Teses / dissertações: "“Stratigraphic” method"

1

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

2

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

3

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/.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

4

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

5

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

6

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.

Texto completo da fonte

Resumo:

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

Estilos ABNT, Harvard, Vancouver, APA, etc.

7

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.

Texto completo da fonte

Resumo:

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
incomplete_metadata

Estilos ABNT, Harvard, Vancouver, APA, etc.

8

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

9

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

10

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

11

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

12

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

13

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

14

Chu, Lap-man Raymond, e 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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

15

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

16

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

17

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

18

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

19

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

20

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.

Texto completo da fonte

Resumo:

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-souabe
The 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

Estilos ABNT, Harvard, Vancouver, APA, etc.

21

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.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

22

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.

Texto completo da fonte

Resumo:

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)

Estilos ABNT, Harvard, Vancouver, APA, etc.

23

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

24

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

25

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

26

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.

Texto completo da fonte

Resumo:

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

Estilos ABNT, Harvard, Vancouver, APA, etc.

27

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.

Texto completo da fonte

Resumo:

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

Estilos ABNT, Harvard, Vancouver, APA, etc.

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.

Texto completo da fonte

Resumo:

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 France
This 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

Estilos ABNT, Harvard, Vancouver, APA, etc.

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

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/.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

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.

Texto completo da fonte

Resumo:

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

Estilos ABNT, Harvard, Vancouver, APA, etc.

32

Shaw, Michael John. "Seismic stratigraphy of the northern KwaZulu-Natal upper continental margin". Thesis, 1998. http://hdl.handle.net/10413/4420.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

33

Miller, Warwick Richard. "The bathymetry, sedimentology and seismic stratigraphy of Lake Sibaya- Northern KwaZulu-Natal". Thesis, 1998. http://hdl.handle.net/10413/4431.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

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.

Texto completo da fonte

Resumo:

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.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Teses / dissertações sobre o tema "“Stratigraphic” method"

Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos