Trenton-Black River reservoirs in the Appalachian Basin are typically associated with fault-related hydrothermal dolomites that are sealed by unaltered host rocks. However the details of fault geometry and where porosity develops around faults remains poorly documented. Integration of 3-D seismic, wireline and production data from Saybrook Field in northeastern Ohio has shown that the productive trend is controlled by a 3.4mi (5.5 km) long, NW-SE oriented basement fault that was probably reactivated during the Taconic Orogeny in the Mid- to Late Ordovician. The far-field stresses of this compressional activity caused strike-slip movement of the pre-existing fault to create echelon synthetic shear faults that branch 1350ft (411.5m) upward into the Trenton-Black River interval. Circular collapse structures between overlapping shear faults are the primary drilling targets. Faults were mapped using amplitude and coherency versions of the seismic data. Curvature analysis of horizons mapped in the seismic data allowed us to further constrain the location and orientation of subtle structures. Fault morphology provides insights into the path of the dolomitizing fluids. The distribution of porosity, and thus the location of the reservoir, has been mapped in 3-D using a seismic attribute study that integrated wireline log-based measurements of porosity with seismic attributes. Our results show that the best porosity is developed in areas between overlapping synthetic shear faults. These locations likely represent areas where antithetic shear faults formed, and when combined with minor dip-slip movement created conduits for subsequent porosity generating fluids. The results of this study and the methodology presented here have application in analog settings elsewhere.

The Grey River Area lies on the south coast of Newfoundland. In general, it includes the land between Grey River and Haie de Vieux, lat. 470 40’ - 47°50’, long. 51’001 - 57°15 1. The area may be reached by steamer, which runs weekly between Port aux Basques and Argentia. The nearest major settlement is Burgeo, 24 miles west along the coast; Ramea, a minor fishing port lies 12 miles southwest on Ramea Island. The Grey River area is 87 miles due south of Buchans. It is accessible from the air, and both Grey River and Long Pond have adequate facilities for landing small sea planes. The Grey River fishing settlement lies on Grey River, about half a mile from the open sea. It is built on a small triangular alluvial cone, about 400 by 600 feet in dimension, inhabited by 30 families, with a total population of 250. The settlement is bordered on two sides by cliffs, which rise steeply to 800 feet above sea level. Inland, the country is uninhabited. / fr

Gaspé peninsula forms a tongue of land which extends into the Gulf of St. Lawrence, in the eastern part of the Province of Quebec. From its western boundary, the valley of the Matapedia river, to its eastern one, the Bay of Gaspé, the peninsula has a length of approximately 150 miles and a width, between the St. Lawrence estuary and the Bay of Chaleurs, of between 70 and 90 miles.

Dolomitization of Leduc Formation (Upper Devonian) along the southern part of the Rimbey-Meadowbrook trend in central Alberta occurred early by pervasive replacement, and later by minor cementation. Replacive dolomitization postdates submarine cementation and deposition of overlying shales, overlaps stylolitization, and produces $ delta sp{18}$O values indicating precipitation between 45 and 75$ sp circ$C. Therefore, this dolomitization likely originated at burial depths of more than 500 m. Strontium isotope ratios suggest that dolomitizing fluids were slightly more radiogenic than Upper Devonian sea water. Dolomite cements, however, are slightly depleted in oxygen-18, and contain primary fluid inclusions with high homogenization temperatures and salinities reflecting the different fluids responsible for their formation. / The distribution of pore types is governed by depositional facies, whereas effective porosity and permeability are strongly controlled by post-depositional processes. Late-stage cementation (anhydrite, dolomite, calcite, and native sulphur) reduces porosity. This cementation decreases northward, resulting in better reservoirs north of the Medicine River field, above present depths of 3000 m. Replacement dolomitization modified original pore type distribution, improved permeability, and helped retain porosity because dolomites are more resistant to pressure solution than limestones. Burial dissolution of dolomites may have been induced by mixing corrosion, maturation of organic matter, and thermochemical sulphate reduction.

Four types of dolomites occur in the Middle Devonian Presqu'ile barrier: fine-crystalline, medium-crystalline, coarse-crystalline, and saddle. Fine-crystalline dolomite formed penecontemporaneously by Middle Devonian seawater, because it is interbedded with Muskeg anhydrite in the back-barrier facies, and has O and Sr isotopic values of Middle Devonian seawater signatures. Medium-crystalline dolomite is interpreted to have formed: (1) at shallow burial depths by fluids derived from compaction, as indicated by its depleted $ delta sp{18}$O values and slightly radiogenic $ sp{87}$Sr/$ sp{86}$Sr ratios; or (2) soon after deposition by Middle Devonian seawater derived from the Elk Point basin, as suggested by its spatial distribution. Coarse-crystalline and saddle dolomites formed after sub-Watt Mountain exposure during burial. The homogenization temperatures of saddle dolomite fluid inclusions indicate that dolomitization occurred at temperatures exceeding maximum burial temperatures. The gradual decrease in Sr isotopes and homogenization temperatures with corresponding increase in O isotopes eastward along the Presqu'ile barrier suggests the basin-scale migration of hot and radiogenic dolomitizing fluids updip from west to east along the Presqu'ile barrier. Fluid movement probably was most active during Late Cretaceous and early Tertiary mountain building in conjunction with a gravity-driven flow system caused by uplift of the foreland basin. The Pine Point MVT deposits also occurred at this time since they overlapped with saddle dolomites. Extensive hydrothermal dissolution of carbonates preceded and overlapped with saddle dolomites.

Trends in relative sea-level change, shown by curves drawn from drill core and outcrop sections in Llandoverian carbonates of the Hudson Bay Platform, were used to correlate individual parasequences among widely separated localities. Two sequences, bounded by regional disconformities, include: (1) the Severn River Formation, and (2) the Ekwan River, Attawapiskat, and Kenogami River Formations. Initial onlap of marine facies at the base of the Severn River Formation progressed from north to south, occurring first in the Hudson Bay Basin, then in the Moose River Basin; final retreat of the seas at the end of Attawapiskat time was in the opposite direction. The most extensive inundations occurred during Ekwan River and Attawapiskat depositional times. Large-scale trends in the curves delineate four major Early Silurian sea-level highstands also recognized in other basins. / Reefs in outcrops along the Attawapiskat River represent one interval of reef growth, had a syndepositional relief of 8-10 meters, and were terminated by a relative sea-level fall. Their present distribution is controlled by variously uplifted fault blocks. / The most important diagenetic processes were early marine cementation and shallow burial diagenesis, and in the southwestern Moose River Basin early secondary dolomitization.

The East Fork Dike Swarm (EFDS) at Lost Trail Pass (LTP) is one of many dike swarms that lie within the North American Cordillera, a region that has been transformed through the complex interactions between contemporaneous tectonics and magmatism. Determining the age of the EFDS at LTP, and the LTP pluton into which the dikes are emplaced, further constrains the timing of regional extensional tectonics during the Eocene. Classifying variations in lithology and geochemistry in these rocks provides insight into the petrogenetic relationships between the rocks in this study and other regional intrusive and extrusive igneous features. Petrographic analysis was used to characterize variations in lithology within the dike swarm and pluton related to differences in cooling history and composition. X-ray fluorescence (XRF) whole rock geochemistry of the EFDS at LTP and the LTP pluton was compared to geochemical data from regional igneous features to determine the petrogenesis of the rocks of the dikes and pluton. 40Ar/39Ar thermochronology of biotite from 6 samples yielded cooling ages of 48 to 50 Ma for each sample. Petrographic analyses determined that the large range of cooling histories within the field area, evidenced by textures ranging from aphanitic to phaneritic, suggests partial crystallization within a magma chamber and rapid cooling upon shallow emplacement of magma. Additionally, geochemical results showed that there was a large degree of variation in compositions ranging from mafic to felsic, and variations in aluminum content from metaluminous to peraluminous. Based on these results it has been determined that the LTP pluton was emplaced shallowly, cooled quickly, and fractured while still warm at which time the EFDS at LTP was emplaced and experienced rapid cooling. The dikes and pluton in this study are petrogenetically related to the dikes swarms assessed by Simonsen (1997), and the Challis intrusive suites studied by Gaschnig et al. (2011), specifically the lithologically variable quartz monzodiorite suite. The EFDS at LTP and LTP pluton are likely sourced from reactivated arc magmas related to Sevier and Laramide orogenesis during the Cretaceous.

Thesis (M.S. - Geosciences)--University of Arizona. / Includes bibliographical references.

Thesis (M.S. - Geology)--University of Arizona. / Includes bibliographical references.

Thesis (M.S. - Geology)--University of Arizona. / Includes bibliographical references.