JOURNAL OF GEOTECHNICAL GEOLOGY (APPLIED GEOLOGY)
Year:2008 | Volume:4 | Issue:3|Papers Count:8

Landslides are among the most costly and damaging natural hazards in mountainous regions of Babolrood Watershed. The watershed is one of the major water basins in Mazandaran Province in which drain the water of northern part of Alborz Mountain into Caspian Sea. Due to the high density of population, farm lands, forests and infrastructure installations such as dams, roads and power lines, it is necessary to carry out the investigate of slope instabilities in the area. The aim of this work is to obtain an estimate of areas susceptible to landslide and to suggest mitigation methods to reduce the destruction effect of the hazard.Although many factors affect the instabilities of slopes, but in this research only the type of rock and the related geological formation is considered as a main factor. In this regards the locations and the type of landslides occurrence are distinguished and the information were plotted on geological based map. Then by the aid of ARC-GIS-9 program, and the use of Area Density Method, the percentage of landslide events in each geological formation was identified. The results show that marl, mudstone and siltstone of Neogene’s deposits have high potential of Area Density of landslides. On the other hand, Shemshak Formation presents the highest number of landslide events. Carbonate rocks of Delichai, Lar, and Elika Formations were among the most resistible to landslide.It is also concluded that due to high rate of annual precipitation in the area, rocks with high percentage of clay minerals are more susceptible to landslide than others.

The metamorphic units of structuring zone of Sanandaj- Sirjan in Aligudarz includes complexes of bedding rocks of precamberian – paleozuic. That contain in them resource kinds of structuring, decorative and façade rocks. The noticeable feature of this area is the proliferation of occurrence of carbonate metamorphic rocks (metamorphic limse) besides granitoid intrusive massives that have granted an excellent situation to this area. By use of desert operation and conducted discovering in the area, investigated bad rock horizons include two kinds of magmatic and carbonates resources. The resources of carbonates rocks that are mostly observed in precamberian-permian units include lime and dolomite marble (known as crystal and rock bedding) and magmatic rocks resources of granite- granitoides kinds. In addition to this, the constructing geology investigation of the area under study indicates two dominant general processes of split in south – eastern – north – western and south – western –north – eastern.

The study of each part of petroleum system is necessary. However, recently, petroleum geologists focused their attention on the study of source rock, migration and accumulation with use of different geochemical methods. Of these, carbon isotope and biomarkers or chemical fossils are new scopes in petroleum geology especially in correlation. The member 1 of Gachsaran formation divided can be into 6 keybeds that B keybed is very important specially in drilling of Pazanan oil wells. The aim of this study is the evaluation of the cap rock in the Pazanan oil field in view of lithology, isotope and chemical variations. Bituminous shale sample was analysed geochemically. The analytical data of Bitumen`s biomarkers belong to member 1 of Gachsaran Formation applied to evaluate sedimentary basin and maturity evaluation of probable source rocks in the caprock. The presence of tricyclic terpanes, bisnorhopane and low quantity of Gammacrane index is subsidiary of low salinity.Some organic geochemical indicators of caprock are also indicating lagoonal environment. Maturity analyses showed that bituminous shale of keybed B is immature. d13C in extracted saturate and aromatic parts of bitumen is measured -25.1 and -22.8‰ respectively. Carbon isotope value (d13C) of carbonate samples is -20.7. The value d34S of anhydrite in mudstone is 16.6-16.8‰, but it increased in anhydrite samples (20.8-21.1‰).These values reflects the presence of two fluids, diagenetic (brackish) and primary sea water. This measurements indicating non-marine source. These data and lithological variations verify a Sabkha-lagoonal environment. The hot-wet and hot-dry climate can be concluded.

The study area is located in south-east of Iran, in Zahedan-Bam road. Antecedent River and pull-apart basin are structures which formed in due to faults system. Antecedent Rivers has fix path and faults acts cannot changes the river path so river changes the lateral walls. Pull-apart basin formation in transtentional strike-slip faults. These features from the geological and the geomorphological aspects are worth mentioning and the study of them can provide us valuable data about the geomorphical evolution of the area. Undoubtedly, the major Faults of this area (Kahurk & Nosrat Abad) have had an important role in constructing these structures. In this study by processing the satellite data, the features has been clarified and analyzed by field data. Nosratabad and Kahurak Faults attitude in the formation these features have important rule.

This study is the first record of eight plant macrofossil species (Equisetale) from Shemshak Group in Imamzade Hashem, Central Alborz, between Mosha Valley and Ghale Dokhtar Village, including: Equisetites beanii, Equisetites cf. laterale, Equisetites cf. laevis, Equisetites muensteri, Neocalamites cf. meriani, Neocalamites carcinoides, Neocalamites hoerensis, Neocalamites nathorsti.According to their stratigraphical distribution, Rhaetian and Middle Jurassic age can be inferreded for the sediments containing them.

Tarbur Formation in the east of Lordegan includes mainly limestone, 182m thickness.Tarbur Formation lower contact with Gurpi Formation is disconformity and Upper contact with Pabdeh Formation, graded. Age of Tarbur Formation based on index fossil is Middle to Upper Mastrichtian (Upper Cretaceous). Microfacies include grainstone, wackestone to packstone and wackestone that shows open marine, bar (reef) and lagoon environment in the study area. Tarbur Formation in the study area deposited in Epicontinental platform.

The assessment of groundwater vulnerability to nitrate pollution in Hamedan-Bahar plain, west of Iran, has been conducted through modifying weights of DRASTIC parameters via the use of simple statistical methods. Also the weights of parameters were assigned based on Analytical Hierarchy Process (AHP) under a Geographical Information System (GIS) environment. In addition to usual ratings of DRASTIC method, the present research has also used a fuzzy method for scaling criterion maps as well as their preparations for integration. Further, Spearman' s rho coefficient and Kendall ' s tau coefficient have been employed in order to determine suitable weight in the DRASTIC model from the correlation between nitrate concentrations and DRASTIC parameters. As a matter of fact, it was distinguished that soil media, aquifer media and depth to groundwater with the weights of 5, 4, and 3.5, respectively indicate the highest correlation with the nitrate concentrations. Thus the new equation named as DAS (D: Depth to groundwater, A: Aquifer media, S: Soil media) was substituted with DRASTIC for assessment of groundwater vulnerability in Hamedan-Bahar plain. On the basis of the weights resulted from AHP method, both the deterministic and fuzzy layers of DRASTIC are integrated with each other, separately. After determining the correlation coefficients in different models, it is found that the DAS model with deterministic rating layers has the highest correlation about 70 percent with nitrate concentrations.For preparing pollution risk map, land use was considered as an additional parameter. The correlation coefficient between nitrate concentrations and pollution risk reached to 78 percent, using this paremeter. The risk map shows that 5% of study area is completely risky while 10%, 29.95%, 26%, 21.3%, 9%, 7% of it has very high, high, high to moderate, moderate to low, low, and the least pollution risk, respectively. Only 0.75% of study area is without any pollution risk.

This research studied the biostrigraphy of Upper Cretaceous deposits (Santonian –Masstrichtian) regarding to Coccolithophorids South east Isfahan, Central Iran. Nannofossils out of two sections from south and south-east Isfahan had good preservation and high variety. Lithostratigraphic unit have different thicknesses that, include marly limestone, shale, and limestone. Fine grained sediments, normally consisting of shale and marly limestone, have the best chance to contain nannofossils with respect to their content in calcareous nannofossils. The following genera and species were identified from deposits: Arkhangelskiella cymbiformis, Biscutum magnum, Braarudospheara sp., Calculites obscurus, Ceratholitoides self-trailiae, Ceratolithoides aculeus, Ceratolithoides amplector, Ceratolithoides brevicornicalans, Ceratolithoides kamptneri, Ceratolithoides pricei, Ceratolithoides sp., Cyclagelosphaera margerelii, Lithraphidites carniolensis, Lithraphidites quadratus, Lucianorhabdus cayeuxii, Lucianorhabdus maleformis, Micula murus, Micula praemurus, Micula prinsii, Nannoconus dauvillieri, Quadrum gartneri, Quadrum trifidus, Thoracosphaera opercula, Watznaueria barnesae.Most of them have good preservation and high variety. Totally 16 genera, 26 species related to the calcareous nannofossils have been identified.