Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. / Restricted until May 2005. Bibliography: leaves 145-153. Also available online.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 135-144. Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (M. Sc.)--University of Hong Kong, 2003.

No description available.

The Zerrissene turbidite system of central-western Namibia is a late Proterozoic sequence which consists of dominantly siliciclastic turbidites interbedded with minor turbiditic and hemipelagic marbles. The basin in which these sediments were deposited is located at the junction of the coastal and intra-cratonic arms of the Pan-African Damara Orogen, and an understanding of the sedimentary evolution of this basin is therefore important to the understanding of the development of the orogen as a whole. One major and two minor phases of folding have deformed the sediments, but the grade of metamorphism is low and sedimentary structures are often well preserved. Further, the area lies entirely within the Namib Desert and the lack of vegetation cover results in good outcrops providing an unusual opportunity for examining a large Precambrian turbidite system. The system consists of five formations: three siliciclastic and two mixed carbonatesiliciclastic units. The floor of the system is not exposed, and the oldest sedimentary rocks which outcrop are siliciclastics of the Zebrapiits Formation. This is overlain successively by the Brandberg West Formation (dominantly calcareous), the Brak River Formation (siliciclastic), the Gemsbok River Formation (calcareous) and the Amis River Formation (siliciclastic). Nine silicilastic turbidite facies have been recognised in the basin. These are facies A₂ (disorganised onglomerates), B₁ (horizontally laminated to massive greyackes), C₂ ("classical" turbidites), Dl (sandstone-shale couplets with base cut-out Bouma sequences), D₂ (sandstone-shale couplets with less sand than shale and base cut-out Bouma sequences), E (coarse, discontinuous sandstone-shale couplets), F (slumped units), G (shale) and H (glacial dropstones). Four facies are associated with the carbonate horizons, and these carbonate facies are given the suffix c to distinguish them from similar siliciclastic facies. These are facies Ac (disorganised and graded marble breccias), facies Cc (graded carbonates), facies Gc (hemi-pelagic marbles) and facies G (pelagic shales). The basal Zebrapiits Formation is made up of relatively thin packages of thin- to thickbedded, laterally continuous facies D₁, D₂ and B₁ beds encased in thick envelopes of shale. This type of sequence is typical of a distal lobe-fringe, and requires an unconfined basin-floor on which it can develop. The overlying Brandberg West Formation consists of a basal portion of interbedded facies Cc and G, followed by a sequence dominanted by facies Gc. This sequence is interpreted as representing outer-apron carbonate turbidites, derived from multiple point sources (facies Cc), with background pelagic settling (facies G) overlain by hemi-pelagic deposits (facies Gc). A reversal back to siliciclastic turbidites followed with deposition of the Brak River Formation. This sequence comprises relatively thick packages of laterally continuous facies B₁, D₁, and D₂ beds sandwiched between facies G shales, a succession characteristic of a lobe to lobe-fringe environment with intermittent abandonment of lobes. An unconfined basin floor adjacent to a passive margin is required for the development of this type of sequence. Glacial dropstones (facies H) are found in the upper portions of this formation, and slumped beds are also present (facies F), but are uncommon. The facies F beds are only found in association with facies H and are therefore considered to be genetically related. Slumping of beds was possibly caused by an oversupply of sediment from ice-rafting which caused instability. The overlying Gemsbok River Formation has a sequence similar to the Brandberg West Formation in that the basal portion consists of interbedded facies Cc and G, which is overlain by a thick sequence of largely facies Gc beds. Minor facies Ac beds occur near the top of the overall sequence. This formation is interpreted as an outer-apron succession with the facies Ac beds representing distal inner-apron deposits, indicating progradation of the system. The youngest unit in the basin, the Amis River Formation, shows strong lateral variation from west to east. In the west the sequence comprises laterally continuous facies B₁, C₂, D₁ and D₂ with rare, discontinuous facies E beds. Facies G is relatively minor in the sequence. In the east the succession is dominated by facies D₁, D₂ and G, and this succession is interpreted as a sequence of distal turbidites which were deposited on a basin-plain. The system developed by aggradation rather than progradation as only minor cycles are developed. Geochemical and petrological features indicate that the entire siliciclastic system was derived from a granite-recycled orogen terrane. Palaeocurrent data are unreliable because of the deformation, but transport was initially from the south-west, moving later to the west and north-west. The provenance of the carbonates is uncertain as reliable palaeocurrent indicators are rare, but they could have been derived either from South America or from the extensive carbonate deposits developed on the north-western margins of the basin. The Zenissene siliciclastic turbidite system represents the distal portion of a major submarine turbidite system, the more proximal parts of which now lie west of the exposed basin, either under the Atlantic Ocean or in eastern South America. The calcareous deposits developed as an apron adjacent to a multiple point source, the position of which is at present unknown.

Alluvial fan construction within British Columbia was dependant upon temporary conditions resulting from deglaciation; there is no significant fan aggradation at present. Five study areas were selected from the semi-arid sections of the Fraser, Thompson, Bonaparte, South Thompson and Similkameen valleys. The Tertiary and Quaternary geo-morphic histories of these areas are similar in many respects--most significantly, one or more phases of Pleistocene glaciation were followed by fluvial and lacustrine aggradation--but vary regarding the amount of subsequent downcutting by major rivers. This ranges from several hundred feet in the Fraser and Thompson valleys to a few feet or none in the Similkameen and Bonaparte valleys. Stratigraphic evidence from the Fraser Valley indicates that fan building commenced soon after the valley floor became ice-free, probably whilst glacial conditions persisted in tributary basins. It continued during aggradation by major rivers and for sometime afterwards. In the Thompson and South Thompson valleys fans were most recently built upon degradational river terraces. The occurrence of Mazama volcanic ash within fans indicates that construction continued until after 6,600 years B.P. Fans were built during a phase of landscape readjustment from predominantly glacial to predominantly fluvial conditions. They resulted from the secondary deposition of glacial drift and locally weathered material by streams and mudflows. Fan composition was dependant upon the nature of the available material and upon the character of the parent basin. For example, the widespread occurrence of glacio-lacustrine silt in the Thompson Valley gave rise to fans composed of silty mudflow gravels. Generally, small, steep basins produced mudflows whereas larger basins had more constantly flowing streams which deposited fluvial gravels. Fan aggradation declined as the drift supply was exhausted; deposition of material derived by current weathering was insufficient to maintain the growth of the fans. After deposition ceased many fans were dissected as a result of local base-level lowering controlled by degradation of major rivers and/or fan-head trenching initiated as the debris supply declined. Fan-head trenching is best developed in the South Thompson Valley; base-level dissection predominates in the Fraser and Thompson Valleys. Where fan building persisted during degradation, multilevel fans were constructed. Statistical correlations among morphometric parameters describing fans and related basins indicate that basin characteristics exerted an influence upon fan geometry through the nature of the fan building stream. There relationships vary regionally, possibly reflecting lithologic, climatic and geomorphic contrasts. British Columbia fans are steeper and display a greater variation of morphometric relationships than fans of the arid American Southwest. Fans resulting from deglaciation are distinguished by use of the prefix "para-glacial". / Arts, Faculty of / Geography, Department of / Graduate

M.Sc. (Geology) / Please refer to full text to view abstract

Pitt River, 30 km inland from. Vancouver, British Columbia at the southern margin of the Coast Mountains, links Fraser River estuary and Pitt Lake. Salt water seldom extends to within 10 km of Fraser - Pitt confluence; nevertheless, tides modulate Fraser flow and cause Pitt River to fluctuate 2 m and Pitt Lake as much as 1.2 m. There is an upstream movement of sediment in Pitt River from Fraser River, evidenced by identical mineralogy of Pitt River and Fraser River sediments, a decrease in grain size from the Fraser to Pitt Lake, and a predominance of flood-oriented bedforms in the river channel. A delta of 12 km2 area has accumulated at the lower (draining) end of the lake. The purposes of the study were to: (1) examine aspects of the hydrodynamics of Pitt River and Pitt Lake as a tidal system; (2) evaluate the effect of bidirectional flow on river and delta morphology; (3) determine processes of sediment movement in the river and of-sediment dispersal on the delta; and (4) estimate present sedimentation rate on the delta. Water Survey of Canada stage data from 3 locations in the system, used in conjunction with velocity measurements (profiles and tethered meter), revealed large seasonal and tidal variations in discharge. Calculations indicate that flood basal shear stress peaks early in the flow, whereas ebb currents have a lower basal, shear stress which peaks late in the flow. Thus, sediment moves farther forward on a flood flow than it moves back on the succeeding ebb. Studies of the river channel using hydrographic charts revealed regular meanders (^M = 6100. m) and evenly spaced riffles and pools which are scaled to the strongest flow (winter flood current, Qe). Meander point bars are accreting on the "upstream" side indicating deposition by the flood-oriented flow. The three dimensional geometry of the large-scale bedforms which cover the sandy thalweg of both river and delta channel was determined by echo sounding and side-scan sonar. Three distinct sizes (height/spacing = 0.8 m/10-15m; 1.5m/25-30 m; 3 m/50-60 m) of large-scale bedforms (sand waves) were found; their linear-relationship of height vs. spacing (XD) on log-log plot suggests a common genesis. The size appears to be related to channel geometry, not to depth of flow. Largest forms are found in reaches which shallow in the direction of water movement and smallest forms occur on relatively flat topography. The following tentative relationship is suggested for sandy meandering rivers: ^M/^B = Qe. Pitt delta morphology was studied with aerial photos and depth soundings. Its shape is considered an excellent example of sediment diffusion and deposition from a simple jet into a low energy lacustrine environment. Analysis of 190 sediment samples from river, delta, and lake bottom shows the sediment to be polymodal. Graphical partitioning of the cumulative probability plots reveals that sediments are composed of up to 4 log-normal distributions. Each distribution is interpreted as a population related to a process of sediment transport. Five subenvironments in the Pitt system are characterized by unique combinations . of these "process" populations. Cores in the delta topsets and lake bottom sediments reveal silt and clay rhythmites, interpreted as varves. The coarse layers are deposited during winter when discharge of Fraser River is low and tidally induced discharge in Pitt system is high. The fine layers are deposited during spring run-off when additional fines are added to the lake from the Pitt basin. 137Cs dating of sediments shows that as much as 1.8 cm/yr are accumulating in the active portions of the delta with an estimated 150 +/- 20 X 103 tonnes deposited annually. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The author has sampled the recent bottom sediments in Tillamook Bay, Oregon. Sediment distribution is assessed in relation to sediment source areas and related to sedimentary environments. Particular attention was directed to the precision with which granulometric data can be stated. It was found that variance is quite high for granulometric parameters of the bay sediments. Sediment distribution using different measures are displayed on charts of the bay. Size distributions of sediments at any given location are examined for geologic significance. Plotting of size distribution on graph paper using probability ordinate is shown to increase the ease of geologic interpretation. Total heavy minerals were X-rayed and provenance determinations from this and other data show a marine sediment source for a small area of the bay near the mouth and terrestrial source for the remainder of the bay.