Exhibition of lanthanide tetrad effect in PAAS-normalized REE patterns, and non-CHARAC (non-CHArge-RAdius Control) behavior of Y/Ho and Zr/Hf in limestone of the Ruteh Formation, Kanigorgeh district (NW Iran), were studied in order to understand the reasons of occurrence of lanthanides tetrad effects. The computed values show that the third and fourth tetrads can be used as a good and powerful geochemical tool for investigation of physicochemical conditions of the depositional environment of the limestones. Here, a new mathematical-based method using polar coordination system for tetrad effect values (Tp) was used to evaluate under studying limestone. The correlation between Tp and some geochemical parameters revealed that the limestone was likely deposited under two different conditions. The obtained results indicated that paleo-redox conditions, adsorption and scavenging by kaolinite and metallic oxides, degree of detrital input, diagenesis intensity, and complexation by polycarbonate ligands are likely the main mechanisms for occurrence of tetrad effect phenomenon in REE distribution patterns in the limestone. This means that tetrad effect phenomenon in REE distribution patterns of limestone can be applied as a good geochemical indicator to evaluate the deposition conditions in limestones., Ali Abedini, Mansour Rezaei Azizi and Ali Asghar Calagari., and Obsahuje bibliografii
Many of the known Tertiary porphyry Cu deposits (PCDs) are situated in the Central Iranian Volcanic Belt (CIVB). The study area is located in the southern part of the CIVB and southern part of the Kerman Cenozoic magmatic arc. This research highlights the significance of the synergetic use of operational land imager aboard the Landsat-8 (OLI), Sentinel-2, and advanced space-borne thermal emission and reflection radiometer (ASTER) data for exploration of copper mineralization in a mine scale. Multispectral images in the visible and near infrared bands of (0.45-1.0 µm) the OLI and Sentinel-2 were used to identify the gossan zones. ASTER short wave infrared (SWIR) data with the wavelength between 1.65 and 2.43 µm were used for mapping hydrothermal alteration zones. Laboratory spectra obtained from minerals such as muscovite and illite (phyllic alteration), kaolinite and montmorillonite (argillic alteration), epidote and chlorite (propylitic alteration) were applied in mixture tuned matched filtering (MTMF) algorithm on the ASTER data to enhance the existence of these minerals. The spectra of the index minerals from each alteration type were used in this algorithm and the abundances of minerals in the MTMF image were rescaled to be within the ranges of 34-54 %, 54-74 % and 74-100 %. and The studied mineralized zone is associated with the iron rich phyllic and argillic hydrothermal alteration types which can be best detected by using integrated ASTER, OLI, and Sentinel-2 images. The diamond drill cores data also indicate that copper is more enriched below the gossan zones. The gossan index minerals (GIM) including goethite, jarosite, and hematite were identified by X-ray diffraction (XRD) method, spectral analyses, and petrographic examinations. The Sentinel -2 data proved to provide remarkably better mapping result for iron oxide minerals than the OLI and ASTER data. The directed principal component analysis (DPCA) method, In the data of the Landsat-8 and Sentinel-2 were used for mapping of the gossan index minerals such as goethite, jarosite and hematite and the argillic, phyllic and propylitic hydrothermal alteration types were enhanced using the MTMF methods. The hydrothermal alteration pattern and the distribution of the gossans in the study area show a porphyry-type mineralization. This study showed that the synergetic use of different satellite images with different spatial and spectral resolutions can be used for mineral exploration in a large scale. The use of laboratory spectra obtained from hydrothermal alteration minerals in MTMF method depicts that the alteration minerals were mapped more accurately relative to those MTMF images that are derived from standard spectral libraries. The samples collected from the surficial hydrothermal alteration zones as well as diamond drill cores showed that the copper mineralization occurres mainly along the border of the phyllic and argillic alteration zones, and the magnetite mineralization in the propylitic zone.
Fluorite mineralization is controlled by the multiple geological processes such as structural control, geochemical characterization of hydrothermal fluids, temperature and depth. The mineralization associated with the alteration of the host rocks and trapping of fluid in the host rock crystallographic defects. Alteration in the host rocks due to circulation of hydrothermal fluids and several techniques were applied to discriminate the associated alterations in fluorite deposition using the ASTER images. The resulting images indicated that the fluorite mineralization in the studied area accompanied by propylitic and phyllic alterations. The results of micro-thermometry analysis of the fluorite hosted fluid inclusions indicated that the maximum homogenization temperature was 253 C°. These data implies that the temperature of hydrothermal fluids probably had an essential role in the propagation of the alteration zones. The depth versus homogenization temperature diagram for fluorite mineralization in the studied district revealed that the depth of fluorite mineralization varies between 33 to 256 m. Two fluorite generations were distinguishing in the study district. The first generation is characterized by high salinity (18-25 wt% NaCl) which developed on the deeper level and along the fault zone. The second generation is characterized by low salinity (6-13 wt% NaCl) on shallow depth and deposited in the fractures. The results revealed that fluorite deposition was not contemporaneous with host rock deformation and deposited in the late-stage deformation phase.