Iranian Journal of Earth Sciences
Volume:14 Issue: 4, Oct 2022

Excavability is a measure of material which can be excavated with classical excavation equipment. Studies to decide the rock excavability characteristics contribute to the suitability of engineering projects. In this study, a limestone quarry (in Bayburt, Turkey) was analysed with excavability classification systems and appropriate systems were determined. To accomplish this aim, point load index and Schmidt hardness tests were practiced and changed to uniaxial compressive strength tests. After that, findings were categorized with classification systems in excavation and matched against practices from field. In this study, rock mass was addressed as “pre-explosion”, “hard ripping” and “hammer and blasting” in accordance with distinctive classification systems. All determined as rock mass should be blasted for loosening then dug with hydraulic breakers. This practice is totally compatible with in-site excavations fulfilled. According to study results, the most suitable parameters to decide surface excavational classification are load strength index, geological strength index and the degree of rock mass weathering.

Khyber Formation of Paleozoic age, has been studied here to access its physiochemical and mechanical characteristics. There has been several studies on the sedimentology of the Khyber limestone, however, much more detailed study is required to understand it aggregate potential in desired resolution and precision. It is achieved by understanding the rock types, microscopic textures and physical/ mechanical properties. The Khyber Formation is widely exposed in eastern and central parts of district Khyber, Khyber Pakhtunkhwa (KP) Province, Pakistan. It is a thick bedded hard limestone unit. The carbonates in the Khyber Formation are dominated by calcite, with dolomite, and other accessory minerals as minor component. The mechanical and physical properties of aggregates like specific gravity (2.69), water absorption (0.80%), soundness (2.34%), Los Angeles abrasion value (23.60%), aggregate crushing value (12.18%), aggregate impact value (12.76%)  flaky index (10.15%), elongation index (13.02%),  California bearing ratio (90.35%), coating and stripping values (96.32%), Schmidt rebound attains (34.23) and compressive strength (38.58Mpa) are according to the available standards. The petrographic analyses of samples of Khyber Formation and energy dispersive X-Rays analysis (EDX) illustrate that it dominantly consists of calcite (88-92%) with small to trace assemblage of dolomite (2-8%), ungraded quartz (1-3%) and ores (1-2%). The chemical and petrographic examinations show that the limestone units of the Khyber Formation are inoffensive in terms of Alkali Silica Reaction (ASR) and Alkali Carbonate Reaction (ACR). These characteristics of the limestone units demonstrating that these deposits are potential aggregate for large-scale projects in the KP Province (Pakistan) and region.

This study provides a evaluation of the initial carbonate mineralogy, and diagenetic condition of the Ruteh Formation, a middle-late Permian carbonate sequence, in the Emarat section in Central Alborz, northern Iran. 200 samples were examined for petrographical contents and thirty-four samples were collected for geochemical analysis. The high Sr and Na contents, Sr/Na>1, and the presence of dolomites and dissolution fractures are indicative aragonite early mineralogy. The diagenetic process in the Ruteh Fm. are an indication of the marine, meteoric and burial diagenetic environments. The original carbonate texture in the Ruteh Fm. are Severely affected by diagenetic process. The data obtained from the values of the Major (Ca and Mg), minor (Sr, Na, Fe, and Mn), oxygen and carbone isotopes show the initial aragonite composition of the Ruteh Fm. deposited in a subtropical shallow water. An open diagenetic system was indicated by changes in the values of Sr / Ca and δ18O vs. Mn. The shallow burial diagenetic temperature of the Ruteh carbonate was approximate 28.6°C with the maximum diagenetic temperature of 53.4°C.

The separation of geochemical anomalies from the background plays a pivotal role in geochemical exploration. Fractal and multifractal modeling of geochemical data has been recently used by numerous geoscientists. Three fractal methods were used to identify elemental geochemical anomalies in a case study from the east of the Qhaen region, southern Khorasan Province, East of Iran. These methods include concentration–area (C–A), concentration–perimeter (C–P), and concentration –number (C-N) methods. Copper mineralization occurs as vein and veinlet. Based on the analysis of heavy mineral samples, Cu contents are also observed in the southeastern, northern, and eastern parts of the Qhaen ore district, which are consistent with the results of the C–A fractal model and are genetically correlated with the andesitic unit. Indeed, after fieldwork and comparing the types of fractal models calculated, it can be concluded that the results obtained from the concentration-area method in this area were more efficient than other methods and are closer to reality.

The Tarom metallogenic belt of the Alborz magmatic belt in NW Iran is characterized by two alignments of intrusion in its northern and southern parts. The northern intrusion is younger than the southern one. Mineral chemistry investigations on the northern and southern intrusions characterize calc-alkaline magmatism. The northern intrusion consists mostly of quartz monzonite, and the southern intrusion comprises 1) gabbro - pyroxene quartz monzodiorite – quartz monzodiorite series and quartz syenite; 2) gabbro-diorite. Electron microprobe chemistries indicate that the northern plagioclases are An22 to An49 (oligoclase to labradorite). Plagioclases from the southern intrusion are An35 to An54 (andesine to labradorite) and gabbro-diorite plagioclases are An65 to An61 (labradorite). All pyroxenes correspond to the Quad (diopside, augite, and clinoenstatite) and crystallized at <2 to 5 kbar and H2O=10%. Formation temperatures of pyroxenes from the northern intrusion are in the range of 1100-1175°C. The northern feldspars show temperatures ~550°C. Formation temperatures for the clinopyroxene and feldspar from the southern intrusion are estimated at 1140-1185°C and 550-600°C, respectively. The Fe-rich biotite minerals from the northern intrusion suggest high oxygen fugacity magma. The northern and southern intrusions formed in an arc-related tectonic setting. The northern magma is sourced from the melting of a mixed mantle-crust in a subduction-related environment. The mineral composition of the northern intrusion implies magma fertility and porphyry mineralization which can be due to its high oxygen fugacity magma and lower crystallization pressure relative to those of the southern intrusion.

In this research, remote sensing and aeromagnetic data sets were integrated to investigate structural features and alteration zones of Rashid-Abad mining area. This area is located approximately 45 km north of Zanjan, in the Alborz (western)-Azerbijan zone, NW Iran. For this reason, two main lineaments with the E-W and NW-SE trends were detected using a sun-angle filter of OLI data and, analytic signal (AS) and first-order vertical derivative (FVD) techniques of aeromagnetic data. The other lineaments with other trends in the area are controlled by the same two major lineaments. In order to identify alterations, the methods of band ratio (BR) in ETM+ and OLI, false-color composite (FCC), relative absorption band depth (RBD), and spectral angle mapper (SAM) in ASTER image processing were used in the study area. The results showed the presence of iron oxide, argillic, phyllic, propylitic, and silicic alterations. Also, the area’s aeromagnetic response to different alteration regions was investigated by matching aeromagnetic anomalies with alteration zones. In addition, it was concluded that, iron oxide alterations with negative magnetic anomalies, phyllic alterations with moderate positive magnetic anomalies, and also argillic and silicic alterations with moderate to increasing positive magnetic anomalies were associated. Also, propylitic alterations did not show a significant relationship with magnetic values.