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EN
Biological soil crusts (BSCs) have a vital role regarding vegetation and soil development in arid and semi-arid areas in the world, and apparently in Iran, where they comprise more than 85% of the land. In this research, the relationship between BSCs and plant functional groups, considering soil parameters along an arid alluvial fan located in Khorasan Razavi province in northeastern Iran, was examined. The sampling carried out in summer, systematically from apex towards base part of alluvial fan, using a 0.25 m2 quadrat over a 5-cm thick soil surface. Surface levels were classified into three categories: apex, middle, and base. At each level, 16 samples were taken; in total 48 samples were collected along the alluvial fan from the apex point to the base district. The results showed a strong relationship between BSCs and the soil surface features, and a weak correlation between the plant functional group and soil parameters. BSCs indicated an ecological evolution from apex to the base geomorphic level by soil development; so that BSCs are more developed on the base of alluvial fan, but their diversity is reduced.
EN
Sandstones and conglomerates, which northwards of Brno agglomeration build a hill (ridge) named Babí lom are strongly diagenezed (anchi-metamorphozed) and tectonically deformed. Their regional distribution and stratigraphic position between the Cambrian(?) clastics and Upper Devonian limestones, as well as their appearance meant that they age is considering as Middle Devonian. They are distinguished as the so-called „Basal Devonian Clastics“. Almost all primary sedimentary features are well preserved and distinct. In the metasediments of the Babí lom hill were distinguished both the facies and structures typical of alluvial fans and rivers. Among others they are channel lags with imbricated grains, cross beddings and debrites. Within sedimentary association was established the way-up direction what clearly evidences a coarsening upwards sequence. Assuming the lack of rotation of series of sediments in the X-Y plane, the palaeotrasport was toward the north while major supply with material was from the east.
EN
The upper part of the Lower Miocene Sloboda Conglomerate, a 250–1400 m thick unit, was deposited mainly on an alluvial fan and fan delta during the early stages of Carpathian Foredeep development. During of the Old Styrian overthrust movements of the Carpathian orogen, a forebulge was formed, which supplied clasts to the conglomerate. The clasts are dominated by Late Proterozoic–Early Cambrian phyllites, while Paleozoic carbonates are common, and Mesozoic and other rocks are rare. The source area formed mainly by a prolongation of the Małopolska Massif that was involved in the forebulge; this was located close to a palaeovalley cut into Mesozoic and Paleozoic rocks, buried under younger strata. Additional material was derived from the advancing front of the Carpathian Flysch nappes.
EN
The sediment study of the alluvial bottom of Prosna river valley and of alluvial fan in the floodplain terrace, with the special attention paid to its origins, anthropogenic conditions at that time and also to lithofacial variability, enabled to draw the following conclusions. The fan was the result of erosion-denudation processes triggered after 6220š140 BP (Gd-4677) (about 4300 BC). The beginning of these processes can be associated with the Neolithic human beings activity, having taken into account conditions of the Holocene Climatic Optimum as well as presence of Neolithic cultures found in the investigated area. The lithofacial analysis of the sediments has revealed a simple fractionation sequence: D right arrow B right arrow C right arrow A for the alluvial filling of the river bottom. This indicates its accumulation as the result of meandering river activity. Cyclical lithofacies transitions for the alluvial fan sediments have been observed: A (sandy) into F (sandy-silty) and into E (silty).
EN
The development of agriculture accelerated soil erosion processes and the deposition of erosion products in the form of alluvial fans at the mouths of dry or temporarily drained valleys. The age of the alluvial fan in Borucin, in the Psina basin, has been established and the stages of its formation have been reconstructed with the use of radiocarbon dating of the roof of peat underlying the mineral sediment of the fan. The fan started to form in the second part of Suboreal period (3650 š 70 BP). Maximum fan progradation occurred at the end of the Period of Roman Influence when the area was settled by the agricultural Przeworsk culture( 1670 š 70 BP). In the Early Middle Ages, silty clays eroded from cultivated slopes no longer reached the outer fan zone, which points to a lower population density/less intensive agriculture in the area. The period of formation of the second fan under examination, located at the mouth of a side valley of the Odra, has been preliminarily determined on the basis of archaeological research. The progradation of this fan is probably related to the agricultural activity of the Lusitian Culture and forest clearances linked to the construction of a stronghold (9th-7th century BC).
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