Search results for "Luvia"
showing 10 items of 223 documents
Morphological characterization of calanchi (badland) hillslope connectivity
2017
Calanchi, a type of Italian badlands created by a combination of water erosion processes and local geomorphological and tectonic controls, is a striking example of long-term landscape evolution. In small temporal/spatial scales, the calanchi exhibit many of the geomorphic processes and landforms that may be observed in fluvial landscapes, hence they may be considered as micro-basins where geomorphic dynamics and landscape features can be related. The goal of this research is testing the use of simple morphometric variables for assessing sediment connectivity of calanchi landforms. In order to detect the morphological characteristics controlling the landscape connectivity of calanchi basins,…
Influences of surface processes on fold growth during 3-D detachment folding
2014
In order to understand the interactions between surface processes and multilayer folding systems, we here present fully coupled three-dimensional numerical simulations. The mechanical model represents a sedimentary cover with internal weak layers, detached over a much weaker basal layer representing salt or evaporites. Applying compression in one direction results in a series of three-dimensional buckle folds, of which the topographic expression consists of anticlines and synclines. This topography is modified through time by mass redistribution, which is achieved by a combination of fluvial and hillslope erosion, as well as deposition, and which can in return influence the subsequent defor…
The discovery of a Mycenaean-type tholos tomb in the Bronze Age necropolis of the Gazzi buried floodplain (Messina, Southern Italy): new geological a…
2019
This paper deals with a monument that is, up to this date, unique in Sicily and in the Italian peninsula: the Mycenaean-type tholos tomb of the Gazzi necropolis in Messina. A recent excavation in the alluvial deposits revealed extensive traces of a funerary area with a tholos tomb and several enchytrismos tombs with skeletal remains, presumably dated back to the end of the Early or the initial stage of the Middle(?) Bronze Age. The present multi-disciplinary investigation has been developed to analyse new data related to sediments, building stones and skeletal remains of this funerary area. The stratigraphic succession hosting the necropolis was formed by overbank sediments deposited on the…
Morphometric indices as indicators of tectonic, fluvial and karst processes in calcareous drainage basins, South Menorca Island, Spain
2007
This study proposes using morphometric indices to discriminate the processes that shape calcareous drainage basins. To illustrate this, a DEM of the southern part of Menorca Island (Migjorn) was created and basin slope, drainage density, hypsometric curve and integral, and the area occupied by open and closed dolines were extracted from it. These indices show an important dependence on tectonics, which govern the morphology of these drainage basins and encourage the predominance of karst and/or fluvial processes in the different sectors. The morphometric indices are clearly influenced by the geological Migjorn structure, a carbonate Upper Miocene reef platform gently folded as an asymmetric…
Testing GIS-morphometric analysis of some Sicilian badlands
2014
Abstract Calanchi badlands are erosion landforms characterized by areas with scarce or absent vegetation, steep slopes, knife-edge divides and high erosion rates. They are originated by a combination of morphogenetic processes, partly similar to those shaping bigger fluvial landforms, and therefore can be considered as field “laboratories.” This paper presents the results of an investigation carried out in two badland sites located in Sicily, where the geometry of 25 calanchi has been characterized using Digital Elevation Models having a mesh size equal to 2 m. For each landform, a power length–volume relationship is established. This relationship demonstrates that length of calanchi channe…
Fan Deltas and Floodplains in Valencian Coastal Plains
2018
The Valencian coastal plains are formed at the end of two important mountain systems: the Iberian Mountain Range to the north and the Baetic Mountains to the south. As a result of tectonic and neotectonic activity, several graben have been formed at the foot of these reliefs, which have been filled with Plio-Quaternary deposits. In all the coastal plains a depositional sequence is repeated in which the river deposits -fan deltas and alluvial plains- alternate with lagoons/marshes. Basin dimensions, sediment input, tectonics and neotectonics in the study area all determine the size, style and characteristics of fluvial forms, which in turn, influence the characteristics of the coast. Ephemer…
Tectonic beheading of fluvial valleys in the Maestrat grabens (eastern Spain): Insights into slip rates of Pleistocene extensional faults
2013
Abstract Interaction between faulting and landscape evolution in regions of active tectonics allows us to use subtle geomorphological markers for estimating fault slip rates. Geomorphic features of two valleys connected with the bottom of the Alcala de Xivert graben, at the Maestrat graben system (eastern Spain), suggest that they correspond to the lowest segments of ancient valleys whose original heads were located at the axis of the neighbouring Irta range. They were beheaded owing to displacement of the Torreblanca and Irta faults during a period of active extensional faulting in Middle Pleistocene times. These faults produced a negative inversion of the relief, sinking a narrow graben (…
Kinematic and sedimentological evolution of the Manyara Rift in northern Tanzania, East Africa
2005
We describe the stratigraphical/sedimentological and structural evolution of the Manyara Rift in the Tanzania Divergence Zone, East Africa. The rift-related Manyara Beds on the shoaling side of the Manyara Rift were deposited between <1.7 and 0.4 Ma and can be separated into a lacustrine lower member and a fluvial upper member. The transition from lacustrine to fluvial sedimentation at ∼ 0.7 Ma appears to be related to a southward shift of major rift faulting. Fault geometry and the kinematics of the faults are consistent with major faulting during NE/E-directed extension. There is also evidence for other extensional directions including radial extension, which might be caused by magmati…
Rift-controlled fluvial/tidal transitional series in the Oukai¨meden Sandstones, High Atlas of Marrakesh (Morocco)
1996
Abstract The Carnian formation of the Oukai¨meden Sandstones was deposited in the northwestern corner of the African craton along tectonic troughs grouped as a WSW-ENE rift system on the southwestern margin of the Tethys. Red sandstones represent mainly distal braided-stream deposits where very extensive sand flats with 3D dunes, 2D sand waves and high-regime horizontally laminated sandstones predominate. The similarities in orientation between current patterns and trough border faulting, the sudden large variations in the thickness of deposits and the occurrence of lateral alluvial fans along the marginal faults are all evidence of the tectonic control of sedimentation. The middle part of …
Sedimentation in a fluvially infilling, barrier-bound estuary on a wave-dominated, microtidal coast: the Oueme River estuary, Benin, west Africa
2002
The Oueme River estuary is located on the seasonally humid tropical coast of Benin, west Africa. A striking feature of this microtidal estuary is the presence of a large sand barrier bounding a 120 km2 circular central basin, Lake Nokoue, that is being infilled by heterogeneous fluvial deposits supplied by a relatively large catchment (50 000 km2). Borehole cores from the lower estuary show basal Pleistocene lowstand alluvial sediments overlain by Holocene transgressive–highstand lagoonal mud and by transgressive to probably early highstand tidal inlet and flood-tidal delta sand deposited in association with non-preserved transgressive sand barriers. The change in estuary-mouth sedimentatio…