Effect of  physiographical location and geological formations age on weathering of some Iraqi soils

	Effect of physiographical location and geological formations age on weathering of some Iraqi soils
journal of kerbala university
Article 1, Volume 10, Issue 1, 2014, Pages 133-144 PDF (0 K)
Abstract
Five locations for soil pedons were chosen, within the coordinates (42º13'49ʺand 45º55'59.0ʺ)east of longitude and the coordinates (32º15'60ʺand 34º48'17.51ʺ)north of latitude from the middle of Iraq, having the case of variation in the topographic and geologic formation affecting the genetic and formative condition in the region .Soil pedons were exposed and described according the survey manual used in Iraq . Soil samples were taken from all soil horizons for chemical ,physical and mineral analysis. Results indicated that the studied soils showed variation in the formative condition, viz; in the type and thickness of horizons and their arrangement because of locational factors for each Pedons as well as the impact of dry environmental conditions. All soils involved in this study did not show a certain pattern of distribution of soil fraction with the depth in all soil pedons reflecting the weakness of pedoginic process responsible for the composition as a result of the impact of the sedimentary condition for parent material and the prevailing drought conditions. The reason of prevailing coarse texture in soils to the nature of the parent material originally, as well as the content of gypsum and limestone that present with the sizes of different sands The results indicates that the original source, which derived from it minerals components formative for the study soils is mainly metamorphic rocks and low degrees of turning and high degrees of transformation and igneous rocks (acidic and alkaline) and sedimentary rocks re-deposited. It also indicates that there is a similarity in the nature of the mineralogical composition of the soils, involved in the current study, in terms of proportions of distribution of light and heavy minerals and variations. The results showed the prevalence of effect of the parent material on the rest of the soil formative factors in determining the mineralogical composition of most soils that reflect the nature of the geological formations and the physiographical locations .It was also found that there was a difference in weathering index values of light and heavy minerals resistant to weathering to the easy weathering between the same horizon. The results indicated high rates of weathering index values for heavy minerals in soils which represents the desert regions of the oldest geological ages. Weathering index values were found to be high for light minerals in soils that represent the sedimentary regions of modern geological ages because of their effect in the value of feldspar mineral caused by the fluctuation of the ground water level .

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