Bulletin of the Mineral Research and Exploration (BMRE)
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Accurate whole-rock geochemistry analysis by combined ICP-OES and LA-ICP-MS instruments
No full textICP-OES and LA-ICP-MS instruments routinely used to assess the geochemical properties of the various natural and synthetic materials. In this contribution, the analytical routines and method development procedures of the ICP-OES and LA-ICP-MS facilities installed at the İstanbul University-Cerrahpaşa Geological Engineering Department, Geochronology and Geochemistry Laboratory have been evaluated using well-known international rock standards. Sample preparation techniques, method development, experimental setup and measurement conditions for the both ICP-OES and LA-ICP-MS instruments were discussed and specific analyze results of NIST SRM 614, BCR-2, AGV-2, BCR-2G and AGV-2G were evaluated. Flux-free USGS glass standards were produced by in-house techniques and flux-bearing glasses were produced by fusion of sample with the mixture of ultra-pure lithium-tetraborate, lithium metaborate and lithiumbromide were evaluated and compared with the well-known reference values in the literature. Relative standard deviation (RSD) values for the major oxide measurements for standards changes between of 0.0 wt. % to 1.5 wt. %. RSD values for the trace and rare-earth-elements values were mainly lower than 10 wt. %. The results confirm that the both flux-bearing and flux-free glasses reasonably match with the world-wide inter-laboratory values for international standards samples. The combination of these two instruments can be used to conduct geochemistry of various solid earth materials
Geology, fluid inclusion characteristics and mineral resource estimation of the Güzelyayla porphyry Cu-Mo mineralization (NE Türkiye)
No full textMagmatic processes that emerged with the evolution of the Neotethys ocean and associated lithospheric plates caused the formation of significant mineralization in the Tethys belt. The Eastern Pontides, which are located in the northeast of Turkey and are a part of the Tethys metallogenic belt, are particularly rich in porphyry-type mineralization and represent an important region for Cu-Mo exploration. A large number of Cu, Pb and Zn anomalies have been determined in a large region including the Güzelyayla Cu-Mo field by stream sediment sampling. The Güzelyayla occurrence is Cu-Mo mineralization associated with andesitic/basaltic volcanic rocks and intrusive dacites crosscutting these rocks. The Güzelyayla Cu-Mo mineralization developed in the stockwork and fault-controlled silicified zones. Homogenization temperature values vary between 324 °C and 420 °C (average 374 °C). Salinity values range between 2.2 and 18.6% NaCl (average 9.1% NaCl). A concentric alteration zoning surrounding the potassic alteration indicates a gradual change in the physicochemical properties of the solutions forming the mineralization. The Güzelyayla mineralization was formed in the Eocene (50.7 ± 1.0 million years) period in the Upper Cretaceous volcanic rocks in relation to post-collisional processes in the magmatic arc environment. Contrary to previous studies, estimation zone models were created and an estimated 54.2 million tons of extracted/potential mineral resource with an average grade of 0.20% Cu and 0.014% Mo (0.26% Cu equivalent grade) was made in the Güzelyayla field. https://doi.org/10.19111/bulletinofmre.107448
Evaluation of potential rock falls with three-dimensional analysis: Example of Oltanbey and Hasanbey districts (Gümüşhane city center)
No full textThe central district campus of Gümüşhane, located on the Trabzon-Erzurum Highway, has a steep topography, and because of the effect of climatic and morphological structure, frequent rockfall events can cause loss of life and property from time to time. For these reasons, the slopes in some parts of the Oltanbey and Hasanbey districts of the central district of Gümüşhane, which pose a great threat in terms of rockfall potential, were chosen as the study area. In this study, three-dimensional rockfall analyzes were carried out using the RocPro3D program on the lines determined in the rockfall source zones with a high probability of rockfall. As a result of the analysis, it was determined that the rock blocks rolled from the O1, O2 and H1 source rock lines determined at the upper elevations of the study area threaten the settlements and road networks in Oltanbey and Hasanbey districts. With the 3D rockfall analysis, steel barrier was applied as a precautionary structure in the areas determined to be under the risk of rockfall, and the analyzes were carried out again considering the precautionary structures. By examining the results of the analyzes, the safest and most economical different barrier types have been proposed to eliminate the danger of rockfall. https://doi.org/10.19111/bulletinofmre.97792
Investigation of the slaking behavior of weak geological units in terms of undercutting rate
No full textIt is aimed in this study to measure the undercutting rate of weak geological units under field conditions and to determine the relationship between this parameter and other indexes and physical properties of related rocks. Thus, 11 different locations in which weak materials were found and undercutting problems were observed in the road slopes were selected. In these road cuts, the undercutting depths in many locations were obtained by measurements taken at different dates from the pins installed in the fresh surface of weak units. In addition, undercutting depth was directly taken by using the amount of erosion between durable and weak rock units in the road slopes with a known date of the excavation. Samples having suitable amounts and sizes were collected at the measured locations to be used in physical and durability tests. In the analyses, the applicability of the results of slake index and durability tests, as well as the disintegration ratio in the determination of the disintegration behavior of these geological units, was investigated, and statistically significant empirical equations were obtained. Considering the results obtained from different weak geological units, it was determined that the depth of undercutting values change approximately between 10.1 and 45.8 mm. https://doi.org/10.19111/bulletinofmre.89801
A walkaway vertical seismic profiling modeling and imaging study and combining its results with migrated surface seismic images
No full textThis paper presents and analyzes results from a Finite Difference Modeling (FDM), processing, and imaging study of a Walkaway Vertical Seismic Profiling (WVSP) survey, and discusses how the images from WVSP enhance those from the surface seismic data. It is shown that the results from the WVSP integrate well with the image from the surface seismic performed in the same line. For the study, a seismic model with vertically and horizontally varying velocities was built and a WVSP data set was generated. The surface seismic had difficulty showing clear images from the layers with steep dips and near vertical displacements on the model due to the lack of ray coverage. The study demonstrates that the WVSP geometry can record reflections from near vertical layers facing the borehole, which help with imaging the parts of the subsurface structure which were missing in the surface seismic. With the proper combination of the images from the WVSP and the surface seismic, a more complete image profile of the subsurface can be constructed around the borehole. However, while contributing to surface seismic, it is also seen that the WVSP introduces more migration artifacts related to source interval distance and interbed multiples than the surface seismic data. https://doi.org/10.19111/bulletinofmre.98194
A graph method for interpretation of magnetic anomalies over 2D dikes and vertical faults
No full textSimple geometric assumptions for dikes and faults are often used for interpreting the parameters of these structures from magnetic anomalies. The magnetic anomaly of a 2D dike or a vertical fault consists of two components; one with even and the other with odd symmetries. The function resulting from the ratio of the even and odd components is independent from the amplitude coefficient. The abscissa of the half-maximum of the even component and the maximum of the odd component of a dike or a vertical fault is related to its depth and its half-width. Incorporating this relation into the corresponding equations for dikes and vertical faults, the half-width value can be eliminated from the equations. Thus, the resulting ratio can be used for determining the model parameters. Using the ratio of the even component to the odd component for given distances, curves can be obtained for different depth-index parameter pairs, and from the graph of these curves, parameters of 2D dikes and vertical faults can be determined. The validity of the method is tested using synthetic models for dike and vertical fault cases. The method is also implemented on two different field data, and the results obtained are compared to previous studies
Mud systems applied to problematic formations in core drilling rigs
No full textThe two most important features of drilling rigs based on the core drilling principles are the drill set rotating at high speeds and the very precise spacing between the pipe and the well wall. Formation pieces that swell, flow into the well, spill or collapse during the drilling of problematic formations mix into the mud or narrow the annulus and cause well problems by restraining the rotation of the drill string and circulation. The spilled formation pieces cause an excessive solid material increase in the mud structure and due to the effect of centrifugal force, the solids adhere to the inner wall of the pipes near the surface and form a cake. Excessive cake thickness in the pipes obstruct the descent of the core barrel inner tube catcher into the well. During the removal of the inner tube, a vacuum occurs in the well due to the mud discharged from the rod and the problematic formations are poured into the annulus and block the core between the core barrel and the well wall. In this study, the performance of mud systems determined by trial and error method against the problems encountered in unconsolidated claystone, mudstone (shale), siltstone and sand - pebble stones in core coal exploration drillings in Çorum - Amasya region were evaluated. Monitoring and regular improvement of the rheological values of the mud compositions, changing the mud composition according to the well conditions, keeping the gel strength high and increasing its density with salt was found to play an important role in keeping the unconsolidated formations physically balanced. Salt mud also minimized the formation of cake in the pipe
Sedimentology and Miocene-Pliocene depositional evolution of the stream-dominated alluvial fan deposits at circum-Sultandağları region
No full textYalvaç and Ilgın basins surrounding Sultandağları were opened due to the orogenic collapse in the early Miocene. The NW-SE trending Çakırçal and Akşehir fault zones, forming boundaries with these basins, caused both the opening of the basins and uplifting of Sultandağları. During the Miocene-Pliocene period, the alluvial fans fed from Sultandağları developed on the basin margins, while the lacustrine carbonate and clastic depositions formed in the basin’s interior. The alluvial fan deposits are laterally and vertically transitional with lacustrine sediments and alternate several times in the sequence. The alluvial fans, widespread in the region, consist of debris flow, hyperconsantrated stream flood, braided river and meandering river deposits. Fan deposits that pass from high-energy fluvial facies at the basin margin to the low-energy fluvial facies towards the basin interior have been interpreted as stream-dominated alluvial fan deposits. The age data obtained from the fan deposits of the Yalvaç and the Ilgın basins show that Sultandağları concurrently feeds the alluvial fans on both flanks. Alluvial fan deposition around Sultandağları formed under the control of tectonic and climatic processes. The tectonism led to the formation of basins and source areas. Simultaneously, the climate maintained the streams to be perennial by precipitation, thus proving a continuous sediment supply to the basins. Tectonism and climate-controlled base-level changes determined the quantity of sediments carried to the basin from the source area, causing regressive or transgressive developments
Separation efficiency of different methods in treatment of a low-grade iron ore
No full textIn the present study, characterization and beneficiation tests were performed on an iron ore sample for the evaluation of separation efficiency (SE) of different methods. Results showed that the decrease in feed size fraction increases the SE irrespective of to beneficiation method. It was determined from the liberation analyses that the increase in SE values at finer size fractions is related with higher liberation. Calculated SE values revealed that operational parameters significantly affect the SE of all methods and the net forces acting on particles play an important role on SE of different size fractions. Mean SE of different size fractions showed that the separation efficiencies of gravity concentration and magnetic separation takes similar values above 1 mm, however, SE of magnetic separation is significantly higher than gravity concentration below 1 mm for the studied sample. For low grade ores, it is very crucial to develop a flow sheet to achieve the optimum grade and recovery while decreasing the cost likely by using optimum method. Therefore, SE calculations used in this research can be used as a basic method to compare the efficiency of different beneficiation methods. SE method has advantages as they provide fast evaluation of efficiency by using experimental results
Petrography and geochemical decomposition parameters of crystalline rocks; Demirköy intrusive body (DIB), NW Turkey
No full textThe crystalline rocks represent the most weathering rock groups due to their textural and mineralogical decomposition. This study, focused on the petrographic properties and geochemical variation of the altered rocks from Demirköy Intrusive Body (DIB) located at NW Turkey were examined based on the location of structural and morphological properties. DIB consists ofintrusive rocks in the composition of ranging from granite to gabbro. The sampling made from the dominant rock units composing of granodiorite and quartz diorite, within the DIB a cross weathering section divided into three levels as regolit, saprolite and saprock. For each level of all the section Ruxton ratio (Ro), chemical alteration index (CIA), chemical weathering index (CIW), plagioclase alteration index (PIA) were determined. The results show a linear decrease from the surface to the core of the host rock. The chlorite-carbonate-pyrite index (CCPI) versus Ishikawa alteration index (AI) variation diagram shows that decomposition in profiles occurred in diagenetic alteration and where the hydrothermal alteration effect is not observed. On the other hand, Mg, Fe, Ti, Ca decreased remarkably while the ratio of the elements such as Si, Na, K, Al increased. The increasing and decreasing of geochemical elements are related to their physical strength and chemical behavior. Chemical variation diagrams of all the levels revealed that the regolites exhibit chemical compounds from hydrothermal fluids in the immediate vicinity of the source rocks. https://doi.org/10.19111/bulletinofmre.79379