The offshore Sierra Leone basin is an exploration frontier area with commercial hydrocarbon potential. The basin is located at the northernmost end of the equatorial Atlantic margin in the South Atlantic; it is bound to the South by the Gulf of Guinea Petroleum province. The Sierra Leone margin has not had the exploration attention like most basins in the equatorial Atlantic, such lack of attention may be explained by the structural complexity of the basin. Despite the recent successful petroleum activities in the basin, very little geological information have been placed in the public domain by the operators. This research will be the first published detailed analysis of the offshore Sierra Leone basin. This work focuses on the broader aspects of basin structural evolution, seismic stratigraphy and reservoir development. The basin analysis is based on 2D seismic dataset, acquired in 2002 by TGS-NPEC. Seven megasequence boundaries have been identified in the offshore Sierra Leone basin. There is one megasequence boundary each in the pre-transform and syn-transform phases. The post-transform phase is composed of five megasequences. They have been dated using well data information and through correlation with the seismic surfaces of adjacent basins in the region. The Sierra Leone margin is structurally divided into three segments, which evolved through transtensional and/or extensional rifting. From a geological perspective, this basin straddles a major tectonic transition zone (the Sierra Leone Transform). The Mesozoic-Cenozoic tectonic evolution of the basin was partly controlled by basement heterogeneity and plate kinematics. This study also highlights the importance of N-S and ENE-WSW trending Archaean structural lineaments, which were vectors for the Sierra Leone margin segmentation. The structural division of the Sierra Leone margin into the Northern, Central andSouthern segments is based on varying structural geometries. The Northern and Central segments developed as rift-transform margins, while the Southern segment developed as a volcanic rifted margin. Syn-transform sequences (late Early Cretaceous) show the influence of normal fault related subsidence and uplift, modified by localised transpressional deformation. The basin bounding faults and half grabens are oriented at high angles to the ensuing passive margin slope strike. Post-transform sequences (Late Cretaceous to Present) are dominated by major phases of slope failure and the development of extensive lowstand submarine fan systems. Some models of slope failure and synchronous development of submarine channel and canyon systems have been developed for this basin. Extensional slope failure is controlled by pre-existing structural trends. Submarine canyons which developed in the hanging-walls of these fault-blocks, became the site of rapid head-ward expansion of turbidite filled channels. The temporal development of these systems are expected to have profoundly affected the distribution and quality of key play elements, such as reservoirs and stratigraphic traps in slope settings, and the distribution of sands in deeper water and base of slope plays.

This study shows how the use of modern geological investigative techniques can reopen old, “drained” hydrocarbon fields. Specifically, it looks at the White Castle Field in South Louisiana. This field has pay sections ranging from late Oligocene to late Miocene. The late Oligocene package is underexplored and understudied and contains 3 primary reservoirs (Cib Haz (CH), MW, and MR). This study established the depositional history of these reservoirs. During most of the late Oligocene, the White Castle Salt Dome was located in a minibasin on the continental slope. The CH and MW deposited in this minibasin. The CH is an amalgamation of slumped shelfal limestones, sandstones, and shales deposited during a lowstand systems tract (LST). The MW comprises a shelf-edge delta that is part of a LST. The MR is an incised valley fill located in the continental shelf that was deposited during LST after the minibasin was filled.

The Arcadia Formation is a mixed carbonate-siliciclastic rock unit that existed as a shallow carbonate ramp to platform environment during the Late Oligocene to Early Miocene Epoch. It can be divided into two distinct, informal sections based on lithological properties: the upper Arcadia Formation and lower Arcadia Formation. The sections are part of a major, third-order sequence that can be further divided into four higher-frequency, lower magnitude sequences: ARS1, ARS2, ARS3, and ARS4. The sequence boundary separating ARS2 and ARS3 represents a drastic change in the depositional regime from a high-energy, inner ramp/platform to a lower-energy, deep outer ramp environment. ARS3 represents the period of maximum flooding and constitutes a major portion of the regressive system tract (RST) of the third order depositional sequence. In certain sections, the Arcadia Formation is heavily bioturbated including ichnotaxa from the glossifungites, cruziana, and scolithos inchofacies. Thalassinoides sp. burrows of the glossifungites ichnofacies were found to be commonly associated with firmground substrates and breaks in sedimentation. The lithofacies associations were grouped into paleodepositional environments that ranged from restricted marine to deep outer ramp with lithology ranging from grainstone to wackestone to mudstone with variable amounts of siliciclastic and phosphatic constituents. Each sequence boundary extends regionally south from Broward County to southern Miami-Dade County utilizing gamma-ray geophysical signatures unique to each sequence. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

The Monkton Formation of the western shelf stratigraphic sequence in Vermont (VT) is identified as a Lower Cambrian regressive sandstone unit containing parasequences recording tidal flat progradation. Previous workers identified cycles believed to represent parasequences in a portion of a 1034' deep geothermal well drilled at Champlain College in Burlington, Vermont. For this study, both outcrop and well geophysical surveys were completed to better identify gamma emission curves and relative values for parasequences and select lithologies that are indicators of bathymetry and sea level. After using physical stratigraphic techniques to assemble a composite stratigraphic section for the Monkton Formation, analysis of the gamma emission curve and relative gamma values resulted in the identification and characterization of parasequences and select lithologies within the Monkton. Interpretation of bathymetry-sensitive lithologies along with parasequence architecture and thickness trends reveals three distinctive intervals over the thickness of the Monkton. It is recognized that the succession of these intervals represents an overall decreasing rate in accommodation space generation through Monkton deposition. Previous workers have suggested that biostratigraphic relationships of the Monkton Formation to the Potsdam Group in New York (NY) suggest that that they would be at least partially correlative. To further refine age relationships and constrain and compare the provenance of the Vermont stratigraphy locally and regionally, zircon samples were collected from the Monkton and the overlying Danby Formations and radiometric age determinations were completed by laser ablation–inductively coupled plasma mass spectrometry (LA-ICPMS) at University of Arizona Laserchron Center. Zircon age probability distribution curves show two dominate age peaks between 1.05-1.09 Ga and 1.15-1.18 Ga for the Monkton and Danby suggesting either a continuity of provenance through the Cambrian or the cycling of the Monkton's sand. The 1.05-1.09 Ga age range corresponds to rocks generated during the Ottawan Orogeny while the 1.15-1.18 Ga range is associated with the Shawinigan Orogeny and anorthosite-mangerite-charnockite-granite (AMCG) plutonism. Dominant age peaks in the Vermont samples between 1.15-1.18 Ga are similar to the 1.16 Ga age peak reported by other workers from the Altona and Ausable Formations of the Potsdam Group of New York. The shared dominant age peak and close proximity of the Vermont and New York stratigraphy may suggest a primarily shared provenance.

"February 2001" / Bibliography: p. 335-349. / xxix, 394 p. : ill. (some col.), maps (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 2004

A 3D seismic volume was acquired summer 2000 over the southern end of Hydrate Ridge (FIR), an anomalously shallow ridge 100 km offshore Newport, Oregon. The survey followed a succession of scientific expeditions aimed at studying the gas hydrates present in the shallow subsurface that gave the name to the ridge. This thesis consists of a seismic sequence analysis of the high-resolution (125 Hz) 3D survey. Identification of seismic units and interpretation of depositional sequences observed on the seismic sections is presented. The sequence analysis is compared with the results from nine sites cored during ODP Leg 204 during summer 2002. The first objective is to document in detail the stratigraphy of the ridge so that we can compare it with the gas hydrate distribution. The second is to reconstruct the structural evolution through time of this complex anticline as inferred from the depositional history. The result is a time series of structural evolutionary cross-sections as well as a series of paleo-bathymetric maps revealing the development of and interplay between the structures now buried in the subsurface of southern HR. The structural evolutionary diagrams show the existence of three anticlines, interpreted as thrust-related folds. They formed at the deformation front and controlled the distribution and deformation of the sediments during the Pleistocene. The current southern HR started its uplift less than 0.5 Ma. A seismic relict in the form of a double BSR is a witness to the evolution of the gas hydrate system of HR. It confirms the recent uplift of the ridge and consequent shallowing of the base of the gas hydrate stability zone (GHSZ). Further detailed studies of the stratigraphy reveal stratigraphic controls on the fluid flow, which in turn control the distribution of gas hydrates. Analysis of the amplitude map of the bottom-simulating reflector (BSR), which is a proxy for the free gas distribution, shows a relationship between anticlinal features within the older strata (older than 1.6 Ma) and strong amplitude anomalies of the BSR, which confirm previous observations suggesting a very low permeability for the young slope-basin sediments and an accumulation of gas within the older sediments underneath. / Graduation date: 2004

Middle-Late Ordovician Mt. Wilson Quartzite, southern British Columbia, Canada, is a supermature quartz arenite deposited in shallow marine-marginal marine environments on the Early Paleozoic western Laurentian passive margin. Facies-stacking patterns indicate the Mt. Wilson Quartzite is an unconformity bounded, 2nd-order depositional sequence, containing two 3rd-order sequences, and numerous parasequences. Detrital zircon age spectra of six samples of the Mt. Wilson Quartzite have numerous peaks that are unique to Middle to Late Ordovician quartz arenites of western Laurentia. The main peaks, 1800-2000 Ma, 2000-2200 Ma, and 2300-2400 Ma are interpreted to have been derived from basement rocks that were exposed east of the study area: Trans-Hudson Orogeny (1800-2000 Ma), Taltson Orogen (1800-2000 Ma), Buffalo Head Terrane (2000-2400 Ma), Paleoproterozoic crust (2000-2400 Ma), and the Wopmay Terrane (2000-2400 Ma). It is likely that these areas were sourced by local rivers and tributaries draining the Transcontinental Arch and delivered sediment to the deposition location of the Mt. Wilson Quartzite. While longshore transport was a viable distribution method for sediment along the passive margin, it is unlikely that the Peace River Arch (located northwest of the Mt. Wilson Quartzite) was its sole point source; rather it is more likely that there were multiple sediment sources for these western Laurentian quartz arenites. Temporal changes in provenance indicate different areas of basement rock were exposed throughout the deposition of the Mt. Wilson Quartzite, most likely reflecting long-term flooding of North America. The potential for spatial changes in provenance remains unsolved.

High resolution sampling was performed along the &Uuml / z&uuml / ml&uuml / Formation exposed near the YeniceSihlar village of Mudurnu (Bolu). Field and thin-section analyses showed that the &Uuml / z&uuml / ml&uuml / Formation is composed of cm to m scale cycles of 4th and 5th order. The 4th order cycles are equivalencies of parasequences and have 0.4 Ma average duration. 5th order cycles are interpreted as episodic. Upper Albian (OAE1c or OAE1d) and Cenomanian/Turonian (OAE2) anoxic events are observed as black shale levels in the studied section. Position of black shale levels is interpreted using cyclostratigraphy and sequence stratigraphy. Four types of cycle are determined. A and B-type cycles are placed in transgressive and Highstand System Tract. C and D-type cycles are placed in Lowstand System Tract. Two type 3 and one type 1 sequence boundaries are recorded. The boundary between the Soguk&ccedil / am Limestone and the &Uuml / z&uuml / ml&uuml / Formation is interpreted as the first type 3 sequence boundary. The second one separates the &Uuml / z&uuml / ml&uuml / Formation and the Yenipazar Formation and is observed at the top of the section. Type 1 boundary is represented by a conglomeratic level in the middle of the succession. Provenance analysis of sandstones indicates that during the Cenomanian the source area changed from magmatic arc setting to continental setting.

The late Permian Queen Formation (115 m thick) is a succession of mixed clastics, carbonates and evaporites deposited in the northeastern margin of Central Basin Platform of the Permian Basin, west Texas, USA. Depositional facies, stacking patterns of cyclic facies associations and statistical correlation of rock property variations define geologic controls on reservoir rock properties. Textural, compositional, petrophysical and diagenetic variations within lithofacies exhibit systematic changes with stratigraphic position, which can be related to base level changes that were controlled by high-frequency, low-amplitude, sea level fluctuations during a greenhouse period. Ten lithofacies record variations in clastic input, shallow marine carbonate production, and evaporate precipitation in sabhkas and salinas. Four different types of lithofacies associations define: (1) transgressive deltaic deposits; (2) upward-shallowing evaporite and carbonate tidal-flat deposits; (3) transgressive beach ridge and sand flat deposits; and (4) upward-shallowing evaporite salina-sabhka deposits. Stacking patterns of lithofacies associations define sixteen depositional cycles that can be grouped into eight cycle sets. Cycle sets in turn are grouped to define two high-frequency sequences. Sequence 1 progresses from fluvial to carbonate tidal flat cycles. Sequence 2 consists of salina-dominated upward-shoaling cycles. Lateral continuity of cycles indicates restricted sedimentation on low-accommodation inner platform areas updip of prograding highstand platform-margin carbonate buildups, and a long-term trend of accommodation decrease. The Queen Formation contains two reservoir types; (1) siliciclastic reservoirs capped by evaporites and (2) layer-cake carbonate reservoirs. Of the four reservoir zones identified, R11 in lowstand fluvial-deltaic deposits has relatively little cement and the best reservoir characters.

The sequence stratigraphy, depositional systems and reservoir geology of the lower and middle Oligocene Frio Formation in the Red Fish Bay field, Nueces County, Texas, are examined based on 1,800 feet (548.6 m) of core, 28 wireline-logs and 30 mi2 of 3-D seismic data. The study interval is composed of an incomplete 3rd-order stratigraphic sequence with an incomplete lowstand systems tract (LST), a complete transgressive systems tract (TST) and an incomplete highstand system tract (HST). This 3rd-order succession is divided into 12 4th-order sequences with average thickness of 150 feet (45.7 m). The lowstand system tract (LST) from 4th-order sequence 1 to 4th-order sequence 7 displays an aggradational stacking pattern in cross-sections. The regressive part of each 4th-order sequence has an upward-coarsening trend that reflects a transition of depositional environments from offshore to lower, middle and upper shoreface. The transgressive part of each 4th-order sequence exhibits an upward-fining trend, commonly associated with backstepping cycles composed of shoreface, washover-fan, and back-barrier lagoonal deposits. Sandstone maps of 4th-order sequence and stratal-slice maps from 3-D seismic data within 3rd-order lowstand system tracts display a strike-elongate geometry, indicating wave-dominated depositional systems. The 3rd-order transgressive system tract (TST) displays a retrogradational stacking pattern in cross-sections. The overall upward-fining trend records water deepening during transgression, interpreted as a transition from lower-shoreface to shelf environments. The 3rd-order highstand system tract (HST) from 4th-order sequence 8 to 4th-order sequence 12 displays a progradational stacking pattern in cross-sections. It is upward-coarsening and upward-thickening, indicating a transition from to distal- to proximal-shoreline setting. The geometry of framework sandstone bodies, inferred from gross-sandstone and stratal-slice maps is relatively lobate, suggesting a wave-modified deltaic system. The sandstone body continuity is very good and heterogeneity is very low within shoreface or wave-dominated deltaic systems in LST and HST sequences in Redfish Bay. Sandstone thickness expands towards the growth fault, owing to structurally controlled accommodation, but is thicker in the southwest part of study area, where it is controlled by paleogeomorphology, related to the presence of a deltaic depocenter. The sandstone body thickness of each 4th-order sequence is as much as 240 ft (73.2 m) and commonly ~100 ft (30.5 m) in average. Sandstone development in the study succession is controlled by the sequence stratigraphic context, and modification by depositional processes. The average porosity and permeability of study interval are 19.4% and 33.6 md respectively. Lithology is the main control on porosity and permeability. Sedimentary and biogenic structures also modify grain-size sorting, indirectly affecting porosity and permeability. Reservoir quality in LST is higher than that in the HST, as the depositional environment in LST is within proximal-delta-front facies, whereas in the HST is within distal-delta-front facies. Reservoir quality varies greatly within each 4th-order sequence, owing to different levels of intensity in bioturbation per each sandstone bed. / text