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Calvès, Gérôme. "Tectono-stratigraphic and climatic record of the NE Arabian Sea." Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until Feb., 18, 2010, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25475.
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Calvès, Gérôme. "Tectono-stratigraphic and climatic record of the NE Arabian Sea." Thesis, University of Aberdeen, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=25475.
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This study describes the tectono-stratigraphic and climatic record of the NE Arabian Sea during the Cenozoic. Compilation of regional knowledge and subsurface observations has in this thesis provided new interpretations and insights into the records present along this passive margin. The first is the rifting period (80-65 Ma) and the identification of a syn-rift volcanic sequence, comparable to other volcanic rifted margins. This is followed by the record of a drift sequence (~65 Ma to present day), composed of extensive carbonate platforms and an infill sequence of siliciclastic deposits. The analysed drift sequence (sink) is partly the result of the erosion of the hinterland (source) characterised by the India-Eurasia continent-continent collision. Influence of regional climate and/or tectonic forces on the accumulation rate in the sink was tested, but not conclusive as the study area (Upper Indus Fan) covers only a limited part of the sedimentary record of the Indus Fan. The thermal regime of the western margin of India is sparsely sampled, but once analysed, allows the definition of first order constraints on multiple rifting events. The post-rift subsidence of the margin is slow and anomalous for >28 m.y. after break-up, potentially in relation with vigorous asthenospheric convection and a sharp ocean-continent boundary. Past and present fluid flow is recorded in the sedimentary sequence of the Upper Indus Fan. The first is related to gas hydrate occurrence and is the result of the migration of fluids by a plumbing system to the shallow subsurface, expressed by bottom-simulating reflections crosscutting stratal reflections. A longer term fluid migration is recorded in this basin by the longest lived (~22 m.y.) mud volcano field recorded to date.
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Lampshire, Laura Dermody. "Crustal structures and the Eastern extent of the Lower Paleozoic Shelf Strata within the Central Appalachians : a seismic reflection interpretation /." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-02162010-020628/.
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Burton, Andrew Joseph. "Seismic imaging methods applied to Devonian carbonate reef environments of western Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/MQ42356.pdf.
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O'Neal, Ryan J. "Seismic and well log attribute analysis of the Jurassic Entrada/Curtis interval within the North Hill Creek 3D seismic survey, Uinta Basin, Utah : case history /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2017.pdf.
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Weisenburger, Kenneth William. "Reflection seismic data acquisition and processing for enhanced interpretation of high resolution objectives." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/74518.
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Reflection seismic data were acquired (by CONOCO, Inc.) which targeted known channel interruption of an upper Pennsylvanian coal seam (Herrin #6) in the Illinois basin. The data were reprocessed and interpreted by the Regional Geophysics Laboratory, Virginia Tech. Conventional geophysical techniques involving field acquisition and data processing were modified to enhance and maintain high frequency content in the signal bandwidth. Single sweep processing was employed to increase spatial sampling density and reduce low pass filtering associated with the array response. Whitening of the signal bandwidth was accomplished using Vibroseis whitening (VSW) and stretched automatic gain control (SAGC). A zero-phase wavelet-shaping filter was used to optimize the waveform length allowing a thinner depositional sequence to be resolved.
The high resolution data acquisition and processing led to an interpreted section which shows cyclic deposition in a deltaic environment. Complex channel development interrupted underlying sediments including the Herrin coal seam complex. Contrary to previous interpretations of channel development in the study area by Chapman and others (1981), and Nelson (1983), the channel has been interpreted as having bimodal structure leaving an"island" of undisturbed deposits. Channel activity affects the younger Pennsylvanian sediments and also the unconsolidated Pleistocene till. A limit to the eastern migration of channel development affecting the the Pennsylvanian sediments considered in this study can be identified by the abrupt change in event characteristics.Master of Science
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Miller, Steven B. "Application of complex trace attributes to reflection seismic data near Charleston, South Carolina." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/50058.
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Complex trace attribute analysis has been applied to 24-fold VIBROSEIS reflection data acquired on the Atlantic Coastal Plain near Charleston, S. C., to yield an expanded interpretation of a Mesozoic basin concealed beneath Coastal Plain sediments. Complex trace attributes express the seismic trace in terms of a complex variable and emphasize different components of the original seismogram. Attributes derived from synthetic seismograms of thin beds are used to interpret the patterns observed on the real data. Complex trace attributes derived from the original seismic trace complement the interpretation of a Mesozoic basin originally imaged by conventional data. The combination of single-sweep recording and use of complex trace attributes is believed to support an interpretation of a transition from basin border conglomerates into finer-grained siltstones nearer to the center of the basin.Master of Science
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Titus, Willard Sidney III. "Development and application of some quantitative stratigraphic techniques to the Coos Bay coalfield, a Tertiary fluvio-deltaic complex in southwestern Oregon." PDXScholar, 1987. https://pdxscholar.library.pdx.edu/open_access_etds/3730.
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A computer technique for interpreting geophysical logs of drill-holes in quantitative lithologic terms has been developed and tested on the deposits of the late Eocene Coaledo Formation, a well-studied fluvio-deltaic complex in southwestern Oregon. The technique involves the use of induced and natural gamma logs for separation of coal and claystone from coarse-grained detrital rocks and the use of the ratio of resistivity and natural gamma responses (defined here as the "grain size index") to divide the coarse elastic rocks into a series of textural classes corresponding to the Wentworth-Odden particle size scale.
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O'Brien, Jennifer Ann. "Jurassic biostratigraphy and evolution of the Methow Trough, southwestern British Columbia." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/558073.
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Gehring, Iris. "Volcanostratigraphy using geophysical methods on La Fossa di Vulcano (S-Italy)." Doctoral thesis, [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964401533.
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Fang, Linhao. "Terrestrial carbon-isotope stratigraphy : an exploration of the method from Miocene and Jurassic examples." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:883ef59a-f3aa-44ac-b539-d0f81317296e.
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Terrestrial carbon-isotope stratigraphy has proven a promising tool for stratigraphic correlation between the different exchangeable carbon-isotope reservoirs, as well as a powerful approach to reconstructing the evolution of δ13C of atmospheric CO2, which is closely associated with the evolution of palaeoenvironment and palaeoclimate. However, the limited understanding of pitfalls in specific application potentially restricts the method’s utility for stratigraphic correlation and palaeoenvironmental reconstruction. This thesis takes advantage of three case studies at two vital geological intervals which are both characterized by the significant carbon-isotope perturbation in the exchangeable reservoirs, to explore the nature of terrestrial carbon-isotope stratigraphy. Two of the case studies focus on the late Early to Middle Miocene, the period of the so called Monterey Event that is marked by remarkable positive carbon-isotope excursions in benthic and pelagic marine carbonate records. There are few terrestrial carbon-isotope records for the Monterey Event. In the present study, shallow marine sediments were collected from boreholes in the New Jersey margin, USA (IODP, Expedition 313) and North Sea Basin, Denmark. Phytoclasts are concentrated from palynological residues as the basis for a terrestrial carbon-isotope stratigraphy from the two locations. The carbon-isotope curves obtained can be correlated in detail locally, and correlated crudely on a global scale. However, there are no definite positive carbon-isotope excursions observed in the terrestrial isotopic stratigraphic records through the biostratigraphically determined Langhian interval equivalent to the Monterey Event. The reasons for the absence of relatively positive carbon-isotope excursions in terrestrial carbon-isotope stratigraphy might be caused by the reworking deposits of woody phytoclasts from older strata or some other process related to reworking. Another case study centres on the Triassic-Jurassic boundary and Early Jurassic fluvial and lacustrine succession in the Kuqa section, Tarim Basin, NW China. Macrofossil wood samples were collected to generate the terrestrial carbon-isotope stratigraphy. On the basis of the biostratigraphy and potential Stage/Age (sub-) boundaries implied by biological overturns, the terrestrial carbon-isotope stratigraphy in the Kuqa section can be well correlated with both terrestrial and marine carbon-isotope stratigraphic records from UK through the Early Jurassic. For the Triassic-Jurassic boundary, more precise correlation was made globally and an exact the position of Triassic-Jurassic boundary is proposed in the Kuqa section. In light of the biostratigraphy and the carbon-isotope stratigraphy obtained in the present study, an updated age assignment of the lithostratigraphic units is proposed to Age/Stage level in the Early Jurassic across the Northern Tarim Basin. The carbon-isotope stratigraphy thus significantly improves the terrestrial stratigraphic resolution. Terrestrial carbon-isotope stratigraphy is a powerful tool for global stratigraphic correlation and unifies stratigraphic correlation over marine and non-marine strata in cases when potential biasing factors are excluded.
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Morakinyo, Jimoh Akindele. "Development of an optimal hazard assessment method for contaminated sites." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369754.
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Maguire, Henry C. "Application Of Geophysical And Geochronological Methods To Sedimentologic And Stratigraphic Problems In The Lower Cambrian Monkton Formation: Northwestern Vermont." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/938.
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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.
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Chu, Lap-man Raymond, and 朱立民. "Material identification and subsurface stratigraphy of Penny's Bay reclamation site: by the method of subsurfaceexploration : piezocone penetration test and drilling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B42576660.
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Barens, Leonardus Maria. "Seismic and well test analysis methods to characterise fluvially deposited reservoir elements." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/510.
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Chu, Lap-man Raymond. "Material identification and subsurface stratigraphy of Penny's Bay reclamation site : by the method of subsurface exploration : piezocone penetration test and drilling /." Click to view the E-thesis via HKUTO, 2002. http://sunzi.lib.hku.hk/hkuto/record/B42576660.
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Bigio, Erica Renee. "Late Holocene Fire and Climate History of the Western San Juan Mountains, Colorado: Results from Alluvial Stratigraphy and Tree-Ring Methods." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/311587.
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In the past few decades, wildfires have increased in size and severity in the Southwest and across the western US. These recent trends in fire behavior are a drastic change in arid, ponderosa pine and mixed conifer forests of the Southwest compared with tree-ring records of fire history for the past ~ 400 years. This study presents a late Holocene record (~ 3,000 years) of fire history and related changes in fire regimes with climate variability over annual to multi-decadal time scales. Tree-ring and alluvial-sediment sampling sites were paired in four small, tributary basins located in the western San Juan Mountains of Colorado. In our study sites, tree-ring records show that fire return intervals were longer and fire behavior was more severe on the north-facing slopes with relatively dense mixed conifer stands. Increased fire barriers and steep topography decreased the fire frequency and extent relative to gentle terrain elsewhere in the range and leading to a lack of synchrony among fire years in different parts of the study area. The alluvial-sediment record showed four peaks in high-severity fire activity over the past 3,000 years ranging between 200 - 400 years in length. The timing of peaks coincided with decadal-length drought episodes and were often preceded by multiple decades of above average winter precipitation. The sampling of alluvial-sediment and tree-ring data allowed for site-level comparisons between recent alluvial deposits and specific fire years interpreted from the tree-ring records. We found good correspondence between the type of fire-related sediment deposit (i.e. geomorphic response) in the alluvial record and the extent of mixed and high-severity fire estimated from the tree-ring record, and the correspondence was well-supported by the debris flow probability model results. The two paleofire data tend to represent particular components of the historical fire regime, with alluvial-sediments biased towards infrequent, high-severity events during recent millennia, and the tree-ring record biased toward lower severity fires during recent centuries. The combined analyses of different paleofire proxy types in the same study sites, therefore, can enhance and expand our understanding of fire and climate history beyond what is possible with either proxy alone.
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Sopher, Daniel. "Characterization of the structure, stratigraphy and CO2 storage potential of the Swedish sector of the Baltic and Hanö Bay basins using seismic reflection methods." Doctoral thesis, Uppsala universitet, Geofysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-280684.
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An extensive multi-channel seismic dataset acquired between 1970 and 1990 by Oljeprospektering AB (OPAB) has recently been made available by the Geological Survey of Sweden (SGU). This thesis summarizes four papers, which utilize this largely unpublished dataset to improve our understanding of the geology and CO2 storage capacity of the Baltic and Hanö Bay basins in southern Sweden. A range of new processing workflows were developed, which typically provide an improvement in the final stacked seismic image, when compared to the result obtained with the original processing. A method was developed to convert scanned images of seismic sections into SEGY files, which allows large amounts of the OPAB dataset to be imported and interpreted using modern software. A new method for joint imaging of multiples and primaries was developed, which is shown to provide an improvement in signal to noise for some of the seismic lines within the OPAB dataset. For the first time, five interpreted regional seismic profiles detailing the entire sedimentary sequence within these basins, are presented. Depth structure maps detailing the Outer Hanö Bay area and the deeper parts of the Baltic Basin were also generated. Although the overall structure and stratigraphy of the basins inferred from the reprocessed OPAB dataset are consistent with previous studies, some new observations have been made, which improve the understanding of the tectonic history of these basins and provide insight into how the depositional environments have changed throughout time. The effective CO2 storage potential within structural and stratigraphic traps is assessed for the Cambrian Viklau, När and Faludden sandstone reservoirs. A probabilistic methodology is utilized, which allows a robust assessment of the storage capacity as well as the associated uncertainty. The most favourable storage option in the Swedish sector of the Baltic Basin is assessed to be the Faludden stratigraphic trap, which is estimated to have a mid case (P50) storage capacity of 3390 Mt in the deeper part of the basin, where CO2 can be stored in a supercritical phase.
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Mele, Antoni Rosell i. "Long-chain alkenone and alkyl alkenoate, and total pigment abundancies as climatic proxy-indicators in the the northeastern Atlantic : analytical methods, calibration and stratigraphy." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386102.
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Chu, Minqi. "Culture laïque dans un espace provincial byzantin : production et transmission des livres manuscrits et du savoir profanes grecs en Italie méridionale (Xe-XIe siècle)." Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUL046.
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La transmission du savoir laïque, en particulier celui hérité de l'Antiquité, était dynamique à Constantinople durant l'époque macédonienne. Cependant, cette effervescence intellectuelle ne semble pas avoir eu le même écho dans les espaces provinciaux, tel que l'Italie méridionale hellénophone (à l'exception de la Terre d'Otrante). Le faible nombre de manuscrits grecs profanes, produits et diffusés dans cette province durant les Xe et XIe siècles, témoigne de cette situation. Malgré leur quantité limitée, ce corpus de manuscrits grecs présente une diversité thématique riche, comprenant des œuvres de grammaire, de rhétorique, de lexicographie, de calcul, de droit civil, de médecine, ainsi que de littérature et de philosophie antiques. L'examen approfondi de chaque manuscrit de ce corpus, au prisme de la méthode « stratigraphique » qui intègre les données paléographiques, codicologiques et philologiques, nous permet d'établir un portrait aussi complet que possible de leur production et diffusion locales entre le Xe siècle et le XIe siècle. Ce travail révèle comment ces livre-manuscrits et ces connaissances séculières s'intégraient et étaient utilisées au sein de la société locale, dévoilant ainsi un pan souvent occulté par les sources historiques. En outre, la comparaison de ce corpus profane byzantin avec celui de l'ère normando-souabe illustre la pérennité de l'héritage byzantin local tout en soulignant l'apparition de nouveautés caractéristiques de la période normando-souabeThe transmission of secular knowledge, particularly that inherited from antiquity, was dynamic in Constantinople during the Macedonian era. However, this intellectual effervescence did not seem to have the same echo in provincial areas such as Hellenic-speaking southern Italy (with the exception of Terra d'Otranto). The small number of secular Greek manuscripts produced and circulated in this peripherical province in the 10th and 11th centuries prior to the Norman Conquest bears witness to this situation. Despite its limited quantity, the corpus of local secular Greek manuscripts presents a rich thematic diversity, including works of grammar, rhetoric, lexicography, scientific calculation, civil law, medicine, as well as ancient literature and philosophy. The in-depth examination of each manuscript in this corpus, through the prism of the “stratigraphic” method that integrates paleographical, codicological and philological data, enables us to establish as complete a picture as possible of their local production and circulation between the 10th century and the first half of the 11th century. This work reveals how these book manuscripts and secular knowledge were integrated and used within local society, revealing an aspect often obscured by historical sources. Furthermore, the comparison of this Byzantine secular corpus with that of the Norman-Swabian era illustrates the durability of the local Byzantine heritage, while highlighting the appearance of novelties characteristic of the Norman-Swabian period within local secular culture
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Obrocki, Lea Marit [Verfasser]. "Advances in geoarchaeological site formation research by integrating geophysical methods, direct push sensing techniques and stratigraphic borehole data - case studies from central Europe and the western Peloponnese around ancient Olympia - / Lea Marit Obrocki." Mainz : Universitätsbibliothek Mainz, 2019. http://d-nb.info/118923730X/34.
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Cugny, Pierre. "Associations paleontologiques et paleoenvironnements : analyse quantitative des facies dans diverses formations cretacees des marges neotethysiennes et atlantique." Toulouse 3, 1987. http://www.theses.fr/1987TOU30162.
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On montre comment l'utilisation conjointe des methodes classiques d'etude des formations geologiques (analyse sequentielle, sedimentologie, paleontologie) et de methodes quantitatives (analyse des donnees multidimensionnelles, tests statistiques) permet de reconstituer les paleoenvironnements, leur evolution et de proposer des modeles paleoecologiques. Les exemples sont pris en domaine de plateforme, dans les series du cretace des marges neotethysiennes (pyrenees, espagne, bulgarie, maroc, algerie) et atlantique (portugal)
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Tyrie, Elizabeth Katharyn. "Combining Quantitative Eye-Tracking and GIS Techniques with Qualitative Research Methods to Evaluate the Effectiveness of 2D and Static, 3D Karst Visualizations: Seeing Through the Complexities of Karst Environments." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1351.
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Karst environments are interconnected landscapes vulnerable to degradation. Many instances of anthropogenic karst disturbance are unintentional, and occur because of the public's lack of understanding or exposure to karst knowledge. When attempts are made to educate the general public about these landscapes, the concepts taught are often too abstract to be fully understood. Thus, karst educational pursuits must use only the most efficient and effective learning materials. A technique useful for assessing educational effectiveness of learning materials is eye-tracking, which allows scientists to quantitatively measure an individual's points of interest and eye movements when viewing a 2D or 3D visualization. Visualization developers use eye-tracking data to create graphics that hold the observer's attention and, thereby, enhance learning about a particular concept. This study aimed to assess and improve the educational effectiveness of 2D karst visualizations by combining eye-tracking techniques with Geographic Information Systems, knowledge assessments, and semi-structured interviews. The first phase of this study consisted of groups of 10 participants viewing 2D karst visualizations with one category of manipulated visual stimuli. The second phase consisted of groups of 10-15 participants viewing 2D karst visualizations that were created based on the results from the first phase. The results of this study highlighted both effective stimuli in karst visualizations and stimuli that hinder the educational effectiveness of visualizations.
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Mpanda, Samson. "Geological development of the East African coastal basin of Tanzania." Doctoral thesis, Stockholms universitet, Institutionen för geologi och geokemi, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-48370.
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The East African coastal basin of Tanzania, which is characterised by an extensional tectonic style, is located along the passive continental margin of the western Indian Ocean. The present study is concerned with the Mafia Island and the Mafia Channel which together form a subbasin within the north-south elongated coastal sedimentary basin of Tanzania. In the time interval from late Paleozoic to Recent, the passive margin of the region was subjected to a three-fold geological development, namely the Karoo rifting phase (1) which is characterised by extensional tectonics, the Gondwana break-up and opening of the Somali basin (2) which was contemporaneous with the movement of Madagascar off the east African coast in the Mesozoic, and the Cenozoic East African rift system (3). This structural framework made provision to the basin deposition history. The development started with the deposition of the continental, terrigenous, Karoo sequence in the Upper Permian to Lower Jurassic. The Karoo deposition was followed by a series of transgressions and regressions under full marine conditions which started in the Middle Jurassic and continued into the Tertiary. The deposits include marine marls, detrital limestones, fossiliferous shales and calcareous sandstones, reaching in places thicknesses of more than 4000 m of Mesozoic, and more than 6000 m of Cenozoic, sediments. Seismostratigraphic techniques applied in the Mafia Channel and Island identified five deposition sequences separated by regional unconformity surfaces i.e. sequence boundaries. Including the pre-Upper Cretaceous sequence they are; the Upper Cretaceous to Middle Eocene sequence (DS I), the Middle Eocene to Lower Miocene sequence (DS II), the Lower Miocene to Pliocene sequence (DS III), and the Pliocene to Recent sequence (DS IV). In the Mafia Channel up to 6000 m of sediments are present. Their ages range from Middle Eocene to Quaternary. The deposits start with marine shales which are overlain by carbonate rocks of Upper Eocene . These carbonates are in the present investigation regarded as the acoustic basement in the central and northern parts of the study area. On top of Upper Eocene carbonates, deltaic and shallow marine sediments are deposited. Southwards in the Channel, the sequences are located at shallower depths which makes it possible to trace also the Upper Cretaceous sequence with confidence. On the Mafia Island, the deposition on top of the Upper Cretaceous (Campanian) acoustic basement mainly includes deltaic sandstones, followed by intercalations of carbonate and argillaceous rocks. The structural framework reflects the different tectonic regimes which prevailed in the area. Above the acoustic basement structural elements of Mafia Channel and Island are interpreted as originating from the superimposition of the Cenozoic East African rifting event, and from the uplifts of the mainland coast and Mafia Island during Late Eocene time. As a result the central part collapsed and formed an asymmetric sag structure in the channel. These elements are seismically identified and subdivided as (from northwest to southeast), the Dar-es-Salaam Platform Offshore, the Central Mafia Channel and the Mafia Island Rise. These domains are separated by respective NE-SW major faults (MF1, MF2 and MF3) and can be demonstrated in the profiles which run in a NW-SE direction. With respect to petroleum potential, the Mafia Channel and Island indicate a considerable content. Three hydrocarbon plays are introduced, namely; 1) the Neocomian regressive sands of Songosongo play 2) the Upper Eocene limestone and 3) the Upper Oligocene turbidites.
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Çimen, Görkem. "The excavations of the P-building and the R-bath at Labraunda: Archaeology in the 1950s based on Inge Dahlén's three excavation diaries." Thesis, Uppsala universitet, Antikens kultur och samhällsliv, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324217.
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The area which today covers the Doric House, the Roman East Bath and the Byzantine East Church at the Karian sanctuary of Zeus at Labraunda in south-western Turkey, was by Swedish archaeologists called the P-building and the R-bath during the early 1950s. The excavations of this area in 1951 and 1953 were documented in three excavation diaries by archaeologist Inge Dahlén, written in Swedish. These diaries have, however, never been published. This thesis therefore focused to analyse Dahlén’s three excavation diaries in terms of three aspects. The first aspect was to understand the archaeological work and documentation methods at Labraunda during the 1951 and 1953 excavations and consequently, determine how the archaeology functioned in practice at the site in the early 1950s. The second aspect was to present in what ways Dahlén’s diaries could contribute to the current and future excavations at the East Bath at Labraunda. The last aspect was to study Dahlén’s own archaeological interpretations which occured in the diaries. In order to present all the three aspects, the analysis and discussion on the diaries were organised into four headings: archaeological work, archaeological finds, stratigraphy and documentation methods. Studying the diaries based on these headings showed that certain improvements occurred in the diaries from 1951 to 1953. Dahlén’s excavation diaries reveal a large amount of archaeological data regarding the progress of the excavations and the numerous discoveries from the excavated areas. They need, therefore, to be taken into consideration for a better understanding of both the early and the new excavations that are being conducted at the same area.
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Grosheny, Danièle. "Paléoécologie et dynamique sédimentaire d'un modèle de banc à rudistes : exemple du Santonien de la Cadière (Sud-Est France)." Aix-Marseille 1, 1986. http://www.theses.fr/1986AIX11018.
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Ce memoire traite de la biosedimentologie de la formation de la cadiere, var. Cette formation peut etre subdivisee en cinq unites lithostratigraphiques constituees principalement de couches de calcaire a rudistes. Toutefois, on observe des variations laterales des facies dont les relations sont precisees et synthetisees grace a une analyse sequentielle. On montre que les sequences elementaires s'inscrivent dans une sequence de comblement. L'analyse des microfacies sur le plan sedimentologique et paleoecologique permet d'envisager la reconstitution des paleoenvironnements et de leur evolution. Les phenomenes de dissolution et de dolomitisation observes suggerent l'existence d'emersions temporaires. Enfin on presente une analyse systematique des miliolina dans laquelle de nouvelles especes sont decrites
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Samson, Philippe. "Équilibrage de structures géologiques 3D dans le cadre du projet GOCAD." Vandoeuvre-les-Nancy, INPL, 1996. http://docnum.univ-lorraine.fr/public/INPL_T_1996_SAMSON_P.pdf.
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L’équilibrage de structures géologiques 3D est une méthode de validation d'un modèle structural par analyse de sa déformation au cours du temps. L’équilibrage étant basé sur le principe de conservation de la matière (i. E. De volumes) une approche tridimensionnelle est plus satisfaisante que les approches 2D classiquement utilisées. Toutefois, la troisième dimension génère des difficultés supplémentaires. Il faut être capable de construire le modèle initial. Nous avons utilisé GOCAD pour résoudre ce problème. L’approche discrète a base de triangles proposée dans GOCAD, permet de construire des modèles géologiques complexes. En contrepartie, il nous fallait être capable d'adapter le maillage au problème pour lequel le modèle a été réalisé. Une surface n'étant pas nécessairement dépliable, nous proposons une étude préalable des courbures afin d'obtenir des informations précieuses au dépliage tout comme pour l'étude du plissement et la détection de failles. Nous avons développé un algorithme de respect de l'aire des surfaces au cours de la déformation. Le but étant de déplier un modèle complet, nous sommes capables de combiner le respect du volume des couches avec le respect de l'aire des surfaces. Nous proposons aussi une méthode de cisaillement simple qui permet de déplier certains modèles (notamment en extension) et de faire une mise à plat rapide permettant aux sédimentologies de faire des corrélations entre puits tout en respectant le modèle structural. Enfin, un modèle pouvant être composé de plusieurs blocs délimités par des failles, l'ajustement entre blocs rigides dépliés indépendamment, que nous proposons, rétablit la cohérence du modèle. Ces méthodes permettent aux géologues de déplier des modèles complexes et de tester la validité de leurs hypothèses sur la géométrie de la structure actuelle et sur le mode de déformation
28
Sastre, Jurado Carlos. "Exploitation du signal pénétrométrique pour l'aide à l'obtention d'un modèle de terrain." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC003/document.
Full textAbstract:
Ce travail porte sur la reconnaissance de sols à faible profondeur grâce aux données de résistance de pointe recueillies à l'aide de l'essai de pénétration dynamique à énergie variable, Panda®. L'objectif principal est d'étudier et de proposer un ensemble d'approches dans le cadre d'une méthode globale permettant d'exploiter les mesures issues d'une campagne de sondages Panda afin de bâtir un modèle géotechnique du terrain.Ce manuscrit est structuré en quatre parties, chacune abordant un objectif spécifique :dans un premier temps, on rappelle les principaux moyens de reconnaissance des sols, notamment l'essai de pénétration dynamique Panda. Ensuite on réalise un bref aperçu sur le modèle géotechnique et les techniques mathématiques pour décrire l'incertitude dans la caractérisation des propriétés du sol;la deuxième partie porte sur l'identification automatique des unités homogènes du terrain, à partir du signal pénétrométrique Panda. Suite à l'étude réalisée sur l'identification "experte" des couches à partir du signal Panda, des approches statistiques basées sur une fenêtre glissante ont été proposées. Ces techniques ont été étudiées et validées sur la base d'un protocole d'essais en laboratoire et sur des essais effectués en sites naturels et en conditions réelles;la troisième partie porte sur l'identification automatique des matériaux composant les unités homogènes détectées dans le signal Panda à partir des méthodes proposées en partie II. Une méthode de classification automatique basée sur des réseaux de neurones artificiels a été proposée et appliquée aux deux cas d'étude : la caractérisation de sols naturels et la classification d'un matériau granulaire argileux industrialisé (bentonite) ; enfin, la dernière partie est consacrée à la production d'un modèle de terrain basé sur la modélisation et la simulation de la résistance de pointe dynamique au moyen de fonctions aléatoires de l'espace. Cette modélisation est basée sur une approche par champs aléatoires conditionnés par les sondages Panda du terrain. Sa mise en œuvre a été étudiée pour un terrain expérimental situé dans la plaine deltaïque méditerranéenne en Espagne. Des études complémentaires en vue de raffiner cette démarche ont été réalisées pour un deuxième site expérimental dans la plaine de la Limagne en FranceThis research focuses on the site characterization of shallow soils using the dynamic cone penetrometer Panda® which uses variable energy. The main purpose is to study and propose several techniques as part of an overall method in order to obtain a ground model through a geotechnical campaign based on the Panda test.This work is divided into four parts, each of them it is focused on a specific topic :first of all, we introduce the main site characterization techniques, including the dynamic penetrometer Panda. Then, we present a brief overview of the geotechnical model and the mathematical methods for the characterization of uncertainties in soil properties;the second part deals with the automatic identification of physical homogeneous soil units based on penetration's mechanical response of the soil using the Panda test. Following a study about the soil layers identification based only on expert's judgment, we have proposed statistical moving window procedures for an objective assessment. The application of these statistical methods have been studied for the laboratory and in situ Panda test;the third part focuses on the automatic classification of the penetrations curves in the homogeneous soil units identified using the statistical techniques proposed in part II. An automatic methodology to predict the soil grading from the dynamic cone resistance using artificial neural networks has been proposed. The framework has been studied for two different research problems: the classification of natural soils and the classification of several crushed aggregate-bentonite mixtures;finally, the last chapter was devoted to model the spatial variability of the dynamic cone resistance qd based on random field theory and geostatistics. In order to reduce uncertainty in the field where Panda measurements are carried out, we have proposed the use of conditional simulation in a three dimensional space. This approach has been applied and studied to a real site investigation carried out in an alluvial mediterranean deltaic environment in Spain. Complementary studies in order to improve the proposed framework have been explored based on another geotechnical campaign conducted on a second experimental site in France
29
Harbison, John Edwin. "Groundwater chemistry and hydrological processes within a Quaternary coastal plain: Pimpama, Southeast Queensland." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16647/1/John%20Harbison%20Thesis.pdf.
Full textAbstract:
The Pimpama estuarine plain in subtropical southeast Queensland is comprised of Quaternary sediments infilling older bedrock. These multilayered unconsolidated sediments have various depositional origins, and are highly heterogeneous. The plain is low-lying and the surface drainage is controlled by flood mitigation measures including tidal gates and channelised streams. The control of surface drainage potentially affects the shallow water table. This modification of hydrology has implications for future viability of agriculture and also the environmental health of waterways. Increased landscape modification and water management is likely in the coming years. The combination of sediment heterogeneity, low hydraulic gradients, and artificial drainage modification result in the plain being hydrogeologically complex. In order to understand hydrologic processes in this setting, a multi-disciplinary research programme was conducted which included a drilling program, overland electromagnetic induction and other geophysical surveys (downhole gamma log, electromagnetic induction and magnetic susceptibility) to initially establish the geologic framework. These surveys were followed by hydrogeochemical testing which includes for major and minor ions and also stable isotopes, and mineralogical analysis of drillhole material. Underlying basement rock occurs at up to 60 m depth. Unconsolidated gravel and sand deposits occur within incised paleo-valleys and are overlain by predominantly low-permeability fluvial sandy clays and estuarine and lagoonal muds. Fine-grained delta sands occur in the top 15 m of the sub-surface. Within the unconsolidated sediments, hydrodynamic trends clearly discriminated between upper unconfined and lower semi-confined aquifer systems. A comparison of surface water and shallow groundwater levels indicate limited interaction of groundwater and surface water. Hydrogeochemical analysis effectively distinguished between groundwater bodies, and also distinguished saline groundwater from seawater. Trends in major ion chemistry in the semi-confined system (particularly Na/Cl and Ca/Cl ratios) showed ion exchange accompanying saline intrusion. However, due to factors such as mineral dissolution, major ion chemistry does not clearly identify solute flux trends in the shallow aquifer system. Water stable isotope analysis (δ18O and δ2H) indicated the provenance of fresh and saline groundwater and also the relative importance of the principal hydrologic processes, i.e. evaporation and water uptake by plants. Groundwater exhibited a wide range in salinity, from very fresh to hypersaline. The formation of hypersaline groundwater was attributed largely to uptake of water by mangrove forests. Since mangrove forests were more extensive at the time of the Holocene maximum sea level (approximately 6,000 years ago) than at present, some of this groundwater may represent relict salinity from this earlier time. The relationship of relict salinity to low permeability sediments, particularly at intermediate depths, and their depositional history was examined. Vertical salinity gradients and hydrogeochemistry within these sediments varied according to position within the plain, suggesting deposition under various hydrological and sea level regimes. A preliminary investigation using analysis of stable sulfate isotopes (δ34S and δ18OSO4) was made. This study shows substantial potential for the application of this technique for quantification of solute flux and sulfur chemical transformations within settings such as this coastal plain. To establish shallow groundwater flow processes, a MODFLOW-based numerical model was used to inversely estimate aquifer parameters under various recharge scenarios. The model was designed to examine the relative importance of evapotranspiration and discharge to surface waters. However, largely due to the complexity of the drainage network and non-uniform surface water flows, the quantification of surface water- groundwater interaction by consideration of hydrodynamics is problematic. Therefore, the chemistry of groundwater and surface water was compared. While the estimated contribution of rainfall to groundwater level fluctuations was significant (46%), high evapotranspiration rates reduced net recharge and it was concluded that baseflow to drains and creeks during dry periods was insignificant, and groundwater velocities in the shallow aquifer are low. The study illustrates the value of both hydrodynamic and hydrogeochemical analyses in estuarine settings where relict salinity and groundwater-aquifer interactions impact significantly on water quality. Saline groundwater is chemically distinct from theoretical mixtures of seawater and freshwater. The study also demonstrates the value of particular chemical parameters, e.g. Na/Cl and SO4/Cl ratios and stable water isotopes, for identifying hydrologic processes in this setting.
30
Harbison, John Edwin. "Groundwater chemistry and hydrological processes within a Quaternary coastal plain: Pimpama, Southeast Queensland." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16647/.
Full textAbstract:
The Pimpama estuarine plain in subtropical southeast Queensland is comprised of Quaternary sediments infilling older bedrock. These multilayered unconsolidated sediments have various depositional origins, and are highly heterogeneous. The plain is low-lying and the surface drainage is controlled by flood mitigation measures including tidal gates and channelised streams. The control of surface drainage potentially affects the shallow water table. This modification of hydrology has implications for future viability of agriculture and also the environmental health of waterways. Increased landscape modification and water management is likely in the coming years. The combination of sediment heterogeneity, low hydraulic gradients, and artificial drainage modification result in the plain being hydrogeologically complex. In order to understand hydrologic processes in this setting, a multi-disciplinary research programme was conducted which included a drilling program, overland electromagnetic induction and other geophysical surveys (downhole gamma log, electromagnetic induction and magnetic susceptibility) to initially establish the geologic framework. These surveys were followed by hydrogeochemical testing which includes for major and minor ions and also stable isotopes, and mineralogical analysis of drillhole material. Underlying basement rock occurs at up to 60 m depth. Unconsolidated gravel and sand deposits occur within incised paleo-valleys and are overlain by predominantly low-permeability fluvial sandy clays and estuarine and lagoonal muds. Fine-grained delta sands occur in the top 15 m of the sub-surface. Within the unconsolidated sediments, hydrodynamic trends clearly discriminated between upper unconfined and lower semi-confined aquifer systems. A comparison of surface water and shallow groundwater levels indicate limited interaction of groundwater and surface water. Hydrogeochemical analysis effectively distinguished between groundwater bodies, and also distinguished saline groundwater from seawater. Trends in major ion chemistry in the semi-confined system (particularly Na/Cl and Ca/Cl ratios) showed ion exchange accompanying saline intrusion. However, due to factors such as mineral dissolution, major ion chemistry does not clearly identify solute flux trends in the shallow aquifer system. Water stable isotope analysis (δ18O and δ2H) indicated the provenance of fresh and saline groundwater and also the relative importance of the principal hydrologic processes, i.e. evaporation and water uptake by plants. Groundwater exhibited a wide range in salinity, from very fresh to hypersaline. The formation of hypersaline groundwater was attributed largely to uptake of water by mangrove forests. Since mangrove forests were more extensive at the time of the Holocene maximum sea level (approximately 6,000 years ago) than at present, some of this groundwater may represent relict salinity from this earlier time. The relationship of relict salinity to low permeability sediments, particularly at intermediate depths, and their depositional history was examined. Vertical salinity gradients and hydrogeochemistry within these sediments varied according to position within the plain, suggesting deposition under various hydrological and sea level regimes. A preliminary investigation using analysis of stable sulfate isotopes (δ34S and δ18OSO4) was made. This study shows substantial potential for the application of this technique for quantification of solute flux and sulfur chemical transformations within settings such as this coastal plain. To establish shallow groundwater flow processes, a MODFLOW-based numerical model was used to inversely estimate aquifer parameters under various recharge scenarios. The model was designed to examine the relative importance of evapotranspiration and discharge to surface waters. However, largely due to the complexity of the drainage network and non-uniform surface water flows, the quantification of surface water- groundwater interaction by consideration of hydrodynamics is problematic. Therefore, the chemistry of groundwater and surface water was compared. While the estimated contribution of rainfall to groundwater level fluctuations was significant (46%), high evapotranspiration rates reduced net recharge and it was concluded that baseflow to drains and creeks during dry periods was insignificant, and groundwater velocities in the shallow aquifer are low. The study illustrates the value of both hydrodynamic and hydrogeochemical analyses in estuarine settings where relict salinity and groundwater-aquifer interactions impact significantly on water quality. Saline groundwater is chemically distinct from theoretical mixtures of seawater and freshwater. The study also demonstrates the value of particular chemical parameters, e.g. Na/Cl and SO4/Cl ratios and stable water isotopes, for identifying hydrologic processes in this setting.
31
Ruellan, Etienne. "Géologie des marges continentales passives : Evolution de la marge atlantique du Maroc (Mazagan) : Etude par submersible, seabeam et sismique réflexion : Comparaison avec la marge N.O. africaine et la marge homologue E. américaine." Brest, 1985. http://www.theses.fr/1985BRES0014.
Full textAbstract:
Cadre geodynamique de la marge marocaine. Structure et evolution tectonique et sedimentaire de la marge el jadida. Comparaison des resultats avec ceux connus sur la marge nord-ouest africaine jusqu'au plateau de guinee et sur la marge conjuguee de la nouvelle-ecosse, georges bank
32
Shaw, Michael John. "Seismic stratigraphy of the northern KwaZulu-Natal upper continental margin." Thesis, 1998. http://hdl.handle.net/10413/4420.
Full textAbstract:
This study presents the interpretation of Edo-Western and Sparker seismic
geophysical data acquired on the northern KwaZulu-Natal upper continental margin
by various organisations since 1981.
Five seismic sequences are recognised and these are traceable across the entire
length of the study area. The oldest is interpreted as a late Cretaceous marine
sequence (Sequence A), probably the offshore equivalent of the St. Lucia Formation
exposed onshore. This sequence is overlain by a progradational, probable late
Tertiary shelf sequence (Sequence B) onlapping in places against the underlying
marine sequence. The outer portion of this sequence on the upper continental slope
is characterised by complicated reflection termination patterns indicating the
possible presence of discreet sequences within this shelf and slope unit. These
shelf and slope sediments are overlain by a thin (less than 20m) reworked and
eroded Pleistocene shelf unit (Sequence C), itself overlain by linear Pleistocene
aeolianites (Sequence D) in places. The youngest sequence observed is the
Holocene unconsolidated sediment wedge (Sequence E) on the inner shelf,
attaining thicknesses of greater than 20m in places. The various sequences were
mapped out and sediment isopach maps were produced (wherever possible) as well
as an overall geological subcrop map of the study area.
150 kilometres of shallow penetration Edo Western seismic records acquired off the
Sodwana Bay continental shelf were interpreted. Two sediment types are
recognised, namely consolidated beach rock/aeolianite and unconsolidated
Quaternary shelf sand/bioclastic reef derived sediment. In places, accumulations of
bioclastic sediment in subaqueous dune troughs which have been subsequently
buried by migrating bedforms manifest themselves on seismic records as dark semi-continuous
reflectors beneath the migrating bedform. Close inshore, seismic records
show prominent reflectors interpreted as consolidated sediment beneath varying
thicknesses of unconsolidated sediment. Close to the shelf break (occurring at
approximately -60m), seismic interpretation indicates that thin beach rock
developments perch directly upon unconsolidated shelf sand, with the beach rock
having been eroded through in places to expose unconsolidated sediment beneath.
A sediment thickness map for this area was compiled from the seismic data. The
limited penetration of the Pinger system necessitated "greater-than" values being
used in many areas. Greatest sediment thicknesses occur in subaqueous dune
fields where unconsolidated sediment thickness is at least 11 m. In inshore areas
absent of subaqueous dune fields, sediment thicknesses are typically low, varying
between 1 and 3m. A prominent submerged dune ridge close inshore limits
substantial unconsolidated sediment build-up to landward of this feature. On the
seaward side substantial build-up is limited by the action of the Agulhas Current
which is actively transporting sediment into the head of submarine canyons which
incise the continental shelf at Sodwana Bay. This study shows that on the northern
KwaZulu-Natal continental shelf where there is a dearth of unconsolidated
Quaternary sediment, the Edo Western seismic system is a useful tool for
discerning thin veneers of unconsolidated sediment less than 4m thick. When
considering the overall low volumes of unconsolidated sediment present on the
shelf, this hitherto unconsidered volume of sediment constitutes an important part of
the shelf sediment budget.
Submarine landslide features observed on sparker seismic records are described
and discussed. Submarine landslides are present which affect a) Sequences A and
B, b) Sequence B only and c) Sequence A only, ages of these sediment failures can
thus be inferred as being either post- Late Cretaceous or post- Late Tertiary.
Offshore Kosi Bay, submarine landslide features affecting Sequence A are buried by
unaffected Sequence B sediments, indicating a post- Late Cretaceous to pre- Late
Tertiary age of occurrence. Style of failure tends towards mass flow in those
submarine landslides in which Sequence B only sediments are affected, while those
in which Sequence A is affected exhibit some slide features indicating a greater
degree of internal coherency of these sediments compared to Sequence B. Slope
stability analysis of a submarine landslide feature offshore St. Lucia Estuary Mouth
indicates the failed sediment mass would have been stable under static conditions
and that external dynamic forces such as storm waves or seismic activity would
have been necessary to induce failure. It is demonstrated that the Zululand
earthquake of 1932 would have exceeded the intensity necessary to induce
sediment failure and this event should therefore be considered as a possible cause.
Seismic evidence of fluvial incision/subaerial exposure at the boundaries between
Sequences A and B and C and E are further evidence of lowered sea-levels
probably during the Oligocene and Late Pleistocene. The position of the incision
into Sequence C relative the present course of the Mkuze River indicates the
possibility that this incision could represent the palaeo-outlet of this river.
Seismic expression of 3 submarine canyons in the study area indicate that they are
currently undergoing active headward erosion, independent of any direct modern
fluvial influence. In the case of Ntabende Canyon, a nearby continental shelf
incision postulated to be the palaeo-Mkuze outlet indicates that provision of
terrigenous material to this portion of the continental shelf could well have
accelerated mass wasting processes within the canyon itself. This submarine
canyon could therefore have progressed more rapidly to a relatively mature phase
of development. Subsurface structure indicates the lack of any post- Late Tertiary
fault features beneath the canyons, thus excluding faults active in post- Late
Tertiary times as a developmental factor.
It is shown that the overall, external morphology of the KwaZulu-Natal upper
continental margin is strongly influenced by seismic stratigraphic relationships, with
the main influencing factors being outcrop position of the various sequences and
depositional angle of sediments of which a sequence is comprised. External
morphology has also been greatly modified in places by mass-wasting processes. It
is demonstrated also that relating the observed seismic stratigraphy to onshore
geological cross sections is problematic due to the distances involved and lack of
confident offshore dates for the seismic sequences observed.
Seismic relationships observed contribute to an understanding of relative sea-level
movements since the Late Cretaceous and the overall geological evolution of the
northern KwaZulu-Natal upper continental margin, details of which are discussed.Thesis (M.Sc.)-University of Natal, Durban, 1998.
33
Miller, Warwick Richard. "The bathymetry, sedimentology and seismic stratigraphy of Lake Sibaya- Northern KwaZulu-Natal." Thesis, 1998. http://hdl.handle.net/10413/4431.
Full textAbstract:
The morphology of Lake Sibaya is a product of an ancient fluvial system that drained a coastal
landscape dominated by aeolian processes. The sedimentary processes within the lake are driven
by wind generated currents. The dominant sedimentary process is one of lake segmentation,
whereby prograding bedforms isolate the lake into smaller water bodies. The prograding
bedforms include cuspate forelands and sand spits. The size and mobility of these bedforms is a
function of sediment availability and current regime.
The bathymetry of Lake Sibaya is discussed, with emphasis on geomorphic features derived from
the ancient aeolian landscape as well as features related to modern sedimentary processes. The
presence of underwater knickpoints and terraces indicate that lake level fluctuations have been
common in Lake Sibaya. It is during lake highstands that large volumes of sand are eroded from
aeolian dunes which surround the lake and made available for shoreline progradation. Ancient
dune topography is preserved to depths of 20 m below water-level within the lake.
Surface sediment distribution maps were compiled from 515 grab samples and thirteen core
samples. Fine grained, well sorted, coarse skewed quartz sand comprises the majority of the
surface area of the lake floor. Gyttja is the other dominant sediment type and accumulates in
palaeovalleys and depressions on the lake floor. Sediment distribution in Lake Sibaya is discussed
in terms of modern lacustrine processes as well as inherited sedimentary characteristics.
The stratigraphy of the sediments underlying Lake Sibaya was investigated using a Uni-Boom
seismic profiling system. Seismic profiles were compiled by identifying acoustically reflective
surfaces that show regional development. Thirteen seismic overlays were prepared, and are
illustrated as west - east and north - south seismic profiles. Five sequences ranging in age from
late Cretaceous to Holocene were identified from the seismic profiles, and are described in terms
of sequence stratigraphic principles. The seismic sequences were interpreted within a
lithostratigraphic framework and are presented as a series of idealised geological sections.
Thirteen sediment cores were collected from the Lake Sibaya area in order to ascertain the
accuracy of the stratigraphic interpretation of the seismic records, to investigate reflective
horizons identified from seismic records and to collect dateable material. Interpretation of the
sediment cores reveals that a proto Lake Sibaya existed on drowned dune topography, during the
period ± 43500 BP to ± 25500 BP prior to the Last Glacial Maximum. During the early to mid
Holocene the Lake Sibaya site was occupied by a saline lagoon which underwent isolation from
the sea ± 5030 BP. Since the mid-Holocene the lake has evolved to totally freshwater conditions
and has undergone little sedimentation.
The geological evolution of the Lake Sibaya area is discussed in terms of the geometry of the
identified seismic sequences, the sedimentary characteristics of these sequences and the
radiocarbon dates provided from the sediment cores. Palaeo-environmental conditions during the
accumulation of the sedimentary sequences is discussed where fossil remains permit.Thesis (M.Sc.)-University of Natal, Durban, 1998.
34
Ramazanova, Rahila. "Sequence stratigraphic interpretation methods for low-accommodation, alluvial depositional sequences: applications to reservoir characterization of Cut Bank field, Montana." 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1127.
Full textAbstract:
In South Central Cut Bank Sand Unit (SCCBSU) of Cut Bank field, primary
production and waterflood projects have resulted in recovery of only 29 % of the
original oil in place from heterogeneous, fluvial sandstone deposits. Using highresolution
sequence stratigraphy and geostatistical analysis, I developed a geologic
model that may improve the ultimate recovery of oil from this field.
In this study, I assessed sequence stratigraphic concepts for continental settings
and extended the techniques to analyze low-accommodation alluvial systems of the Cut
Bank and Sunburst members of the lower Kootenai formation (Cretaceous) in Cut Bank
field. Identification and delineation of five sequences and their bounding surfaces led to
a better understanding of the reservoir distribution and variability.
Recognition of stacking patterns allowed for the prediction of reservoir rock
quality. Within each systems tract, the best quality reservoir rocks are strongly
concentrated in the lowstand systems tract. Erosional events associated with falling baselevel
resulted in stacked, communicated (multistory) reservoirs. The lowermost Cut Bank sandstone has the highest reservoir quality and is a braided stream parasequence.
Average net-to-gross ratio value (0.6) is greater than in other reservoir intervals. Little
additional stratigraphically untapped oil is expected in the lowermost Cut Bank
sandstone. Over most of the SCCBSU, the Sunburst and the upper Cut Bank strata are
valley-fill complexes with interfluves that may laterally compartmentalize reservoir
sands. Basal Sunburst sand (Sunburst 1, average net-to-gross ratio ~0.3) has better
reservoir quality than other Sunburst or upper Cut Bank sands, but its reservoir quality is
significantly less than that of lower Cut Bank sand.
Geostatistical analysis provided equiprobable representations of the
heterogeneity of reservoirs. Simulated reservoir geometries resulted in an improved
description of reservoir distribution and connectivity, as well as occurrences of flow
barriers.
The models resulting from this study can be used to improve reservoir
management and well placement and to predict reservoir performance in Cut Bank field.
The technical approaches and tools from this study can be used to improve descriptions
of other oil and gas reservoirs in similar depositional systems.