عنوان

تکامل خاک در واحدها و سطوح مختلف ژئومرفولوژی بر اساس بعضی شاخص‌های تکامل در منطقه مرند

Text of Note

shaped that caused geomorphic units and surfaces to seen repeated at south and north. At the south part mountain, rock and mantled pediments, young alluvial fan piedmont and alluvial plain are distinguished. This south part does not contain old alluvial plain and in north part does not exist alluvial plain. The mountain unit was rich in geogenic carbonate that transformed to pedogenic carbonate in upper parts of soil. The geogenic carbonate of parent material acts as source of carbonate for lower geomorphic units and surfaces and causes increasing of secondary carbonate in south rock pediment. Transported coarse fragments (>2 mm) from mountain unit and rock pediment start to deposit at the beginning of the alluvial fans and has produced coarse texture soil with sequences of discontinuity. The course texture sediments were caused more differences in soil characteristics of this units and piedmont and alluvial plain. Piedmont plain had finer sediments and relatively deep soils and alluvial plain is the last unit which has observed at south part of study area that its texture is finer due to more distance from sediment source. Also, in north part of the region units and surfaces and same as the south part and their difference is related to parent material of mountain unit (igneous). Generally Physicochemical results of studied soils showed that clay content, clay accumulation Index coarse fragment (>2mm), CEC, CEC/Clay, pedogenic and total Iron is following geomorphic situation and irregularly decrease from mountain to alluvial plain. In this manner changes of rock and mantled pediment surfaces in both south and north parts which disrupt the trend of changes and so surface stability is important factor in soil evolution. According to several indices, soils in alluvial fans of piedmont are different from other surfaces and clay mineralogy of soils show that the soils of rock and mantled surfaces of pediment have more kaolinite and illite in comparison with piedmont and alluvial plains and indicate young surfaces. The high content of smectite and vermiculite in piedmont and alluvial plains showed the evolution of soil and MISODI micromorphological index content of 5 in the south mantled pediment and 20 in piedmont and alluvial plains showed differences between evolution of soil in different geomorphologic positions. Generally, soil evolution in geomorphic units and surfaces in the both north and south parts of study area can be arranged as fallow: South part: AP>SPP>SRPS>SM>SMPS>SYA North part: NPP>NOA>NMPS>NRPS>NYA>NM -topography relationship using topography and geology maps and Google Earth software and then. 50 pedon soils were sampled according to geopedologic method. Finally after analyzing of soil samples and study of reflection between soil morphological, physivochemical properties and different clay minerals and Iron forms, soils were classified and their maps were prepared. Field studies and soil morphology showed that mountain, rock and mantled pediments, young and old allunial fans, piedmont plain and alluvial plain are common in the study area. Therefore topography, parent material and slope aspect are effective factors in changes of soil characteristics. Study area was valley-Marand region belonging to East Azarbyjan is one of the important cities for cropping especially orchard crops. Deep soil, nonsaline irrigation water and industrious people are the divine gift which has changed Marand city to the most important city in producing kitchen garden especially tomato. However, there are no base studies of soil to universalize the information of region. This study was carried out in 15000 ha in east of Marand with extension of investigation of soil evolution at various geomorphic units and surfaces based on some indices in Marand region which is located between 38 23' 55'' to 38 28' 59''N to 45 49' 16'' to 45 57' 12''E and with deifferent landforms of mountain, pediment and plain that form a valley. In this research work distribution of clay minerals, different iron forms and micromorphological features were determined in geomorphologic units and surfaces and used for investigation of the relationship between soil formation and rate of evolution in geomorphologic units and surfaces. Geomorphologic units and surfaces were distinguished based on soil