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Investigation of textural characteristics of sediments of Sandy dunes in eastern of Jask County
IntroductionOne of the most important wilderness areas, including the study area wind erosion processes that lead to coastal erosion features such as sand dunes in the absence of migration consolidation of its location addressing. Various erosion processes are involved in desrt areas, and wind erosion is one of the major constraining factors that limited human activities in this area like resources, natural resources, human facilities, etc. Identifying resources that constituted this area's sandy hills will be effective in management of this area because unstability hills damage water and soil resources ,human constructions and so on. Study area situated in eastern of Jask county coast in Hormozgan province of Iran.
Materials And MethodsThe use of hydrodynamic granulometry analysis and interpretation of the environment by Hill strom (1939) was used. The results of sedimentology were used for the computation of sediment texture. For this purpose, 200 grams of each sample prior to sift according to the proposed method Ingram (1971) with hydrochloric acid to separate the organic material is washed and then dried in it. because, according to Petty, John (1936), Swan (1979), Friedman and Johnson (1982), the results of the moment, especially in the stretch and tilt towards drawing closer to the reality of the index calculated median, mean, sorted, is tilting. Using textural parameters of sediments such as diameter, average, compatibility and skewing is an attempt towards recognition of mechanism and understanding environment of sediments. In this study 10 cases are sampled and after granulometry, considered parameters were explored. Texture parameters are calculated by moment method. In addition microscopic and macroscopic investigation are used. Charts were prepared using Excel software. Using topographical maps and satellite images to the software of GIS maps were provided .The geological map was used for petrography. To search for fossils in sediment samples and help to identify the type of sedimentary origin from two sediment samples were studied thin sections were prepared with binocular microscope.
Results And DiscussionSamples 1, 2 and 5 has a negative tilt, sorting good, transparent particles greater than 20 percent and also has fossils of marine environments that show these characteristics is the origin of coastal sediments.In Example 3, there are fossils of sea and transparent grain of marine origin shows.The Histograms and cumulative curves of samples 1, 2 and 5 is similar to Example 3 but sample 3 has a positive skewness and sorting the sample average. The reason could be that the samples greater distance from the beach and the relative humidity at a distance from the sea ratio declined slightly as a result of adhesion of deposits is low and wind power, carrying sediment fine and deposits of fine to this place More fine-grained sediments brought abundance and samples have been positive skewness and sorting average. Sorting good indicator of river flooding and sediment samples 4 may be the side that is not there to carry sediments. Samples, 6, 7, 9 and 10 will be caused by the action of wind and removing the sediment is fine. Cumulative curves of samples, 6, 7, 9 and 10 bends upward, which indicates the presence of flooding and sediment side. According to the geological map of examples 6, 7, 8, 9 and 10 near the deposition of alluvial zones, flood, sabkha, salt mud, sand clay coastal been picked to be the origin of the sediments when torrents or the sediments brought by the wind to the region. The average median and mean of the samples is high In addition more examples that show relatively good sorting, so it can be said, sediments have traveled low distance from origin to the samples area. More sediment samples diameter in classes 125 and 250 microns, the median in the sample were on average 210 microns, the mean diameter grains in a sample of 178 microns and more samples were sorted relatively good show so are constituent particles hill not far from the lands of origin are close to the samples.
ConclusionRegarding to average diameter of mean and most of the samples had better compatibility, it can be said that distance of sediments carrying was less. Similarity of average diameter of grains is the sign of lack of energy fluctuation in sediments environment. Negative skewing, better compatibility, existence of sea fossils and transparent grains in 1, 2, 5 samples determine coastal source for samples. We can see positive skewness and good sorting compatibility biomodal histogram and Curvature of accumulative curve of 6, 7, 9, and 10 samples is marker of river overflowing materials. Thus it can be said the origin of the samples is river.
فصلنامه اطلاعات جغرافیایی (سپهر), Volume:26 Issue: 101, 2017
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