Th. doct.--Sci. terre--Paris--Ec. natl. sup. mines, 1992. / Résumé en anglais. Bibliogr. p. 223-236.

Th.--Sci. nat.--Lille 1, 1980. N°: 499.

Diss. Techn.Wiss. ETH Zürich, Nr. 4233, 0000. Ref.: Bach, R. ; Korref.: Bollmann, W.

Thesis--Freiburg. / Vita.

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 117-122.

The soft sedimentary deposits of the Waitemata Group which outcrop on the eastern coastline of the Auckland region are a coastal cliff erosion hazard. The determination of the rate that these cliffs erode for hazard zonation purposes still requires research. A database has been collated of a range of structural, geological, geomorphic and climate parameters from 16 representative cliff sites in order to statistically assess what parameters influence cliff erosion and why erosion rates vary within the relatively uniform geology. Four different lithological units have been defined: sandstone beds of turbidites; sandstone beds of densites (contain rip-up clasts); sand to gravel beds of debrites; and siltstone beds. Cliff rock has very weak to weak intact rock strength; apertures of 0.1 to 15 mm; infill types are soft clay and grit, and hard calcite and iron; spacing of discontinuities are smaller in siltstone beds (≥ 5 mm), and up to 5 m in sandstone and debrite beds; bedding and fault planes are continuous, joints are non-continuous; block size is dictated by bed thickness and non-continuous joints. Shore platform widths were used to determine long-term erosion rates which range from 1.2 to 53.0 mm y-1. Platform morphologies are either sloping or horizontal or are a combination of both. Higher platform benches found at some sites are considered to be the result of a higher period of sea-level or are high-tide benches. Intact and rock mass strength increases northwards. Cliff heights are 8 to 38 m; cliff angles are 51 to 79 . Conditions for sporadic planar and wedge failure were determined at some sites; frittered siltstone and low durability sandstone allow smaller-scale, continual erosion. Castor Bay, Army Bay, Waiwera Beach and Leigh Marine Reserve have the lowest rock mass quality. Musick Point, Narrowneck Beach and Waiake Bay have good rock mass quality. A conceptual model for coastal cliff erosion has been developed for Waitemata Group coastal cliffs, based on the dominant processes that act on the cliffs determined from statistical analysis (student t-test, correlation and regression) and field observations. The primary factor for cliff erosion is bed dip, whereby seaward dipping beds have higher erosion rates than landward dipping beds. The secondary factors for cliff erosion include: the intact and rock mass strength of the rock; the rock mass quality; strength of the siltstone beds; strength and structure of the sandstone beds; and orientation of the bedding planes with respect to the cliff face. Shear stresses are enhanced when beds dip seaward and thus shear failure along continuous surfaces is achievable. When beds dip landward the influence of shear stresses along bedding planes, and their contribution to the removal of individual blocks of rock, is severely inhibited resulting in reduced rates of erosion. There is no relationship between cliff height and erosion rates and cliff heights are mainly controlled by the pre-existing landscape. Cliff angle is controlled by the proportion of sandstone and siltstone (whereby lower cliff angles are more siltstone-dominated), rock mass strength and weathering. Erosion rates do vary in Waitemata Group rock of the Auckland region because of the variation in structural and geomorphic conditions of the cliff, most strongly controlled by the dip angle of bedding planes.

Thèse (D.R.Min.) -- Université du Québec à Chicoutimi, 2005. / Bibliogr.: f. 208-256. Document électronique également accessible en format PDF. CaQCU

Le Flysch a Helmintho(')ides et son substratum de shales noirs constituent des facies extremement repandus des nappes de flysch neocretaces alpins. Malgre ses implications paleogeographiques, la sedimentologie de ces unites reste mal connue. Pour contribuer a combler cette lacune, cette etude s'interesse a un des Flysch a Helmintho(')ides classiques et a son Complexe de base. / Le Complexe de base est constitue de shales noirs associes a des carbonates authigenes. La petrographie, la diffraction X, la microsonde et l'analyse isotopique du carbone sont appliquees a la description de ces carbonates qui ont pour compositions moyennes: dolomite: Ca(,1).(,02) Mg.(,42) Fe.(,24) Mn.(,32)(CO(,3))(,2); rhodocrosite: Ca.(,30) Mg.(,12) Fe.(,07) Mn.(,51)CO(,3); siderite: Ca.(,07) Mg.(,19) Fe.(,54) Mn.(,20)CO(,3). La precipitation s'est effectuee apres quelques metres d'enfouissement, sous la limite de diffusion des sulfates. Le contenu eleve de manganese suggere l'alteration d'un socle basaltique sous-jacent, le manganese s'ajoutant aux produits de l'alteration des mineraux et de la matiere organique de la colonne de sediment. Les shales noirs montrent des traces de bioturbation et suggerent une accumulation dans une Tethys a niveau a minimum d'oxygene etendu, comme dans d'autres oceans au Cenomanien-Turonien. / Le Flysch a Helmintho(')ides (couplets de gres-mudstone calcaire intercales avec des hemipelagites de shales noirs) est associe aux gres grossiers du Gres de l'Embrunais. L'etude des facies, des sequences d'epaisseurs, des paleocourants et des compositions montre qu'il s'agit d'un cone d'alluvion sous-marin developpe sous la profondeur de compensation de la calcite de met en relief les processus actifs dans ce milieu d'accumulation. Le Flysch a Helmintho(')ides correspond au remplissage d'une plaine abyssale etroite orientee nord-ouest-sud-est. Le Gres de l'Embrunais est interprete comme un remplissage de vallees alimentant la plaine a partir d'un socle granito-gneissique situe a l'ouest ou au sud-ouest. L'environnement paleogeographique suggere n'est pas facilement compatible avec une accumulation en ocean piemontais, comme precedemment inferee. La presente etude suggere une position palinspatique plus interne, entre la zone de Sesia et la zone d'Ivree.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1964. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 144-152).

Thèse (Ph. D.)--Université Laval, 2005. / Titre de l'écran-titre (visionné le 28 septembre 2005). Bibliogr.