A basin analysis of the Oligocene Porter Group rocks in Castle Hill Basin, Canterbury, was completed. The Porter Group contains the Coleridge Formation which comprises a lower sandstone unit and an upper micritic limestone unit, and the Thomas Formation which consists of biosparite limestone and interbedded tuffs. Basin analysis provided evidence that the Coleridge Formation lower sandstone unit was deposited in an inner shelf setting based upon its moderate sorting, large grain size range, laterally continuous geometry and lack of bedforms due to intense bioturbation. The upper micritic limestone is a mid shelf deposit composed of micrite and minor clastic grains. Provenance analysis has classified the lower sandstone unit as a quartz arenite. Both metamorphic and plutonic source areas are likely for the sandstone, along with reworked grains from underlying Formations based on QFL, SEM-CL, heavy mineral and glauconite analysis. The Thomas Formation limestone is a typical New Zealand cool water biosparite deposited on the inner shelf as a result of storms and debris flows, with the upper cross-bedded limestone lithofacies being reworked by currents in shallow water. Petrographic data showing multiple stages of diagenesis at the upper contact of the Thomas Formation provides evidence for a major tectonic event. The interbedded tuffs are a result of basaltic marine volcanism on the inner to mid shelf. The tuffs are reworked and deposited by turbidity current, debris flow and storms. Analysis of a dike within the Thomas Formation volcanics showed a weakly alkaline geochemical signature that is indicative of volcanism related to extension. A regional synthesis compared the Porter Group rocks in Castle Hill Basin with Oligocene rocks in North Canterbury, West Coast and North Otago. Oligocene quartz-rich sandstones are found in Castle Hill Basin, Harper Valley, Avoca and Culverden while micritic limestone is found on the East Coast from Marlborough to Otago. Oligocene basaltic volcanics interbedded with limestone and karst unconformities are found in Castle Hill Basin, Culverden and Otago. Normal faulting may be responsible for thickness variations and several regional karst unconformities in the eastern South Island. Plate reconstructions based on sea floor magnetic anomalies also suggests the New Zealand region was tectonically active during the Oligocene. Mounting evidence, including Eocene-Oligocene faulting and volcanism in the South Island, suggests that New Zealand may not be best described as a passive margin during the Early-Mid Tertiary.

Graduation date: 1952

Graduation date: 1999

Through the analysis of the stratigraphic and spatial distribution of organic walled dinoflagellate cysts (dinocysts) from climatologically and oceanographically key sites, this project aims to contribute to a better understanding of the Eocene-Oligocene (E/O) environmental changes and their timing. A central issue is to identify the global environmental changes which are responsible for the Eocene cooling and its underlying mechanisms with the focus on the Oligocene isotope-1 (Oi-1) event, thought to mark the onset of major Antarctic glaciation. Two low-latitude sites were selected, Blake Nose (western North Atlantic) and Massignano (central Italy). For the first time a coherent taxonomy and biostratigraphy of dinocysts was established for the late Eocene at these latitudes. A high resolution correlation was established between the Massignano E/O Stratotype Section and the stratigraphically more extended ‘Massicore’. The composite section was used to analyse sea surface temperature (SST) change across the greenhouse-icehouse transition by means of dinocyst distribution. At Massignano, the Oi-1 event was recognised both qualitatively and quantitatively. In the power spectrum of the SSTdino the ~100 and ~400 kyr eccentricity cycles may be distinguished and correlated with La04. When orbitally tuned, the E/O GSSP dates ~100 kyr older than the Oi-1 event. The boundary’s age could either be ~33.75 or ~34.1 Ma, both differ significantly from the ~33.9 Ma age in the GTS 2004. Furthermore, when the data from the low-latitude sites were combined with extensive datasets from the Proto North Atlantic and adjacent regions, a suite of species sensitive to changes in SST was recognised. Their first and last occurrences reflect seven distinct phases of decreasing SSTs during the Middle Eocene to earliest Oligocene. These results clearly indicate that atmospheric cooling together with higher frequency orbital forcing played a key role in the transition from the Greenhouse to the Icehouse world.

In the mid-Cenozoic, New Zealand underwent slow subsidence interspersed with unconformity development, however significant controversy exists around both the extent of submergence below sea level during this period of maximum drowning, as well as the causes of these unconformities. Detailed field observations, combined with extensive petrographic analyses, stable isotopes, cathodoluminescence, and thin section staining were used to develop lithofacies, depositional, and sequence stratigraphic models of the mid-Cenozoic succession in the Waitaki region, South Island, to address these controversies. Twelve facies types have been described for Late Eocene-Early Miocene sedimentary rocks, leading to the identification of two major (Mid Oligocene & Early Miocene) and one minor (Late Oligocene) sequence boundaries. Surtseyan volcanism in the east produced a palaeohigh, resulting in a submerged rimmed cool-water carbonate platform, with low-lying land to the west. This eastern palaeohigh developed karst during sea-level lowstands, which correlate with silty submarine bored hardgrounds in the west. Glauconitic and phosphatic facies deposited during early marine transgression suggest an authigenic factory supplied by terrigenous clays existed during lowered sea level that was progressively shut down in favour of a carbonate factory as sea level rose and terrigenous supply decreased. The eastern palaeohigh served to nucleate this carbonate factory by raising the sea floor above the influence of siliciclastic sediment supply and providing a shallow substrate for marine colonisation. The higher energy eastern facies display dissolution of aragonitic taxa, while deeper western facies retained an aragonitic assemblage. This early bathymetric high created a barrier to submarine currents, but was gradually reduced by erosion during subsequent lowstands. Calcareous facies were often subjected to minor seafloor cement precipitation to shallow burial diagenesis, while eastern facies developed some meteoric cement during subaerial exposure. Comparisons between sea-level change in the study area and the New Zealand megasequence indicate eustatic changes as the primary driver of water depth in the Waitaki region until the development of the modern plate boundary in the Early Miocene.

A basin analysis of the Oligocene Porter Group rocks in Castle Hill Basin, Canterbury, was completed. The Porter Group contains the Coleridge Formation which comprises a lower sandstone unit and an upper micritic limestone unit, and the Thomas Formation which consists of biosparite limestone and interbedded tuffs. Basin analysis provided evidence that the Coleridge Formation lower sandstone unit was deposited in an inner shelf setting based upon its moderate sorting, large grain size range, laterally continuous geometry and lack of bedforms due to intense bioturbation. The upper micritic limestone is a mid shelf deposit composed of micrite and minor clastic grains. Provenance analysis has classified the lower sandstone unit as a quartz arenite. Both metamorphic and plutonic source areas are likely for the sandstone, along with reworked grains from underlying Formations based on QFL, SEM-CL, heavy mineral and glauconite analysis. The Thomas Formation limestone is a typical New Zealand cool water biosparite deposited on the inner shelf as a result of storms and debris flows, with the upper cross-bedded limestone lithofacies being reworked by currents in shallow water. Petrographic data showing multiple stages of diagenesis at the upper contact of the Thomas Formation provides evidence for a major tectonic event. The interbedded tuffs are a result of basaltic marine volcanism on the inner to mid shelf. The tuffs are reworked and deposited by turbidity current, debris flow and storms. Analysis of a dike within the Thomas Formation volcanics showed a weakly alkaline geochemical signature that is indicative of volcanism related to extension. A regional synthesis compared the Porter Group rocks in Castle Hill Basin with Oligocene rocks in North Canterbury, West Coast and North Otago. Oligocene quartz-rich sandstones are found in Castle Hill Basin, Harper Valley, Avoca and Culverden while micritic limestone is found on the East Coast from Marlborough to Otago. Oligocene basaltic volcanics interbedded with limestone and karst unconformities are found in Castle Hill Basin, Culverden and Otago. Normal faulting may be responsible for thickness variations and several regional karst unconformities in the eastern South Island. Plate reconstructions based on sea floor magnetic anomalies also suggests the New Zealand region was tectonically active during the Oligocene. Mounting evidence, including Eocene-Oligocene faulting and volcanism in the South Island, suggests that New Zealand may not be best described as a passive margin during the Early-Mid Tertiary.

<p> About half the Caribbean hermatypic corals died out at the Oligocene-Miocene boundary, about 25 Ma. Roughly two thirds of those corals which died out in the Caribbean are still extant in the Indo-Pacific. The coral and coral associate faunas of three Upper Oligocene and three Middle Miocene fossil reefs in western Puerto Rico were compared. Corals on these sites suffered 59% generic extinction, and 54% species extinction. Nearly all coral genera which are tolerant of turbidity or turbidity and cold water survived. All corals found exclusively or principally on Oligocene shelf-edge reefs became regionally extinct. There are no shelf-edge reefs documented from the Miocene in the Caribbean.</p> <p> Coral associates, the endolithic organisms which live in coral skeletons, were almost completely unaffected by this extinction. Likewise, reef and off-reef gastropods, bivalves, and echinoids suffered only insignificant reductions in diversity. Only corals and large benthic foraminifera were strongly affected by the extinction. It is significant that zooxanthellate organisms were the primary victims of this extinction. There is no evidence to suggest effects at higher trophic levels.</p> <p> Paleontological evidence from corals, coral associates, and gastropods suggests enhanced upwelling in the Caribbean during the Miocene and Early Pliocene. This enhanced upwelling could account for the extinction by cooling Caribbean coastal surface waters and restricting reef development to on-shelf patch reefs, where corals would be subject to more intense sedimentation. Paleoceanographic models indicating West to East deep circulation through the Central American Seaway during the Miocene provide a mechanism for this enhanced upwelling.</p> <p> Life history characteristics may have influenced survivorship among the corals, but apparently had no effect on coral associates. Corals which brood their larvae survived in greater proportions than corals which broadcast. This pattern is opposite that observed in studies on molluscs and other invertebrates.</p> <p> This regional extinction was important in the division of a previously cosmopolitan reef fauna into the modern provincial faunas. Explaining this minor mass extinction may contribute to an understanding of the volatile record of reefs in the larger mass extinctions of the Phanerozoic.</p> / Thesis / Master of Science (MSc)

The Josef Coal has the largest extent of all the Coals in the Sokolov Basin. The diploma thesis is concerned with studying of two profiles of the Josef Coal located in the opencast mines Medard-Libík and Družba for the purpose of micropetrograhic and chemical analyse. The goal of the diploma thesis is an interpretation of the sedimentary enviroment leading to formation of the Josef Coal based on the comparison of the petrographic and geochemical parametres of both profiles. Both studied profiles were initially macropetrographically described and sampled in a field. Samples were subsequently used for by maceral a chemical- technological analyses. The analysis of all 50 collected samples were performed at the Institute of Rock Structure and Mechanics Academy of Sciences of the Czech Republic. The micropetrographic composition was compared with chemical-technological standards. The macropetrographic description indicates some differences between both studied coal sections. The lower part of The Profile Josef 1 consists of the humic coal which in middle part evolves into the sapropelic one and that type persists the rest of the profile. The Profile Josef 2 is formed by sapropelic coal throughout the entire section except four decimeter thick benches of intercalated humic coal. Diferences in...

Durante o Eoceno e o Oligoceno (55 a 23 Ma) a Terra esteve sujeita a período de grandes mudanças climáticas. Registros geológicos, reforçados por modelos climáticos, indicam que o clima global durante esse período passou de estágio praticamente livre de calotas polares para situacao climática próxima a que hoje podemos encontrar na Antártica. Grande parte desses registros são indiretos, retirados de sedimentos de fundo marinho ou de material fóssil. Evidência terrestre clara da variação climática (greenhouse-icehouse) para o Eoceno-Oligoceno pode ser encontrada em Wesele Cove, ilha Rei Jorge, Antártica Ocidental. Tais evidências correspondem a uma sucessão de cerca de 60m com pelo menos 13 derrames de lava basáltica, de alguns metros de espessura cada, sobreposta, em contato erosivo, por diamictito e arenito. A sucessão basáltica é correlacionada com a Formação Mazurek Point/Hennequin, datada radiometricamente como do Eoceno, e o diamictito e arenito correspondem ao Membro Krakowiak Glacier da Formação Polonez Cove, datada, paleontológica e radiométricamente como pertencente ao Oligoceno inferior. Cada camada de basalto toleítico exibe uma zona inferior, mais espessa (1 a poucos metros), de rocha fresca, que é seguida transicionalmente por uma zona de alteração, variando de alguns decímetros a 1-1,5 m de espessura. O pacote de basalto está inclinado 25º para leste, provavelmente por tectonismo. A sucessão foi recentemente exposta devido ao rápido recuo da atual geleira Wyspianski. A evidência inicial de campo sugere que a sucessão representa um registro geológico de variação paleoclimática de condições mais amenas para condições glaciais, que pode ser correlacionada com a mudança do ótimo climático do final do Eoceno (greenhouse) para as condições de icehouse do Oligoceno, registradas na curva de paleotemperatura cenozóica estabelecida pela determinação de 18O em carapaças de foraminíferos. Este estudo teve como foco central a análise estratigráfica e geoquímica da ocorrência, a fim de interpretar a sucessão de eventos paleoclimáticos documentados no afloramento e analisá-los, no contexto da história paleoclimática da Antártica. Os dados obtidos mostraram que a transição de zonas não alteradas para alteradas observada em cada derrame de basalto pode de fato ser atribuídas à ação moderada de processos intempéricos no topo de cada derrame. Eles também demonstram uma origem glacial, em parte subglacial com contribuição marinha, dos diamictitos sobrepostos, que apresentam feições, tais como, clastos de litologias e tamanhos variados, facetados e estriados, clastos tipo bullet shaped, clastos partidos por congelamento, estrias intraformacionais e fósseis marinhos encontrados na matriz do diamictito. As condições climáticas amenas responsáveis pelo intemperismo do basalto durou até o surgimento do último horizonte de lava, seguida por movimentação tectônica que inclinou o pacote. Esses eventos indicam condições paleoclimáticas menos rigorosas relativamente longas durante o Eoceno, precedendo o estabelecimento do manto de gelo oligocênico nesta parte da Antártica. / During the Eocene and Oligocene (55 23 Ma) the Earth was undergoing a period of great climatic changes. Geological records, reinforced by climate models indicate that global climate during this period went from a stage in which the Earth was virtually free of polar ice caps to a stage close to what we find today in Antarctica. Most of these records are indirect, taken from the deep-sea cores or fossil material. Clear terrestrial evidence of climate change (greenhouse-icehouse) for the Eocene-Oligocene transition is found in Wesele Cove, King George Island, West Antarctica. This evidence includes a succession of at least thirteen, few meters thick, basaltic lava flows overlain disconformably by diamictite and sandstone. The basaltic section is correlated with the Mazurek Point/Hennequin Formation, radiometric dated as Eocene, and the diamictite and sandstone correspond to the Krakowiak Glacier Member of the Polonez Cove Formation, dated as Early Oligocene, on paleontological and radiometric basis. Each tholeiitic basalt layer exhibits a lower, thicker (1 to few meters) fresh zone, transitionally followed up by a zone of saprolith, varying from decimeters to 1-1.5 m in thickness. The entire basalt package of around 60 m, is tilted 25º to the east. The succession has been recently exposed due to fast retreat of the present Wyspianski Glacier. The initial field evidence suggests that the succession represents the geological record of paleoclimatic variation from mild to glacial conditions, that could correlate with the change from the late Eocene optimum climatic (greenhouse) to icehouse conditions in the Oligocene, as recorded on the Cenozoic paleotemperature curve established by 18O determinations on calcareous foram tests. This study had focus on the stratigraphy and geochemistry analysis of the occurrence, in order to interpret the succession of palaeoclimatic events documented in outcrop and analyze them in the context of paleoclimatic history of Antarctica. Data obtained consistently showed that the supposed transition from unaltered to altered zones observed in each basalt layer may in fact be assigned to the moderated action of weathering processes on top of each flow. They also demonstrate a glacial, in partly subglacial with marine contribution, origin for the overlying diamictites, which has features such clasts of diverse lithologies and sizes, faceted and striated clasts, bullet shaped clasts, clasts broken by freezing and thaw, intraformational striae and marine fossils found in the matrix of the diamictite. The mild paleoclimatic conditions responsible for weathering of the basalt lasted until the emplacement of the highest lava horizon, followed by tectonic movement that tilted the package. These events indicate a relatively long paleoclimatic mild conditions during the Eocene, preceding the establishment and displacement of the Oligocene ice-sheet in this part of Antarctica.

Grasshopper basin, located in southwest Montana, is an east-tilted graben bounded by the listric Muddy-Grasshopper fault and the Meriwether Lewis fault on the eastern and western margins of the basin, respectively. This basin contains a complex stratigraphy of intertonguing facies comprised of five unconformity-bounded sequences of Tertiary alluvial, flu vial, deltaic, and lacustrine sedimentary and volcanic rocks. Sequence 1 consists of the Challis volcanic Group (Middle Eocene). The sedimentary rocks of the Medicine Lodge beds (Late Eocene-Late Oligocene) represent sequence 2 and approximately 90% of the basin-fill within Grasshopper basin. Sequence 3 consists 11 of the Sedimentary Rocks of Everson Creek (Late Oligocene-Early Miocene), sequence 4 is represented by the Sedimentary Rocks of Bannack Pass (Middle-Late Miocene), and the Six Mile Creek Formation (Late Miocene?) corresponds to sequence 5. Sequence 2 is the synrift deposit for the Muddy-Grasshopper fault, and was dominated by lakes that filled axially by rivers from the north. Transverse sediment influx was present on small fan-delta complexes shed into the lake from the eastern margin and periodic large fluvial-dominated alluvial fan and deltaic deposition from the western margin. Paleocurrent analyses are consistent with these observations and show predominantly south-southeastward axial paleoflow directions with west-directed and east-directed paleoflow on the eastern and western margins, respectively. Petrologic studies, including sandstone petrography and conglomerate petrology, reveal a mixed "basement uplift" and "recycled orogen" tectonic provenance. These findings support a model for Eocene-Oligocene rifting characterized by moderate to high relief superimposed on the Cretaceous-Early Tertiary Sevier fold-and-thrust belt. Paleogeographic reconstructions of Grasshopper basin reveal the lack of a southern basin margin. A correlation of the basin-fill contained in the Medicine Lodge and Horse Prairie basins to the south with the Medicine Lodge beds (sequence 2) in Grasshopper basin suggests that each of these basins represents a third of a larger preexisting extensional basin that was partially dismembered by later phases of continued extension. Large extensional folds in Grasshopper basin had a small influence on facies architecture in the basin.