Iranian Journal of Earth Sciences
Volume:7 Issue: 1, Apr 2015

Gold was obtained through washing or panning of the river sands during initial periods of civilisation. With the advent of knowledge of metallurgical processing of ores it was recovered through mining of in-situ quartz reefs, and then from auriferous sulphide ores. The metal mining activities are evidenced in the form of large number of ‘ancient metal mines’ or ‘old workings’ and ‘placer mining sites’ almost in all the States of India. Gold artefacts have been found in Early Harappan sites. Some of the ancient gold mines are found to be more than 200 metres deep, probably the deepest of that period in the world. Geological surveys, investigations and explorations initiated during nineteenth century, are being continued mainly by the field officers of Geological Survey of India in different parts of the country to locate the gold prospects i.e. past and the future. Ground geological and archaeological findings related to gold have been brought out by several workers. The voluminous data existing on the ancient gold mining activities has been synthesized here for an overview.

Tested water samples taken from the ophiolite region of Forumad show that most of the concentrations of calcium, magnesium, sodium, sulfate, potassium, bicarbonate, and nitrate elements are in the standard range. Hydrogeochemical studies of the water samples show the existence of magnesium sulfate, chloromagnesium, and chlorosodium. Results of measuring the physical properties of the water shows that the above values were lower than the 1053 standard of Iran and water hardness is higher than the standard in only some cases. Water pH in the studied region is within the alkaline range. Assessing the distribution of heavy metals through statistical methods (Pearson coefficient and cluster graph), two different origins (anthropogenic and lithological origins) have been identified that are responsible for the entry of heavy metals into the water resources of the studied region. The anthropogenic origin of the distribution of heavy metals in the region is due to local mining of the chromite and ophiolitic rocks and the lithological origin is a result of local mining of conglomerate and volcanic rocks. Evaluating the metal index of MI and HPI shows the water contamination by heavy metals. The zoning map shows that the metallic contamination surrounding Forumad village is low and reaches its maximum amount around the chromite Forumad mine. The qualitative index of GQI (non-metallic cations and anions including calcium, sodium, chlorine, magnesium, sulfate, and dissolved solids in water) shows that the water quality is within the acceptable range. Based on the zoning map, the water quality GQI index is higher in the downstream around Forumad village.

Organic geochemical evaluation of the Madbi Formation as the main source rock of the Al-Jawf Basin, NE Central Yemen was the main objective of this study. The organic geochemical methods used in the study include: rock-eval pyrolysis, total organic carbon, and optical measurements as the vitrinite reflectance and thermal alteration index. In this study, 67 well core and side-well core samples of the H-1 and K-1 exploratory wells of the Al-Jawf Basin were analyzed to calculate the several organic geochemical and optical parameters. The obtained results show the presence of strong source rock probabilities within the Madbi Formation in this basin. The results are classified into three categories: poor, fair, and good source rocks, with a mixed marine Kerogen type II/III and continental Kerogen type III. The maturation of source rocks was affected by heating and re-cycling of heat events during the Cretaceous and Tertiary periods. This interpretation is strongly related to the breakup of the southern Gondwanaland and the opening of the Red Sea and Gulf of Aden. Based on the evaluation of the source rocks, the shale, calcareous shale, and claystones of the Madbi Formation are considered the main source rocks in this basin. According to the present study, the hydrocarbon potentiality is good to fair grade in the Al-Jawf Basin.

Iran''s mud volcanoes are clearly visible on the coastal plains of the Oman and Caspian Seas. There are 30 Gatan Mud Volcanoes located in the southeast of Iran: 15 of which are located between Jask and Minab in Hormozgan province, nine are between Chabahar and Jask Ports, and another six are between Chabahar and the Iran-Pakistan border in Sistan and Balouchestan Province. After some studies and investigations, research was performed on some of the mud volcanoes in the western Jask city located in the west of lower Gatan village. Gatan is located in the eastern coast of Hormozgan Province between the counties of Jask and Minab and on the coastal region of Makran. Being located on the entrance of the Strait of Hormuz and due to marine currents, it has certain sedimentology circumstances. Formation of Gatan Mud Volcanoes is a result of rising muddy water along the faults and cracks in the crust to the earth''s surface. Results of mineralogical studies indicate that clay and limestone samples contain fossils and abundant minerals include quartz, albite, illite, calcite and dolomite.

Liquefaction is one of the most determinant factors in the collapse of transportation infrastructures. This is especially true for roads and railroads located on saturated, fine-sand substrates under seismic conditions. The damage and human casualties resulting from liquefaction highlight the importance of understanding and mapping this phenomenon. Soil liquefaction occurs as a natural hazard in saturated, loose sand due to increased pore pressure and low shear strength. The purpose of this study was to prepare a soil liquefaction hazard zonation map for Kordkuy County, located in Golsetan Province, using data collection, basic digital mapping (soil deposits map, ground water depth and earthquake acceleration map), three parametric Stanford Watershed Models (SWM) and ArcGIS software . An empirical liquefaction model as a function of the three studied variables was used to model liquefaction in four hazard classes using ArcGIS software. According to the results, most areas fall into the nonhazardous and moderately hazardous risk classes. A portion of the Eastern County was classified as highly hazardous due mostly to its close proximity to an earthquake focal point.

Understanding the folding style of a fold-thrust belt is crucial to understand the nature and structural history of structures that may trap natural resources within the belt. In this research, the geometry and mechanism of a number of fault-related folds has been investigated based on field data and satellite image interpretations. The main study areas are: the Sohrevard and Ushtaniyan anticlines, Bahman and Halab synclines, and Gharahdagh, Halab, and Gheydar thrust faults, which have a NW-SE direction. These thrust faults control the morphology and structural framework of the Halab-Gheydar area. Geomorphic features of the folds suggest that they are fault-related folds. The structural style of the faults and associated folds indicate that these faults were reactivated during the Alborz deformation event.

Metamorphic and various intrusive rocks in the Urmia area are located in a transpressed active continental margin. These complexes in the Zagros orogen were deformed during an oblique convergence scenario between the Arabian and Sanandaj–Sirjan blocks in NW Iran. The Urmia area contains both NW-SE striking dextral strike-slip and SW verging NE dipping ductile reverse shear fabrics. Ductile shear fabrics are overprinted by subsequent younger thrust and strike-slip fault systems. Abundant syn-tectonic granitoides have been intruded into the Urmia area during convergent. Shear deformation fabrics are well identified in both deformed intrusive and metamorphic rocks. The geometry and kinematics of shear fabrics indicate a deformation partitioning in both ductile and brittle conditions during a progressive transpression tectonic regime.

This research focusses on the facies distribution, paleoenvironment and paleoecology of the foraminifera of the Guri Member in the northern Bandar Abbas Hinterland located in the Roydar area of southern Iran. The Guri Member is 570 meters thick and composed of limestone, argillaceous limestone and marl. The distribution of the foraminifera in the study area indicates the existence of three biozones ranging from early to middle Miocene in age. Based on petrographical studies, depositional textures and fauna, eight microfacies were identified. The paleoecology, lithology and environmental interpretations were characterized by an open marine environment with an upward, gradually shallowing trend. Additionally, three distinct depositional settings were identified: tidal flat, inner ramp and middle ramp. Microfacies (MF) 1, representing a distal middle ramp setting, was characterized by the occurrence of hyaline, benthic and planktonic foraminifera. MF2 and MF3 were characterized by the occurrence of Miogypsina, Elphidium and red algae. They represent a deeper low energy in the wave base of a middle ramp setting. MF4 was characterized by an abundance of rotaliids and red algae representing a proximal middle ramp environment. MF5 and MF6 were identified by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water inner ramp setting. MF7 and MF8 were characterized by the occurrence of gastropods and bivalves in a shallow-water setting of tidal flats influenced by both wave and tidal processes. Palaeolatitudinal reconstructions based on skeletal grains suggest that the Guri Member existed in tropical waters within a carbonate ramp.

Conodonts are the most important fossil remains from the largest Phanerozoic extinction as well as the mass extinction of the late Paleozoic and could be used for exact dating during this period. Triassic deposits located in the Elikah Formation contain exposures in most of the Alborz sections as well as the Zal section in northwestern Iran. In this study, the Elikah Formation was investigated from a biostratigraphy point of view in the type section and Ruteh section of the Alborz Mountains and Zal section in the Jolfa region based on the existing conodonts. Biostratigraphy study of more than 300 samples taken from these three sections, resulted in the identification and introduction of the following conodont biozones: Taxone Range Zone Hindeodus parvus and Pachycladina symmetrica – Pachycladina Oblique Assemblage Zone in the type section, Hindeodus parvus Taxon Range Zone, Hadrodontina – Pachycladina Assemblage Zone and Parachirognathus – Furnishius Assemblage Zone in the Ruteh section and finally Hindeodus parvus Taxon Range Zone, Isracicella staeschei Taxon Range Zone and Arachirognathus – Furnishius Assemblage Zone in the Zal section. These biozones indicate that the Elikah Formation, in the three previously defined sections, is Early Triassic (Griesbachian). Additionally, comparison of the biozones in these sections illustrates a biostratigraphic correlation of Early Triassic deposits in the Zal, Ruteh and type sections.