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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.
291

40Ar/39Ar Dating of the Late Cretaceous

Gaylor, Jonathan 11 July 2013 (has links) (PDF)
As part of the wider European GTS Next project, I propose new constraints on the ages of the Late Cretaceous, derived from a multitude of geochronological techniques, and successful stratigraphic interpretations from Canada and Japan. In the Western Canada Sedimentary Basin, we propose a new constraint on the age of the K/Pg boundary in the Red Deer River section (Alberta, Canada). We were able to cyclostratigraphically tune sediments in a non-marine, fluvial environment utilising high-resolution proxy records suggesting a 11-12 precession related cyclicity. Assuming the 40Ar/39Ar method is inter-calibrated with the cyclostratigraphy, the apparent age for C29r suggests that the K/Pg boundary falls between eccentricity maxima and minima, yielding an age of the C29r between 65.89 ± 0.08 and 66.30 ± 0.08 Ma. Assuming that the bundle containing the coal horizon represents a precession cycle, the K/Pg boundary is within the analytical uncertainty of the youngest zircon population achieving a revised age for the K/Pg boundary as 65.75 ± 0.06 Ma. The Campanian - Maastrichtian boundary is preserved in the sedimentary succession of the Horseshoe Canyon Formation and has been placed ~8 m below Coal nr. 10. Cyclostratigraphic studies show that the formation of these depositional sequences (alternations) of all scales are influenced directly by sea-level changes due to precession but more dominated by eccentricity cycles proved in the cyclostratigraphic framework and is mainly controlled by sand horizons, which have been related by autocyclicity in a dynamic sedimentary setting. Our work shows that the Campanian - Maastrichtian boundary in the Western Canada Sedimentary Basin coincides with ~2.5 eccentricity cycles above the youngest zircon age population at the bottom of the section and ~4.9 Myr before the Cretaceous - Palaeogene boundary (K/Pg), and thus corresponds to an absolute age of 70.65 ± 0.09 Ma producing an ~1.4 Myr younger age than recent published ages. Finally, using advances with terrestrial carbon isotope and planktonic foraminifera records within central Hokkaido, Northwest Pacific, sections from the Cretaceous Yezo group were correlated to that of European and North American counterparts. Datable ash layers throughout the Kotanbetsu and Shumarinai section were analysed using both 40Ar/39Ar and U-Pb methods. We successfully dated two ash tuff layers falling either side of the Turonian - Coniacian boundary, yielding an age range for the boundary between 89.31 ± 0.11 Ma and 89.57 ± 0.11 Ma or a boundary age of 89.44 ± 0.24 Ma. Combining these U-Pb ages with recent published ages we are able to reduce the age limit once more and propose an age for the Turonian - Coniacian boundary as 89.62 ± 0.04 Ma.
292

Stratigraphy and Sedimentology of the Bisbee Group in the Whetstone Mountains, Pima and Cochise Counties, Southeastern Arizona

Archibald, Lawrence Eben January 1982 (has links)
The Aptian-Santonian(?) Bisbee Group in the Whetstone Mountains comprises 2375 m of clastic sedimentary rocks and limestones. The basal Glance Conglomerate unconformably overlies the Pennsylvanian-Permian Naco Group. It consists of limestone conglomerates which were deposited in proximal alluvial fan environments. The superadjacent Willow Canyon Formation contains finer grained rocks which were deposited in the distal portions of alluvial fans. The lacustrine limestones in the Apache Canyon Formation interfinger with and overlie these alluvial fan facies. The overlying Shellenberger Canyon Formation is composed mostly of terrigenous rocks derived from westerly terranes. This formation contains thick sequences of fluvio-deltaic facies as well as a thin interval of estuarine deposits which mark a northwestern extension of the marine transgression in the Bisbee -Chihuahua Embayment. The youngest formation (Upper Cretaceous?) in the Bisbee Group, the Turney Ranch Formation, consists of interbedded sandstones and marls which were deposited by fluvial and marine(?) processes.
293

Analyse spatiale en écologie : développements méthodologiques

Blanchet, Guillaume January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
294

Impacto da geometria urbana e da legisla??o de uso e ocupa??o do solo no microclima de c?nions urbanos / Impact of urban geometry and land use and occupation legislation on the urban street canyon microclimate

G?al, L?gia Parreira Muniz 07 February 2017 (has links)
Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2017-03-23T13:25:54Z No. of bitstreams: 1 L?GIA PARREIRA MUNIZ G?AL.pdf: 5270981 bytes, checksum: 96b0646b01e474b8307ad43548bce884 (MD5) / Made available in DSpace on 2017-03-23T13:25:54Z (GMT). No. of bitstreams: 1 L?GIA PARREIRA MUNIZ G?AL.pdf: 5270981 bytes, checksum: 96b0646b01e474b8307ad43548bce884 (MD5) Previous issue date: 2017-02-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The formation of cities has shaped the urban street canyons, defined by the street and the buildings that extend along its sides. The land use and occupation are agents that modify the climate, however this is rarely considered in the urban planning of cities. Aspects like height and width ratio, sky view factor, albedo of the surface materials and the presence of vegetation in the canyon have been widely studied in association with the local climatic behavior. Understanding the influence of these parameters on the microclimate of urban street canyons is indispensable to achieve sustainability between urban occupation and thermal comfort. Therefore, the objective of this thesis is to investigate the interference of land use and occupation legislation and urban geometry in the microclimate of an urban street canyon in Campinas/ SP. The methodology used involves the climatic monitoring of the study area in Cambu? (neighborhood), the urban and climatic characterization of three points with different land use and occupation configurations and the selection of the canyon used for simulation scenarios. These scenarios involve two main aspects: the local urban legislation and the canyon geometry (height width ratio - H/W and length height ratio - L/H). The simulations were performed using the microclimatic simulation model ENVI-met 4.0 preview. Scenarios in agreement with the local legislation showed that, in winter, only 25% of day perceived discomfort to heat. In the other hand, in the summer period, a comfortable feeling was perceived in only 25% of the day, providing discomfort to the heat for the rest of the day. In the scenarios varying the urban geometry it was verified that, for scenarios with the same H/W ratio, the PET (Physiological Equivalent Temperature) value did not suffer significant alteration. However, when the L/H ratio was fixed and the H/W ratio varied, we noted that deeper canyons led to lower PET peaks. The scenario A, for example, with a lower H/W ratio (0.5) and lower L/H (3) ratio, showed PET peak 7.3?C higher than the scenario I with a higher H/W ratio (2.0) and higher L/H ratio (7). The results showed that there is a strong correlation between the H/W ratio and the thermal comfort of the urban street canyons: deeper canyons yield lower PET values. Moreover, it was verified that the climatic conditions of the canyon are independent of their length (L/H ratio) and that canyons oriented in the prevailing wind direction (SE) reached lower PET values. Finally, it was evidenced that shading and wind speed are fundamental in determining comfort in urban street canyons. / A forma??o das cidades tem configurado os chamados c?nions urbanos, definidos pela interface composta pela via e as edifica??es que se estendem em suas laterais. O uso e ocupa??o do solo s?o agentes modificadores do clima e, no entanto, este ?ltimo tem sido pouco levado em considera??o no planejamento urbano dos munic?pios. Entretanto, aspectos como a rela??o altura e largura do c?nion, o fator de vis?o do c?u, o albedo dos materiais de superf?cie e a presen?a de vegeta??o no c?nion t?m sido amplamente estudados em associa??o com o comportamento clim?tico local. Neste contexto, entender a influ?ncia desses par?metros no microclima de c?nions urbanos ? de fundamental import?ncia para se atingir a sustentabilidade entre ocupa??o urbana e conforto t?rmico. Em vista disso, o objetivo deste trabalho ? analisar a interfer?ncia da legisla??o de uso e ocupa??o do solo e da geometria urbana no microclima de um c?nion urbano da cidade de Campinas/ SP. Para isso foi utilizada uma metodologia que envolve o monitoramento clim?tico do recorte de estudo selecionado no bairro Cambu?, a caracteriza??o urbana e clim?tica de tr?s pontos com diferentes configura??es de uso e ocupa??o do solo e a escolha do c?nion de interesse para simula??o de cen?rios que envolvem dois aspectos principais: a legisla??o urban?stica local e a geometria do c?nion (rela??o altura largura ? H/W e rela??o comprimento altura ? L/H). As simula??es foram realizadas com o modelo de simula??o microclim?tica ENVI-met 4.0 preview. Nos cen?rios respeitando a legisla??o o desconforto para o calor foi observado em apenas 25% do dia no per?odo de inverno; j? no per?odo de ver?o a sensa??o de conforto foi obtida em apenas 25% do dia, sendo observado desconforto para o calor no restante do dia. Nos cen?rios variando a geometria urbana verificou-se que, para cen?rios de mesma rela??o H/W, o valor do PET (Physiological Equivalent Temperature) n?o sofreu altera??o significativa. J? quando se fixou a rela??o L/H e variou-se a rela??o H/W, ficou claro que c?nions mais profundos levaram a picos de PET mais baixos. O cen?rio A, por exemplo, de menor rela??o H/W (0,5) e menor rela??o L/H (3), apresentou pico de PET 7,3?C mais alto que o cen?rio I, de maior rela??o H/W (2,0) e maior rela??o L/H (7). Os resultados mostraram que existe forte correla??o entre a rela??o H/W e o conforto t?rmico dos c?nions urbanos: quanto mais profundo, menores os valores de pico do ?ndice PET. Al?m disso, verificou-se que c?nions orientados na dire??o predominante dos ventos alcan?aram valores de PET mais baixos. Por fim, foi evidenciado que o sombreamento da superf?cie e a intensidade da velocidade do vento s?o fundamentais na determina??o do conforto t?rmico em c?nions urbanos.
295

Karsts côtiers et canyons sous-marins de la marge provençale au Cénozoïque : Contrôle géodynamique, eustatique, hydrologique et structural.

Tassy, Aurélie 20 December 2012 (has links) (PDF)
La marge provençale, localisée au Nord-Ouest de la Méditerranée, constitue avec la marge du Golfe du Lion et la marge ligure, la bordure septentrionale du bassin Liguro-Provençal. L'objectif principal de ce travail est la reconstitution de l'histoire géodynamique, structurale et géomorphologique de la marge depuis le Tertiaire. Sa structure est principalement le résultat des phases tectoniques anté-miocènes. Sur la marge provençale la transition entre le plateau continental et le bassin est étroite et caractérisée par des pentes abruptes affectées par des phénomènes d'instabilité gravitaire dans l'axe du canyon sous-marin de Cassidaigne. A terre, la marge provençale est caractérisée par une compression pyrénéenne, des fossés oligocènes, et une sédimentation mésozoïque à cénozoïque essentiellement carbonatée propice à l'infiltration des eaux en profondeur. L'origine des cours d'eau de la région est essentiellement karstique, et les sources côtières de Port-Miou et Bestouan constituent des réseaux karstiques noyés développés sur plusieurs kilomètres dans le calcaire urgonien, au droit du canyon de Cassidaigne. Les travaux antérieurs suggèrent (1) que l'absence de réseau fluviatile de surface en amont et la forme de reculée karstique de la tête du canyon de Cassidaigne sont le résultat d'une connexion karstique entre les sources côtières et le canyon, (2) que la marge provençale n'ait pas été affectée par l'érosion messinienne et la transgression pliocène, (3) que certains dépôts transgressifs marins miocènes sont situés à des altitudes anormalement élevées par rapport à leurs niveaux de dépôt théorique. Ces faits témoignent d'une évolution géodynamique récente, mais encore peu documentée dans la région. Cette thèse applique une approche intégrative géologique, géomorphologique et hydrogéologique afin de caractériser l'évolution et le fonctionnement du karst côtier et des canyons sous-marins. Les méthodes utilisées sont principalement : (1) l'acquisition et l'interprétation géologique des données de sismique marine (2740 km) et de 74 carottages, (2) l'analyse tectonique et/ou eustatique de marqueurs géomorphologiques de paléo-niveaux de base, (3) le suivi hydrogéologique et l'imagerie électrique des aquifères karstiques côtiers de Cassis, (4) la modélisation géologique 3D de surfaces terre-mer dans le géomodeleur gOcad, et (5) la restauration de l'évolution de la paléotopographie depuis le Tortonien. Les résultats de l'interprétation sismique sont (1) une carte détaillée de la surface d'érosion messinienne du plateau continental mettant en évidence la présence d'un canyon messinien de direction E-W, baptisé " canyon de Bandol ", (2) une carte géologique inédite du plateau continental et des coupes géologiques terre-mer qui s'étendent de l'extrémité ouest de la Nerthe au Cap Sicié. L'évolution sédimentaire du canyon de Cassidaigne durant la période messino-pliocène est génétiquement liée à celle du canyon de Bandol. Deux modèles stratigraphiques ont été proposés pour expliquer l'histoire du remplissage sédimentaire de ces deux canyons. L'altitude et la bathymétrie des transgressions marines miocènes reconnues à terre et en mer ont permis de définir une carte de déformation de la topographie de la marge à grande longueur d'onde depuis le Burdigalien. Les restaurations en 3D mettent en évidence la bascule de la marge et le rajeunissement des reliefs pyrénéo-provençaux à terre du NE vers le SW. Un schéma d'évolution du réseau hydrogéologique de la marge, cohérent avec le modèle restauré est présenté. Un karst profond, connecté à un réseau inférieur de la grotte de Port-Miou, émerge pendant le Messinien dans la partie amont du canyon de Cassidaigne. Il est confiné par des structures géologiques défavorables à la karstification situées juste au sud. Des cours d'eau mineurs, provenant du Massif des Calanques ou du secteur vallonné du bassin de Riou façonnent la partie ouest de la tête du canyon de Cassidaigne. Le canyon de Bandol, de direction ouest-est, est principalement incisé par les cours de la Reppe-Destel, du Gapeau.
296

Biogeoquímica dels fluxos de partícules en canyons submarins de la Mediterrània nord-occidental: Els efectes de les cascades d'aigües denses de plataforma

Pasqual Mas, Catalina 27 May 2011 (has links)
L‘estudi dels fluxos de partícules té per objectiu quantificar el carboni que s‘exporta cap a l‘oceà profund, el qual controla el segrest de CO2 atmosfèric a llarg termini. Els marges continentals juguen un paper important en aquest cicle oceànic, ja que són una bomba de carboni i nutrients entre l‘ecosistema terrestre i l'interior de l'oceà. En aquest treball s‘ha investigat la transferència de material al llarg del marge continental del golf de Lleó. Aquest mar-ge, situat al nord-oest de la Mediterrània occidental, està format per una ampla plataforma que s‘estén fins a un talús solcat per un gran nombre de canyons submarins. La major part dels sediments que entren al golf de Lleó provinents dels rius o resuspesos de la plataforma, circulen cap al sud-oest empesos per la circulació ciclònica de la massa d‘aigua i són deflectits majoritàriament a través dels canyons submarins més occidentals (canyons de Cap de Creus i Lacaze-Duthiers) cap a l‘interior de la conca. Aquest procés té lloc sobretot durant les tempestes marines d‘hivern i durant els esdeveniments de cascades submarines. L‘objectiu d‘aquest treball és estudiar la variabilitat temporal i espacial dels fluxos de partícules així com l‘origen i el grau de degradació de la matèria orgànica dins els canyons de Lacaze-Duthiers i Cap de Creus i al talús de la zona més meridional del golf de Lleó. La mesura directa dels fluxos ha estat possible gràcies al fondeig de línies instrumentades dotades amb trampes de sediments i correntímetres al llarg de tres transsectes. Les dades obtingudes indiquen que hi ha una ràpida resposta del sistema als forçaments físics. Així, es detecta una forta relació entre els condicionants atmosfèrics (que desencadenen la cascada d‘aigua densa, les onades i les aportacions fluvials i atmosfèriques), la producció primària, i la quantitat i qualitat del material que sedimenta al llarg del marge continental. La cascada d‘aigua densa de plataforma continental (DSWC) enregistrada durant els mesos de gener, febrer i març de 2006, esdevé el principal factor que controla la sedimentació de partícules a la zona estudiada. Les aigües de la cascada que s‘enfonsen canyó avall, escapen de la constricció que suposa el canyó a la zona baixa, continuen el seu camí paral•leles a les isòbates, i afecten el talús superior. Aquest fet denota la capacitat de la cascada per conduir el material erosionat de la plataforma continental cap als canyons i dispersar-lo cap al talús sud. Per tant, la DSWC pot esdevenir un factor important en la sedimentació en els canyons, el talús i el fons de la conca de la Mediterrània nord-occidental. Independentment dels esdeveniments de DSWC, les parts altes dels canyons estan afectades per un continu intercanvi de material amb la plataforma. Per contra, la zona d‘oceà obert (les zones baixes dels canyons i el talús) rep l‘arribada de material de la plataforma només com a conseqüència directa de la DSWC, mentre que durant la resta de l‘any hi imperen condicions de calma amb el predomini de fluxos pelàgics. La DSWC va ser el principal factor que controlà l‘arriba de matèria orgànica tant marina com terrestre al sistema, amb la transferència de grans quantitats de matèria orgànica d‘orígen terrestre durant el gener de 2006 (provinent de dipòsits de la plataforma), i matèria orgànica d‘orígen marí durant març i abril de 2006 (provinent del bloom fitoplanctònic). Per tant, la dispersió del material orgànic marí i terrestre va ser controlat per les condicions energètiques que afavoriren la resuspensió i el transport mar endins del material de la plataforma. La matèria orgànica es degradà no només durant el seu transport al llarg dels canyons, sinó també a través de la columna d'aigua, abans d'arribar a la zona de convergència dels canyons i al talús obert. Tot i que les aportacions laterals de matèria orgànica de la plataforma adjacent predominaren durant els esdeveniments de DSWC, les aportacions provinents d‘esdeveniments esporàdics de producció primària i la constant advecció de material marí varen ser evidents durant períodes de condicions energètiques i fluxos baixos. / Particle flux studies aim at quantifying the amount of carbon and other components that are exported into deep ocean, which controls the long term atmospheric CO2 sequestration. Continental margins play an important role in this oceanic cycle as they pump carbon and nutrients from aerial ecosystems to the interior of the ocean. This work analyzes the transference of material along the continental margin of the Gulf of Lion. This margin, located in the northwestern Mediterranean, is a broad platform that extends to a slope cut by a large number of submarine canyons. Most of the sediments entering the system by rivers or resuspension in the shelf travel to the southwest due to the cyclonic circulation where are deflected mainly through the Cap de Creus and Lacaze-Duthiers submarine canyons to the deep basin. This process occurs mainly during winter sea storms and dense shelf water cascading events. The pourpose of this study is to analyze the temporal and spatial variability of particle fluxes and the source and degree of degradation of the organic matter within the Lacaze-Duthiers and Cap de Creus submarine canyons and the southern slope, in the Gulf of Lion. Direct flux measurements has been carried out by the deployment of 9 in-strumented lines equipped with sediment traps and currentmeters along three transects along the axis of the Lacaze-Duthiers and Cap de Creus canyons and the southern slope. Data indicate that there is a quick response of the system to physical forcings, with a close relation among atmospheric drivers (that trigger the dense water cascade, waving and river and atmospheric inputs), primary production, and the quantity and quality of settling material across the continental margin. The severe dense shelf water cascading (DSWC) event observed during January-March 2006 was the main factor controlling the sedimentation in the studied area. The dense waters escaped the lower canyon where it widens to flow along the isobaths and impacted the southern open slope. This denotes the capacity of such events to funnel and spread southwardly shelf eroded material through canyons. Therefore DSWC may become an important factor for the sedimentation in the middle and lower slope of the northwestern Mediterranean. Upper and middle canyon was primarily affected by continuous cross-slope exchanges with the shelf. The deeper ones were less affected by horizontal transferences and shelf material arrived only associated to the DSWC event, whereas outside the DSWC period pelagic fluxes become a significant part of the total mass flux. The severe DSWC event controlled also the arrival of organic matter to the sea floor, with the transfer of large quantities of land derived organic matter in January 2006 (from shelf deposits), and marine derived organic matter in March-April 2006 (from the concomitant spring bloom). Therefore, the timing of the dispersion of both terrigenous and marine derived organic material was controlled by the energetic conditions that enhance the resuspension and offshore transport of material in the shelf. In addition, this organic matter was degraded not only during its transport along the canyons but also in the water column before reaching the canyon mouth and open slope, as indicated by trends in amino acid and chloropigment concentrations and compositions. Furthermore, although lateral input of organic matter from the adjacent shelf predominated during DSWC events, sporadic primary production events and constant advection of land derived material were also evident during low energy and low flux periods.
297

Chemical and Biological Problems in the Grand Canyon

05 May 1973 (has links)
A survey of chemical and bacteriological water quality in the Grand Canyon was undertaken to assess possible health hazards to river travelers. The water quality of the main Colorado River channel is relatively stable with only slight increases in ionic concentration and bacteriological load with respect to distance from Lee Ferry and time over the summer season. The tributary streams show extreme temporal variability in chemical water quality and bacteriological contamination as a result of the summer rain and flood patterns in the tributary canyons. These side streams pose a definite health hazard to unwary river travelers. More extensive sampling is called for to determine the sources of this contamination and to protect the quality of the Grand Canyon experience.
298

Analyse spatiale en écologie : développements méthodologiques

Blanchet, Guillaume January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
299

In the aftermath of migration assessing the social consequences of late 13th and 14th century population movements into southeastern Arizona /

Neuzil, Anna A. January 2005 (has links) (PDF)
Thesis (Ph. D.)--University of Arizona, 2005. / Includes bibliographical references (leaves 537-572).
300

Ichnology, depositional dynamics and sequence stratigraphy of the Plio-Pleistocene Orinoco Delta: Mayaro and Morne L’Enfer formations, southern Trinidad

2015 November 1900 (has links)
During the Late Pliocene and early Pleistocene, when the paleo-Orinoco delta system transited over the Amacuro Shelf and reached the paleo-shelf-break along the southeastern shoreline of Trinidad. At this time onwards, the shelf-edge delta clinoforms developed further eastward. These deltaic clastic wedges serve as the unique analog in the geological record for an accommodation-driven inner-shelf and shelf-edge delta, developed at an oblique foreland tectonic setting situated at a tropical-equatorial paleogeographic setting. These deposits were influenced by strong Atlantic longshore current, tropical storms, and phytodetrital pulses, and with an exceptionally high sediment accumulation rates. These four aspects make the clastic wedges unique candidates for sedimentological, ichnological, and stratigraphic investigation. The primary objectives of this thesis are to: (a) collect, analyze, and integrate outcrop data on lithofacies, trace fossils, and discontinuity surfaces into a comprehensive depositional and ichnological model for the first growth-fault-guided shelf-marginal pulse of the paleo-Orinoco delta, as recorded in the Mayaro Formation outcrops in southeast Trinidad; and (b) deduce the dominant sedimentary processes during the across shelf transit and their impacts on the benthic infauna as preserved in the Morne L’Enfer Formation outcrops of southwest Trinidad, which are possibly slightly older than the Mayaro Formation. The basal interval of the Morne L’Enfer Formation has specifically been investigated for this purpose, where the deltaic clastic wedges are preserved directly above shelf deposits. The entire Mayaro Formation megasequence is categorized into deposits belonging to twelve different subenvironments based on lithofacies associations and ichnological characteristics. Ichnological evidence indicates that the shelf-edge deltas are one of the most extreme marine environments for benthic metazoans to colonize. However, the combinations and ranking of stress factors affecting the colonizing fauna are diverse and distinct in every individual subenvironment indicating the relative dominances of river-influence, waves, and/or sediment-gravity-flows vis-à-vis slope instability. Due to variations in stress factors, the megasequence also displays dual ichnologic and sedimentologic properties of both the shelf-edge delta lobe(s) and the outer shelf delta lobe(s). A minor transient tidal influence can only be observed in the architectural elements, e.g. elongated interbar embayment and interlobe prodeltaic depocentres, which control topography and enhance tidal effect. Discovery of an unusual monospecific Glossifungites Ichnofacies along an incision surface in the midst of the Mayaro Formation succession enabled a substantial overhaul of the earlier understanding of the formation in terms of its depositional model and stacking pattern. The surface has been re-identified as a canyon/gully cut at the shelf-edge, which possibly acted as a conduit for (a) the mass movements and for (b) the coarse clastic (mostly silt to medium-grained sand) sediment transfer to deep marine settings. The monospecific nature of the Glossifungites Ichnofacies suite indicates that the incision surface was under substantial ecological stresses for the colonizing infauna. The stresses might have arisen from slope instability of the steep canyon/gully walls, mass movements above the incision surface, elevated water turbulence, and lowered salinity from river influx. Five different facies tracts have been identified within the canyon/gully-fill, which crosscuts the shelf-edge delta-front. The facies tracts are dominated by different types of sediment-gravity flow deposits, which are systematically stacked and are almost devoid of trace fossils due to rapid sedimentation rates and slope instability. They are also strikingly different from the surrounding deltaic facies. A high-frequency sequence stratigraphic model involving the influence of growth-fault tectonics on the relative sea-level curve has been invoked to explain the incision of the canyon/gully and its sequential filling processes. On the other hand, the transition from the open shelf to inner-shelf deltaic condition as displayed by the basal members of the Morne L’Enfer Formation is strongly dominated by evidences of river influence with the transient background action of fair-weather waves and storm waves. A peculiar pattern of disappearance of trace fossils produced by irregular sea-urchins highlight that the river influence was quite strong not only at the sediment-water interface but also in the water-column, which affected invertebrate larvae. The initial progradation of the clastic wedge on the shelf was dominated by hyperpycnal flows and waves in contrast to tidal domination in the younger members of the formation.

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