The aim of this project is to integrate structural and stratigraphic data from major normal fault zones in the Suez Rift (Thal Fault Zone) and the northern North Sea Rift (Murchison-Statfjord North Fault Zone), to investigate the structural evolution of normal faults and the controls exerted on the temporal and spatial development and variability of the adjacent syn-rift stratigraphy. Analysis of well exposed syn-rift sediments from the hanging wall of the Thal Fault Zone has enabled a succession of continental to fully marine, clastic-dominated facies to be identified. Key, regionally correlatable stratal surfaces within the syn-rift define time-equivalent stratal units that exhibit considerable dip and strike variability. Integrating this stratigraphic data with the structure reveals that: (1) during initial rifting (<6 Myr), antithetic faults were most active and controlled deposition, whilst the Thal Fault (or its precursor strands) were insignificant, (2) a displacement gradient existed between fault strands at the centre and tip of this early fault population, controlling gross stratal thickness and implying that interaction was occurring between the fault strands, (3) during later rifting (>6 Myr) fault activity switched to the main [Thal] fault, (4) local, along-strike variability in stratal thickness near the fault tip was related to a persistent fault strand boundary (relative high) that also provided a transport pathway (relay ramp) for sediments into the basin, and (5) in general, low rates of faultcontrolled subsidence and accommodation development at the tip, coupled with a high sediment supply produced a strongly progradational delta. Interpretation of structural and stratigraphic subsurface data from the North Sea, indicates that the Murchison-Statfjord North Fault Zone has grown by fault linkage. Isolated fault strands (<4 km in length) with local hanging wall depocentres developed during the initial c. 13 Myr of rifting, and controlled mudstone-dominated deposition. The fault strands progressively linked along-strike forming two segments (10 km in length) separated by a relay ramp, that controlled mudstone and turbidite deposition during the ensuing 10.5 Myr. A regionally significant footwall island became exposed, supplying turbidites that were transported down the relay ramp and captured within structurally controlled hanging wall depocentres, and (3) the fault zone hard-linked during the final 7 Myr of rifting, and the breached relay ramp no longer acted as a major sediment transport pathway. Thus, fault evolution controlled the size and distribution of depocentres, the generation of local accommodation space, the creation of sediment source areas, and the creation and destruction of sediment transport pathways. These key observations from the Suez and North Sea rifts suggest that: (1) patterns of fault growth and linkage can only be fully determined and temporally constrained using syn-rift stratigraphy, and not by structural data alone, (2) major blockbounding faults may not have always experienced the greatest subsidence throughout rifting or have persistently had the main syn-rift depocentres in their hanging walls; in fact, a considerable thickness of early syn-rift strata can be controlled by intra-block faults that do not develop into the major, block-bounding faults, (3) the stratigraphic development of a half-graben is often influenced by adjacent fault zones, affecting sediment supply and distribution. Thus, it is essential to consider adjacent and regional structures, to gain a complete insight into tectono-stratigraphy during rifting, (4) alongstrike variations in stratal thickness and stratigraphic architecture occur on a large scale (i. e. 30 km) between the centre and tips of major normal faults, due to significant differences in fault-controlled subsidence and sediment supply, and (5) in addition, small-scale (<10 km) stratal variability may occur along the entire length of major basin-bounding fault segments (including the tip region), related to the persistence of strand boundaries (intra-basin highs) during fault growth. The results of this study have general implications for tectono-strati graphic development and variability during rift basin evolution.

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This study has involved an investigation of the Dibunophyllum Zone (Upper Avonian) limestones of South Wales. The aims of this work have been to erect a system of lithostratigraphy and to analyse environments of deposition and diagenesis. To achieve these objectives, detailed field logging has been supplemented by petrographic work on thin sections and pools and, where necessary, certain geochemical examinations. This investigation has shown that sedimentation in South Wales during Dibunophyllum Zone times was controlled by the presence of a high energy shoreline in the vicinity of the North Crop and an area of quiet water, offshore sedimentation in Gower and the Vale of Glamorgan. The massif of St. George's Land which lay to the north of the ancient shoreline provided a source for the occasional influx of terrigencous detritus. The overall pattern of sedimentation in South Wales was modified by seven periods of marine regression and transgression which led to the migration of the shoreline and offshore fades belts. The pattern of cyclic sedimentation that resulted from this history of regression and transgression forms a basis for the system of stratigraphy used in this study. This investigation also provides evidence to support the views of earlier workers who had suggested the possibility of a tectonic control on sedimentation in the north-eastern portion of the study area. Diagenesis in the marine, meteoric and subsurface environments are shown to have considerably altered the original character of the Dibunophyllum Zone sediments. Pressure solution and dolomitisation, in particular, have modified the field appearance of many limestones and played a large role in the formation of the pseudobreccias that occur throughout much of the Dibunophyllum Zone.

The Congo Fan has been accumulating sediment since the mid-Oligocene, and is of particular interest to the oil industry due to abundant large reservoirs contained within the meandering sandy palaeochannels from largely Miocene and Oligocene deposits. The high sedimentation rates and rich benthic foraminiferal faunas also provide an interesting record of Miocene and Oligocene palaeoceanographic change in the southeast Atlantic, a stratigraphic time interval that has had no recovery from proximal ODP and DSDP Sites. Three oil wells spanning the Upper Oligocene to Middle Miocene from the distal part of the Congo Fan (Block 31, approximately 2000 m water depth) are studied for both benthic and planktonic foraminifera using ditch cutting samples at 10 m spacing. In addition to assemblage data, 8,80 and 813C measurements have been obtained from Cibicidoides spp. for the Miocene which, along with several planktonic foraminiferal datums, provides a relatively well-constrained age model. The Oligocene sections are dominated by agglutinated benthic foraminifera and the age model is less accurate. A full taxonomy has been carried out on all foraminifera encountered, with over 150 agglutinated, 80 calcareous benthic, and 27 planktonic species described and pictured. A number of sedimentological environments contain characteristic faunas. Channel deposits are either barren or contain current-sorted calcareous specimens, levee deposits have higher abundances of transported calcareous specimens and are affected by hydrodynamic sorting, overbank deposits are dominated by high diversity in situ agglutinated faunas. Oligocene sediments from the Congo Fan consist almost entirely of agglutinated foraminifera due to deposition below a locally raised CCD. A level of decreased diversity and increased abundance (the 'Scherochorellcf event) in the intra-Upper Oligocene records a probable expansion of the oxygen minimum zone associated with polar cooling. During the Early Miocene a gradual and persistent increase in the percentage of calcareous foraminifera is mirrored by increasing benthic 813C, suggesting reduced bottom-water acidification and a lowering of the CCD. A dramatic shift in the shallow infaunal morphogroup (-16 Ma) indicates lower oxygen and a second episode of oxygen minimum zone expansion, which is coincident with cooling in this location and adds evidence for raised colder bottom waters. Global cooling at this time was probably responsible for increasing the strength of the polar front, and in turn strengthening offshore winds affecting an increase in upwelling and surface water productivity.

Palynological investigation of the Carboniferous-Permian Nilawahan Group of the Salt Range, consisting of the Tobra, Dandot, Warchha, and Sardhai formations, led to age determination and palynostratigraphic correlation. The sedimentological analyses of these units resulted in the palaeoenvironmental syntheses. The palynological assemblages from the Late Pennsylvanian Tobra Formation correlate with the Oman, and Saudi Arabia Palynological Zone 2 (OSPZ2), the South Oman 2165B Biozone, the eastern Australian Microbaculispora tentula Oppel-zone and western Australian Stage 2 (sensu Backhouse 1991). The Tobra Formation represents deposition via glacio-fluvial processes associated with the final stages of the Gondwana glaciation. The overlying Dandot and Warchha formations are found to be barren of palynomorphs during the present study. The Dandot Formation occurs between the Upper Pennsylvanian Tobra Formation, and the Artinskian Stage Warchha Formation and it therefore ranges from the Late Pennsylvanian to Artinskian. The Dandot Formation represents deposition in an intertidal to shallow marine settings that developed as sea level rose following waning of the Carboniferous-Permian glaciation. The Warchha Formation is dated as Artinskian Stage, based on the presence of plant megafossils. The Warchha Formation represents deposition in a fluvial system. The Sardhai Formation at the top of the Nilawahan Group is dated as Middle Permian, Wordian Stage, based on the presence of stratigraphically diagnostic Florinites? balmei, and is correlated with the Oman and Saudi Arabia Palynological Zone 6 (OSPZ6). This correlation shows that Florinites? balmei is endemic to the southern neo-Tethys area. The Sardhai Formation was deposited in a shallow marine setting, associated with neo-Tethys opening and sea floor spreading during the Wordian.

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