Iranian Journal of Earth Sciences
Volume:6 Issue: 2, Oct 2014

GIS is considered an important technique as well as a prerequisite for cost effective mineral exploration and determination of high potential areas. The purpose of this research is to determine high potential iron zones for detailed exploration using index overlay GIS method. Index Overlay was used to combine the geology, topography (scale: 1:1,000), lineaments, remote sensing (ASTER and ETM+) and geochemical data. Appropriate weights were allocated to each layer based on the significance of each data layer. Concentration-area fractal method was applied to data acquired from trenches in order to isolate iron anomalies and add them to the geochemical layer. Evaluation of the information layers along with fractal analysis, differentiated three geochemical iron populations. By combining the information layers obtained from GIS, high potential zones were determined. Regions with codes 1, 2 and 3 are the most promising areas, respectively, and are proposed for more detailed exploration and drilling.

The Tazerj travertine deposits are located 25 km northwest of Haji Abad and 5 km northeast of Tazerj Village in Hormozgan Province, southern Iran. This area is part of the Folded Zagros Zone. The studied travertine deposits are located on Eocene deposits and were most likely formed through the dissolution and re-deposition of groundwater and atmospheric waters onto the Asmari limestone. The petrographic evidence shows calcite to be the dominant mineral forming the microscopic sections of the Tazerj travertine deposits. The textural characteristics of the sediments confirm that microbial and biological activity was present at the time of deposition. XRD results confirm the existence of calcite-type calcium carbonate. In addition, XRF results confirm low levels of strontium and relatively high levels of magnesium. Finally, the geological evidence indicates that the rocks were created as a result of tectonic activity. The circulation of atmospheric deep water and its reappearance on the ground as hot springs through fractures and faults, formed meteogenic travertine deposits in Tazerj along large faults and fractures. The temperature of the hot springs responsible for creating the travertine deposits is estimated at approximately 30 °C.

The objective of this study is to identify the most suitable portions of the C1 coking coal seam in the North Block of the East-Parvadeh coal deposit (Central Iran), according to ash and sulfur values, using C-N fractal modeling. Based on the C-N log-log plots, different geochemical populations were evaluated based on their sulfur and ash content. They were then divided into five populations each according to their sulfur and ash percentages. The first sulfur containing population, located in the northern and western sections of the area, contains the best quality coking coal. The sulfur content ranges from 0-1.51%, known as “very low”. Situated primarily in the western and northeastern sections of the North Block are two ash populations with ash values between 0 and 12.88%. Known as “very low” and “low”, they are also of suitable quality for coking coal.

This research focusses on the biostratigraphy and paleoecological implications of the carbonatesof the Asmari Formation. The Asmari Formation is located in the Siah Kuhanticline of Izeh, Zagros Basin, SW Iran. It is of Late Oligocene (Chattian) - Early Miocene (Burdigalian) age. In this stratigraphic section, the Asmari Formation overlies the Pabdeh Formation and underlies the Gachsaran Formation. It consists of cream-colored limestone intercalated with marl. 182 thin sections were prepared and the benthic foraminifera distribution analyzed. Examination of large benthic foraminifera from the 228 m-thick Asmari Formation led to the identification of 3 biozones: the Lepidocyclina- Operculina- Ditrupa Assemblage Zone, Miogypsina-Elphidium sp. Assemblage Zone and the Borelis melocurdica- Meandropsina iranica Assemblage Zone.

Landslides are among the most damaging natural hazards in mountainous regions. In this study, landslide hazard zonation was conducted in the Baba Heydar Watershed using logistic statistical regression to determine landslide hazard areas. First, a landslide inventory map was prepared using aerial photograph interpretation and field surveys. Next, ten landslide conditioning factors including altitude, slope percentage, slope aspect, lithology, distance from faults, streams, villages and roads, land use, and precipitation were chosen as effective factors on landslide occurrence in the study area. Then, a landslide susceptibility map was constructed using a logistic regression statistical model in a geographic information system (GIS). Relative Operating Characteristics (ROC) and Pseudo R2 indices were used for model assessment. Finally, a risk map was created based on a risk equation using a combination of the susceptibility map, elements at risk and vulnerability. Results showed that the logistic regression statistical model provided slightly higher prediction accuracy of landslide susceptibility in the Baba Heydar Watershed with ROC equal to 0.876. The results revealed that about 44% of the watershed area was located in both the high and very high hazard classes. Additionally, 35% of the surveyed watershed was located in the high and very high-risk classes. This information is critical for the risk management, landslide risk and land planning of this mountainous area..

Both the Sistan Suture Zone of eastern Iran and the Nehbandan Fault contain Plio-Quaternary Nehbandan mafic lavas. Positive anomalies in the large ion lithophile elements (LILE) and negative anomalies in Nb (niobium) exist in these mafic lavas. This indicates the occurrence of subduction magmatism and post-collision volcanism. Petrologic and geochemical analyses distinguished two groups of lava. Group I contains alkaline basalts with a slight depletion in Nb while Group II contains sub-alkaline basaltic andesite to andesite with a sharp depletion in Nb. Geochemical studies show that fractional crystallization and crustal contamination played an important part in the evolution of the Nehbandan lavas. Group II, however, was more greatly affected than Group I. Geochemical studies also indicate that these lavas may have been generated due to a low degree of partial melting (<5%) of garnet and the spinel-bearing lithospheric mantle; Group I shows more garnet than spinel while Group II shows the opposite. The research carried out for this paper suggests that the Plio-Quaternary Nehbandan mafic lavas were formed as a result of slab detachment or delamination and domination, an extensional condition correlated to the thinning of the crust and lithosphere in the Sistan Collision Zone. These conditions are concomitant with localized stretching along the Nehbandan Fault and the upwelling of magma forming mafic lavas.

In this paper the geometrical relationship of the folds which exist in the Folded Zagros Mountains, including Asef Mountain (northern Iran), were studied. The southern and western zones of the Zagros Mountains are called the Folded Zagros. These zones extend approximately 1,375 km in length with a width ranging from 120 to 250 km. Asef Mountain is located in northern Shiraz (from northern Sarda to the vicinity of Zarghan) and is part of the southwestern zone of the Folded Zagros. In this area, Cenozoic formations are folded due to the effects of the tectonic process. This study was done in order to identify these folding features. The results of this research indicate that the axial surface of the folding has a dominant northwest-southeast trend which does not conform to the general trend of the Zagros. The folds are placed into the classes: upright gently plunging, steeply inclined gently plunging, steeply inclined moderately plunging, upright moderately plunging, upright sub horizontal, moderately inclined sub horizontal and moderately inclined gently plunging with respect to their geometry and floating divisions (Fluety,1964), on the basis of axial surface and hinge line trends of the Cenozoic formations. Additionally, these folds are categorized in close and open fold classes on the basis of limb inclination (Fluety, 1964).

The area under study is located in northern Iran at 36° 47’ latitude and 50° 12'' longitude. It is 15 km from southeastern Deylaman. Petrological study of the kaolin mother rock (Eocene age) under a microscope shows that the rock is vitric tuff with a rhyolitic combination containing falcated and embowed glass shards. The thickness of the layer is approximately 20 meters, formed unconformably on a layer of conglomerate with a thickness of approximately 400 meters. Because the shards have a falcated and embowed shape and the percentage of reworked material within them is low, the tuff can be considered a type of pyroclastic airfall. The results of the study prove that ash falling occurred in the water. The stratabound layers show syngenetic deposits to be the main factor in the formation of the clay, bound as a result of alterations.