Mémoire (M.Sc.A.)-- Université du Québec à Chicoutimi, 1986. / "Mémoire présenté en vue de l'obtention de la maîtrise en sciences appliquées en géologie" Page 157 manquante. CaQCU CaQCU Bibliogr.: ff. 99-110. Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--Brigham Young University. Dept. of Geological Sciences, 2008. / Includes bibliographical references (p. 39-44).

Four groups of equids, "Anchitheriinae," Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, and only the Equini remains after 16 million years of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes controlling the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. I investigated two methods of quantitative analysis, Occlusal Enamel Index for shape and fractal dimensionality for complexity. I used analyses of variance and an analysis of co-variance to test hypotheses of process. Results suggest that enamel shape was controlled by phylogeny, tooth position, and climate. The lower taxonomic levels are shown to have a strong effect on complexity, suggesting behavior is driving complexity rather than overarching phylogenetic constraint.

Orientador: Francisco Sérgio Bernardes Ladeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-17T17:08:46Z (GMT). No. of bitstreams: 1 PaviaJunior_Alexandre_M.pdf: 16328754 bytes, checksum: b892c6cf5e1d588b161b2bd2a28a8f81 (MD5) Previous issue date: 2011 / Resumo: O estudo de paleossolos tem se mostrado como uma importante ferramenta interdisciplinar na interpretação paleoambiental. Neste sentido, a interpretação de evidências paleopedológicas em paleossolos da Formação Marília (Maastrichtiano), membro litoestratigráfico superior do Grupo Bauru, se mostra de grande valia para a interpretação paleogeográfica do momento de sedimentação e posterior pedogênese dos depósitos arenosos. Os paleossolos da Formação Marília, na região de Duartina/SP, são constituídos por arenitos finos e médios, que se distribuem por horizontes pouco profundos e que demonstram uma paleosuperfície bastante aplainada, com estrutura de solo, predominantemente, composta por blocos nos horizontes B e ausente nos horizontes C, são paleossolos ricos em cimentação carbonática, nódulos carbonáticos, bioturbações e rizoconcreções. Dessa forma, este trabalho objetiva a análise de dados macro e micromorfológicos, químicos e paleontológicos para a interpretação paleogeográfica vigente, especialmente, durante os processos pedogenéticos. Tal análise se sustenta em atividades de campo e coleta de material, correlações bibliográficas e análises laboratoriais compostas por espectrometria de fluorescência de raios X e análises micromorfológicas. Os resultados obtidos corroboram com aqueles apresentados por diversos autores que analizaram os aspectos paleontológicos, químicos, macro e micromorfológicos e apresentam aspectos de pedogênese desenvolvida sob condições de semi-aridez e aridez. A geoquímica e a mineralogia das amostras, associadas aos aspectos paleontológicos, reforçam a idéia de ambientes de baixo grau de intemperismo na maioria dos horizontes analisados, mas também apontam para maior oferta de água aparentemente relacionada à variações topográficas. / Abstract: The study of paleosols has proven to be an important tool in interdisciplinary palaeoenvironmental interpretation. In this sense, the interpretation of evidence palaeopedogenic paleosols in the Marília Formation (Maastrichtian), upper lithostratigraphic member of the Bauru Group, is proving invaluable for the palaeogeographic interpretation of the moment of sedimentation and subsequent pedogenesis of sandy deposits. The paleosols of the Marilia Formation in the region of Duartina / SP are composed of fine sandstones and medium spread over the shallow horizons and demonstrate a paleosurfaces quite flattened, with soil structure predominantly composed of blocks in B horizons and absent in C horizons, are rich in paleosol carbonate cementation, carbonate nodules, bioturbations and rhizoliths. This study aims to analyze data macro and micromorphological, chemical and paleontological for interpreting paleogeographic force, especially during pedogenic processes. This analysis is based on field activities and sample collection, laboratory analysis and correlations bibliography composed by fluorescence spectrometry X-ray and micromorphological analysis. The results are consistent with those presented by several authors who analyzed the paleontological aspects, chemical, micro and macro aspects of pedogenesis have developed under conditions of semi-arid and arid. The geochemistry and mineralogy of samples associated with the paleontological aspects, reinforce the idea of environments with low degree of weathering in most horizons analyzed, but also point to increased supply of water apparently related to topographic variations. / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia

Two sets of cores were recovered from the southern Kenya Rift (Koora and Magadi basins) through the Hominid Sites and Paleolakes Drilling Project and the Olorgesailie Drilling Project. These contain a detailed environmental Quaternary history with records of up to ~1 million years. This period correlates with much of the Olorgesailie Formation record of 1.2 Ma in the Olorgesailie Basin. The Magadi cores reached trachyte at ~ 194 and 133 m with this project focussed on the longer core, MAG14-2A, which includes limestone, zeolitic, laminated and massive clay and silt, massive mud, chert, trona, gravel and sand. The Koora Core (OLO12-1A) extended to depths of 166.14 m and contains laminated and massive diatomites, fine to coarse sands; lime and siliciclastic muds with pumice-rich gravels. The two cores are particularly important because they provide environmental records that help to fill erosional gaps in the history of the Olorgesailie Basin, which includes important evidence for changing hominin cultures and evolution. The high-resolution lacustrine-terrestrial stratigraphies of the two basins have shown how landscapes were transformed because of complex interactions between tectonic and climatic processes. Volcanism also had a significant impact, partially damming lakes at Olorgesailie. Diatoms are present in much of the Koora Basin sequence and large parts of the Magadi sediments. These are dominated by a variety of planktonic Aulacoseira, Cyclotella and Thalassiosira taxa in both basins. Species comprising these genera and other planktonic, benthonic and epiphytic taxa preserve a detailed record of lakes that fluctuated in depth, extent and chemistry. The data document the presence of freshwater and saline lakes as well as wetlands. Diatom transfer functions from the Koora and Magadi basins indicate that these water bodies fluctuated widely in conductivity between ~200 to >20,000 µs cm−1, with pH changing between about 7.5 and 11.5. The palaeolakes also periodically exceeded diatom tolerance limits and intermittently dried out. Pollen are generally lacking in the Koora basin sediments, but deposits in the Magadi core contain common pollen that document a wide range of habitats, including forests, woodlands and grasslands that could have supported the presence of hominins and their activities in the region. Fungal spore data support pollen inferences and indicate periods when large mammals might have been common. The microfossil record shows that there was a broad trend towards more arid conditions in the southern Kenya Rift after about 510 Ka, interrupted by periodic wetter conditions. A major episode of desiccation developed between about 450 Ka to 400 Ka that partially correlates with a period of mammal extinctions and a change from Acheulean to Middle Stone Age toolkits in the Olorgesailie Basin, suggesting that these changes might have been related to environmental conditions at that time.

The Jurassic Twist Gulch Formation of central Utah was deposited in the active Arapien sub-basin of the Western Cordillera foreland trough. We herein demonstrate the utility of integrating facies analysis, terrestrial sequence stratigraphy, and detrital zircon (U-Pb) ages to improve paleogeographic reconstructions as well as identify regional unconformities, locate fluvial depocenters, and infer sediment supply/accommodation space ratios. Strata of the Twist Gulch Formation in Pigeon Creek Canyon (PCC) near Levan, Utah consists primarily of alluvial deposits, while in Salina Canyon (SC) the Twist Gulch Formation is comprised of a mix of alluvial and marginal marine deposits associated with the Jurassic Western Interior Seaway. Within the PCC section, a change from high accommodation system (HAS) mudstones to low accommodation system (LAS) multi-storied channel sandstones and back to HAS deposits exists. This same pattern exists in the SC section but culminates with marine deposits. Terrestrial sequence stratigraphy predicts that the change from HAS to LAS deposits indicate a sequence boundary and thus an unconformity. The J-3 unconformity, a regional unconformity on the Colorado Plateau, separates strata of Callovian age from Oxfordian age in Utah. Using detrital zircons (U-Pb), the first radiometric ages were obtained for the Twist Gulch Formation. The J-3 unconformity is bracketed by detrital zircon (U-Pb) ages and stratigraphic relationships in the study area. These new ages suggest that the Twist Gulch Formation is time-equivalent to the Entrada Sandstone, Curtis, and Summerville formations of the Colorado Plateau. Further, integrating facies analysis, terrestrial sequence stratigraphy, and detrital zircon (U-Pb) ages predicts that the PCC section was an active depocenter during the early Oxfordian in which sedimentation outpaced accommodation space, prograding the Oxfordian shoreline of the Jurassic Western Interior Seaway shoreline eastward. This integration process also predicts that subsurface sandstones positioned above the J-3 unconformity on the west side of the Wasatch Plateau are of a different age, depositional system, and systems tract from subsurface sandstones on the east side of the Wasatch Plateau.

No description available.

Thesis (doctoral)--Universität Bremen, 2005. / Includes bibliographical references (p. 113-125).

Erosion beveled the Laramide Front Range uplift in Colorado to a surface of low relief by the end of the Eocene. This study uses paleobotanic climate analysis techniques to determine the paleoelevation of this regional surface by examining the overlying 34.9 Ma Florissant flora. Multiple regression models explaining 93.4% of the variance in mean annual temperature (MAT), 86.1% of the variance in growing season precipitation (GSP) and 65.7% of the variance in rainfall distribution were derived from J. A. Wolfe's dataset of 31 leaf physiognomic character states from 86 modern vegetation sites. When applied to a new collection of 29 species from the Florissant flora, estimates of MAT = 10.7 ± 1.5°C, and GSP = 55.6 ± 12.5 cm, with precipitation occurring mostly during the growing season, are derived. This paleoclimate estimate is corroborated by data from late Eocene Sequoia affinis from Florissant. Higher mean ring width of the fossil trees as compared to modern counterparts can be explained by a climate with summer mean monthly temperatures ≥ 14°C and summer mean monthly rainfall >1.5 cm. The estimated MAT, when combined with coeval sea level MAT and terrestrial lapse rate, implies an elevation of 2.3-3.3 km for Florissant, which is indistinguishable from the modern elevation of 2.5 km. The elevation of Florissant is tied to that of the Great Plains by the Wall Mountain Tuff, so the Great Plains were also high. The elevation was created either by underplating and/or mass transfer in the Laramide, or by mantle uplift of crust thickened by pre-Laramide tectonics. This elevation estimate implies that: (1) Pliocene uplift is not required to explain the present elevation. Thus, late Tertiary plateau uplift in the western US was not a contributing factor to the marked global cooling since 15 Ma; and (2) in the late Eocene, regional surfaces of planation could be formed at elevations significantly above sea level but below tree line. The surface was possibly formed from a lack of storminess; a preponderance of small storm events will diffusively smooth topography.

The epeiric Transvaal Sea covered the Kaapvaal Craton of southern Africa during the Early Proterozoic and its remnant strata represent one of the oldest known carbonate depositories. A genetic stratigraphic approach has been used in this research on the evolution and syndepositional tectonics of the Transvaal Sea; research also emphasized the development of basement precursors, which influenced the Transvaal Sea. Eight subfacies were initially recognized and their interrelationships through Transvaal Sea time and space were used to identify ten depositional systems. Paleogeographic reconstructions indicate that the depositional systems developed on morphological variations of a distally-steepened carbonate rarp and that the depositional character of each was simply a function of water Backstripping of the depositional systems indicates that the Transvaal Sea was compartmentalized; three compartments are preserved on the Kaapvaal Craton. Backstripping also indicates that the depositional center of the Transvaal Sea lay over the western margin of an underlying rift. Rifting had developed a major, north-south-trending structure, and its geographical interrelationships with the east-west-trending Selati Trough created the compartment architecture of the basement. Interpretation of syndepositional tectonics suggests that six stages of subsidence influenced the Transvaal Sea. Early subsidence consisted of mechanical (rift) subsidence followed by