Typescript (photocopy). Some maps folded in pocket. Includes bibliographical references. Also available online.