Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Also available in an electronic version.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

No description available.

<p> Sediment samples were taken from the exposed facies of two quarries north of Burford Ontario. The samples were then dry sieved and the results were plotted as frequency histograms to show the type and quantity of sediment present. Moreover, measurements of soil tongues, sand lenses and strata depths were recorded to provide a comprehensive understanding of the depositional history and processes.</p> <p> The above research was then combined with the present day comprehension of the depositional history of southern Ontario. The conclusions reached in this paper are useful, as they contribute and improve the understanding of the depositional history of southern Ontario.</p> / Thesis / Candidate in Philosophy

The Late Mesozoic Bisbee basin of southeastern Arizona was an intracratonic back-arc rift basin. Extension was coupled with seafloor spreading in the Gulf of Mexico and back-arc extension behind a magmatic arc along the convergent Pacific continental margin. Tectonostratigraphic evolution of the basin occurred in three phases. Initial mid-Jurassic rifting of the basin, marked by eruption of the Canelo Hills Volcanics, may have been complicated by sinistral strike-slip motion along the Mojave-Sonora megashear. During continued rifting, from latest Jurassic to Early Cretaceous time, the Glance Conglomerate was deposited by alluvial fans and braided streams in grabens, half-grabens, and caldera-related depressions; locally interbedded volcanic rocks represent waning rift-related back-arc magmatism. The upper Bisbee Group was deposited during Early to earliest Late Cretaceous passive thermotectonic subsidence. The Bisbee Group and correlative strata occur in most mountain ranges in southeastern Arizona, and are subdivided into southeastern, northwestern, northern, and western facies. Southeastern facies were deposited in alluvial fan, meandering fluvial, estuarine, marginal marine and subtidal shelf environments as a transgressive-regressive sequence including a marine interval that was continuous with Gulf Coast assemblages during Aptian-Albian marine transgression. Northern facies were deposited in alluvial fan and braided stream environments along the northern rift shoulder of the basin. Southeastern and northern facies sandstones are dominantly quartzose, and were derived mainly from cratonic sources to the north. Subordinate volcaniclastic sandstones in the southeastern facies become more abundant to the west, proximal to eroding Jurassic and Cretaceous volcanic arcs. Basal northwestern facies arkosic strata deposited in alluvial fan, braided stream and lacustrine environments were derived from local basement uplifts, and were ponded in a northwestern depocenter by rift-related topography. A thin estuarine interval within overlying dominantly fluvial facies indicates integration of regional drainage networks by the time of maximum transgression. Transition upward to quartzose sandstone compositions reflects wearing down of local basement uplifts and increasing abundance of craton-derived sediment in the northwestern part of the basin. Western facies alluvial fan, braided stream and lacustrine intramontane deposits are composed of locally-derived arkose and lithic arkose.

Thick Paleogene sequences occur in the southern deformed fold and thrust belt of the Himalayas. In this thesis I describe detailed litho- and biostratigraphy from ten key stratigraphic sections in the Kohat Basin, the Potwar Basin and the Trans Indus Ranges (TIR). These stratigraphies combined with microfacies analysis resulted in a new interpretation of the tectono-stratigraphic history of the area, which is dominated by India-Asia collision but where eustatatic effects can also be identified. Of particular interest is documenting the timing of the final closure of the northern rim of the Tethys caused by this collision. The Kohat and Potwar Basins represent foreland basins within the collision zone. Their stratigraphies document effects of local tectonics and eustatic sea level. The biostratigraphy is based on occurrences of larger benthic foraminifera. Taxonomy of the species is included in the thesis. The Paleogene rocks of the study area are divided into local larger benthic forminiferal biozones: BFZK 1- BFZK 6 in the Kohat Basin and BFZP 1-BFZP 3 in the Potwar Basin and the TIR. These local biozones are correlated to the global standard biozonation schemes of Höttinger (1960), Schaub (1981), and Serra Kiel et al. (1998). The ages of the sequences are Late Paleocene (Thanitian) to Middle Eocene (Upper Lutetian) in the Kohat Basin, and Late Paleocene (Thanitian) to Early Eocene (Middle Cuisian) in the Potwar Basin and the TIR. The sediments were deposited along a carbonate ramp platform in both areas (sensu Read, 1982, 1985). The sequence stratigraphic histories of the two basins are described as follows. In the Kohat Basin, Thanitian to Middle Cuisian strata record the first Transgressive-Regressive cycle (TRK 1). The first sequence boundary (SBK 1) is followed by Middle Cuisian-Upper Cuisian lowstand progradational deposition that marks the end of TRK 1 cycle. Middle Lutetian 1-Upper Lutetian strata represent the second Transgressive-Regressive cycle (TRK 2). The second sequence boundary (SBK 2) ends TRK 2 deposition, after which no more deposition took place. In the Potwar Basin and the TIR, Thanitian strata comprise the first Transgressive- Regressive cycle (TRP 1), whilst Lower Lllerdian-Middle Lllerdian 1 strata constitute the second Transgressive-Regressive cycle (TRP 2). Middle Lllerdian 2 to Middle Cuisian strata mark the third Transgressive-Regressive cycle (TRP 3). Three sequence boundaries (the SBP 1, the SBP 2 and the SBP 3), marked by exposure surfaces, separate the three depositional cycles. The SBP 1 and SBP 2 sequence boundaries are controlled by local tectonics. In contrast the SBP 3 and SBK 1 sequence boundaries are synchronous at 49.5 Ma, and represent a phase of significant relative sea level fall, possibly driven by the combined effect of uplift (collision tectonics) and eustatic sea level fall (e.g. Haq et al., 1987). This implies that proto-closure of the northern rim of the Tethys occurred around 49.5 Ma. Reestablishment of marine conditions in the Kohat Basin occurred in the Middle Lutetian 1 around 45.8 Ma, possibly caused by a combination of flexural loading of the Indian plate (Pivinik & Wells, 1996) and eustatic sea-level rise (e.g. Haq et al., 1987). The final closure of the Tethys, marked by the end of marine sedimentation in the Kohat Basin, occurred in the Upper Lutetian (41.2 Ma). Finally, Himalayan foreland molasses sedimentation occurred during Miocene to Pliocene.

A investigação foi realizada no extremo sul do Brasil, nos derrames básicos da Formação Serra Geral, entre os municípios de Santa Cruz do Sul-Herveiras e Lajeado. Na área estão expostas sucessões de derrames baixo Ti com morfologias pahoehoe e rubbly, pertencentes a Província Ígnea Paraná-Etendeka. Na sequência de derrames em Santa Cruz do Sul-Herveiras foram identificadas 16 litofácies e três associações de litofácies 1- pahoehoe composta inicial, 2- pahoehoe simples inicial e 3- rubbly simples tardia. Nos derrames pahoehoe compostos (< 1m espessura), o rápido resfriamento permitiu a geração de pipe vesículas e vesículas V1. Nos derrames pahoehoe simples (2-6 m de espessura), uma grande quantidade de estruturas de segregação foi gerada: proto-cilindros e cilindros; pods; camadas de vesículas S1 e S2 e camadas de cilindros; pipes, vesículas V1 e gigantes. Nos derrames rubbly (> 30m espessura), apenas vesículas tipo V1 e gigantes são preservadas. Estudos petrográficos indicaram que os processos de dissolução de cristais e liberação de gás originaram porosidades primárias, enquanto processos de alteração e fraturamento geraram uma grande quantidade de porosidades secundárias. No entanto, a precipitação de minerais secundários nos poros tende a reduzir o espaço disponível para armazenamento de fluidos, demonstrando que apenas a existência de poros é insuficiente para a existência de um reservatório vulcânico. Geoquimicamente, todos os derrames estudados podem ser classificados como do tipo Gramado. As composições variam de basaltos a andesito basálticos de afinidade toleítica nos perfis Santa Cruz e Lajeado, enquanto na área do Morro da Cruz, os derrames do tipo ponded pahoehoe exibem composições de andesitos. A assimilação crustal sugerida para estas sequências vulcânicas permite explicar as altas razões isotópicas iniciais de Sr (0,707798–0,715751), e os valores baixos de Nd (-8,36 a -5,41), com associadas variações isotópicas de Pb (18,42 <206Pb/204Pb< 18,86; 15,65 <207Pb/204Pb< 15,71; 38,62 <208Pb/204Pb< 39,37). A evolução magmática dos derrames básicos de Santa Cruz do Sul-Herveiras e Lajeado iniciou com o armazenamento de líquidos máficos durante um curto período em câmaras magmáticas rasas, associados a um processo de contaminação crustal significativo, o qual permitiu a ascensão de magmas com composição de olivina basaltos, os quais exibem morfologia pahoehoe composta em superfície. A contínua cristalização fracionada dentro da câmara magmática concomitante com assimilação em graus variáveis de distintos contaminantes com idades Paleoproterozoica e Neoproterozoica, somada a uma contribuição significativa de recarga de magma permitiu a ascensão de magma com composição andesito basáltica, o qual exibe morfologia pahoehoe simples em superfície. A contínua recarga de magma na câmara magmática concomitante a graus mais elevados de assimilação levaram a formação de lavas andesito basálticas com assinaturas isotópicas mais contaminadas e que exibem na superfície morfologia rubbly pahoehoe. Processos de diferenciação dos líquidos concomitantes as maiores taxas de assimilação de distintos contaminantes durante um período prolongado em um câmara magmática rasa, a qual é distinta daquela onde os magmas de Santa Cruz do Sul-Herveiras e Lajeado estavam armazenados, favoreceu a formação dos andesitos do Morro da Cruz, que exibem as assinaturas mais contaminadas da ombreira sul da Sinclinal de Torres. / This study was performed in the southern Brazil, in the basic lava flows of the Serra Geral Formation, between the localities of Santa Cruz do Sul- Herveiras and Lajeado. Low Ti lava flow successions with pahoehoe and rubbly morphologies occur in the study area, which belong to Paraná-Etendeka Igneous Province. In the volcanic sequence of the Santa Cruz do Sul-Herveiras, the basaltic lava flows were divided into 16 lithofacies and grouped into three lithofacies associations: 1- early compound pahoehoe, 2- early simple pahoehoe, and 3- late simple rubbly. In the compound pahoehoe lava flows (< 1m thickness), the fast cooling allowed the generation of pipe vesicles and V1- type vesicles. In the simple pahoehoe lava flows (2-6 m thickness), a large amount of segregation structures were generated: proto-cylinder, cylinder, pods, S1 and S2-type vesicle sheets, pipe vesicles, V1-type and giant vesicles. In the rubbly pahoehoe lava flows (> 30 m thickness), just V1-type and giant vesicles are preserved. Petrographic studies indicate that the dissolution of deuteric crystals and gas releasing processes formed the primary porosities, while processes such as alteration and fracturing generated the secondary porosities. However, the precipitation of secondary minerals in vesicles and cavities decreases the available space for fluid storage, which suggest that the existence of pores alone is insufficient for creating volcanic reservoirs. Geochemically, all the studied lava flows could be classified in the Gramado type. The geochemical compositions in the Santa Cruz do Sul-Herveiras and Lajeado profiles range from basalt to basaltic andesites with tholeiitic affinity, while in the Morro da Cruz area, the ponded pahoehoe lava flows exhibit andesite compositions. The process of crustal assimilation suggested for these volcanic sequences allow explains the high and widespread initial Sr isotopic ratios at 0.707798–0.715751 and the low εNd at −8.36 to −5.41, with associated Pb isotopic variations (18.42 < 206Pb/204Pb < 18.86; 15.65 < 207Pb/204Pb <15.71; 38.62 < 208Pb/204Pb < 39.37). The magmatic evolution of the SCSH and LJ basic lava flows begins with the storage of mafic liquids during a short period at shallow-level magma chamber, associated to significant crustal contamination that allowed the magma ascent with composition of olivine basalts that exhibit compound pahoehoe morphology at surface. The continuous fractional crystallization within the magma chamber coupled with variable assimilation degrees of distinct contaminants with Paleoproterozoic and Neoproterozoic ages, in addition to significant contribution of magma recharge led to magma ascent with basaltic andesite composition that display at surface the simple pahoehoe morphology. The continuous magma recharge in the magma chamber coupled with higher assimilation degree allowed the formation of basaltic andesite lavas with more contaminated isotopic signatures that exhibit rubbly morphology at the surface. Differentiation process of liquids coupled with the highest assimilation degrees of distinct contaminants during longer time in a shallow-level magma chamber, which is distinct from that where SCSH and LJ magmas have been stored, led to formation of andesites of the Morro da Cruz that exhibit the most contaminated isotopic signatures of south hinge of the Torres Syncline.

Geóloga / En las nacientes del río Huasco en la Región de Atacama aflora una sucesión volcanosedimentaria de edad permotriásica, pertenecientes a la Formación Guanaco Sonso. Ésta se habría depositado en una configuración tectónica de colapso extensional tras un período de engrosamiento cortical relacionado con el desarrollo acrecionario del Paleozoico Superior. El registro de este evento corresponde a una serie de cuencas siliciclásticas cuyo desarrollo fue acompañado de un amplio magmatismo de características propias de una corteza en etapa de adelgazamiento. En este contexto, el estudio del registro geológico de este periodo, particularmente, en las cuencas y sus depósitos, aportará al entendimiento de la paleogeografía y configuración tectónica del margen continental. Este trabajo pretende estudiar una cuenca triásica en particular, la cual albergó los depósitos volcánicos y sedimentarios de la Formación Guanaco Sonso. Para ello, se realizó un análisis de facies piroclásticas y sedimentarias que permite relacionar los procesos sedimentarios, volcanosedimentarios y tectónicos, caracterizando la evolución de la cuenca en el área de estudio. En la zona de estudio, esta formación presenta un espesor mínimo de ca. 400 m, y está compuesta, principalmente, por una serie de capas piroclásticas riolíticas a dacíticas de espesores métricos a decamétricos, intercalados en sedimentitas de origen fluvial, aluvial y lacustre. La depositación de estas unidades estuvo controlada por numerosas fallas normales de poco desplazamiento y corta vida que condicionaron la geometría y distribución de las facies, tanto piroclásticas como sedimentarias. Si bien, se logra establecer que la subsidencia estuvo controlada por numerosas fallas normales, la ausencia de fallas mayores no permiten establecer con seguridad la naturaleza de la cuenca. La configuración tectonoestratigráfica podría ser interpretada como un desarrollo de la etapa inicial de un sistema de rift, o su origen podría estar ligado al colapso de un sistema volcánico, generando cuencas de caldera en un ambiente de intra-arco. Ambas hipótesis están aún por ser probadas, aunque no se descarta que ambos procesos geológicos puedan haber estado presentes a esta longitud durante el permotriásico. / Este trabajo ha sido financiado por el Plan Nacional de Geología de SERNAGEOMIN

During the Late Pliocene to Middle Pleistocene Ages, sediments of the study area were deposited in the intra-slope salt withdrawal basin where sand-prone sediments deposited as turbidite lobes and channel fills are the main reservoirs of the Northern Gulf of Mexico. The main purpose of this study was to identify and characterize these sand-prone sediments. Sequence stratigraphic analysis of well logs, biostratigraphic data, and 3-D seismic data provided a chronostratigraphic framework of the study area, within which seismic facies analysis was carried out. Each sequence was subdivided into separate seismic bodies characterized by specific amplitude, coherence of reflectors, and shape of reflectors. The descriptions of each seismic facies combined with well logs were compared with turbidite facies models to infer their geological information. Five turbidite elements were identified: depositional channel fills and overbank deposits, erosional channel fills, turbidite lobes, mud turbidite fills and sheets and hemipelagic and pelagic drapes. Depositional channel fills are usually deposited in lower parts of interpreted sequences, surrounded by shale-prone overbank deposits. The lateral variation of these turbidite elements was revealed by horizon slices, in which depositional channels are generally trending NE-SW or NNE-SSW with elongated sinuous forms. Well logs indicate that depositional channel fills usually consist of bell or cylinder type sand-prone sediments. Turbidite lobe was found only in the 1.1-0.8 Ma sequence, in which it laps out onto the underlying sequence boundary and shows high-amplitude and a high-coherence of mound shape. This facies is interpreted as sand-prone, but wells available penetrated only the marginal parts of this facies and showed poor reservoir qualities. Horizon slices could partly reveal its lapout boundary due to the limitation of vertical seismic resolution. Mud turbidite fills and sheets are the most dominant turbidite facies, which usually occurred in the upper parts of sequences and overlain by hemipelagic and pelagic drapes. Hemipelagic and pelagic drapes were deposited very widely, wrapping down the previous topography with consistent thickness throughout the basin. Erosional channel was observed only in the 0.8-0.7 Ma sequence where it cut into the underlying sequence and was filled by shale-prone sediments. Depositional channel fills and turbidite lobes are the main reservoir facies in the study area. Seismic facies analysis using vertical seismic sections and horizon slices combined with lithology data made it possible to identify and systematically describe these sand prone turbidite elements in intra-slope salt withdrawal basin.

Thesis (Ph. D.)--University of Adelaide, Dept. of Geology and Mineralogy, 1983. / Twenty four folded leaves of ill. in pocket inside the back cover of v. 2. Includes bibliographical references (leaves 146-164 (v. 1)).