Textural and Geochemical Evidence for Multiple, Sheet-Like Magma Pulses in the Limeira Intrusion - Paraná Magmatic Province, Brazil

Quantitative petrographic, structural, and textural parameters are integrated with geological, geochemical, and Sr-isotope data to examine the emplacement, growth processes, and the magmatic evolution of the high-Ti tholeiitic Limeira Intrusion, in the Paraná Magmatic Province - Southeastern Brazil. Our data strongly support a multiple-stage evolution, due to the nested emplacement of distinct crystal-bearing magma pulses that probably evolved independently, except at their boundaries. A stage of cooling and crystallization between magma injections originates a stepwise T-t path, leading to variations in the plagioclase residence times and effective growth rates inwards, also occasioning sudden changes in crystal shape and size at the boundaries of each magma pulse. The time delay between pulses allows preserving internal “chilled margins” and the development of near-rigid surfaces at their contacts, increasing the alignment and clustering of crystals during magma replenishment. Isotopic and textural data demonstrate a complex assembly history, in which the appearance of mixed plagioclase populations in between magma pulses coincides with the onset of initial Sr isotope ratio increase, which can be attributed to a locally enhanced cooling-rate, and the extraction of residual melts from the previous crystallizing batches and mixing with the younger pulses. Typical C- and S-shaped MgO (wt.%) compositional profiles within individual pulses indicate that the first pulse probably evolved by in situ fractional crystallization followed by melt migration inward, while the younger ones have contributions from both compaction of the lowermost crystallization front and compositional convection. Mafic globular structures are found at the boundaries of magma pulses and constituting the mafic-rich layers in layered rocks. They are interpreted as evidence for chemical disequilibrium, arguably associated with the trigger of silicate liquid immiscibility. The upwards compositional convection of the silica-rich residual liquid and the accumulation of the Fe-Ti-P-rich crystal-bearing end member in the bottom of the latest magma pulses might represent the most significant mechanism of differentiation in the Limeira Intrusion.

Mineralogical and morphometric aspects of the rock analysis as the basis for choosing a scheme for ore preparation

The complexity of deep processing of fine-grained and refractory mineral raw materials is determined by the difficulty of disclosing aggregates of ore components during disintegration and extracting them into commercial products of standard quality. The main task of the disintegration of such ores is to destroy the object along the phase boundaries without overgrinding while minimizing energy costs. To implement selective disintegration, a precise study of the properties of the mineral components of the ore is necessary. However, there are no systematic data on the effect and relationship of the mineralogical-technological, structural-textural and physical-technical properties of minerals, rocks and ores with the processes of selective disintegration. The article presents the results of computer microtomographic and optical-microscopic studies of the structural and textural characteristics of typical sulfide copper-nickel ores using a SkyScan-1173 microtomograph from Bruker (Belgium), as well as a specialized, accredited as a measuring tool, Thixomet Pro software (Russia). The studies made it possible to identify automatically 19 morphometric parameters of ore grains in three mutually perpendicular sections, the most informative of which were the grain size of individual ore minerals, their perimeter, distance between grains and grain shape (sphericity, edge roughness, and others). The obtained quantitative characteristics of the structural and textural parameters, the analysis of the granulometric composition of the grains of ore minerals make it possible to assess the possibility of using selective grinding at various stages of ore preparation.

Result of modeling temperature anomalies on the water surface of the research basin of the institute of hydromechanics NAS of Ukraine

The results of the research and physical modeling of temperature anomalies of natural or man-made origin on the water surface are presented. The information for the research was obtained from the experimental basin of the Institute of Hydromechanics of the National Academy of Sciences of Ukraine from the self-propelled model as the generator of hydrodynamic processes. The information obtained after image processing allowed to significantly expand the existing ideas about the mechanism of formation of anomalies on the open surface with the hydrodynamic disturbances from hydrocarbon deposits and moving submerged object. The interaction of the emerging hydrodynamic disturbances with the near-surface water layer and the occurrence of unmasking temperature anomalies on the open sea surface have a lot in common between the hydrocarbon deposits and the moving submerged object. The application of the difference of the above structural and textural parameters by calculating the value of "entropy" has been proposed as the informative feature for decoding the images of the water surface with the presence of hydrocarbon deposits or moving immersed objects. The decoding of temperature anomalies consists of two stages: learning and proper decoding. The first stage is the supervised learning, during which the system is being researched using the existing set of images, in which only the background and no hydrocarbon deposits or moving submerged object. Training is carried out in order to determine the signs of belonging to the background or hydrocarbon deposits, moving submerged object. It was determined that the background has minimal entropy values, and with the appearance of an anomaly, the entropy grows to the maximum value, after which, as the temperature trace dissipates, it begins to fall to background values. This confirms the informativity of the entropy feature for decoding the optical anomalies of man-made and natural origin on the sea surface from aerial photos.

Structural and Textural Characteristics of Selected Copper-Bearing Rocks as One of the Elements Aiding in the Assessment of Gasogeodynamic Hazard

The characteristics of copper-bearing rocks that include the structural and textural parameters are an important factor determining a possible gas accumulation in those rocks. In September 2009, in the Rudna copper mine in Poland, an outburst of gases and dolomite occurred. The analysis of the outburst mass showed that one of the main causes of the outburst was the different structural properties such as high porosity and presence of gas in the pores. This paper presents data from the structural analysis of dolomite from the Polkowice-Sieroszowice copper mine and the Rudna copper mine. Seven rock samples from various areas of the mines were tested by the following methods: mercury porosimetry (MIP), low pressure gas adsorption (LPNA), scanning electron microscopy (SEM), computed microtomography (micro-CT). The SEM analyses of the rock samples allowed pores of various sizes and shapes to the observed. The porosity (MIP) of the dolomite changed in the range of 3-15%. The total micro and mesopore volume (LPNA) was from 0.002 cm3/g to 0.005 cm3/g. The macropore volume (MIP) was from 0.01 cm3/g to 0.06 cm3/g and the mean macropore diameter was from 0.09 μm to 0.18 μm. The dolomite samples varied in the surface area (LPNA) (0.7-1.5 m2/g) and the pore distribution. The structure of dolomite determines the possibility of the occurrence of gasogeodynamic phenomena and hence it is urgent that research be conducted into its changeability. To better understand the gasogeodynamic processes in copper-bearing rocks, it is necessary to constantly monitor and analyse in detail those areas that have different structural properties.