No description available.

The Qilian Fold Belt is a suture belt between the China-Korea craton and Qaidam craton. There are manly Paleozoic volcanic rocks of marine origin occurred in the Qilian suture belt. According to the previous studies, these volcanic rocks are mainly spilite and keratophyre. In the present study, we have used methods of petrography and mineral chemistry to study alteration and low-grade metamorphism of Ordovician volcanic rocks in Mayahsuehshan, Minleh and Changma areas. These three areas are located in eastern, middle and western of Northern Qilian Fold Belt, respectively. On the basis of the parageneses of secondary minerals, it is indicated that the metamorphic grade of the Lower Ordovician volcanic rocks is equivalent to greenschist facies, whereas that of the upper part of the Middle Ordovician volcanic rocks is equivalent to prehnite-pumpellyite facies. The lower part of the Middle Ordovician volcanic rocks is a transition zone between prehnite- pumpellyite and greenschist facies. The metamorphic grades are thus lower for the younger volcanic rocks. The metamorphic grades of Minleh and Changma areas are prehnite-pumpellyite and prehnite-actinolite facies, respectively. The mineral parageneses of the volcanic rocks are generally consistent with that of spilite or keratophyre. It was considered earlier that the spilite and keratophyre were formed by direct crystallization from a mixture of magma and seawater. However, metamorphic grades of the volcanic rocks are shown to be equivalent to that of the intercalated metaclastic rocks in the present study. Therefor, it is implied that the spilitic volcanic and metaclastic rocks in the Mayahsuehshan area have formed as a reasult of regional metamorphism. The spilitic and keratophyric volcanic rocks from Minleh and Changma areas, respectively, are also inferred to have formed as a result of regional metamorphism. It is therefore more adequate to name them metabasalts or metandesites. Mineral assembleges and mineral chemistry are different in different parts of the rocks, because of varied effective compositions during metamorphism. According to the chlorite compositions, the chlorite/smectite mixed layering is not prevailing in the volcanic rocks of the three areas. However, interstratification of chlorite and illite appears in groundmass of some volcanic rocks in Minleh area. There are few chromium-spinel in the volcanic rocks of Mayahsuehshan area. The plots of Mg/(Mg+Fe) versus Cr/(Cr+Al) of the chromium-spinel imply that the volcanic rocks in Mayahsuehshan area may have occurred in island arc environments.

Thesis (M.S.)--Oregon State University, 2003. / Includes folded maps in pocket. Typescript (photocopy). Includes bibliographical references. Also available online.

No description available.

Thesis (Ph. D.)--Oregon State University, 2000. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S. in geology)--Washington State University, May 2010. / Title from PDF title page (viewed on June 23, 2010). "School of Earth and Environmental Science." Includes bibliographical references (p. 87-96).

An extensive suite of hydrothermally altered basalts, gabbros, and plagiogranites, was recovered from the trench-facing slope of the Tonga forearc. The tectonic setting, lithology, and geochemistry of these samples make them a unique collection for comparison with suprasubduction zone (SSZ) ophiolites. Petrography, mineral chemistry, and geothermometry are used to constrain the metamorphic evolution of ocean crust formed in a modern SSZ setting. We report the discovery of the first suite of oceanic epidosites. Tongan epidosites metasomatically replaced basaltic and plagiogranite protoliths and formed under similar conditions to epidosites hosted in many SSZ ophiolites. The range of alteration temperatures and mineral assemblages in basalts and gabbros are similar to those described from both SSZ ophiolites and mid-ocean ridges (MORs). However, the degree of alteration in basalts and the presence of epidosites in the Tonga collection are most similar to alteration characteristics in SSZ ophiolites. We show that the trace element chemistry of epidote may be linked to the composition of fluids circulating deep in hydrothermal systems. This is possible due to the subordinate role crystal chemistry may play in controlling the trace element chemistry of hydrothermal minerals. Whole rock oxygen isotope ratios of the Tonga samples are generally similar to values determined from MOR and SSZ ophiolite samples; however, enriched values in plagiogranites and gabbros may indicate a late, low temperature metamorphic overprint associated with tectonic unroofing during trench rollback. Basalts show an interesting northward decrease in oxygen isotope ratios that remains unresolved. / Graduate

Orientador: Sandra Elisa Contri Pitton / Banca: Antonio Carlos Tavares / Banca: Deise Fabiana Ely / Resumo : O presente trabalho tem por objetivo caracterizar o clima da região oeste de Paraná e fazer uma relação deste com a presença do lago artificial da Usina Hidrelétrica de Itaipu, formado em 1982, bem como a percepção climática dos moradores da região em relação à presença do lago e suas influências no clima local. Isso torna-se importante visto que, em geral, o clima local é bastante influenciado por ações antrópicas; no reservatório de Itaipu houve o armazenamento de 29 bilhões de metros cúbicos de água, inundando um total de 1.350 km2 de área, atingindo 15 municípios no oeste do Paraná, e um no estado do Mato Grosso do Sul, ocasionando uma grande alteração na paisagem. Para atingir o referido objetivo trabalhou-se, num primeiro momento, com dados das estações meteorológicas dos municípios lindeiros, obtidos através do banco de dados do IAPAR e do SIMEPAR, compreendendo o segmento temporal de 1983 a 2004 (este segmento foi adotado visto ser toda a série histórica existente na área); a metodologia proposta baseia-se, primeiramente, na comparação dos dados, estatisticamente, entre estações que se localizam próximas e distantes do lago, para a verificação da variabilidade ou não dos parâmetros analisados, conforme proposto e testado por GRIMM (1986), a qual obteve resultados satisfatórios para tal procedimento; após esta comparação analisam-se dados do satélite NOAA sobre os parâmetros climáticos da região. Num segundo momento, a partir dos dados meteorológicos analisados, são elaborados questionários, aplicados em entrevistas abertas com pessoas residentes na região em torno de 30 anos, tanto no meio rural quanto urbano, conforme metodologia proposta por SARTORI (2000), visando compreensão da percepção climática da sucessão dos tipos de tempo bem como em relação à presença do lago e suas influências no clima local por parte... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this work is to characterize the local weather of Parana's west region making a comparison between it and the Hydroelectric Itaipu's artificial lake presence created in 1982, as well the climatic perception of the inhabitants of the region in relation to the presence of the lake and its influence into the local weather. This becomes important considering that generally the local weather is strongly influenced by anthropic actions, there have been a caching of 29 billions cubic meters of water in the Itaipu's reservoir, flooding a total area of 1,350 km2, reaching 15 cities in the west of Parana and one in Mato Grosso do Sul, making a great alteration in the landscape.To achieve the referred objective meteorological stations data from the surrounding cities have been used, obtained from IAPAR and SIMEPAR databases, comprehending the period from 1983 to 2004(this period have been adopted because it is all the existent historical serial in the area). The methodology suggested works primary comparing the data statistically, between near to the lake stations and distant ones, to verify the variability or not of the analyzed parameters, as stated and suggested by GRIMM(1986), witch have acquired satisfactory results in such procedure; after this comparison data from the NOAA satellite about the climatic parameters of the region are analyzed. In a second moment, considering the analyzed meteorological data, surveys are made with people who have lived in the region by 30 years, both in the country side as the urban area, according to the methodology suggested by SARTORI (2000), heading to the comprehension of the climatic perception of the succession of weather types as well in relation to the presence of the lake and its influences in the local weather by the people who experiment this fact. In the analyses of the data it was not found a relation between... (Complete abstract click electronic access below) / Mestre

No description available.

Thesis (doctoral)--Universiteit Utrecht, 2007. / Includes bibliographical references (p. 99-104).