Boston University. University Professors Program Senior theses. / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-02

>Magister Scientiae - MSc / Separation between the South American and African plate’s occurred along the present day Atlantic margin during the Middle to Late Jurassic leading to the formation of a passive margin along the west coast of Southern Africa. The margin then later developed into the large Orange Basin flanking the west coasts of South Africa and Namibia. The Orange Basin on the west coast of South Africa covers an area of roughly 130 000 square kilometers relevant to the 200 m isobath and has roughly one well drilled for every 4000 square kilometers. The basin has proven hydrocarbon reserves and potential for further discoveries. The study area is located within South African exploration licencing blocks 3A/4A and 3B/4B and covers a region of roughly 97 km by 150 km. The study aims at understanding the geological processes responsible for the formation of the Orange Basin with a focus on the evolution of source rock maturity. The methodology involved utilizing the Petrel software for seismic interpretation and well correlation utilising twodimensional seismic data and all the relevant well data including geological well logs, petrophysical well logs, well top data, check-shot data, borehole temperature data and geochemical well data such as Rock Eval and vitrinite reflectance data. PetroMod (IES, Version 10) was utilized to simulate the Orange Basin evolution and the affect on source rock maturity. Seismic interpretation of the Post-Hauterivian succession shows a relative thickening of the sedimentary sequence westward as the basin evolves from the early drift to complete drift phase. Results from the petroleum system modeling indicate that the Barremian - Early Aptian source rock is at present overmature and producing mostly gas in the shelf areas whereas the potential for oil are most likely present in the deep water area of the basin where Tertiary progradation has resulted in renewed petroleum generation. Petroleum system modeling results indicate that the younger Cenomanian - Turonian source rock is less mature than the older Barremian - Early Aptian source rock as indicated by a lower transformation ratio and is mainly producing oil.

No description available.

High-resolution sampling of Neoproterozoic basin-floor to slope deposits in the Windermere Supergroup, east-central British Columbia indicates three distinct stratigraphically ascending clusters suggesting temporal changes in sediment provenance. Assemblage 1 has a characteristic northwestern Laurentia bimodal detrital zircon distribution with low εNd values, and intermediate to mafic igneous provenance as indicated by discriminant function analysis of major elements, low Th/Sc and Zr/Sc, high Co/Th, and high Cr abundance. This suggests derivation from western Laurentia basement rocks and Archean mafic and ultramafic suites from the Central Hearne province supracrustal belt. Assemblage 2, although compositionally similar, has an additional 655 Ma detrital zircon age population, higher εNd values, and felsic igneous to recycled provenance, suggesting a significant Neoproterozoic igneous rift-related source. Assemblage 3 marks the end of input from the juvenile ca. 655 Ma source and felsic igneous to recycled provenance, suggesting a return to western Laurentian cratonic sources.

Deep-marine basins linked to active continental margins by sloped ocean-floor profiles commonlyhost the final accumulation of sediment that was eroded and transported from the continents. Thedeep-marine sediment archives preserved in these settings commonly offer the most completerecord of sediment transfer from continents to ocean basins over geologic time scales. This isespecially true in basins associated with regions of active tectonism, where loss or alteration ofsediment source terrains leave submarine basin deposits as the only record of the tectonic and cli-matic forcings that govern the transfer of sediment to the deep basin. The overarching goal of thisdissertation is to evaluate controls on submarine slope and basin-floor sedimentation that considersboth large-scale system drivers and the internal complexities and autogenic processes associatedwith sediment routing systems. In pursuit of this goal, the research presented in this dissertationspans a range of spatial and temporal scales. At the largest scale, the influence of sediment recy-cling is addressed to evaluate how changes in intrabasinal sediment sources reflect phases of basinevolution and what influence recycling of previously deposited basin sediments has on the fidelityof the deep-marine sedimentary record at geologic time scales. At the smaller scale, analysis ofsedimentation units and characterization of sedimentary bodies form the foundation for linkingthe stratigraphic preservation of depositional processes to discrete submarine geomorphic condi-tions. Such a linkage can provide insight into changes in slope gradient and the transition fromsediment transport and bypass to sediment deposition along the slope profile. Thirdly, a detailedinvestigation of deformed slope deposits addresses how depositional processes and stratigraphicstacking of submarine fan deposits influences slope stability. Synthesis across these broad spatialand temporal scales required integration of various tools and data types including: (1) detailedoutcrop measurements, (2) cliff-face correlation and characterization of depositional architecture,(3) geologic mapping, (4) basin-scale correlation, (5) detrital geochronology, and (6) carbonategeochemistry. / Ph. D.

No description available.

Factors controlling cyclic sedimentation are discussed in a parallel study of two evaporite-bearing sequence, the Zechstein of Germany and the Silurian Salina Group of the Appalachian Basin. The Zechstein sequence was deposited in a basin that had received the debris swept in from the Variscan orogenic zone. The deposition of the evaporite-bearing sequence took place during a period of tectonic calm, preceded and succeeded by mild late Variscan movements. The sequence is divided into four major cycles by shale horizons accompanied and basinwards partially replaced by dolomites and anhydrites. Halite is the dominant sediment, it contains beds of anhydrite and potash salts, less commonly of shale, forming with the halite sedimentary cycles of diverse magnitudes. The Salina Group has been deposited in a basin that had previously received debris from the Taconic orogenic zone. The last orogenic movements had virtually ceased before the deposition of evaporites commenced. The evaporite-bearing sequence is divided into three major cycles by shale suites related to alluvial, fans of debris swept in from the previous orogenic zone. The shale beds are accompanied by dolomite beds containing stromatolitic horizons. The salt contains shale and dolomite beds of diverse thicknesses, giving rise to cycles of varied magnitudes. With increasing distance from the orogenic zone, the thinner shale interbeds in the salt grade into anhydrite. In contrast to the Zechstein sequence, in the Salina Group thicker anhydrite beds are rare and no potash zones have been found. The anhydrite deficiency is attributed by the author to bacterial reduction of the CaSO₄. The H₂S thus formed is in part retained in the sediments, in part it deposited FeS₂ or re-oxidized. The lack of potassium salts indicates a less inhibited communication with the open sea, as also witnessed by repeated incursions of marine fauna. In both sequences, most sedimentary cycles are controlled by the periodic entrance of diluted waters into the basin. Rain water enters directly as well as in the form of terrestrial run-off from the adjacent mountains, introducing mud and foreign ions, diluting and changing the ion ratios of the brines. Sea water enters the basin continuously or periodically, the concentration increases caused by the concomitant inflow of dissolved salts are mitigated by the reflux of more concentrated brines. Abrupt dilution of the brines by sea water followed by slow evaporation produces cycles of progressive solubility in the sediments resembling experimental successions. The periodic entrance of rain and sea water can be controlled by several factors. Increases in rainfall, particularly in the detritus source area, may reflect morphologically or astronomically induced climatic changes; the morphologic factors may in turn be controlled by tectonism, erosion and sediment accumulation. The ingress of sea water can be caused by intermittent subsidence in the bar area, or by a rise of sea level induced tectonically, glacio-eustatically, or simply by a change in wind direction. A few models involving parallel control of terrestrial and marine inflow are presented at the end.

No description available.

>Magister Scientiae - MSc / The Sable Field constitutes a Basin Floor Channel (BFC) complex (E-BD reservoir) and a Basin Floor Fan (BFF) complex (E-CE reservoir). The reservoir sands were deposited during early-drift sedimentation in the Bredasdorp Basin. Paleo-current flows from the west, filling the basin with sediments that are eroded off the continental shelf (Agulhus Arch) and deposited on the base of the continental slope and basin floor. Turbidite flows off the Agulhus arch have deposited the Sable Fields reservoirs, where the larger channelized reservoir body takes an 80° bend off the continental slope and flows onto the basin floor. This 3-D reservoir highlights the reservoirs internal heterogeneity and complexity at the well bore and away from the well bore. Well tops tie wells to the 3-D seismic cube for; reservoir location and delineation, velocity modelling and subsequent conversion of the mapped surfaces from time to depth. Core and petro-physical analysis were used to outline the depositional facies within the investigated wells namely: E-BD5, E-BD2, E-BD1 and E-CE1. Correlation of depositional facies at the well bore with their corresponding seismic facies, allows for extrapolation of facies away from the well bore. The internal heterogeneity of the reservoir is outlined using an integrated methodology, which is based on log scale depositional features (channels, sheets, lobes) that are extrapolated to field scale (sand rich complex) using corresponding top and base reservoir seismic responses. The investigated thick region of sediment accumulation on: the continental slope, the base of the continental slope and basin floor is deposited on the 13AT1 early drift unconformity. The reservoir is outlined from the up-dip to the down-dip reaches of the field. Well E–BD5 has tapped into the proximal region (up-dip), with reservoir comprising of amalgamated channel sands that are deposited by laterally switching and stacking channelized sand bodies. Channel meander facies are seen in the upper portion of the reservoir, with massive channel fill in the lower parts. The channel fill constitutes a high net to gross with little to no lateral facies variations. This confined environment is dominated by amalgamated massive sands (on-axis) that are thinner bedded towards the banks of the channels (off-axis). A high degree of channel amalgamation has been interpreted in both up-dip wells E-BD5 and E-BD2. This channelized reservoir is at least 2km wide and 6km long, before the larger channel makes a rapid 80° change in paleo-current direction. This is possibly the result of basin floor topography and the stacking of previously deposited sand complexes which alter local sea floor topography. The vertical and lateral continuity of the channelised reservoir is generally excellent due to the high degree of channel amalgamation. The stacked channel complex constitutes a gross thickness of 76.2m (68.5m Net sand) in well E-BD5, and a gross thickness 25m (23m Net sand) in well E-BD2. Channel sands in well E-BD5 have an average porosity of 15% while the average porosity of channel sands in well E-BD2 (further down-dip) is 17%. This up-dip channelised region results in high amplitude reflections due to hydrocarbon charged sand juxtaposed against hemipelagic muds and silty levee facies. Well E-BD1 has tapped into a relatively confined sand complex deposited at the base of the continental slope. The amalgamated lobe and sheet sand complex is entirely encased in hemi pelagic mud. These reservoir sands are interpreted to be deposited in the Channel Lobe Transition Zone (CLTZ), thus the reservoir sands are interpreted to have a transitional depositional style (generally channelized sheets). The CLTZ region is thus dominated by both channel complex and lobe complex elements. The E-BD1 reservoir constitutes a number of amalgamated elements that result in a reservoir zone with an average porosity of 16.4%. These include: amalgamated thick bedded sheet sand (lobe axis) associated with deep depositional feeder channels; thin bedded sheet sands (off lobe axis), broad thin amalgamated lobe elements, layered thick bedded sand sheets and deep broad depositional channels. The low sinuosity broad depositional-channels and elongate lobe elements are expressed as lobate amalgamated sheets of sand which is up to 2-3km wide, 5km long and 30m thick (29.7m nett sand) at the well bore. Well E-CE1 has intersected 50m thick reservoir sand (50m nett sand) which constitutes the axis of a lobe complex where the reservoir zone has an average porosity of 14%. The sand rich complex is deposited on the unconfined basin floor. This reservoir complex constitutes amalgamated thick bedded lobe architectural elements which are massive in nature. The laterally continuous hydrocarbon charged lobe elements result in bright parallel seismic reflections. The amalgamated lobe complex is more than 5km wide. Sub-parallel horizons are attributed to the thin bedded off axis portion of the lobe complex where the net to gross is considerably less than the highly amalgamated axis of the lobe complex. The lobe complex has a moderate to good net to gross of 40-60%. The high aspect ratio of the lobe complex severely impacts the reservoirs vertical permeability, however horizontal permeability is quite good due to the extensive lateral continuity of good quality sheet sands. Based on the nature deep water architectural elements observed in this study, the internal heterogeneity of the Basin floor Fan and Basin floor channel complex’s may constitute an entire sand rich reservoir zone. All the sands may be in hydraulic communication if they are genetically related. These sands and stretch from the up-dip (wells E-BD5 & E-BD2) through to the transitional (E-BD2) and pinching out in the distal regions (E-CE1) on the basin floor. The seal constitutes a prominent shale horizon T13PW3 (8-10m thick) which is draped over the entire reservoir complex. This top seal is extrapolated from all the wells and correlated with seismic facies, thus outlining the lateral continuity and thickness variations of the top seal. This draped shale horizon exposes the thick axial portion of the amalgamated channel complex and amalgamated lobe complex.

The Early Permian coal samples for the study were obtained from the Vasse Shelf, southern Perth Basin, located approximately 200 km south- west of Perth. The selected coal samples for the study were also obtained from the Premier Sub-basin of the Collie Basin and the Irwin Sub-basin of the Perth Basin. The Early Permian coal measures are described as the Sue Coal Measures from the Vasse Shelf, the Ewington Coal Measures from the Premier Sub-basin and the coal measures from the Irwin sub-basin are described as the Irwin River Coal Measures.The Vasse Shelf coal is finely banded and the dominant lithotypes are dull and dull banded types, followed by bright banded and banded types, with minor bright types. The variation of dull and bright lithotypes represents fluctuating conditions of water table level during the growth of peat in the swamp. The maceral composition of the coal is predominantly composed of inertinite, followed by vitrinite and minor exinite and mineral matter. The coal is characterized by very low to medium semifusinite ratio and medium to high vitrinite content, supporting the deposition in anaerobic wet conditions with some degree of oxidation. The coal is classified as sub- bituminous to high volatile bituminous of the Australian classification. In terms of microlithotype group, the predominance of inertite over vitrite suggests the coal was formed under drier conditions with high degree of oxidation during its deposition. On the basis of the interpretations of lithotypes, macerals, microlithotypes and trace elements, the depositional environment of the coal is braided and meandering deltaic-river system without any brackish or marine influence.The maceral composition of the Collie coal predominantly consists of inertinite and vitrinite, with low exinite and mineral matter. The very low to low semifusinite ratio and low to medium vitrinite content of ++ / the coal indicate that the coal was formed under aerobic dry to wet conditions with some degree of oxidation. The coal is categorized as sub-bituminous according to the Australian classification. The domination of inertite and durite over vitrite and clarite contents in the coal reflects the deposition under drier conditions with fluctuations in the water table. On the basis of the interpretations of macerals, microlithotypes and trace elements distribution, the depositional environment of the coal is lacustrine, braided to meandering fluvial system, without the influence of any marine influx.The maceral composition of the Irwin River coal consists predominantly of vitrinite and inertinite, and minor exinite and mineral matter. The coal has very low semifusinite ratio and medium to high vitrinite content, suggesting the coal was deposited in anaerobic wet conditions with some degree of oxidation. The coal is classified as sub-bituminous of the Australian classification. The predominance of vitrite and clarite over inertite and durite contents in the coal indicates that the coal was formed in wetter conditions and in high water covers with a low degree of oxidation. Based on macerals and microlithotypes contents, the depositional environment of the coal is braided fluvial to deltaic, which is in accordance with the interpreted non- marine and mixed marine environment of deposition in the sub-basin.The petrological comparisons of Vasse Shelf, Collie and Irwin River coals show that the average vitrinite content of the Irwin River coal is highest (49.1%) and of the Collie coal is lowest (37.3%) of the three. The inertinite content is highest in Collie coal (49.1%), followed by Vasse Shelf (46.4%) and Irwin River (39.2%) coals. The exinite content is low in Irwin River coal (6.3%) as compared with Vasse Shelf (9.0°/,) and Collie (8.3%) coals. The mineral matter content ++ / is relatively low for all the three coals. The rank of the Vasse Shelf coal is high as compared with the Collie and Irwin River coals, either due to tectonic uplift after the deposition in post-Permian in the southern Perth Basin, or due to the average depth of burial over Vasse Shelf which is much greater than that of Collie and Irwin River coals.The comparisons of the coal from Western Australia with the selected Gondwana coals show that the predominance of inertinite over vitrinite occurs in the Western Australian coals (Vasse Shelf and Collie Basin). On the other hand, the Brazilian, eastern Australian, Indian and Western Australian (Irwin Sub-basin) coals are dominated by vitrinite over inertinite. The exinite content is highest in the Indian coals and lowest in the eastern Australian coals. The mineral matter content is highest in the Brazilian and Indian coals, and lowest in Western Australian (Vasse Shelf) and eastern Australian (Sydney Basin) coals. The rank of the coals ranges from sub- bituminous to medium volatile bituminous according to the Australian classification.