Call number: LD2668 .T4 1986 M45 / Master of Landscape Architecture / Landscape Architecture/Regional and Community Planning

L'étude a pour but de caractériser les facteurs de contrôles de la distribution des propriétés pétrophysiques et mécaniques dans les réservoirs carbonatés. Pour y répondre, il a été entrepris une démarche intégrant des analyses sédimento-diagénétiques (sédimentologiques, pétrographiques, géochimiques…) et de la fracturation (stratigraphie mécanique et stratigraphie de fracture, hiérarchisation, chronologie…). L'acquisition des données a été réalisée sur un analogue de terrain d'un réservoir carbonaté fracturé : la Formation Madison, d'âge Carbonifère inférieur (357-340 Ma), affleurant dans le Bassin de Bighorn (Wyoming, USA) et qui est aussi un réservoir exploité en subsurface. Cette acquisition a été réalisée dans cinq sites : Wind River Canyon, Shell Canyon, Sheep Mountain, Shoshone Canyon, et Clark's Fork Canyon (selon une polarité paléogéographique proximale - distale).Dans le Wyoming (USA), la Formation Madison est une série carbonatée, atteignant une épaisseur de 340 m, formée de sept séquences de dépôt basse fréquence (SBF). Les deux premières (SBF1 et 2) se sont formées sur une rampe qui, en conséquence de progradations extensives, s'est aplanie progressivement pour former une plate-forme sur laquelle se sont déposées les cinq autres séquences (SBF3 à 7). SBF1 à 3, d'âge Kinderhookien à Osagéen inférieur, se sont formées sous climat aride à la faveur d'une subsidence tectonique générale compensant les chutes eustatiques épisodiques. Les cortèges de rétrogradation se caractérisent par le développement étendu des milieux inter- à supratidaux et des processus de précipitation d'évaporites et dolomitisation. / The purpose of this study is to characterize factors controlling the distribution of the petrophysical and mechanical properties in carbonate reservoirs. To do so, a pluridisciplinary approach integrating sedimento-diagenetic and fracturing analyses on a carbonate reservoir analogue: he Madison Formation, (Lower Carboniferous, 357-340 My), outcropping in the Bighorn Basin (Wyoming, USA) and that is also a subsurface reservoir.The Madison Formation is a 340 m thick carbonate series composed of seven low frequency depositional sequences (LFS). The first two (LFS 1 and 2) formed on a prograding ramp passing upward into a vast platform on which the other five LFS deposited (LFS3 à 7). LFS 1 to 3 (Kinderhookian to lower Osagean) deposited under arid conditions during general subsidence that balanced eustatic falls. Retrograding system tracts are characterized by the development of supratidal to intertidal environment dominated by evaporite precipitations and carbonate dolomitization. Prograding system tracts are mainly mainly by early-lithified grainstones. LFS 4 to 7 (Osagean) deposited under humid conditions (glacial conditions in high-latitudes) that contributed to a decrease in evaporite precipitations and carbonate dolomitization but that involved karstifications on tops of LFS 4 to 7 during uplift episodes and eustatic falls.

Thesis. 1977. M.C.P.--Massachusetts Institute of Technology. Dept. of Urban Studies and Planning. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Includes bibliographical references. / M.C.P.

This research investigates different scenarios of deltaic deposition, both in shelfbreak and ramp settings. I address four ancient cases with particular characteristics: 1) A shelf-margin case from the Eocene Battfjellet Formation, West Spitsbergen, Norway, in which deltas were able to migrate to the shelf-edge during rising and sea-level highstand conditions despite the low-supply character of the system (low progradation/aggradation rates compared to analogous margins), with consequent sand starvation on the slope and deeper areas of the basin. The delta system was overall wave-dominated, with restricted tide-influence at the mouth of the distributaries and more accentuated tide-influence during the transgressive transit of the deltas; 2) A shelf-margin case from the Pliocene paleo-Orinoco Delta System, Mayaro Formation, SE-Trinidad, in which high rates of sediment supply from the paleo-Orinoco River and exceptionally high subsidence rates due to growth-faulting, produced a spectacular stacking of sandstones on the outer shelf and shelf-edge areas, but with apparently limited sand delivery into deeper waters. The delta system was overall storm-wave dominated, with fluvial-influence in the lower segment of the system and some tide-influence in association with the fluvial-influence; 3) A case from a shallow-water ramp, Campanian Rock Springs Formation (Western Interior Seaway), in which deltas accumulated along relatively straight, north-south oriented shorelines highly impacted by wave-storm processes. Tide-influence was limited to the mouth of the distributaries, and fluvial deposits mostly developed within the coastal-plain areas; and 4) A case from the same ramp setting as (3) but in an outer-ramp site, Campanian Haystack Mountains Formation, in which a lowering in sea-level translated the delta system tens of kilometers eastwards into the basin. As a consequence of a shallower and narrower seaway, southerly-oriented tidal currents were enhanced and subsequently skewed or re-aligned the delta system to the south. The key contributions of this research concern (1) the feasibility of shelf-margin accretion during rising and highstand of sea level, (2) the critical importance of shelf width and sediment supply (and not only sea-level behavior) to bring deltas to the shelfedge, and (3) the possible tendency for tides enhancement in the distal reaches of shallow seaway ramps, caused by narrowing of the seaway and fault-topography enhancement during falling sea level. / text

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Advances in seismology allow us to obtain "high-resolution" images of the Earth's subsurface. This dissertation summarizes the results of three seismic studies on three different continents, with the aim of better understanding the crust and upper mantle structure of seemingly disparate yet ultimately related regions. The seismic techniques of Pn tomography and P-wave receiver function (RF) analysis are applied to central Turkey (Pn tomography), western Argentina and southwestern Wyoming, USA (RF analysis). These studies look at both a present-day convergent margin (Andean subduction zone, Argentina) and two ancient ones (Bitlis-Zagros collision zone of Arabia-Africa with Eurasia, Turkey; Farallon subduction zone, Wyoming).Using Pn tomography, we were able to detect the limit of the slab rupture edge along the Central Anatolian Fault Zone, Turkey. Slab break-off is an important process that modifies the mantle in tectonically active regions, and the limit of the oceanic Arabian slab break-off along the Bitlis-Zagros Suture Zone, thought to have begun at 11 Ma, was previously undetermined.Using RF analysis, we obtained high-resolution images of the subducting slab beneath the Sierras Pampeanas, Argentina. Continental Moho contours roughly follow terrane boundaries, suggesting that ancient terranes continue to exert control over present-day continental deformation. Overthickened oceanic crust is often cited as a cause of flat slab subduction; our RF results indicate that the crust is moderately overthickened, around 11-16 km. Further, we image offsets in the RF arrivals that indicate the subducted slab is broken or offset in along trench-subparallel fractures.The crustal structure beneath southwestern Wyoming, the location of ancient Farallon flat slab subduction, was studied using RF analysis. Looking at regional crustal structure, results include a new depth to Moho map. Coherency of the seismic signal across the dense LaBarge array (55 stations, ~250 m spacing) was investigated, with results showing that complicated shallow structure can greatly impact the resulting RF signal. Modeling of RFs using synthetics helped to separate the complex signal containing multiple primary conversions and their reverberations, which interact constructively and destructively. The dense spacing of the LaBarge array allowed unique opportunities to investigate coherency of waveforms across very short distances.

In Annie Proulx's interview with Charlie Rose, she states that her stories come "from place." Ecocriticism has been the predominant lens with which to understand Proulx's work; however, ecocriticism's nebulous tenets and theoretical deficiencies perpetuate sentimental pastoralism of geographical determinism. The shaping impact of Wyoming's environment in Proulx's work lends itself to an evolutionary perspective. Proulx's fiction, like evolutionary theory, examines humanity's unique, reciprocal relationship with nature. The evolutionary approach provides readers with a framework to understand the human relationship to our environment, a theme Proulx's work examines. This approach also augments current criticism that notes the importance of place but does not utilize the relevant framework of evolution. Current evolutionary theory provides the theoretical framework necessary to shed light on the relationship between Proulx's colorful characters and the environment that shapes them. Utilizing this evolutionary framework and textual analysis, I examine two short stories, "The Half-Skinned Steer" and "Wamsutter Wolf."

Thesis. 1979. M.C.P.--Massachusetts Institute of Technology. Dept. of Urban Studies and Planning. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: leaves 172-177. / by Daniel P. Kurtz. / M.C.P.

The long-term (>1 Ga) thermal histories of cratons are enigmatic, with geologic data providing only limited snapshots of their evolution. We use zircon (U-Th)/He (zircon He) thermochronology and age composition correlations to understand the Proterozoic-Phanerozoic thermal history of Archean Wyoming province rocks exposed in the northern Laramide ranges of western North America. Zircon He ages from the Wind River Range (54 dates) and Bighorn Mountains (32 dates) show negative correlations with effective uranium (eU), a proxy for radiation damage. Zircon dates from the Bighorns are between 960 Ma (low-eU) and 20 Ma (high-eU) whereas samples from the Wind Rivers are between 582 Ma (low-eU) and 33 Ma (high-eU). We applied forward modeling using the zircon radiation damage and annealing model ZrDAAM to understand this highly variable dataset. A long-term t-T path that is consistent with the available geologic constraints successfully reproduced age-eU correlations. The best fit to the Wind Rivers data involves two phases of rapid cooling at 1800-1600 Ma and 900-700 Ma followed by slower cooling until 525 Ma. During the Phanerozoic, these samples were heated to maximum temperatures between 160 and 125 degrees C prior to Laramide cooling to 50 degrees C between 60 and 40 Ma. Data from the Bighorn Mountains were successfully reproduced with a similar thermal history involving cooler Phanerozoic temperatures of similar to 115 degrees C and earlier Laramide cooling between 85 and 60 Ma. Our results indicate that age-eU correlations in zircon He datasets can be applied to extract long-term thermal histories that extend beyond the most recent cooling event. In addition, our results constrain the timing, magnitude and rates of cooling experienced by Archean Wyoming Province rocks between recognized deformation events, including the >1 Ga period represented by the regionally-extensive Great Unconformity.

A study of a 250 ft. (76.2 m) stratigraphic interval that includes the Eocene-age Felix coal of the Wasatch Formation was undertaken in the Powder River Basin of Wyoming to establish a depositional model based on the interrelations of coal-seam geometry, coal maceral composition, and spatial distribution of adjoining rocks. Regional cross sections and maps of major rock bodies were prepared from 147 measured stratigraphic sections and 56 geophysical logs. Trends in maceral and chemical properties within the Felix coal were identified from petrographic and geochemical analyses of 72 coal channel samples. The combined data sets indicate that the thickest portions of the coal are underlain by widespread, interconnected, sandstone-dominated fining-upward sequences (< 50 ft. or 15 m thick over a 300 sq. mi. or 777 sq. km area) whereas areas of thin or split coal are underlain by stacked predominantly fine grained, coarsening-upward sequences (< 50 ft. or 15 m thick). Above the coal, fining-upward sequences are concentrated over thin coal areas and widespread (> 20 mi., 32 km wide) coarsening-upward sequences overlie thick coal areas. Megascopic and petrographic description of the coal indicates that the brightest coal contains the greatest amount of huminite. This type coal occurs in the lowest portion of the seam and directly above clay partings in thick coal areas and in split benches · on the margin of the deposit. The central and upper portion of the seam is predominantly dull, and inertinite percentages increase towards the top of the seam. The deposits below the Felix resulted from north-northwest flowing meandering rivers. Thick peat represented by thick portions of the Felix coal accumulated upon this sandstone-dominated, poorly compactible platform that was free of sediment influx. Areas of thin and split Felix coal, underlain by fine-grained, more-compactible sediments, attracted water-borne elastics that interrupted peat accumulation. The base and split portions of the seam are the remains of predominantly coniferous trees that grew within a nutrient-rich environment, and the duller central and upper portions of the seam indicate oxidation associated with a raised peat deposit. Ash falls and fires during late stages of peat accumulation may have contributed to the demise of the swamp. After vegetation died large lakes formed and were subsequently filled by crevasse deposits from streams. The final phase of compaction of the fine-grained lake sediments and the thick underlying peat attracted anastomosed alluvial channels.