Call number: LD2668 .T4 1951 C7 / Master of Science

No description available.

The Pleistocene section exposed in the May Stone and Sand Company, Inc., Ardmore Avenue quarry rests in the upper reaches of the Wabash-Erie Channel. The section consists of two distinct till units which are covered by a thick outwash deposit. Analysis of the tills has led to the assignment of the lower till to the Trafalgar Formation, while the upper till is assigned to the Lagro Formation. The 13- to 16-foot outwash unit shows evidence of rapid drainage which may be related to the catastrophic drainage of glacial Lake Maumee. Isolated mud to muck inclusions in the top eight feet of the section show the final depositional environment of the channel. These deposits were produced near the end of late Wisconsinan time. The last major event in the area was the stream piracy of the St. Joseph and Ste. Mary's Rivers by the Maumee River, in Late Wisconsinan or Recent time.

In this thesis, I present new results based on 2D multi-channel seismic data of the Song Hong-Yinggehai and Qiongdongnan Basins, geochemical data derived from ODP Site 1148, and sediment provenance analysis of modern sediment and Cenozoic sedimentary rocks collected along the Red River system. The Song Hong-Yinggehai Basin started opening after ~50 Ma but strong subsidence, triggered by motion on the Red River Fault, only occurred after ~34 Ma.  This process was followed by thermal subsidence after ~21 Ma.  In contrast, the formation the Qiongdongnan Basin is believed to be related to the development of the northern rifted margin of the South China Sea. Sediment budget estimates, coupled with geochemical data show that chemical weathering gradually decreased after ~25 Ma, while physical erosion became stronger.  These data also suggest a period of the monsoon enhancement (~15-10 Ma), although with a likely initial East Asia monsoon strengthening ~23 Ma. U-Pb zircon dating coupled with Hf isotopes, muscovite Ar-Ar dating, bulk sediment Nd isotope and heavy mineral analysis allow me to draw the following points: (1) if the headwaters of the modern Yangtze, Mekong and Salween Rivers were ever connected to the palaeo-Red River then they were disconnected from the Red River no later than the Middle Miocene; (2) The palaeo-Red River flowed northeast of the Day Nui Con Voi during the Miocene and did not flow via Lao Cai and southwest of the range as it is observed today; (3) the Yangtze Craton and the Songpan Garze Block are the most important source regions to the Red River; (4) apart from the main Red River trunk, the Lo River is the most important sediment contributor to the Red River system, while the Da River is only a minor contributor.

The study is based on the post-Messinian depositional sequences of the Ebro continental margin and Nile submarine cone, on the northwestern and southeastern Mediterranean, respectively.  This study is based mainly on the interpretation of 3D geometries and stratigraphical relationships observed on 3D and 2D seismic reflection data. These siliciclastic systems evolved along the Mediterranean ‘passive’ margins at approximately the same time, thus experiencing the same post-Messinian eustatic history.  However, they have been subject to entirely different local forcing, and present markedly different sedimentation histories. while the seismic profiles of the Pliocene-Pleistocene succession of the Ebro continental margin display a complex pattern of well-developed margin-scale clinoforms, seismic profiles on the Nile cone show a succession characterized by mass-transport deposits and channel-levee systems. Major transformations in the long-term architectural style are recognized in both systems and these are correlative in time at the Plio-Pleistocene boundary, suggesting an externally driven mechanism.  Moreover, sediment budget calculations indicate an increase in the amount of sediments delivered to these basins during the Pleistocene. Their architectural development changed not only in response to the effects of changes in external controls on the sedimentary dynamics and sediment transfer processes as the classic sequence stratigraphic model considers, but also through morphodynamic feedbacks.  Oversteepening of the depositional profile as these systems prograded into the deeper basins led to mass failures of the shelf margin and deficits of mass in certain portions of the system that led to their complete re-organization.  The concepts of slope accommodation, mechanisms of sediment redistribution along the continental margin, and the persistence of significant stratigraphic surfaces, are called into question in these systems.

Here is presented a high resolution vegetation model and ecological analysis of an extinct floodplain ecosystem based on the palynology of deposits of the Sagwon Bluffs, northeast Alaska.  This fluvio – lacustrine succession of coal – bearing beds is of Late Palaeocene age and dominated by fine-grained sediment interspersed by coarse sandstones and conglomerates.  Deposition occurred at a latitude of ~ 85° N, but owing to the Palaeocene greenhouse climate, mean annual temperatures as high as 6 - 7°C allowed temperate plant ecosystems to exist.  The palynological dataset has been analysed here using ‘Correspondence Analysis’ (CA) and ‘Fuzzy <i>c</i>-Means Cluster analysis’ (FCM), allowing assessment of proposed ecological groups.  Geochemical analysis has been incorporated using ‘Canonical Correspondence Analysis’ (CCA), demonstrating affiliations of certain taxa to chemical signatures of associated sediments.  These techniques collectively reveal a gymnosperm – dominated floodplain forest with a substantial angiosperm, fern and bryophyte component analogous to modern wooded bogs and riparian swamp forests.  Principal taxa of late seral development include <i>Metasequoia, Taxodium, Sequoia </i>and <i>Nyssa, </i>representing the dominant component of such a forest.  Mid seral floras were characterised by coniferous gymnosperm and broad-leaved angiosperm co-dominance, incorporating <i>Corylus, Alnus, Castanea, Ginkgo </i>and a diversity of Pteridaceous, Polypodiaceous, Osmundaceous and Schizaceaen ferns.  Variably high abundances of <i>Sphagnum-</i>type bryophyte spores suggest extensive peat-forming mires.  The inconsistencies of the ecological structure displayed in the palynological assemblage suggest a dynamic floodplain, however, affected by a changing hydrological and climatic regime.  Climate cooling is considered to have affected the floras concurrent with an increasingly wet floodplain prior to a hypothesised period of mountain building to the south.

Call number: LD2668 .T4 1950 C63 / Master of Science

M.Sc. (Geology) / This study represents the first detailed field, geochemical and geochronological study of Archaean rock units that crop out along the Ncotshane River in the southern part of Swaziland. These rock units were mapped as Mahamba Gneiss in the geological map of Swaziland (Wilson, 1982). However, field examination indicated that the area consists of a heterogeneous assemblage of serpentinite, amphibolite, gabbroic gneiss, quartzite, meta-ironstone, augen gneiss, granitic gneiss and diorite, all of which are intimately associated with weakly foliated granite and dolerite. Serpentinite is regarded to represent the metamorphosed equivalent of komatiite found in the Dwalile Supracrustal Suite, a correlate of the Onverwacht Group, on the basis of similar geochemical characteristics. The silicified part of the serpentinite may compare with silicified komatiite that are widely observed in the Onverwacht Group. It is equally possible however that the ultramafic rocks originated as intrusions that are widespread in the SE Kaapvaal craton and which include both Palaeoarchaean and Mesoarchaean layered complexes. No contacts with neighbouring rocks were observed, thus not allowing unequivocal differentiation between the different possibilities. Amphibolites represent metamorphosed equivalents of the Mozaan Group basalts based on their association with Mozaan quartzite. Gabbroic gneiss, which occurs in association with amphibolite, likely represents an intrusive equivalent of amphibolite.....

Ph.D., Faculty of Science, University of the Witwatersrand, 2011 / The Wahweap Formation is an ~400 m thick clastic sedimentary succession of fluvial and estuarine channel sandstones and floodbasin mudrocks that was deposited in western North America during the Late Cretaceous. It preserves important mammal, dinosaur, crocodile, turtle and invertebrate fossils that have been the subject of recent palaeontological investigations. The Wahweap Formation can be divided into lower, middle, upper, and capping sandstone members based on sand:mud ratios and degree of sandstone amalgamation. Facies analysis reveals the presence of ten facies associations grouped into channel and floodbasin deposits. Facies associations (FAs) from channels include: (1) single-story and (2) multistory lenticular sandstone bodies, (3) major tabular sandstone bodies, (4) gravel bedforms, (5) low-angle heterolithic cross-strata, and (10) lenticular mudrock, whereas floodbasin facies associations include: (6) minor tabular sandstone bodies, (7) lenticular interlaminated sandstone and mudrock, (8) inclined interbedded sandstone and mudrock, and (9) laterally extensive mudrock. The lower and middle members are dominated by floodbasin facies associations. The lower member consists dominantly of FA 8, interpreted as proximal floodbasin deposits including levees and pond margins, and is capped by a persistent horizon of FA 3, interpreted as amalgamated channel deposits. FAs 4 and 6 are also present in the lower member. The middle member consists dominantly of FA 9, interpreted as distal floodbasin deposits including swamp, oxbow-lake and waterlogged-soil horizons. FAs 1, 2, 5, 6, 7, 8, and 10 are present in the middle member as well, which together are interpreted as evidence of suspended-load channels. The upper member is sandstone-dominated and consists of FAs 1, 2, 3, 5, 7, and 8. FAs 5 and 7, which occur at the base of the upper member, are interpreted as tidally influenced channels and suggest a marine incursion during deposition of the upper member. The capping sandstone is characterized by FAs 3, 4, and 6, and is interpreted to represent a major change in depositional environment, from meandering river systems in the lower three members to a low-accommodation, braided river system. Combined results of facies and palaeosol analyses suggest that the overall climatic conditions in which the Wahweap Formation was deposited were generally wet but seasonally arid, and that iv conditions became increasingly moist from the time of lower member deposition up to the time of middle member deposition. Improved age constraints were obtained for the Wahweap Formation by radiometric dating of two devitrified ash beds (bentonites). This allowed for deposition to be bracketed between approximately 81 Ma and 76 Ma. This age bracket has two important implications: firstly, it shows that the Wahweap Formation is synchronous with fossiliferous deposits of the Judithian North American Land Mammal Age, despite subtle differences in faunal content. Secondly, it shows that the middle and upper members were deposited during the putatively eustatic Claggett transgression (T8 of Kauffman 1977) in the adjacent Western Interior Seaway. This is consistent with facies analysis which shows a marked increase in tidally-influenced sedimentary structures and trace fossils at the top of the middle and base of the upper members. Following recent alluvial sequence stratigraphic models, the middle member is interpreted as the isolated fluvial facies tract, while the upper member represents the tidally influenced and highstand facies tracts. Maximum transgression occurred during deposition of the lowest part of the upper member, synchronous with the Claggett highstand in other parts of the Western Interior Basin. The sequence boundary is placed at the base of the overlying capping sandstone member, diagnosed by a major shift in petrography and paleocurrent direction, as well as up to 4 m of fluvial incision into the underlying upper member. The capping sandstone member is interpreted as the amalgamated fluvial facies tract of an overlying sequence. Analysis of the western-most exposures of the Wahweap Formation on the Markagunt and Paunsaugunt plateaus shows facies variations in the proximal and distal parts of the central Western Interior Basin. The inconsistent thickness and variations in fluvial architecture, as well as the presence of unconformities and generally poor exposure in the west, hinder correlation attempts and also prevent the subdivision of the Wahweap Formation into members. Only the capping sandstone, which can be positively identified west of the Paunsaugunt fault, has a consistent thickness and fluvial architecture across the west-east extent of the Wahweap Formation. The capping sandstone also bears remarkable lithological similarity to the Tarantula Mesa Formation which is exposed to the east in the Henry Mountains Syncline, and it is suggested that these two units be equated under the name “Tarantula Mesa Formation”, which has precedence.

No description available.