APPLIED SEDIMENTOLOGY
Year:2016 | Volume:4 | Issue:7|Papers Count:7

The Malayer–Esfahan metallogenic province in the Sanandaj-Sirjan zone hosted several various deposit and occurrences, which occurred in the Lower Cretaceous carbonated rocks at the point of metallogenic view. The Ahangaran Pb-Fe±Ag deposit (southeast Malayer) as the main deposit of this province, occurs mainly within Lower Cretaceous limestone, dolomitic limestone, dolomite and sandstone hosts. The main oldest rocks in the area composed of schist, slate, quartzite, and shale belong to Jurassic which overlaid on Triassic rocks due to disconformity. Mineralization with dolomitic alteration occurred as two types of ores including sulfide (Pb±Ag vein-type) and oxide (Fe-leached cap) ores. Petrographical and mineral chemical studies show at least three types of dolomites in fine crystalline carbonate host rocks of sulfide and oxide ore bodies, including fine-grained (RD1), medium-grained (RD2), and coarse-grained dolomites with zoning (RD3). RD1– and RD2-dolomites mainly occur in sulfide ore and RD3 dolomites occur in oxide ore. The composition of RD2 dolomites indicated high value of Fe (13.5 wt% in average), Pb (80 ppm in average), and Mn (1600 ppm in average), relative to RD1 dolomites. Formation of RD2 dolomites from ore-forming fluid is supported by evidences such as, high content of Pb (100 ppm) in RD2 dolomites, high correlation index between Pb and other Ca (R=0.57), Fe (R=0.60), and Sr (R=0.78) elements and adjacency of these dolomites to ore-bearing Pb veins, has been progress eventuality formation of RD2 dolomites from ore-forming fluid composition.

The Khaneh Kat Formation represents carbonate development of the Triassic sediments in the Zagros Mountains. This formation with a thickness of 691 m at the type locality in 110 km of east Shiraz was studied for facies analysis and reconstruction of sedimentary environment. Detailed field and laboratory investigations showed that the Triassic sedimentary succession in Khaneh Kat anticline consists of limestones and dolomites deposited in tidal flat setting and shallow, relatively quite portion of a carbonate platform. These deposits are mainly results of shallowing-upward cycles consisting of intertidal-supratidal (sabkha) facies repeated over and over in a tidal system under dry climate. In some horizons, the presence of laterally extensive carbonate storm beds has terminated the normal succession of peritidal facies. All these pieces of evidence suggest that the Khaneh Kat Formation carbonates in the study area were deposited in inner part of an open, storm-dominated platform. Comparison of this situation with the sedimentary environment of equivalent deposits in other parts of the basin confirms the widespread expansion of the platform and also the existence of an epeiric sea in Triassic period of these areas. Significant increase of evaporites and siliciclastics in the southern of High Zagros Fault revealed the paramount role of this bounding fault in controlling basin geometry and facies variations during deposition of the Khaneh Kat Formation. The results also indicated that the southern part of the basin was close to the coast and water circulation was restricted. In contrast, the reduction of evaporites and siliciclastics together with the existence of storm beds in High Zagros region showed a further development of marine environment in northern part and its relation to the Neotethys Ocean.

In this research, paleo-climatic conditions and diagenetic system of Bahram Formation (Middle-Upper Devonian) have been investigated using geochemical data of major and minor elements and also oxygen and carbon stable isotopes. For this purpose, three strati graphical sections of this formation including Cheshmeh-shir section (north east of Tabas) with a thickness of 180 m, Kamar-kuh section (south of Kashmar) with a thickness of 188 m and Hoze-dorah section (east Tabas) with a thickness of 192 m have been studied. The studied sections have been composed of thin to thick bedded, gray colored fossiliferous limestones. Based on the obtained geochemical data, the insubstantial values of d18O isotope (mean-7.66‰ at Kamar-kuh, -8.11‰ at Cheshmeh-shir and -8.21‰ at Hoze-dorah section) in most of samples and also normalized ratio by calcite for strontium versus iron and manganese values indicate a relatively open system and high rate of water-rock interactions. The combination of elemental analysis results (including low ratio of Sr/Mn and high Mn content) and the trend of carbon and oxygen isotopes values reveal that the meteoric diagenesis has had the most important effect on these deposits.The calculated sea water temperature at the time of deposition of the studied sections using δ18O values has been estimated between 41o and 45o Celsius which is somewhat higher than the expected temperature for this period of time and might be due to the effect of diagenesis.

In order to study sedimentology, depositional settings and organic geochemistry in the southern part of the South Caspian Basin, 124 surface samples were taken from shallow to deep water with utilizing Van Veen Grab. All samples were analyzed for total organic carbon (TOC), S2 (Rock-Eval Pyrolysis), biota content (bioturbating organisms), particles size and mineralogy. Based on shallow seismic data, a range of depositional settings were distinguished including delta, shelf, slope, and basin plain. Composition of samples revealed detrital particles (quartz, feldspar, muscovite, carbonate and non-carbonate rock fragments and clay minerals (illite, chlorite, kaolinite, smectite)), as well as organic/biogenic components (i.e. bivalves, gastropods, ostracods) and non-skeletal particles (i.e. mud peloids). Several factors (e.g. TOC, organic matter type, biota content) suggest that these sediments were deposited under markedly different redox conditions, namely: (1) shelf and slope settings (oxic sediments), (2) basin plain settings (dysoxic sediments). The dysoxic sediments are enriched in type II organic matter (OM) with high TOC content (>1wt. %) while the oxidized sediments are enriched in infaunal organisms (i.e. ostracods and gastropods), and contain type III OM with low TOC content (<1wt. %). These evidences suggest better preservation of OM in the basin plain setting (deeper areas). Type III OM implies terrestrial input to the shelf and slope.

Groundwater has important role to supply fresh water in the world. In this study, chemical quality parameters of the Dehloran plain groundwater including: cations, anions, the electrical conductivity (EC), concentration of total dissolved solids (TDS), total hardness (TH), sodium absorption ratio (SAR), percent of sodium (Na%) and PH were studied in a 5-years period (2010-2014) in the 10 wells and 100 samples of Water Organization of the Ilam Province. Cations concentrations is as Ca2+>Na+>Mg2+>K+ and Anions concentration is as Cl->SO42->HCO3-. In the five years period (2010-2014). The maximum and minimum of groundwater quality in the Dehloran Plain are as: EC=946-7811 (mmohs/cm), TDS=614-5233 (mg/l), TH=246-3020 (mg/l), SAR=1.19-11.64, percent of sodium (Na %) =7.38-65.02 % and PH=6.89-7.95. According standard indexes of Shoeller and Wilcoks, the Dehloran plain groundwater about some quality parameters such as: the electrical conductivity (EC), concentration of total dissolved solids (TDS) and total hardness (TH) is not appropriate for potable and agriculture, but it have not any problem about sodium absorption ratio (SAR) and PH, can be considered as appropriate for potable and agriculture consumption. Results show that the SAR having high correlation coefficient (0.69) with sodium ion. This correlation shows sodium ion emplace calcium and magnesium ions in colloidal soils. The sedimentary rocks formations have effective role in variation of quality of groundwater in the Dehloran Plain. The gypsum and evaporated rocks (Gachsaran formation) and carbonate rocks (Asmari formation) have caused to decrease groundwater quality. Correlation between HCO3- with Mg2+ (45%) and with Ca2+ (16%) show that the carbonate – dolomitic Asmari formation may be has been more effective role in produce of Mg2+ than to Ca+2. We can suppose that origin of major cations (Ca2+, Na+) and major anions (Cl-, SO4+2) of the Dehloran plain groundwater are evaporatic Gachsaran formation and origin of anions and cations with low abundance (Mg+2 and HCO3-) are carbonate-dolomitic Asmari formation. Origin of some parts of the Mg+2 cations can be marly and shaly members of the Pabdeh and Gorpy formation. The detrital rocks (Bakhtiari conglomerate) have been not effective role in decrease Dehloran plain groundwater quality.

Tsunami study as one of the most serious forms of coastal hazards, is favored by many engineers, planners, and politicians. Depositional effects of the tsunami subdivided to sedimentary and geomorphic landforms. This article is about the sedimentation processes associated with tsunami inundation in the northern coast of Oman Sea (Makran). Tsunami inundation features of flooding are very diverse. At first, this paper presents a conceptual model of coastal tsunami sedimentation processes deduced from the case studies and outlines diagnostic features of tsunami deposits, and then reviews the presence or absence of these features in a storm deposits. Random pits drilled in some of the water entries on the northern coast of Oman from Chabahar to Beris and the sedimentological sequence is investigated in them. Experiments such as granuluometry by wet and dry sieve, hydrometry, calcimetry, and X-ray Diffraction (to recognizing minerals) done. Some pits shows finning upward sequences, Rip Rap structure, shell fracture accumulation, and sudden change in sediment. According to the observed sedimentary structures, sorting, tilt, percentage of calcium carbonate and terrigenous debris, possible deposit of tsunami are detected. The aim of this study has also been to evaluate the ability of sedimentology in detecting evidence of tsunami sediment off the coast of Makran.

The Qom Formation in Talenkuh section with 605 meters thick is located 50 kilometers Southwest of Semnan and includes six rock units which mainly consists of limestone, alternating of limestone and marl, marl, marly limestone, and gypsum. Lower boundary of the Qom Formation in this section with Lower red Formation is unconformable and its upper boundary is missing by faulting or erosion. By biostratigraphic studies, 34 genera and 18 species of benthic foraminifera were identified. Three assemblages have been recognized by distribution of these benthic foraminifera in the studied section that indicate Chattian? Burdigalian age. Field evidences and petrographic studies together with microfacies analysis, led to recognition 1 conglomerate lithofacies, 1 evaporite facies and 10 microfacies that deposited in 5 sedimentary environments consists of: supratidal, tidal flat, lagoon, shoal and shallow open marine. Therefore, for the Talenkuh section, a carbonate platform in the homoclinal ramp has been suggested.