B Ebrahimi; A Seif
Abstract
This study has been carried out with the aim of mapping karst and evaluation of potential karstification of carbonates rocks in Zagros. One objective of this paper is a spatial evaluation of karst development in Zagros considering role of the chief factors affecting karst development. The main considered ...
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This study has been carried out with the aim of mapping karst and evaluation of potential karstification of carbonates rocks in Zagros. One objective of this paper is a spatial evaluation of karst development in Zagros considering role of the chief factors affecting karst development. The main considered factors are those classified by White (1988) into three driving forces (i.e., chemical driving force, physical driving force and hydrogeological setting). Precipitation, temperature, relief, rock type, tectonic setting and stratigraphic thickness of soluble carbonate rocks are the main factors classified to describe the mentioned driving forces. In this study, precipitation and temperature are represented by the chemical weathering conditions during the modern and glacial periods prepared on the basis of Peltier's graphs. All data are mapped, classified, weighted and managed in separate layers in GIS environment. The Karst Index (Ki) is introduced to define the modeled degree of karstification computed by proper combination of six weighted layers and the final theoretical karst map of Iran is prepared based on the ranked Karst Index. According to the combination method, values of Ki could be in a range of zero to 400. The classified theoretical karst map shows that out of 109,313 km2 of carbonate units (25 % of the surface area of the study area) about 34212 km2 (31.3% of carbonate rocks) have very low to low potentials for development of karstic features. About 61272 km2 (56% of carbonate rocks) have moderate potential and about 13829 km2 (12.7% of carbonate rocks) have high to very high potentials for karstification. In other words, 68.7% of the carbonate rocks are carbonate rocks with moderate to high potentials for karstification. Densities of caves and karstic springs are the main and the most important geomorphological features used to check the calculated degree of karstification. For this purpose, complete inventories of caves and springs in Zagros were made. 64 caves and 129 springs (with discharges above 10 l/s) occur in rocks in areas of very low to low potentials for karstification. About 132 caves and 300 springs fall in the moderate class and 51 caves and 162 springs in areas with high to very high potentials for karstification. Cave densities are 0.0014, 0.0020, 0.0022, 0.0036 and 0.0039 caves per square kilometers for very low, low, moderate, high and very high classes respectively. In addition, densities of springs are 0.0035, 0.0039, 0.0049, 0.0111 and 0.0131 springs per square kilometers for very low, low, moderate, high and very high classes respectively. In other words, densities of caves and springs show a good correlation with the evaluated karstification.
S. Alipour
Abstract
Yarim-ghayeh cave, located in the border of Iran and Turkey, is hosted by the Oliogocene-Miocene limestone body. Its in and outside rough topography implies that the cave is very young and infact in the beginning stage of its formation. Overall volume is 9600 m3 with 631 ...
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Yarim-ghayeh cave, located in the border of Iran and Turkey, is hosted by the Oliogocene-Miocene limestone body. Its in and outside rough topography implies that the cave is very young and infact in the beginning stage of its formation. Overall volume is 9600 m3 with 631 m2 dry area and 4700 m3 occupied by water with 4 to 6 meters in depth. Structurally, the cave has been formed by a fault system cause a sinkhole form on the top of the cave aproximately of 10000 m2. Its water is clean and clear with pH of 7.36 and its fluorine is only 1.7 ppm compared to 4.5 ppm in Maku area. Yarimghayeh playa with an area of 5 m2 is in the close eastern part of the cave with permenant water flow. Elevation of the water surface of playa is 1414 m which is 2 m higher than the water surface of the cave (1412 m). 500 m3 water is daily pumped out without any change in water level. Since there is no any other water flowing to the cave, therefore, the playa is supplying the cave water system. The ecosystem of the cave and playa are tight together and any change in one will affect the other. To protect its water quality from contamination, access to this small scale cave must be restricted except for scientific research.
