The South China Sea is a region of significant importance in terms of the records of SE Asian tectonics, including Tibetan Plateau uplift, and the onset and evolution of the East Asian monsoon. The Mekong River has been a dominant sediment source since at least late Miocene time and has headwaters on the eastern Tibetan Plateau. Understanding the Pliocene to Recent stratigraphy of the paleo-Mekong Delta and associated shelf-edge deposits aids in understanding changes in accommodation, sea level, and sediment supply. This record might then be useful in interpreting the longterm history of basin evolution in the Nam Con Son Basin. Nine sequence boundaries and associated sequences are recognized along the late Miocene to latest Pleistocene shelf in the East Nam Con Son Basin. Age constraints were assigned to key stratigraphic horizons by correlating sequence boundaries with published sea level curves. Accommodation in the study area is controlled by shelf -edge compaction, rift-related thermal subsidence, non-rift-related anomalous subsidence,Two primary sources supplied sediment to the southwestern South China Sea during Pliocene to Recent time and likely include the paleo-Mekong Delta and a fluviodeltaic system originating from the Sunda Shelf, such as the Molengraaff River. Changes in thickness, area, and location of Pliocene to Recent shelf-edge delta deposits reflect changes in accommodation and sediment supply over time, as well as progradation of the shelf edge during Pliocene to Recent time and avulsion of the shelf edge delta. Anomalous subsidence of LGM shelf edge deposits is estimated at approximately 40-50 m deeper than expected. The current depth of the LGM deltaic wedge may indicate renewed rapid tectonic subsidence during the last 18,000 yrs, possible compaction effects or a combination of these. eustatic change, and shelf edge faulting.

Eight 4th-order (~400 k.y.) disconformity-bounded mixed carbonate-siliciclastic sequences were deposited in the tectonically-active, tide-dominated Illinois basin during the Late Mississippian greenhouse to icehouse transition. Detailed, lithologic cross-sections were constructed through the Chesterian Ste. Genevieve through Glen Dean interval which show an upward change in character from carbonate-dominated sequences bounded by caliche and breccia paleosols to mixed-carbonate siliciclastic sequences bounded by red, slickensided mudrock paleosols and incised valleys. The 4th-order sequences are composed of 5th-order parasequences that can be correlated basin-wide. Parasequences in the basal, dominantly carbonate sequences are composed of patchy ooid grainstone tidal ridge reservoir facies which interfinger with skeletal limestone and are capped by laterally extensive muddy carbonate units. Parasequences in the overlying mixed carbonate siliciclastic interval commonly have basal quartz sandstone valley fill and tidal sand ridge reservoir facies overlain by skeletal limestone and shale-dominated siliciclastics. The sequences can be bundled into sequence pairs and composite sequences. Composite sequences are composed of 4 sequences and are bounded by better developed disconformities that commonly coincide with biostratigraphic zone boundaries. High energy reservoir facies are widespread in transgressive sequence tracts and late highstand sequence tract (where present) and confined to updip areas in the early highstand sequence tracts. Increasing amplitude 4th-order glacio-eustasy produced the sequences and caused the upward increase in incised valleys and deeper water carbonate deposition. Parasequences were produced by 5th-order glacio-eustatic sea-level fluctuations (20-100 k.y.). Sequence pairs and composite sequences were produced by 3rd-order sea-level fluctuations possibly in combination with local tectonics. Spatial and temporal variations in differential subsidence between the eastern and western shelves and the more rapidly subsiding basin interior caused variations in onlap/offlap geometries of sequences and parasequences. Increasingly wetter wet-dry seasonality caused an upward increase in siliciclastic influx and concurrent decrease in ooid deposition. The increasing-amplitude eustasy and progressively more humid climate were caused by the onset of continental glaciation on Gondwana. / Ph. D.

Se aborda el estudio del karst litoral en la mitad oriental de Mallorca, acometiéndolo desde una perspectiva pluridisciplinar que se ocupa tanto de diferentes aspectos de su modelado epigeo como, sobre todo, de las peculiaridades del rico endokarst existente en el área estudiada. Con respecto a la morfogénesis exokárstica del área, son tratados a lo largo de la presente memoria los siguientes aspectos: el lapiaz litoral, la presencia de calas y sus barrancos asociados y, finalmente, la influencia del paleokarst fini-Mioceno en la morfología de la línea de costa.Los fenómenos subterráneos de Mallorca son estudiados desde un punto de vista genético, describiendo al mismo tiempo las características diferenciales del endokarst en las dos regiones naturales implicadas: las Serres de Llevant y el Migjorn. La atención ha sido focalizada en las numerosas cavidades de la última región kárstica mencionada, la cual destaca por la riqueza y las peculiaridades morfogénicas de sus cavidades hipogeas naturales.Las investigaciones se han centrado en el análisis de las interferencias entre el modelado endokárstico y la dinámica litoral, aportándose datos novedosos sobre un abanico muy variado de materias. Los temas que son abordados abarcan desde aspectos geoquímicos y espeleogenéticos en acuíferos carbonatados litorales, hasta abundantes ejemplos de cuevas mixtas de génesis kárstico-marina. Se presta una particular atención a los rellenos alóctonos de las cavernas costeras, que incluyen tanto materiales detríticos (calcarenitas marinas y/o eólicas) como restos paleontológicos de vertebrados endémicos. Los rellenos autóctonos presentes en las cavidades (espeleotemas, en general) ofrecen especial interés, debido a las grandes posibilidades geocronológicas derivadas de su datación radiométrica. Las interferencias analizadas entre karst y litoral -las cuales han estado controladas en todo momento por la posición del nivel marino- permiten una reconstrucción detallada de la evolución del endokarst a lo largo del Plio-Cuaternario.El mayor interés de los trabajos realizados radica en las valiosas informaciones crono-estratigráficas obtenidas en relación con las oscilaciones pleistocénicas del nivel marino. En concreto, el estudio de los espeleotemas freáticos ha mostrado que éstos constituyen un excelente registro de la historia del nivel del Mediterráneo, durante el Pleistoceno Medio y Superior y el Holoceno. Conviene resaltar los novedosos datos aportados por aquellos espeleotemas freáticos que han sido recolectados por debajo de la presente cota ±0 metros; estas cristalizaciones nos documentan, con gran detalle, las pulsaciones regresivas experimentadas por el nivel marino, las cuales eran bastante desconocidas hasta el momento. Este tipo de depósitos secundarios propios de las cuevas kársticas litorales han sido estudiados mediante diversas técnicas (dataciones radiométricas Th/U, mediciones de ESR, microscopía óptica y electrónica, análisis de isótopos estables...) con vistas a la obtención de datos cronológicos, paleoclimáticos, mineralógicos y cristalográficos precisos.De particular relevancia son las curvas eustáticas propuestas para los últimos 300 ka, en el Mediterráneo occidental, las cuales presentan un detalle fuera de lo común en el rango de edad comprendido entre 150 y 60 ka BP. Centrando nuestra atención en el último evento interglacial (estadio isotópico 5) es posible distinguir cuatro picos transgresivos, situados entre 130 y 80 ka BP, separados por tres pulsaciones frías que produjeron descensos bruscos del nivel del Mediterráneo, de más de 20 metros de amplitud. Las tasas deducidas de ascenso y/o descenso del nivel marino son del orden de 4 metros/ka, poniendo de manifiesto las importantes crisis climáticas acontecidas durante el Pleistoceno Superior. / This thesis deals with the study of littoral karst in the eastern half of Mallorca island, by means of a cross-disciplinary approach that takes into account both the different aspects of its surface modelling (littoral karren, coves and associated gullies, paleokarst features) and the singularities of the rich endokarst existing in this area. The subterranean phenomena in the island are studied from a genetical point of view, describing at the same time the differential characteristics of endokarst in the two natural regions involved: Serres de Llevant and, particularly, the Migjorn area. Our investigations have been specially addressed to analyze the interferences between endokarstic modelling and littoral dynamics. The topics that are discussed cover from geochemical and speleogenetical aspects in coastal carbonate aquifers, to abundant examples of mixed cavities which are karstic-marine in origin. Particular attention is paid to the alochtonous infillings existing in coastal caves, that include both detritic materials (marine and/or eolian calcarenites) and paleontological remains of endemic vertebrates.Specifically, the study of phreatic speleothems has shown that these deposits are an excellent record of Mediterranean sea-level history, during Middle and Upper Pleistocene and Holocene. Abundant data supplied by phreatic speleothems collected below the present-day ±0 metres must be thrown into relief; these crystallizations document us -with a great detail- the regressive pulsations experienced by the sea-level. This deposits has been studied by means of several techniques (radiometric Th/U datings, ESR measurements, optical and electronic microscopy, X-ray diffraction, stable isotope analysis.) in order to obtain precise chronological, paleoclimatological, mineralogical and crystallographical data.Eustatic curves proposed for the last 300 ka in the western Mediterranean are significant. Centering our attention in the last interglacial event (isotopical stage 5) four transgressive peaks are distinguished, situated between 130 and 80 ka BP, separated by three cold pulsations that produced abrupt Mediterranean sea lowerings, about 20 metres in amplitude. The deduced mean rates of sea-level rise and/or lowering are in the order of 4 metres/ka.

La stratigraphie synrift du bloc de faille est divisée en trois groupes stratigraphiques, représentant une épaisseur de 1624 m. Le Groupe inférieur est composé de sédiments fluvio-lacustres, le Groupe moyen comporte les Gilbert-deltas géants et leurs faciès fins associés, le Groupe supérieur est formé de Gilbert-deltas récents à actuels ainsi que de formations superficielles. La discordance basale de l’Unité du prérift présente une paléotopographie. La phase d'extension précoce (Groupe inférieur) est caractérisée par une très faible subsidence assurée par l’activité précoce de la faille de Pirgaki et des failles mineures. La transition avec la phase d'extension principale (Groupe moyen) est marquée par un approfondissement du bassin ainsi que par une augmentation du taux de subsidence. La phase d'abandon et de soulèvement du bloc (Groupe supérieur) est caractérisée par des évènements de creusement-comblement. Le Gilbert-delta géant de Kerinitis se serait déposé dans la période Pléistocène inférieur-Pléistocène moyen, en milieu marin. L’étude de la sédimentologie de faciès a permis de mettre en évidence quatre associations de faciès : topset, foreset, bottomset, prodelta. L’architecture stratigraphique est composée de onze Unités Stratigraphiques (SU) séparées par onze Surfaces Stratigraphiques (KSS). Dans un contexte de création continue d’espace d’accommodation, les SU se déposent pendant les maxima et les périodes de chute du niveau marin. Les KSS se mettent en place pendant des périodes d’augmentation du niveau marin. Les quatres étapes de construction du Gilbert-delta de Kerinitis ont enregistré le début, le maximum et l’arrêt de l’activité du système de failles / Synrift stratigraphy on a normal fault block is subdivided into three groups. The Lower group is composed of continental sediments (fluvio-lacustrine). The Middle group contains the giant Gilbert-type fan deltas and their associated fine-grained facies. The Upper group is composed of the recent to present day Gilbert-deltas and superficial deposits. The Lower group is marked by a low subsidence rate on the young Pirgaki fault and some secondary faults. A marked increase in subsidence rate mark the transition to the Middle group. It is proposed that the increase in subsidence rate is due to the connexion between two major faults. The Upper group was deposited during uplift of the study area in the footwall of the Helike fault. It is suggested that the giant Kerinitis Gilbert-type fan delta was deposited during the Early to early Middle Pleistocene, under marine conditions. Facies characterizing a range of depositional processes are assigned to four facies associations: topset, foreset, bottomset and prodelta. The stratal architecture is composed of eleven Key Stratal Surfaces (KSS) separating eleven Stratal Units (SU). In this subsidence-dominated system, each SU records a highstand period and principally a period of decreasing eustatic sea level. The KSS, record transgressions that took place in periods of rapid sea level rise. The eustatic signal, controlling the deposition of the SU is of higher frequency than the tectonic signal, which controlled four stages of delta growth. The four delta growth stages are linked with the initiation, maximum growth and the abrupt death of the Pirgaki-Kerinitis fault system

The upper Tanglewood Member is the final member of the Lexington Limestone and is well-known for its soft-sediment deformation. This study has confirmed the carbonate-shoal-complex origin of the unit, and detailed study shows that its development took place during five small-scale, sequence-like, fining-upward cycles related to eustasy and tectonics. Four lithofacies are represented in the unit. Facies analysis of each cycle shows that the thickest and coarsest part of each cycle corresponds to previously uplifted basement-fault blocks; the occurrence of thick, coarse facies on the same fault blocks suggests that the blocks continued to experience uplift due to Taconian far-field forces generated on the eastern margin of Laurentia. The upper Tanglewood Member includes six deformed horizons that can be traced into equivalent parts of the Clays Ferry and Point Pleasant formations. Concurrence of four lines of evidence, suggested by Ettensohn et al. (2002d) for interpretation of seismites, indicates that the widespread horizons of deformation are seismogenic in origin. Reactivation of basement structures due to Taconian far-field forces probably induced seismicity on the intra-platform carbonate complex so as to produce soft-sediment deformation. Petrographic investigation indicates that most of the cements in the upper Tanglewood limestones appear to be late diagenetic, fresh-water phreatic cements. Comparing the petrography of deformed and undeformed portions of the same horizon showed no significant differences in terms of cementation, indicating that cementation occurred primarily after deformation. The primary impact of deformation on the microstructure of the unit was the randomization of grain fabric and the increased presence of broken intraclasts.

No description available.