Interpretation Of Geological Processes Research Articles

Mineral prospectivity mapping using a joint singularity-based weighting method and long short-term memory network

The successful application of geographic information system (GIS)-based mineral prospectivity mapping (MPM) essentially relies on two factors: one is reasonable evidential layers that conform to geological cognition, and the other is excellent models that can extract critical prospecting information from evidential layers. Geological features in MPM are usually discretized by categorizing them into classes and assigning the same or linear weights to each class, which suffer from bias in the interpretation of geological processes under ambiguous knowledge. Moreover, either unsupervised or supervised MPM models are constructed based on the assumption that the variables are relatively independent or identically distributed. In terms of these two issues, this study develops a joint workflow that combines a rational evidence layer weighting method and a deep learning MPM model, considering both the spatial and genetic associations of geological features. A data-driven singularity-based weighting method is first applied to evaluate the relative importance of geological features for mineralization and assign continuous weights to evidential layers using a nonlinear function that is consistent with existing geological models. Then, a more recent deep learning model, namely the long short-term memory network, is employed to extract and integrate the deep-level geological prospecting information among the weighted evidence layers. This joint approach was demonstrated with the help of a case study targeting Fe mineralization in southwestern Fujian Province, China. The mineral potential map obtained using this approach revealed that almost all the known Fe mineral deposits developed in the delineated high prospective regions, indicating that the proposed workflow is reasonable and meaningful for MPM.

Atom probe tomography (APT) of carbonate minerals

Atom probe tomography (APT) combines the highest spatial resolution with chemical data at atomic scale for the analysis of materials. For geological specimens, the process of field evaporation and molecular ion formation and interpretation is not yet entirely understood. The objective of this study is to determine the best conditions for the preparation and analysis by APT of carbonate minerals, of great importance in the interpretation of geological processes, focusing on the bulk chemical composition. Results show that the complexity of the mass spectrum is different for calcite and dolomite and relates to dissimilarities in crystalochemical parameters. In addition, APT bulk chemistry of calcite closely matches the expected stoichiometry but fails to provide accurate atomic percentages for elements in dolomite under the experimental conditions evaluated in this work. For both calcite and dolomite, APT underestimates the amount of oxygen based on their chemical formula, whereas it is able to detect small percentages of elemental substitutions in crystal lattices. Overall, our results demonstrate that APT of carbonate minerals is possible, but further optimization of the experimental parameters are required to improve the use of atom probe tomography for the correct interpretation of mineral geochemistry.

Docência e trabalhos de campo nas disciplinas Ciência do Sistema Terra I e II da UNICAMP

The curriculum of introductory geological disciplines should focus on characteristics of the operation and long history of the planet. This requires the objectives of the activities to be clearly defined, and the most relevant themes to be highlighted. Earth System Science I and II disciplines develop geologic contents in the Geology and Geography undergraduate courses of the State University of Campinas. They must approach the nature and ways of production of geologic knowledge, therefore allowing the student to understand the planet. Fieldwork assumes a basic role. A detailed planning of short field trips along two semesters have defined three successive themes to be developed in the field: (a) geology of sand quarries and present-day sedimentation processes; (b) Permian-Carboniferous glaciations at the Parana basin; (c) rock cycle and Geologic Time. The fieldtrip framework stimulate the students: (1) to construct knowledge from observation and interpretation of geological processes and products; (2) to compare their own ideas with those formulated by colleagues and teachers; (3) to understand that science production requires formulation of theories, explanations and hypothesis. Fieldwork helps students to develop, individually or collectively, their proper learning, actively supported by the teachers.

Docência e trabalhos de campo nas disciplinas Ciência do Sistema Terra I e II da UNICAMP

The curriculum of introductory geological disciplines should focus on characteristics of the operation and long history of the planet. This requires the objectives of the activities to be clearly defined, and the most relevant themes to be highlighted. Earth System Science I and II disciplines develop geologic contents in the Geology and Geography undergraduate courses of the State University of Campinas. They must approach the nature and ways of production of geologic knowledge, therefore allowing the student to understand the planet. Fieldwork assumes a basic role. A detailed planning of short field trips along two semesters have defined three successive themes to be developed in the field: (a) geology of sand quarries and present-day sedimentation processes; (b) Permian-Carboniferous glaciations at the Parana basin; (c) rock cycle and Geologic Time. The fieldtrip framework stimulate the students: (1) to construct knowledge from observation and interpretation of geological processes and products; (2) to compare their own ideas with those formulated by colleagues and teachers; (3) to understand that science production requires formulation of theories, explanations and hypothesis. Fieldwork helps students to develop, individually or collectively, their proper learning, actively supported by the teachers.

Experimental study of europium (III) coprecipitation with calcite

Partitioning of Eu(III) in calcite, CaCO 3, was evaluated with the aim of collecting data on partition coefficients and to enhance understanding of the incorporation mechanisms. This information will aid in the interpretation of geological processes from rare Earth element (REE) data and in the use of Eu(III) as a chemical analogue for the trivalent actinides, particularly Am(III) and Cm(III). Coprecipitation experiments were carried out by the constant addition method at 25°C and P CO2 = 1 atm. Eu(III) was strongly partitioned from the solution into calcite. For dilute solid solutions (X Eu < 0.001), Eu partition coefficients were estimated to be 770 ± 290 and found to be independent of calcite precipitation rate in the range of 0.02 to 2.7 nmol mg −1 min −1. This could be explained by the approximately equal values of the Eu partition and adsorption coefficients. Several solid solution models were tested. A vacancy model for Eu 2(CO 3) 3-CaCO 3 is consistent with the experimental results and constraints on geometry for Eu fit in the calcite lattice. For low Eu content, vacancy density is independent of Eu concentration in the solid so logarithm of the ion activity product, log (Eu) 2(CO 3 2−) 3, depends linearly on log X Eu 2. The fit of the data to such a model is good evidence that Eu(III) is taken up as a true solid solution, not simply by physical trapping. A model using EuOHCO 3-CaCO 3 is also consistent with the uptake stoichiometry, but EuOH 2+ substitution for Ca 2+ would be expected to distort the calcite structure more than is compatible with such a high K D. Several other models, including EuNa(CO 3) 2-CaCO 3, were abandoned because their stoichiometric relationships did not fit the experimental data.

Use of clay minerals in reconstructing geological processes: recent advances and some perspectives

AbstractThis article reviews that clay literature from the last ten years, which is devoted to the applications of clay minerals in the interpretation of geological processes in sedimentary basins. The results, selected by the author as being of particular interest, are presented, arranged according to the successive phases of the rock cycle.

Objective classification of oceanic ridge-crest terrains using two-dimensional spectral models of bathymetry: Application to the Juan de Fuca Ridge

An important application of detailed bathymetric mapping is the interpretation of geological processes based on the nature of the fine-scale morphology of the seafloor. This interpretation is usually accomplished through qualitative analysis of contour maps. In this paper, an objective classification technique, based on a two-dimensional spectral model of bathymetry developed by Fox and Hayes (1985) is applied to detailed Sea Beam data from the Juan de Fuca Ridge. Parameters of the model can be directly related to seafloor properties corresponding to 1) isotropic (non-directionally dependent) roughness; 2) anisotropic (directionally dependent) roughness; 3) orientation of the anisotropic component; and 4) spectral rool-off ( ∼ fractal dimension), by fitting the model surface to two-dimensional amplitude spectra of bathymetry determined on a regular grid over the study area. A test area was selected which encompasses the southern volcanic rift zone of Axial Volcano and the northern terminus of the Vance Segment. Parameters of the model clearly define the contrast between the constructional volcanic terrain (rough, isotropic, with high fractal dimension) and the tectonic extensional terrain (smoother, anisotropic, with low fractal dimension). An agglomerative, hierarchical cluster analysis is applied to the data, independent of spatial information, to delineate groups of spectra with similar characteristics. Distinct, mappable regions, corresponding to volcanic and tectonic provinces, are objectively determined. Also, coherent sub-regions of consistent spectral properties occur within the larger volcanic/tectonic divisions. The classification is extended to the Juan de Fuca Ridge system from 44°30′ N to 47°20′ N through combining these results with an a priori technique (K-means clustering). Broad-scale physiographic regions of the Juan de Fuca Ridge are delineated by the technique, which may aid geologists in the interpretation of crustal accretion processes at seafloor spreading centers.