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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Sedimentology, stratigraphy and palaeogeography of Oligocene to Miocene rocks of North Canterbury-Marlborough

Irvine, Janelle Rose Mae January 2012 (has links)
The Cenozoic was a time of climatic, tectonic and eustatic change in the Southern Hemisphere. Cooling at the pole, glaciation and substantial sea ice formation occurred as latitudinal temperature gradients increased and tectonics altered Southern Hemisphere circulation patterns. During this same time frame, the tectonic regime of the New Zealand continental block transitioned from a passive margin to an active plate boundary, resulting in the reversal of a long-standing transgression and an influx of terrigenous sediment to marine basins. In this transition, depositional basins in the South Island became more localized; however, the influence of oceanographic and tectonic drivers is poorly understood on a local scale. Here we apply sedimentological, biostratigraphic and geochemical analyses to revise understanding of the effects of the changing climatic regime and active tectonics on the development of Oligocene and Miocene rocks in the Northern Canterbury Basin. The Late Oligocene to Middle Miocene sedimentary rocks of the northern Canterbury Basin record oceanographic and tectonic influences on basin formation, sediment supply and deposition. The Palaeocene to Late Eocene Amuri Formation in the basin are micrites and biogenic cherts recording deepwater, terrigenous-starved environments, and do not show any influence of active tectonics. The Early Oligocene development of ice on the Antarctic continent and the associated global sea level response is reflected in this basin as the Marshall Paraconformity, an eroded, glauconitized and phosphatised firm ground and hardground atop the Amuri. Sedimentation above this unconformity resumed in the Late Oligocene-Early Miocene with cleaner, deep-water, bathyal planktic foraminifera packstones and wackestones in eastern areas and Late Oligocene inner shelf volcaniclastic packstones in parts of the western basin. Post-unconformity sedimentation resumed earlier in western areas, as the currents responsible for scouring the sea floor moved progressively to the east. The development of tectonic uplift in terrestrial settings is first seen in the northwestern basin in Lower Miocene fine quartz-rich sandstones, and by the Middle Miocene, bathyal sandstones and quartz-rich wackestones appear in the basin, replacing earlier, more pure carbonates. The uplift caused shallowing to the west, in the form of shelf progradation due to sediment influx. This shallowing is not observed to the east; instead, the palaeoenvironments show a deepening as a result of sea level rise.
2

Neovulkanity SZ části mostecké pánve v prostoru uhelných lomů elektrárny Tušimice / Neovolcanic Rocks of the SW part of the Most Basin in the area of Tušimice power plant open pit

Sobotka, Martin January 2016 (has links)
Diploma thesis deals with geological, petrological and geochemical studies of neovolcanic rocks of the SW part of the Most Basin in the area of Tušimice power plant open pit. There are two lava flows affected by coal mining in northern part of the mine. Petrological and geochemical studies with K-Ar dating relatively recent rocks in mostly weatherworn volcanic rocks showed, that they can be classified as Ti-rich basaltic rocks without olivine (tephrites), which belong to the main volcanic phase in the evolution of the Eger graben. It was evidenced geologicaly and with K-Ar dating, that studied rocks were seperated from underlying beda by hiatus which caused erosion of volcanic rocks as well as crystalline bedrock. Mmajor and trace elements composition of co-magmactic volcanics showed that rock were derived from two slightly different sources of upper mantle. Composition of two samples indicates the formation from low degree of partial melting strongly metasomatic asthenospheric mantle. Chemical features of volcanic rocks show that mantle source was comparamble to recent OIB basalts. Last sample arose from less metasomatized and depth distincted mantle which was affected by higher level of partial melting. Melts from which crystallized both rocks were minimaly affected by asimilation or...

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