Iranian Journal of Earth Sciences
Volume:15 Issue: 3, July 2023

The present study seeks to characterize Ni-Cu mineralization at Mpemba hill in Blantyre, southern Malawi by using aeromagnetic and drill hole data. The area has been under-explored for this im-portant economic commodity and as such not much is known regarding its mineralization poten-tial. The minimal curvature gridding technique was utilised to grid the aeromagnetic data, and a grid cell size of 50 m was employed. The Ni-Cu host lithologies are characterized by high mag-netism, and are mostly ultramafic rocks. Drilling results indicates that the mineralization starts at depths from 50m and remains open. The area is associated with disseminated and blebby type of mineralization and the mineralization is associated with high magnetic signatures in ultramafic meta pyroxenite bodies yielding high base metal values. Euler model depths analysis of the mag-netic sources is deep, lies at 3.2 km depth and the shallower magnetic bodies lie between 100 m and 1km. The depth estimates show that the mineralization is near surface and goes deep, so fur-ther exploration should not be limited to shallow depth. The ultramafic rocks are potential sites for Ni-Cu mineralization in the area and Mpemba hill has a huge potential to find economic min-eralization suitable for mining.

The section located in WadiHajar, Haditha area, west of Iraq was sampled for microfacies analysis of the Euphrates Formation. Microfacies analysis led to the recognition of eleven microfacies association types; Mudstone, Peloidalgrainstone, ooidsgrainstone, Miliolids-Peneroplidsgrainstone, Peneroplidsgrainstone, Echinoidalwackestone, Miliolidswackestone, Alveolinidswackestone, Bioclasticpackstone, Peneroplidspackstone and Rotaliidspackstone, were deposited in restricted marine, shoal, and open marine environments. The study of the vertical succession of microfacies shows four primary 4th order cycles (1, 2, 3, and 4) each show a different episode of stills tands sea level rises. Cycle 1 is represented by LST of basal conglomerate followed by a thick succession of open marine facies of TST, overlain by sh0rt episode of still stand. According to minor sea level changes, cycle 2 is subdivided into 2a, 2b, and 2c consisting TST of bioclastic, miliolids, peloidswackestone to packstone, followed by thin HST consisting restricted marine facies. Cycle 3 consists of a short episode of sea level rise of TST followed by a long episode of sea level still standing and subdivided into 3a and 3b. Cycle 4 is marked by open marine facies (TST), overlain by HST of restricted marine facies. The low subsidence rate and eustatic sea-level fluctuation are the main factors that affect the study area.

Knowledge of the in situ stress state is an essential component in rock engineering, especially for underground spaces in civil, mining, petroleum geomechanics and geothermal energy projects. The most accurate methods of measuring the in situ stress of rock are direct and field measurement methods. However, since these methods are time-consuming and costly, indirect rock core-based methods have attracted specialists’ attention for estimating of rock stress memory. Methods based on the rock stress memory, including acoustic emission (AE) and deformation rate analysis (DRA), are among the common methods used for this purpose. In this study has been applied the DRA method to investigate rock type and its characteristic behavior in stress retrieval at different stress levels. To this end, four types of rocks (i.e., granite, zeolite, sandstone, and gypsum) with different behaviors and characteristics were used. The results show that the stress memory retrieval values in the elastic behavior region had better recognizable and higher felicity ratio (FR) for all types of rocks studied. Based on the results obtained from DRA experiments on these rocks, it can be stated that there is no logical and clear relationship between the type of physical properties of rocks and preloading stress levels and the results of stress retrieval.

The benthic and planktonic foraminiferal contents of the Bangestan Group (Sarvak, Surgah and Ilam formations) in the Sepid Kuh anticline in the Lorestan Zone, W Iran, were studied. Bangestan Group consists of limestone, argillaceous limestone, dolomitic limestone and marl with thickness of 5400 m. In this section Bangestan Group overlies Garu Formation disconformably and its upper boundary is not exposed. By micropaleontological study on 176 thin sections, 8 genus and 34 species planktonic foraminifera were identified. 400 m of Sarvak Formation has very little fossil diversity that does not indicate a certain age. For this reason, this interval was called the indeterminate zone, which due to its stratigraphic position, is probably of Cenomanian age. Based on the biostratigraphical range of planktonic foraminifera distinguished, four biozones can be identified: Helvetoglobotruncana helvetica Total Rang Zone (Early- Middle Turonian), Marginotruncana schneegansi partial Range Zone (late Turonian), Diacarinella concavata Interval Zone (Coniacian), and Diacarinella asymetrica Total Zone (Santonian).

The prospecting area is located in the eastern part of Iran. Aster and Landsat 8 satellite images were processed with different spectral analyses techniques to detect the clay representing the alteration zones, with emphasis on bentonite occurrences in the study area. Band ratio (BR), Spectral Angle Mapper (SAM), Mixture Tuned Matched Filtering (MTMF), Principal Component Analysis (PCA), Spectral Feature Fitting (SFF), and Least Square Fit (LS-Fit) techniques were performed to show the promising areas for clay mineral. Band ratios of 6/7, 6/5, and 4/2 from Landsat 8 OLI imagery and 4/6, 5/6, 5/8, from ASTER were used to enhance clay alterations. The results obtained from the supervised classification using the SAM algorithm for minerals from US Geological Survey spectral library (USGS) have been compared with the results of Jet Propulsion Laboratory (JPL) spectral library. The Sequential Maximum Angle Convex Cone (SMACC) algorithm also performed to detect same minerals. Comparing the different analyzing satellite image based on ASTER data indicate all methods generate relatively similar results for clay mineral. Although all methods generate relatively similar results, the SAM method seems to be the best fit with geological evidences to generate reliable promising areas for clay mineral in this area. Based on this study, around 100 km2 of the total studied area was selected as suitable for more exploration and ground survey.

The Burdigalian carbonate of the Central Iran contains very well-preserved specimens of Kuphus polythalamius. The tube of Kuphus polythalamius is a calcareous secretion that enables Pelecypoda to live in the mud of shallow seas. This research focusses on the Paleontology and taphonomy of the Kuphus polythalamius of the Member F (Qom Formation) in the southeast of Kashan located in the Central Iran. The Member F is 60 meters thick and composed of medium bedded limestone. The scattering of the larger benthic foraminifera in the study area indicates the existence of the Borelis melo curdica-Borelis melo melo assemblage zone of Burdigalian age. The presence of Kuphus polythalamius among the porcelaneous foraminiferal and green algal assemblage demonstrate that carbonate generation happened in warm tropical to subtropical marine. The surface of some samples contains distinct horizons of beekite, indicating a break in sedimentation, which is expanded as a silica crust on carbonate tubes.