Miniature mud volcanoes and other injection features in tidal flats, James Bay, Québec

Abstract

Miniature injection features, including mud volcanoes, dikes forming polygonal patterns, and isolated patches of clay, occur in tidal Rats along the east coast of James Bay. They are formed by localized upward ejection of a mixture of fluidized marine clay, silt, and fine sand through a surficial recent mud deposit. Liquefaction is related to the melting of ice in the clayey deposit. Upward flowing of clay, silt, and fine sand seems to result from overloading by the overlying sediments having a higher degree of density, and possibly also by pressures of ice floes orland icefoot.Des micro-formes d'injection vers le haut comprenant des volcans de boue, des dikes formant des reseaux polygonaux, et des epanchements d'argile en nappe ont kt6 observes dans les slikkes de la c6te est de la baie de James. Elles resultent de I'ejection vers le haut d'argile, limon, et sable fin fluidises a travers un dep6t de vase superficiel et recent. La liquefaction est liee B la fonte de glace dans I'argile marine. L'expulsion vers la surface des sediments argileux liquefies semble resulter d'un effet de surcharge des sediments susjacents, ayant une densite plus elevee et possiblement aussi de pressions exercees par des radeaux de glace oulet le pied de glace.

Subaqueous artesian springs and associated spring pits in a Himalayan pond

“…In contrast to processes forming mud volcanoes (e.g. Dionne 1973bDionne , 1976 by extrusion of liquidized material with high sediment/water ratios, upwelling ground water in the Spiti example only caused suspension of fine-grained sediment with low sediment/water ratios which is distributed more evenly, over greater distances from the pits by the weak water currents. Similarly, King & MacLean (1970) describe pockmarks from the Scotian Shelf with sharply defined, steeply sloping rims, without sediment accumulations around the depressions.…”

“…During this process, upward flow of water is controlled by the hydrostatic head and reconsolidation of the sediment grains. In contrast to 'Monroe structures' (Dionne 1973b), which are eye-catching build-ups in tidal-flat mud and similar mud volcanoes (Dionne 1976), both formed by ascending gas/water/sediment mixtures, the rims of the spring pits show hardly any deposition of sediments around them (Figs 2B, 3A). This indicates that the upward directed water jet from the springs was not competent enough to carry sandsized sediment (Allen 1982).…”

Diques clásticos da Formação Corumbataí, Bacia do Paraná, no contexto da tectônica permotriássica do Gondwana Ocidental

“…Este capítulo trata dos processos de formação de diques presentes em depósitos sedimentares, que por sua vez, ocorrem associados a uma vasta gama de sistemas deposicionais, como por exemplo, ambientes glaciais (Johnston, 1993;Le Heron & Ettiene, 2005), lacustres (Aspler & Donaldson, 1986;Martel & Gibling, 1993), fluviais (Oomkens 1966;Plint, 1985), costeiros de deltas ou maré (Reimntiz & Marshall, 1965;Dionne, 1976;Hardie, 1999), marinho raso (Williams, 1976;Johnson, 1977), leques marinhos profundos e turbiditos (Hiscott, 1979;Archer, 1984;Parize, 2003).…”