Search results for "Geomorphology"

Fluid escape structures in the north Sicily continental margin

2014

Abstract High resolution and multichannel seismic profiles coupled with multibeam echosounder (seafloor relief) data, acquired along the northern Sicily continental margin (southern Tyrrhenian Sea), document the occurrence of mound and pockmark features, revealing fluid escape processes. Along this margin, morphology of the high-gradient continental slope is irregular due to the presence of structural highs, slope failures and canyons, and is interrupted by flat areas at a mean depth of 1500 m. Seismostratigraphic analysis tools and methods were used to identify fluid escape structures and to work out a classification on the basis of their morpho-acoustic characteristics. The detailed 3D ba…

STOP 10: Kame terrace in the Upper Daugava depression at Rakuti, near Krāslava

2014

Clastic injection dynamics during ice front oscillations: A case example from Sólheimajökull (Iceland).

2015

18 pages; International audience; Soft-sediment deformation structures are being increasingly used as a tool for reconstructing palaeoenvironments and porewater pressure conditions in glacial settings. However, the potential of hydrofractures and clastic injections in the reconstruction of ice dynamics remains poorly constrained. This paper presents the results of a detailed study of a clastic injection network outcropping in the Sólheimajökull forefield (South Iceland). Sedimentological descriptions are combined with microscopic to macroscopic analyses of clastic injection geometries, sediment-fills, and cross-cutting relationships. The 250 m long and 20 m high exposure observed along the …

Exhumation of high-pressure granulites and the role of lower crustal advection in the North China Craton near Datong

1997

Granulites in the Datong-Huai'an area of North China are characterized by high P-T assemblages (14 16 kbar, -9OOY) that underwent decompression cooling to -7 kbar and -800°C during a 250&2400 Ma tectonic event. Nearly all structures in the grantilites developed during the retrograde exhumation history, and can be subdivided into: (1) the stratigraphically lower, 'lower structural domain' that is characterized by complex folding with 55-10 km wide domes surrounded by concentric troughs, preserving concentric lineation patterns; and (2) the stratigraphically higher 'upper structural domain' that is characterized by a planar gneissic foliation, upright folds and a constant, shallowly SW-plungi…

STOP 14: Morphology and internal structure of the Lāči drumlin at Tērvete village, Zemgale Drumlin Field

2014

Flood risk assessment and mapping in peri-urban Mediterranean environments using hydrogeomorphology. Application to ephemeral streams in the Valencia…

2012

Abstract This paper proposes a methodology for mapping flood risk in ephemeral streams, based on assessing flood hazards and global exposure. The method has been applied to the peri-urban area of Valencia, extended over the floodplains of the Barranco del Carraixet and Rambla de Poyo catchments. Hazard was assessed using hydrogeomorphological methods. Global exposure was estimated as a combination between the economic value of land use and human exposure, following a previous study carried out by Camarasa, A.M., Lopez, M.J. and Soriano, J., 2011. Mapping temporally variable exposure to flooding in small Mediterranean basins using land-use indicators, Applied Geography 31 (19), 136–145. Synt…

Miocene NNE-directed extensional unroofing in the Menderes Massif, southwestern Turkey

1995

Structural investigations in the central part of the Menderes Massif (Odemis-Kiraz submassif) reveal the presence of a large-scale, low-angle extensional shear zone with a top-to-the-N-NE shear sense. Regional ductile deformation was accompanied by the intrusion of two syntectonic granodiorites that have been dated with the Ar-40/Ar-39 method. One hornblende isochron age of 19.5 +/- 1.4 Ma and two biotite plateau ages of 13.1 +/- 0.2 and 12.2 +/- 0.4 Ma, respectively, constrain that extension was already active in the early Miocene. Successive tectonic denudation of the Odemis-Kiraz submassif resulted in the formation of a N-dipping detachment fault, in which ductile fabrics were severely r…

Mitigation of urban flooding: A simplified approach for distributed stormwater management practices selection and planning

2005

The urbanization process and the hydraulic insufficiency of drainage systems are two of the most common causes of urban flooding. In some technical regulations, distributed stormwater management practices (DSMPs) are regarded as a solution for urban flooding problems. They can prevent the formation of runoff, dispose of it locally, or dampen its peak before it reaches the drainage system. Due to their diffuse localization and the wide number of available solutions, the evaluation of their efficiency in terms of flood reduction is very difficult. The methodology proposed in the present paper relies on the concept that the mitigation effects of DSMPs can be expressed as a function of the chan…

Fluid-pressure controlled soft-bed deformation sequence beneath the surging Breiðamerkurjökull (Iceland, Little Ice Age).

2009

16 pages; International audience; The general subject of this paper is subglacial deformation beneath Breiðamerkurjökull, a surging Icelandic glacier. More specifically it discusses the evolution and the role of fluid pressure on the behaviour of subglacial sediments during deformation. During Little Ice Age maximum, the two outcrops studied, North Jökulsarlon (N-Jk) and Brennhola-Alda (BA), were located at 2550 m and 550 m respectively from the front of the Breiðamerkurjökull. Sedimentological analysis at the forefield of the glacier shows thick, coarse glaciofluvial deposits interbedded with thin, fine-grained shallow lacustrine/swamp deposits, overlain by a deformed till unit at N-Jk. BA…

Water resource assessment in karst and fractured aquifers of Termini Imerese-Trabia Mts. (Northern central Sicily, Italy).

2014

The carbonatic siliciclastic Mesozoic reliefs of Termini Imerese-Trabia Mts. (Northern central Sicily) were selected in order to investigate groundwater resources, as these fissured to karstic aquifers are used for potable water supply. These reliefs, part of the Sicilian Apennine Chain, consist of a tectonic units (deformed and emplaced during the Miocene-Pleistocene, and collapsed during the Plio-Pleistocene) mostly formed by clayey pelagic limestones (Sicilidi domain) overthrusting Meso-Cenozoic carbonate and silicoclastic rocks (Imerese Basin, Late Triassic-Early Oligocene) and terrigenous covers (Numidian Flysch, Late Oligocene-Early Miocene). The evolution of karstic network and subsu…