تاثير مواد مادري و تحول خاك بر ويژگي هاي ژئوشيميايي خاك هاي جنگلي منطقه فومن- ماسوله

The Effect of Parent Material and Soil Development on Geochemical Characteristics of Forest Soils in Fuman-Masule Region

Geologic and pedologic controls are the main factors determining the distribution of elements in natural soil environments. In order to assess the role of these factors in the content and distribution of major elements of soil, six parent materials including phyllite (Ph), tonalite (To), periditite (Pe), dolerite (Do), shale (Sh) and limestone (Li) were selected in Fuman-Masule region. Soil genesis and development of representee residual pedons were studied for each parent material. Total content of Si, Al, Ca, Mg, Fe, Mn, K, Na, Ti and P of soil horizons were measured and compared to the geochemical and mineralogical composition of parent materials. Maximum concentrations of Fe203 and MgO were found in the soils derived from Pe and Do; however, these soils had low content of Si02 and A1203, which is in conformity with the geochemical composition of the parent rocks. On the contrary, FeCBD content of these soils was lowest, indicating the low degree of soil development and, by the same fact, the importance of inheritance factor in soil Fe concentration. However, comparison of total Fe and FeCBoin Lil, Sh2 and To2 revealed that relative development of these pedons is higher than the others. Silicon depletion in Phi, To2 and Sh2 pedons, relative to parent rocks, is higher than in Pe and Do pedons. However, this element is enriched in Li pedons. MnO content of Pe and Do pedons is governed by geogenic factors, while in Sh pedons, pedogenic factors, especially redox conditions, play the major role. Exchangeable forms of Ca and Na are determined by soil properties rather than by parent material type. Notwithstanding the redistribution of all major elements throughout pedons due to soil forming processes, the importance of inheritance factor in soil Si, Al, Mg, Fe, K, and Ti is higher than pedogenic factors.