Land mollusc palaeocommunity dynamics related to palaeoclimatic changes in the Upper Pleistocene alluvial deposits of Marche Apennines (central Italy)

2014 ◽  
Vol 133 (2) ◽  
pp. 235-248 ◽  
Author(s):  
Carmine D’Amico ◽  
Daniela Esu ◽  
Mauro Magnatti
Keyword(s):  
Central Italy ◽  
Alluvial Deposits ◽  
Upper Pleistocene

scholarly journals Drainage Rearrangement as a Driver of Geomorphological Evolution During the Upper Pleistocene in a Small Tropical Basin

2019 ◽  
Vol 11 (2) ◽  
pp. 1
Author(s):  
José Martínez Batlle
Keyword(s):  
Dominican Republic ◽  
River Basin ◽  
Tectonic Activity ◽  
River Diversion ◽  
Alluvial Deposits ◽  
Upper Pleistocene ◽  
Basin Morphometry ◽  
Karst Systems ◽  
Geomorphological Evolution ◽  
New Evidence

The development of river networks in contexts where intense tectonic activity converges with great lithological variability, such as the Ocoa River Basin in the south of the Dominican Republic, usually hosts excellent examples of drainage rearrangement. This mechanism is defined as a transfer of part or all of a river’s flow to another river. According to the process involved, drainage rearrangement may be classified in one of four categories: stream capture, river diversion, beheading and, more recently, karst piracy. The Parra River Basin (29.5 square kilometers), part of the Ocoa River Basin, features excellent examples of drainage rearrangement. The aim of this research was to detect and characterize drainage rearrangement evidence in three sub-basins of the Parra River Basin. Several geomorphological features, including striking differences in lithological types of alluvial deposits between terraces and stream beds, a sinkhole in a tributary stream, as well as high variability in basin morphometry computed using GIS techniques, suggest the development of karst piracy during the Upper Pleistocene in the Parra drainage network, along with other minor rearrangement forms. Karst piracy is an understudied model of drainage rearrangement worldwide, and so it is in the Dominican Republic. Hence, this paper contributes to a better understanding of the interaction between rivers and karst systems, at the same time providing new evidence for this little-known phenomenon.

New chronology for the Ardèche river Upper Pleistocene evolution: relationships to glacial/interglacial cycles

2020 ◽  
Author(s):  
Kim Genuite ◽  
Jean-Jacques Delannoy ◽  
Jean-Jacques Bahain ◽  
Marceau Gresse ◽  
Stéphane Jaillet ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Central Place ◽  
Upper Paleolithic ◽  
Alluvial Deposits ◽  
Upper Pleistocene ◽  
Base Level ◽  
Geophysical Surveys ◽  
Karst River ◽  
Absolute Dating ◽  
Dating Method

<p>The Ardèche river canyon (Ardèche, France), is famous for its deep ingrown meanders and represent one of the most touristic assets of the region. It is also a central place of Upper Paleolithic human occupancy with numerous caves containing some of the most ancient and impressive rock art ever discovered like in the Chauvet cave, located at the canyon entrance, which artwork was dated at more than 36000 years cal BP (Quilès et al., 2016). The highly elaborated artwork of the cave, dated at more than 36000 years cal BP (Quilès et al., 2016), was kept in an exceptional state because of successive rock collapses of the cliff overhanging the cave that led to the complete closing of the entrance about 21,000 years ago (Sadier et al., 2012). </p><p>However, the late Quaternary river evolution remains poorly constrained as no absolute dating was conducted on the alluvial deposits, nor in other rivers of the Central Massif mountain eastern margin.</p><p>We present here the results of two independent dating campaigns based on the karst / river base level relationship and geomorphological observations conducted in both environments. We conducted topographical and geophysical surveys in the Ardèche river meanders and floodplains in order to map the different alluvial banks generations. Geomorphological observations were also conducted inside the canyon cavities and were compared to external observations on an altitudinal grids ranging from the current river thalweg to the + 45 m alluvial deposits.</p><p>We exploited U/Th dating method on some cave speleothems located along the river and sampled corresponding alluvial sediments for ESR dating, at the same altitudes. Results were thus compared to a relative chronological model in order to deliver a bayesian statistical model for the Upper Pleistocene deposits of the Ardèche river.</p><p>Chronological modelling can thus be compared to long term Pleistocene climatic evolution and show correlations with glacial/interglacial Upper Pleistocene cycles, and landscape modifications like meander shortcuts.</p>

Aggregates and naturally occurring asbestos: the need of a correct analytical approach

2020 ◽  
Author(s):  
Alessandro Cavallo
Keyword(s):  
Los Angeles ◽  
Central Italy ◽  
Fine Fraction ◽  
Beach Erosion ◽  
Crushed Stone ◽  
Glacial Deposits ◽  
Alluvial Deposits ◽  
Rock Fragments ◽  
Industrial Sectors ◽  
Asbestiform Minerals

<p>Aggregates (sand, gravel and crushed stone) characterized by good mechanical properties and no undesired reactivity, are used in huge amounts in many industrial sectors, especially in construction (e.g. concrete, asphalt, paving). Sand and gravel extracted from alluvial or glacial deposits are typically rounded and well selected, whereas crushed stone is angular and suitable for certain applications (e.g. railway ballast). Use of offshore deposits is mostly restricted to beach erosion control and replenishment. Demand for aggregates is governed essentially by markets, and sources of supply need to be situated close to each other, because of transportation costs. The most common rock types (depending on geology) are represented by basalts, porphyries, orthogneisses, carbonatic rocks and “green stones” (serpentinites, prasinites, amphibolites, metagabbros). Especially “green stones” may contain traces, and sometimes appreciable amounts of asbestiform minerals (chrysotile and/or fibrous amphiboles). For example in Italy, the chrysotile asbestos mine in Balangero (Turin) produced over 5 Mt railroad ballast (crushed serpentinites), which was used for in northern and central Italy, from 1930 up to 1990. The legal threshold for asbestos content in track ballast is established in 1000 ppm: if the value is below this threshold, the material can be used, otherwise it must be disposed of as hazardous waste, with very high costs. The presence of asbestiform minerals must be first assessed by preliminary geological and mineralogical surveys in quarry areas, both for glacial – alluvial deposits and “massive” rock mass (crushed stone). The quantitative asbestos determination in rocks is a very complex analytical issue: although techniques like TEM-SAED and micro-Raman are very effective in the identification of asbestos minerals, a quantitative determination on bulk materials is almost impossible or expensive and time consuming. Another issue is represented by the discrimination of asbestiform minerals (e.g. chrysotile, asbestiform amphiboles) from the common acicular – pseudo-fibrous varieties (lamellar serpentine, non-asbestiform amphiboles). Also, the correct sampling is of crucial importance, considering the size of rock fragments (sand, gravel or silt) and the geological variability within the quarry. In this work, more than 400 samples from the main Italian quarry areas were characterized by a combined use of XRD and an up to date sample preparation and quantitative SEM-EDS analytical procedure. The first step consists in the recognition of “green stones” (presence of serpentine and/or amphiboles) by means of macroscopic petrography (gravel) or XRD (sand, silt). The second step is represented by the “self-grinding” of the rock fragments (Los Angeles rattle test for gravel), and the quantitative SEM-EDS analysis of the “fine” fraction (< 2 mm). The third and last step consists in the complete grinding of the bulk sample and following SEM-EDS quantification. The results show a great variability for serpentinite-rich samples, with a wide asbestos concentration range; on the other hand, metabasites (prasinites, amphibolites) are generally less critical, because the presence of asbestiform amphiboles (especially tremolite - actinolite) is rarer and more occasional. As regards the samples deriving from alluvial and glacial deposits, the fibers tend to concentrate in the fine fraction (<2 mm).</p>

Geotechnical characterization of the upper Pleistocene–Holocene alluvial deposits of Roma (Italy) by means of multivariate geostatistics: Cross-validation results

2008 ◽  
Vol 101 (3-4) ◽  
pp. 251-268 ◽  
Author(s):  
Giuseppe Raspa ◽  
Massimiliano Moscatelli ◽  
Francesco Stigliano ◽  
Antonio Patera ◽  
Fabrizio Marconi ◽  
...  
Keyword(s):  
Cross Validation ◽  
Multivariate Geostatistics ◽  
Alluvial Deposits ◽  
Upper Pleistocene ◽  
Geotechnical Characterization

scholarly journals Structural and hydrogeological features of Pleistocene shear zones in the area of Rome (Central Italy)

1994 ◽  
Vol 37 (1) ◽  
Author(s):  
C. Faccenna
Keyword(s):  
Central Italy ◽  
Fluid Pressure ◽  
Shear Zones ◽  
Fault Zones ◽  
Strike Slip ◽  
Hydrothermal Fluids ◽  
Upper Pleistocene ◽  
Impermeable Barrier ◽  
Hydrothermal Springs ◽  
High Fluid

The last tectonic episode observed in the Latium Tyrrhenian margin (Central Italy), few km cast of Rome, is represented by a set of middIe-upper Pleistocene N-S shear zones, characterised by complex geometric and kinematic setting. The easternmost of these shear zones displays a strike-slip component of motion and is located at the boundary between the Apennine carbonate chain and the volcanic areas. The distribution of travertine deposits and hydrothermal springs suggests that this fault zone acts as an impermeable barrier for lateral flow derived from superficial karstic circuit, and as a preferential upwelling surface for deep hydrothermal fluids. We propose that high fluid pressure could develop inside these fault zones favouring the reactivation of buried pre-existing crustal discontinuities and the local re-orientation of the stress field, as testified by the geometry and the kinematics of the surface fault pattern.

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