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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Tectonic-sedimentary evolution of the Girne (Kyrenia) Range and the Mesarya (Mesaoria) Basin, North Cyprus

McCay, Gillian Anna January 2011 (has links)
The Eastern Mediterranean marks the site of the Southern Neotethys Ocean that was created, then largely destroyed near the northern margin of Gondwana. Sedimentary and structural evidence is well preserved in the Girne (Kyrenia) Range, a several hundred kilometrelong, narrow, E – W-trending, broadly arcuate lineament that encompasses northern Cyprus and a submarine ridge that links southeastern Turkey (Misis–Andırın Complex). This study focuses on the Oligocene-Miocene sequence exposed on both flanks of the Girne (Kyrenia) Range, based on sedimentology, microfacies, Sr-isotope dating and structural analysis. Two related sedimentary basins are today separated by an E – W-trending high-angle, fault zone, the Değirmenlik (Kythrea) Fault. The northern basin encompasses the Range, whereas the southern basin is located between the Değirmenlik (Kythrea) Fault and an E – W trending fault lineament (Dar dere (Ovgos) Fault Zone), to the south of which is the Troodos Ophiolitic Massif. The Değirmenlik (Kythrea) Fault is interpreted as a convergence-related thrust fault that was active during the Mid-Late Miocene creating an E – W submarine ridge that separated subbasins to the north and south. The sedimentary sequence in the northern basin unconformably overlies Mesozoic platform carbonates and latest Cretaceous-Palaeogene pelagic carbonates with interbedded volcanics. Above basal conglomerates (probably derived from underlying Eocene debris flows based on chemical evidence), there is a fining-upward siliciclastic turbidite sequence (Late Oligocene), then biogenic calciturbidites and marls (Aquitanian-Langhian). The northerly basin is characterised by thin-, to medium-bedded, pale hemipelagic calciturbidites and marls (Serravallian; ~400 m thick), overlain by thick-bedded, medium- to coarse-grained lithic sandstones with carbonate concretions (Tortonian; ~250 m thick). The succession in the southern basin, which is more deformed by thrusting, begins with poorly dated pelagic marls (Early Miocene?), followed by regularly bedded siliciclastic turbidites (~1000 m thick), with abundant sole structures (Serravallian-Tortonian). Palaeocurrent evidence shows mainly E to W flow for the southern basin, and locally a generally E to W flow for the northerly basin, at least for the Late Miocene. Gypsum accumulated in local depocentres during the Messinian salinity crisis and was locally deformed by contemporaneous southward thrusting. Petrographic studies of the Serravallian – Tortonian sandstones indicate that the northern basin is richer in recrystallised limestone grains compared to the southern basin, which contains more abundant siliciclastic and ophiolite-derived material; this trend is also present in results from XRD analysis of clays. The likely source area was the Eurasian-African suture zone in the Tauride Mountains to the northeast. The greater detrital limestone abundance in the south may record relatively deep-level erosion of the source area, through ophiolites to an underlying Mesozoic carbonate platform. Two phases of clastic input are recognised from SE Turkey, the first related to Early Miocene continental collision, and the second reflecting Late Miocene suture tightening, both to the east of Cyprus within the Tauride Suture Zone. Based on the measurement and kinematic analysis of a large number (>1290) of faults, combined with a knowledge of the tectono-stratigraphy, the timing and nature of faulting is inferred. The majority of the faults are south-verging, high-angle reverse faults, while sinistral strike-slip faults dominate several areas of the Girne (Kyrenia) Range and the Dar dere (Ovgos) Fault Zone of the south. Most of the faults in the Girne (Kyrenia) Range are attributed to Mid – Late Eocene and Late Miocene – Early Pliocene phase of thrusting, followed by relative quiescence until Pleistocene uplift of the Girne (Kyrenia) Range. The Dar dere (Ovgos) Fault Zone is interpreted as a long-lived terrane boundary that accommodated sinistral movement during Late Miocene to Recent. In summary, the Girne (Kyrenia) Range reflects the diachronous closure of the Mesozoic Southern Neotethys Ocean, culminating in westward tectonic escape from continent-continent collision zone to the east, coupled with thick-skinned uplift that was triggered by collision with a crustal block to the south, the Eratosthenes Seamount.
112

Understanding Miocene Climatic Warmth

Ashley J Dicks (6997760) 13 August 2019 (has links)
<div> <div> <div> <p>The mid-Miocene Climatic Optimum (MMCO), 17-14.50 million years ago, is studied using general circulation models (GCMs). This period of time is characterized by enhanced warming in the deep ocean and in the mid-to-high latitudes. Previous GCMs fail to accurately represent the warmer climate of the MMCO, providing evidence that other warming feedbacks are missing in the models. This study focuses on cloud feedbacks by modifying the Community Earth System Model (CESM 1.0) to explore the MMCO climate. We implement modifications in pre-industrial (284.7 ppm CO2) and modern slab ocean cases (367.0 ppm CO2, 400 ppm CO2, and 800 ppm CO2). One modified case showing the most potential implements an aerosol de- pendent ice nucleation mechanism and a theory based cloud phase separation. This modified case allows the model predicted aerosol concentrations to interact with the cloud microphysics and provide more realistic cloud water contents. The data shows an increase in surface temperature and increase in upper atmospheric cloud fraction when compared to the control case. Preliminary results suggest that this model is able to capture the mid-to-high latitude warming trends and weaker equator to pole temperature gradient. </p> </div> </div> </div>
113

Les phytolithes, marqueurs des environnements mio-pliocènes du Tchad. Reconstitution à partir du signal environnemental des phytolithes dans l'Afrique subsaharienne actuelle / Phytoliths, indicators of the Mio-Pliocene environments of Chad. Paleoenvironmental reconstruction from the modern Sub-Saharan phytolith signal in Africa

Novello, Alice 06 December 2012 (has links)
Ce mémoire présente l'étude du signal phytolithique de sédiments mio-pliocènes du Tchad(Afrique Centrale) datés entre 7-2 Ma, et contemporains des Homininés anciens Sahelanthropustchadensis et Australopithecus bahrelghazali. Une calibration de la relation plantes-phytolithes-solspour l'Afrique tropicale subsaharienne actuelle a d'abord été réalisée pour apprécier la signatureenvironnementale des phytolithes dans le registre fossile. L'analyse des assemblages phytolithiques de98 espèces de graminées (Poaceae) a permis d'élaborer trois nouveaux indices phytolithiques à partirde 43 types propres aux Poaceae. Testés sur une base de 57 sols/sédiments modernes du Tchad, cesindices permettent de tracer les associations graminéennes aquatiques du Lac Tchad, les associationsmésophytiques des milieux humides soudaniens, et les associations xérophytiques des milieux secssahéliens. L'analyse des assemblages phytolithiques des sols/sédiments actuels considérés dans leurensemble a permis d'évaluer le potentiel de ce proxy à caractériser la physionomie des formationssoudano-sahéliennes modernes. La calibration a été appliquée à l'étude d'un enregistrementsédimentaire discontinu du Lac Tchad (6-2 Ma) (forage de Bol, 13°N/14°E) et à celle de 18 niveauxpaléontologiques du Djourab (7-3.5 Ma) (16°N/17°E). Les résultats indiquent la présence de savanesintermédiaires à fermées et de zones de végétation aquatique dominantes à 7 Ma dans le Djourab, puisde savanes plus ouvertes et sèches à 3.5 Ma. Une phase de bas niveau lacustre est enregistrée entre3.6-2.8 Ma à Bol, et un pic d'aridité à 3.2 Ma. Enfin, les résultats montrent l'existence de graminéesen C4 au Tchad depuis 7 Ma. / This thesis dissertation is dedicated to the study of the phytolith signal of Mio-Pliocenesediments from Chad (Central Africa) dated between 7-2 Ma, and contemporary to the early Homininspecies Sahelanthropus tchadensis and Australopithecus bahrelghazali. A calibration work studyingthe relationship plants-phytoliths-soils in modern sub-Saharan tropical Africa was carried out in orderto assess the environmental significance of the phytolith signal in the fossil record. Phytolithassemblages produced by 98 sub-Saharan grass species (Poaceae) were analyzed and the results led tothe development of three new phytolith indices defined from 43 types specific to Poaceae. Tested on adatabase of 57 modern soil/sediment samples from Chad, these indices allow drawing aquatic grassassociations of Lake Chad, mesophytic grass associations of wetlands from the Sudanian domain, andxerophytic grass associations of drylands from the Sahelian domain. The analysis of modern soilphytolith assemblages (total assemblages) was used to assess the potential of this proxy to characterizethe physiognomy of the Sudano-Sahelian vegetation types. The calibration had been applied to thestudy of a discontinuous sedimentary record from Lake Chad (6-2 Ma) (Bol core, 13°N/14°E) and of18 paleontological levels from the Djourab (7-3.5 Ma) (16°N/17°E). The results indicate thedominance of intermediate to closed savannas and areas of aquatic vegetation at 7 Ma in the Djourab,and more open and dry savannas at 3.5 Ma. A limited lacustrine stage is recorded between 3.6-2.8 Maat Bol, and a shift of aridity at 3.2 Ma. Finally, the results show the existence of C4 grasses in Chadsince 7 Ma.
114

The Evolution from Late Miocene West Salton Detachment Faulting to Cross-Cutting Pleistocene Oblique Strike-Slip Faults in the SW Salton Trough, Southern California

Steely, Alexander N. 01 May 2006 (has links)
Field studies in the southwest Salton Trough between Yaqui Ridge and Borrego Mountain show that the West Salton detachment fault was active during the Pliocene and may have initiated during the latest Miocene. At Yaqui Ridge dominantly east-directed extension is recorded by slickenlines on the NW-striking detachment fault, and shows that the fault is actually a low-angle dextral oblique strike-slip fault. Crustal inheritance is responsible for the position of the fault at Yaqui Ridge, which reactivates a late Cretaceous reverse -sense mylonite zone at map scale. Late Miocene to Pliocene basin fill deposits at Borrego Mountain display progressive unconformities, contain detritus shed from the footwall and damage zone of the West Salton detachment fault, record the growth of a large hanging wall anticline, and document the initiation and evolution of the West Salton detachment fault. The Borrego Mountain anticline is a major hanging wall growth fold that trends - N60 °W and has at least 420 m of structural relief. The late Quaternary Sunset conglomerate is - 600 m thick, lies in angular unconformity on Pliocene basin fill, is bound on the SW by the dextral oblique Sunset fault, and coarsens upward and SW toward the fault. It is dominated by plutonic lithologies from nearby areas, contains up to 10% recycled sandstone clasts from Pliocene deposits, and was shed from the SW side of the then-active Sunset fault. Based on lithologic, stratigraphic, compositional similarities, we correlate this conglomerate to part of the - 1. I - 0.6 Ma Ocotillo Formation. The West Salton detachment fault was folded and deactivated at Yaqui Ridge by the dextral oblique San Felipe fault zone starting - 1. l - 1.3 Ma. The Sunset fault is in the middle of a complex left stepover between the San Felipe fault to the NW and the Fish Creek Mountains fault to the SE. Structural analyses and mapping show that syntec tonic conglomerate, the West Salton detachment fault, and footwall crystalline rocks all have similar fold geometries and record similar amounts of NE-SW shortening. The dominant SE-trending population of slip vectors on the Sunset fault is not present on the West Salton detachment fault and suggests limited or no activation of the older detachment fault by the younger fault zone.
115

Investigations on the importance of early diagenetic processes for the mineralogical stabilisation and lithification of heterozoan carbonate assemblages : (Oligo-Miocene, Maltese Islands and Sicily)

Knörich, Andrea Claudia January 2005 (has links)
Diagenetic studies of carbonate rocks focused for a long time on photozoan carbonate assemblages deposited in tropical climates. The results of these investigations were taken as models for the diagenetic evolution of many fossil carbonates. Only in recent years the importance of heterozoan carbonates, generally formed out of the tropics or in deeper waters, was realized. Diagenetic studies focusing on this kind of rocks are still scarce, but indicate that the diagenetic evolution of these rocks might be a better model for many fossil carbonate settings ("calcite-sea" carbonates) than the photozoan model used before.<br><br> This study deals with the determination of the diagenetic pathways and environments in such shallow-water heterozoan carbonate assemblages. Special emphasis is put on the identification of early, near-seafloor diagenetic processes and on the evaluation of the amount of constructive diagenesis in form of cementation in this diagenetic environment.<br><br> As study area the Central Mediterranean, the Maltese Islands and Sicily, was chosen. Here two sections were logged in Olio-Miocene shallow-water carbonates consisting of different kinds of heterozoan assemblages. The study area is very suitable for the investigation of constructive early diagenetic processes, as the rocks were never deeply buried and burial diagenetic pressure solution and cementation as cause of lithification could be ruled out. Nevertheless, the carbonate rocks are well lithified and form steep cliffs, implying cementation/lithification in another, shallower diagenetic environment. To determine the diagenetic pathways and environments, detailed transmitted light and cathodoluminescence petrography was carried out on thin sections. Furthermore the stable isotope (δ<sup>18</sup>O and δ<sup>13</sup>C) composition of the bulk rock, single biota and single cement phases was determined, as well as the major and trace element composition of the single cement phases.<br><br> Petrographically three (Sicily) to four (Maltese Islands) cementation phases, two phases of fabric selective and one of non-fabric selective dissolution, one phase of neomorphism and one of chemical compaction could be distinguished. The stable isotope measurements of the single cement phases pointed to cement precipitation from marine, marine-derived and meteoric waters. The trace element analysis indicated precipitation under reducing conditions, (A) in an open system with low rock-water interaction on the Maltese Islands and (B) in a closed system with high rock-water interaction on Sicily. For the closed systems case, aragonite as cement source could be concluded because its chemical composition was preserved in the newly formed cements.<br><br> By integrating these results, diagenetic pathways and environments for the investigated locations were established, and the cement source(s) in the different environments were determined. The diagenetic evolution started in the marine environment with the precipitation of fibrous/fibrous-bladed and epitaxial cement I. These cements formed as High Mg Calcite (HMC) directly out of marine waters. The paleoenvironmentally shallowest part of the section on the Maltese Islands was also exposed to meteoric diagenetic fluids. This meteoric influence lead to the dissolution of aragonitic and HMC skeletons, which sourced the cementation by Low Mg Calcitic (LMC) epitaxial cement II in this part of the Maltese section. Entering the burial-marine environment the main part of dissolution, cementation and neomorphism started to take place. The elevated CO2 content in this environment, caused by the decay of organic matter, lead to the dissolution of aragonitic skeletons, which sourced the cementation by LMC epitaxial cement II, bladed and blocky cements. The earlier precipitated HMC cement phases were either partly dissolved (epitaxial cement I) or neomorphosed to LMC (fibrous/fibrous-bladed and epitaxial cement I). In the burial environment weak chemical compaction took place without sourcing significant amounts of cementation. In a last phase the rocks entered the meteoric realm by uplift, which caused non-fabric selective dissolution. This study shows that early diagenetic processes, taking place at or just below the sediment-water-interface, are very important for the mineralogical stabilization of heterozoan carbonate strata. The main amount of constructive diagenesis in form of cementation takes place in this environment, sourced by dissolution of aragonitic and, to a lesser degree, of HMC skeletons.<br><br> The results of this study imply that the primary amount of aragonitic skeletons in heterozoan carbonate sediments must be carefully assessed, as they are the main early diagenetic cement source. In fossil heterozoan carbonate rocks, aragonitic skeletons might be the cement source even when no relict structures like micritic envelops or biomolds are preserved. In general, the diagenetic evolution of heterozoan carbonate rocks is a good model for the diagenesis of "calcite-sea" time carbonate rocks. / Diagenetische Untersuchungen an Karbonatgesteinen beschränkten sich lange Zeit auf photozoische Karbonatvergesellschaftungen der tropischen Breiten. Die Ergebnisse dieser Untersuchungen wurden als modellhaft für den Diageneseverlauf vieler Karbonatgesteine angesehen. Erst in den letzten Jahren wurde die Bedeutung heterozoischer Karbonatvergesellschaften, die sich im Allgemeinen außerhalb der Tropen oder in tieferem Wasser bilden, erkannt. Diagenetische Untersuchungen an dieser Art von Karbonatgesteinen sind immer noch selten, deuten aber an, dass der Diageneseverlauf in diesen Karbonaten ein besseres Model für viele fossile Karbonatgesteine ("Calcit-Meer"-Karbonate) darstellt als das bisher benutzte photozoische Diagenesemodel. Ziel dieser Studie war die Bestimmung des Diageneseverlaufs in solch flachmarinen Karbonaten mit heterozoischer Biogenvergesellschaftung. Die Milieus, in denen die diagenetischen Veränderungen stattfanden, sollten bestimmt werden. Besonderes Augenmerk lag auf der Art und Menge von Veränderungen, die frühdiagenetisch, nahe dem Meeresboden, stattfanden. Dabei war vor allem der Anteil an konstruktiver Diagenese in Form von Zementation von Interesse.<br><br> Das Arbeitsgebiet wurde im zentralen Mittelmeerraum gewählt und befindet sich auf den Maltesischen Inseln und Sizilien. Hier wurden zwei Profile in Flachwassserkarbonaten oligo-miozänen Alters aufgenommen, die sich aus unterschiedlichen heterozoischen Biogenvergesellschaftungen zusammensetzen. Dieses Arbeitsgebiet ist für die Untersuchung konstruktiver frühdiagenetischer Prozesse besonders geeignet, da die Gesteinsabfolgen niemals tief versenkt wurden und versenkungsdiagenetisch bedingte Drucklösung und Zementation als Ursache für die Lithifizierung ausgeschlossen werden können. Trotzdem sind die untersuchten Karbonatgesteine gut verfestigt und bilden steile Kliffs, was auf Zementation/Verfestigung in einem anderen, flacheren Diagenesemilieu hinweist. Zur Bestimmung der Diageneseabfolge und der diagenetischen Milieus wurden detaillierte petrographische Untersuchungen im Durchlicht und mit Kathodolumineszenz an Dünnschliffen durchgeführt. Außerdem wurden die Verhältnisse der stabilen Isotope δ<sup>18</sup>O und δ<sup>13</sup>C am Gesamtgestein, an einzelnen Biogenen und an einzelnen Zementphasen bestimmt. Die Haupt- und Spurenelement Zusammensetzung (Ca, Mg, Fe, Mn und Sr) wurde an den einzelnen Zementphasen ermittelt.<br><br> Petrographisch lassen sich drei (Sizilien), beziehungsweise vier (Maltesische Inseln) Zementationsphasen, zwei Phasen von materialabhängiger und eine Phase von materialunabhängiger Lösung, sowie eine Phase von Neomorphismus und eine chemische Kompaktionsphase unterscheiden. Die Messungen der stabilen Isotopenverhältnisse an den einzelnen Zementphasen deuten auf Zementausfällung aus marinen und meteorischen Wässern sowie aus Fluiden marinen Ursprungs hin. Die Spurenelementanalyse lässt außerdem auf Zementausfällung unter reduzierenden Bedingungen schließen. Diese fand einerseits, im Falle der Maltesischen Inseln, in einem offenen System mit geringer Gesteins-Wasser-Interaktion, andererseits, im Falle von Sizilien, in einem geschlossenen System mit großer Gesteins-Wasser-Interaktion statt. Bei der Zementation in einem geschlossenen System konnte Aragonit als Zementquelle bestimmt werden, da seine charakteristische chemische Zusammensetzung im neu gebildeten Zement erhalten blieb.<br><br> Durch die Integration aller Ergebnisse konnten für die beiden Lokalitäten die Diageneseabfolgen und die diagenetischen Milieus sowie die Zementquelle(n) in diesen Milieus bestimmt werden. Die diagenetische Entwicklung begann im marinen Milieu mit der Ausfällung von fibrösem bis fibrös-blättrigem und epitaxialem Zement I. Diese Zemente wurden als Hoch Magnesium Calcit (HMC) direkt aus marinem Wasser ausgefällt. Die paläogeographisch flachsten Abschnitte des Profils auf den Maltesischen Inseln gelangten dann unter den Einfluss meteorischer Wässer. Dieser meteorische Einfluss führte zur Lösung von aragonitischen und HMC Schalen, was die Zementation mit Niedrig (Low) Magnesium Calcitischem (LMC) epitaxialem Zement II in diesem Profilabschnitt speiste. Im marinen Versenkungsmilieu fand anschließend der Hauptteil an Lösung, Zementation und Neomorphismus statt. Der erhöhte CO2-Gehalt in diesem Milieu, verursacht durch den Zerfall von organischem Material, führte zur Lösung von aragonitischen Schalen, was die Zementation mit LMC epitaxialem Zement II, blättrigem und blockigem Zement speiste. Die vorher ausgefällten HMC Zementphasen wurden entweder teilweise gelöst (epitaxialer Zement I) oder in LMC umgewandelt (fibrös/fibrös-blättriger und epitaxialer Zement I). Im versenkungsdiagenetischen Milieu fand anschließend geringe chemische Kompaktion statt, ohne aber die Ausfällung von größeren Mengen an Zement zu speisen. In einer letzten Phase gelangten die Gesteine durch Hebung wieder ins meteorische Milieu, was materialunabhängige Lösungserscheinungen verursachte. Diese Untersuchung zeigt, dass frühdiagenetische Prozesse, die an der Sediment-Wasser-Grenzfläche oder knapp darunter stattfinden, sehr wichtig für die mineralogische Stabilisierung von heterozoischen Karbonatabfolgen sind. Der Hauptteil der konstruktiven Diagenese in Form von Zementation findet in diesem Milieu statt, gespeist durch die Lösung von aragonitischen und, zu einem geringern Teil, HMC Schalen.<br><br> Die Ergebnisse dieser Studie implizieren, dass der ursprünglich vorhandene Anteil an aragonitischen Schalen in heterozoischen Karbonatsedimenten sehr sorgfältig bestimmt werden muss, da diese Schalen die wichtigste frühdiagenetische Zementquelle darstellen. In fossilen heterozoischen Karbonatgesteinen können aragonitische Schalen die wichtigste Zementquelle darstellen, auch wenn keine Reliktstrukturen wie mikritische Hüllen oder Biomolds erhalten geblieben sind. Im Allgemeinen stellt der Diageneseablauf in heterozoischen Karbonaten ein gutes Modell für die Diagenese von "Calcit-Meer"-Karbonatgesteinen dar.
116

Use of 3-dimensional dynamic modeling of CO₂ injection for comparison to regional static capacity assessments of Miocene sandstone reservoirs in the Texas State Waters, Gulf of Mexico

Wallace, Kerstan Josef 01 November 2013 (has links)
Geologic sequestration has been suggested as a viable method for greenhouse gas emission reduction. Regional studies of CO₂ storage capacity are used to estimate available storage, yet little work has been done to tie site specific results to regional estimates. In this study, a 9,258,880 acre (37469.4 km²) area of the coastal and offshore Texas Miocene interval is evaluated for CO₂ storage capacity using a static volumetric approach, which is essentially a discounted pore volume calculation. Capacity is calculated for the Miocene interval above overpressure depth and below depths where CO₂ is not supercritical. The goal of this study is to determine the effectiveness of such a regional capacity assessment, by performing refinement techniques that include simple analytical and complex reservoir injection simulations. Initial refinement of regional estimates is performed through net sand picking which is used instead of the gross thickness assumed in the standard regional calculation. The efficiency factor is recalculated to exclude net-to-gross considerations, and a net storage capacity estimate is calculated. Initial reservoir-scale refinement is performed by simulating injection into a seismically mapped saline reservoir, near San Luis Pass. The refinement uses a simplified analytical solution that solves for pressure and fluid front evolution through time (Jain and Bryant, 2011). Porosity, permeability, and irreducible water saturation are varied to generate model runs for 6,206 samples populated using data from the Atlas of Northern Gulf of Mexico Gas and Oil Reservoirs (Seni, 2006). As a final refinement step, a 3D dynamic model mesh is generated. Nine model cases are generated for homogeneous, statistically heterogeneous, and seismic-based heterogeneous meshes to observe the effect of various geologic parameters on injection capacity. We observe downward revisions (decreases) in total capacity estimation with increasingly refined geologic data and scale. Results show that estimates of storage capacity can decrease significantly (by as much as 88%) for the single geologic setting investigated. Though this decrease depends on the criteria used for capacity comparison and varies within a given region, it serves to illustrate the potential overestimation of regional capacity assessments compared to estimates that include additional geologic complexity at the reservoir scale. / text
117

The comparative paleoecology of late Miocene Eurasian hominoids

Scott, Robert Smith 28 August 2008 (has links)
Not available / text
118

Influence of reservoir character and architecture on hydrocarbon distribution and production in the miocene of Starfak and Tiger Shoal fields, offshore Louisiana

Rassi, Claudia 10 June 2011 (has links)
Not available / text
119

Stratigraphy and depositional history of the Pantano Formation (Oligocene-early Miocene), Pima County, Arizona

Balcer, Richard Allen January 1984 (has links)
No description available.
120

Sedimentology, stratigraphy and palaeogeography of Oligocene to Miocene rocks of North Canterbury-Marlborough

Irvine, Janelle Rose Mae January 2012 (has links)
The Cenozoic was a time of climatic, tectonic and eustatic change in the Southern Hemisphere. Cooling at the pole, glaciation and substantial sea ice formation occurred as latitudinal temperature gradients increased and tectonics altered Southern Hemisphere circulation patterns. During this same time frame, the tectonic regime of the New Zealand continental block transitioned from a passive margin to an active plate boundary, resulting in the reversal of a long-standing transgression and an influx of terrigenous sediment to marine basins. In this transition, depositional basins in the South Island became more localized; however, the influence of oceanographic and tectonic drivers is poorly understood on a local scale. Here we apply sedimentological, biostratigraphic and geochemical analyses to revise understanding of the effects of the changing climatic regime and active tectonics on the development of Oligocene and Miocene rocks in the Northern Canterbury Basin. The Late Oligocene to Middle Miocene sedimentary rocks of the northern Canterbury Basin record oceanographic and tectonic influences on basin formation, sediment supply and deposition. The Palaeocene to Late Eocene Amuri Formation in the basin are micrites and biogenic cherts recording deepwater, terrigenous-starved environments, and do not show any influence of active tectonics. The Early Oligocene development of ice on the Antarctic continent and the associated global sea level response is reflected in this basin as the Marshall Paraconformity, an eroded, glauconitized and phosphatised firm ground and hardground atop the Amuri. Sedimentation above this unconformity resumed in the Late Oligocene-Early Miocene with cleaner, deep-water, bathyal planktic foraminifera packstones and wackestones in eastern areas and Late Oligocene inner shelf volcaniclastic packstones in parts of the western basin. Post-unconformity sedimentation resumed earlier in western areas, as the currents responsible for scouring the sea floor moved progressively to the east. The development of tectonic uplift in terrestrial settings is first seen in the northwestern basin in Lower Miocene fine quartz-rich sandstones, and by the Middle Miocene, bathyal sandstones and quartz-rich wackestones appear in the basin, replacing earlier, more pure carbonates. The uplift caused shallowing to the west, in the form of shelf progradation due to sediment influx. This shallowing is not observed to the east; instead, the palaeoenvironments show a deepening as a result of sea level rise.

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