Researches in Earth Sciences
Year:2010 | Volume:1 | Issue:3|Papers Count:11

Golestan province is always exposed to landslide hazard because of climatic and physiographic conditions. This paper presented a data integration framework based on the Dempster-Shafer theory of evidence for landslide susceptibility mapping with multiple geospatial data. For this purpose, the first landslides inventory map has been created by landslide points of Landslide Data base of Iran (392 landslide points). Then, effective parameters on landslide event such as slope, aspect, altitude, slope curvature, geology, land use, distance of drainage, distance of road, distance of fault, stream power index, sediment transport index, and the zone of rainfall were prepared as a layer in GIS environment. Using of Dempster-Shafer theory weight of each factor has been calculated. These weights were inputted in the effective factor maps and for each factor will be created a weight map. The sum of the weighted layers was used to generate the landslide hazard map. The efficiency of Dempster-Shafer theory in landslide hazard susceptibility mapping was evaluated using ROC and area under curve method. The results indicate that the Dempster-Shafer theory has enough accuracy for producing the landslide hazard zones in this case study.

Geographic information system (GIS) modeling is used in combination with three-dimensional (3D) rockfall process modeling to assess rockfall hazards. A GIS extension, RockFall Analyst (RA), which is capable of effectively handling large amounts of geospatial information relative to rockfall behaviors, has been used. The 3D rockfall model considers dynamic processes on a cell plane basis. It uses inputs of distributed parameters in terms of raster and polygon features created in GIS. Two major components are included in RA: particle-based rockfall process modeling and geostatistics-based rockfall raster modeling. Rockfall process simulation results, 3D rockfall trajectories and their velocity features either for point seeders or polyline seeders are stored in 3D shape files. Distributed raster modeling, based on 3D rockfall trajectories and a spatial geostatistical technique, represents the distribution of spatial frequency, the flying and/or bouncing height, and the kinetic energy of falling rocks. A distribution of rockfall hazard can be created by taking these rockfall characteristics into account for case study.

Gullies, as one of the water erosion’s form, are serious and minatory factor of environmental equilibrium and its sustainability. Study area in this research is Firouzkola cathment where located in Kojour district of Nowshar county of Mazandaran province. Gully morphometric data, using with survey of cross section of gully, measurement of depth and width in different sections, and slope of gully bed are obtained via field study. The data analysis was done using principal canonic analysis (PCA). The PCA result showed that total variance of axes (97.95%) has justified all variation of factors along with these axes. The evaluation exhibits that factor number one, as the most justification (46.616%), has maximum correlation to depth and rate of width to depth. The factors number two and three have justified the whole variance with 29.466 and 23.328 percentages, respectively. Correlation coefficient of axes with factors showed that width to the second axis (0.917), depth to the first axis (0.955), slope to the third axis (-0.890), and proportion of width and depth to the first axis (-0.895) have significantly correlated. In order to gullies sorting in this area, therefore, depth and rate of width to depth have preferred and have the most influence on ordination of gullies.

The phenomenon of informal settlement has followed the emergence of structural changes and the appearance of social and economic problems، such as changes in the method of production, structural changes in the relation between cities and villages and rapid urbanization. Informal settlement in third world countries and Iran is the physical outcome of the urbanization of poverty and structural elements from social, political and economic perspectives in national and intra-national scales. The continuation of urban poverty as the growth and expansion of slums and emergence of new quarters in around the cities leads to further deprivation and accessibility of cultural, social and economic opportunities to poor groups. Unequal distribution of income and weakness of support system in housing challenges the privative measures of informal settlement in the current situation of increasing land and housing price and it has caused problems in providing the poor with houses. This research studies the informal settlement and informal market of land and housing in Nasim shahr is a systemic way. It is tried to discover the causes for the emergence faces and development of informal settlement, as an aside, and to evaluate functions and original actors of housing and land market in this city and dialectic relations of them; on the other hand, research’s results have shown that informal settlements in Nasim shahr are resulted from seeking of shelter in low cost land, irregular and informal market. The main socio – economic have affected by lack of clear, good policy making in urban land use sector and informal land – housing market in this city.

Qom Formation deposits in the Ghohrud area with Oligocene-Miocene age and 325 m thickness located at 45 Km South of Kashan, consist of thin, mediume to thick bedded and massive limestone. These deposites overlay by Eocene volcanic rocks with disconformity and are covered by alluvium deposits. According to the field observation, lithological and macroscopic characteristics of the Qom Formation, four lithological units in Ghohrud area were recognaized. After taking 200 samples from this section, the depositional textures, petrography and fauna were studied and 8 microfacies from two subenvironments: open marine (A-D) and lagoon (E-H) were recognized. Based on microfacies analysis and field investigation, The Qom Formation in the study area is deposited on an open shelf environment.

Chahshalghami mineral index is located 190 km to the south of Birjand in the Lut Block volcanic-plutonic belt. Intrusive rocks of Chahshalghami include quartz monzonite, monzonite, granodiorite and diorite and classified as volcanic arc granites, high-K calc alkaline to shoshonite rocks. Processing Aster Satellite image has detected alteration minerals such as alunite, jarusite, chlorite, dickite, sericite, montmorillonite, quartz and iron oxide. Silicic, sulfide and stockwork zones show anomalies of Au, Cu, As, Bi, Mo, Sb, Pb and Zn. Microcrystalline and disseminated pyrite is associated with silicic alteration and many veins include molibdenite, chalcopyrite, sphalerite, galena and enargite. Intrusive rocks have similar trend on Harker diagrams for several major oxides, suggesting a common source and evolution of their magmas. Primitive mantle normalized trace element spider diagram display strong enrichment in LILE such as Rb, Sr, Ba, Zr, Cs and depletion in some high field strength elements (HFSE) e.g. Nb, P and Y. On chondrite normalized plots, display significant LREE enrichments and high degrees of La/Yb > 21.4-33.7 for intrusive rocks and the lack of Eu anomaly is evident. Sr/Y and La/Yb are respectively 31.6-72.2, 21.5-33.5 and cover characteristics of adakites and Sr-Nd isotope studies show that the source is related to the mantle melts contaminated by the lower crust.

Razi Abad copper index locating in Uromieh-Dokhtar volcano-plutonic belt has Oligo-Miocene intrusive igneous and Eocene volcano-sedimentary rocks. The index is situated 25km northwest of Jiroft Township. Accessing to the area is possible via Kerman-Jiroft road. Surrounding rock units of Razi Abad mineralization are dark beds of shale, volcano-sedimentary units, Eocene andesitic lava, and granular quartz diorite intrusive units. On the other hand, host rocks of the mineralization are Oligo-Miocene subvolcanic units having micro-diorite, micro quartz diorite, porphyritic quartz monzodiorite, and porphyritic granodiorite compositions. Too many acidic, intermediate, and basic dykes are observed in intrusive rocks. Potassic, potassic-phyllic, phyllic, phyllic-argillic, quartz-pyrite, propylitic, and argillic alterations with various intensities have occurred in the study area. Potassic, potassic-phyllic, and phyllic alteration zones contain mineralization.Finally, by considering enrichments and depletions of major, minor, and trace elements in the host rocks of the mineralization, several alteration stages are recognized for the area. Correlation between supraore and subore elements such as zinc and copper implies telescopic shape of the mineralization, which has formed during at least two high- and low-temperature phases. Thus, dominant source of the mineralization and hydrothermal fluids could be a hidden intrusion with porphyritic granodiorite unit. Primary mineralization has occurred by high-temperature fluids in porphyritic micro-diorite rocks and then it has happened in porphyritic granodiorite stocks. The latter phase has affected on pre-existing alteration and mineralization zones. Therefore, porphyritic micro-diorite rocks have undergone several alteration phases and it seems that the primary mineralization has become enriched during next stages.