Geological Tool Research Articles

A Novel Sample Generation Method for Deep Learning Lithological Mapping with Airborne TASI Hyperspectral Data in Northern Liuyuan, Gansu, China

High-resolution and thermal infrared hyperspectral data acquired from the Thermal Infrared Airborne Spectrographic Imager (TASI) have been recognized as efficient tools in geology, demonstrating significant potential for rock discernment. Deep learning (DL), as an advanced technology, has driven substantial advancements in lithological mapping by automatically extracting high-level semantic features from images to enhance recognition accuracy. However, gathering sufficient high-quality lithological samples for model training is challenging in many scenarios, posing limitations for data-driven DL approaches. Moreover, existing sample collection approaches are plagued by limited verifiability, subjective bias, and variation in the spectra of the same class at different locations. To tackle these challenges, a novel sample generation method called multi-lithology spectra sample selection (MLS3) is first employed. This method involves multiple steps: multiple spectra extraction, spectra combination and optimization, lithological type identification, and sample selection. In this study, the TASI hyperspectral data collected from the Liuyuan area in Gansu Province, China, were used as experimental data. Samples generated based on MLS3 were fed into five typical DL models, including two-dimensional convolutional neural network (2D-CNN), hybrid spectral CNN (HybridSN), multiscale residual network (MSRN), spectral-spatial residual network (SSRN), and spectral partitioning residual network (SPRN) for lithological mapping. Among these models, the accuracy of the SPRN reaches 84.03%, outperforming the other algorithms. Furthermore, MLS3 demonstrates superior performance, achieving an overall accuracy of 2.25–6.96% higher than other sample collection methods when SPRN is used as the DL framework. In general, MLS3 enables both the quantity and quality of samples, providing inspiration for the application of DL to hyperspectral lithological mapping.

Environmental impact assessment: Geologic tool to investigate the proposed Enji dam construction, Offa, Kwara state

Environmental impact assessment: Geologic tool to investigate the proposed Enji dam construction, Offa, Kwara state

Delineating the uranium anomalous zones using remote sensing and radiometric data: a case study from Gabal Umm Tinassib area, North Eastern Desert, Egypt

AbstractRemote sensing (RS) and airborne gamma-ray spectrometric (AGS) methods are utilized to delineate significant uranium zones and altered mineralization areas in Gabal Umm Tinassib and its surrounding region, situated in the northern section of the Egyptian Eastern Desert. AGS serves as a valuable tool for mapping surface geology and conducting mineral exploration. It assesses the concentrations of radioactive elements such as potassium (K), equivalent uranium (eU), and equivalent thorium (eTh). The concentration of radioelements exhibits measurable and significant variation according to lithology. On the other hand, several processing steps are employed for the RS data to generate high-quality images for geological mapping and to identify the mineralized alteration zones. The analysis of RS and AGS data in this study led to insightful conclusions. The utilization of False Color Composite (FCC) with the three best bands derived from the Optimum Index Factor (OIF), Principal Component Analysis (PCA) to extract two highly informative datasets, and the application of two band ratios contributed to accurate geological mapping. These band ratios notably identified identical alteration locations on both younger and older granite basement rocks. Additionally, the constrained energy minimization (CEM) technique effectively pinpointed alterations across these strata. The statistical analysis of AGS data revealed that radioactivity levels in the region range from 1.3 to 19.3 Ur for the total-count (TC), 0.2–3.6% for K, 0.09–11.6 ppm for eU, and 1.1–30.0 ppm for eTh. The estimated coefficient of variability (CoV) demonstrated that the three radio-elements exhibited normal distribution patterns across different rock units, with CoV values of less than 100%, except for K in the Malha Formation. High radiometric readings are observed in the outcroppings of younger and older granites. However, the lowest readings are recorded over undifferentiated Upper-Cretaceous sediments, Abu Rimth Formation, Galala Formation, and some parts of Quaternary sediments. The derived ternary radio-elements map highlights significant radiometric and related uranium anomalous zones as bright white regions. A strong correlation was found between high radiometric anomalous zones and the presumed occurrence of alteration zones in the study area.

Organic petrography and palynofacies of the Upper Cretaceous (Campanian-Maastrichtian) organic rich strata of the Quseir-Safaga Region, Eastern Egypt

The Campanian-Maastrichtian organic-rich rocks in the Quseir – Safaga Region in the Eastern Desert of Egypt have growing economic importance. This economic importance is discussed in many of previous studies by many of different geological tools that lacked the petrographic examination of organic matter occurrence modes. The organic petrography provides the essential tools for microscopic analysis to study the organic matter that are applied for the first time in the present study. The palynofacies and organic petrography are used in the present study to investigate the nature of the organic matter and the paleoenvironmental settings that controlled their distribution in the Duwi and Dakhla formations in the Younis and Mohamed Rabah areas (Egypt). The study of dinoflagellate cysts allowed the identification of the biostratigraphically characteristic assemblages of the Campanian – Maastrichtian in the Eastern Desert including Assemblage II/I (in Duwi Formation) and Assemblage III (in Dakhla Formation) that were identified in Egyptian oil shales of this time range. The identified assemblages are correlated with local and regional studies to delineating the formal biozonation. The organic matter in the Duwi Formation comprises rich fluorescent amorphous organic matter, prasinophytes, sporomorphs, dinocysts as well as a minor terrigenous component of phytoclasts. In the Dakhla Formation, the fluorescent AOM is found to be highly mixed with Botryococcus in addition to prasinophytes and marine palynomorphs. The paleoenvironmental analysis indicates deposition in distal anoxic to proximal suboxic marine conditions with high paleoproductivity. The results are confirmed with the inorganic geochemical composition of redox sensitive elements. The analysis reveals that the Younis section is differentiated into two palynofacies types (proximal, suboxic high productivity in the Duwi Formation and distal anoxic in the Dakhla Formation). The Mohamed Rabah section, one palynofacies type is recognized that is proximal, suboxic high productivity. The principal component analysis is used to interpret the distribution of organic matter abundances. The kerogen types are distinguished based on the area percentages of the fluorescent organic matter and application of kerogen plots. The samples of both formations fall within oil prone kerogen type II. The spore coloration and measured vitrinite reflectance indicate immature kerogen in the studied sections. The organic matter in the studied rocks comprises hydrogen rich compounds that can be treated for direct composition or retorted to extract shale oil. The heavy metals concentrations are significant and present technology will increase its economic value.

Magnetic Induction-Based Susceptometer: Calibration Procedure for Complex Susceptibility Measurement and Extended Application in Natural Scenarios

The fast and in situ measurement of the complex magnetic susceptibility stands a potential geological tool for enhanced characterization of rocks and comprehension of the geological context of the landing and exploration sites when used on board planetary rovers. The real part of susceptibility is related to the capability to acquire magnetization and the imaginary part, with resistivity and magnetic energy loss mechanism of rocks. Therefore, the determination of the rocks’ susceptibility provides key information as to the need for the presence of water in the formation of certain minerals, which can be used as one of the rocks selection criteria, in sample return missions. Previous work has been done in the conception of a novel portable instrument, based on magnetic induction, to measure the complex susceptibility of rocks in the context of planetary exploration. The next step is to create a comprehensive calibration procedure to extract magnetic properties information from the direct readings. This work describes a novel instrument calibration methodology. The calibration of the novel instrument comprises a comparative methodology with representative patterns for the real and the imaginary components of the susceptibility. Therefore, the work also includes calibration sample conception, manufacture, and characterization by different techniques.

African sandstorms, blood rain and continental mineral delivery to the Canary Islands

The origin of volcanism in the Canary Islands has been a matter of controversy for decades. Discussions have hinged on whether the Canaries owe their origin to seafloor fractures associated with the Atlas Mountain range or to an underlying plume or hotspot of uprising hot material from the deep mantle. The debate has recently concluded, however, following the discovery of nannofossils preserved in the products of the 2011–2012 submarine eruption at El Hierro, which constrain the age and growth history of the westernmost island of the archipelago and so cement a clear East to West age progression within the archipelago. Light‐coloured, quartz‐bearing pumice‐like ‘floating rocks’ (xeno‐pumice) were found on the sea surface during the first days of the 2011 El Hierro eruption and proved to be fragments of pre‐island, sedimentary strata that were picked up by ascending magma. Upper Cretaceous to Pliocene calcareous nannofossils such as coccolithophores were retrieved from the xeno‐pumice fragments, and these marine micro‐organism biostratigraphical markers now provide crucial evidence that island growth at El Hierro commenced in the Pliocene. Here we discuss how these essentially continental (quartz‐bearing) sediments on the African continental shelf derive from dominantly wind‐blown Sahara dust and marine (re)‐deposition and describe present‐day aeolian processes that are in operation in the region. We investigate the mineralogy of Sahara dust that is currently deposited in the Canary Islands and discuss source areas and intra‐transport fractionation of mineral dust during trans‐Atlantic transport. Finally, we explore how present‐day dust deposition can be used as analogue to explain the deposition of pre‐island continental material in the East‐Atlantic Ocean basin beneath the Canary archipelago and we show how the dust‐derived sedimentary deposits can be utilized as geological tool in the Canary Islands.

Biostratigraphy and paleoenvironment correlation based on benthic foraminifera from the cenozoic Marajó and Pirabas formations, Eastern Amazon Coast, Brazil

The Oligocene-Miocene foraminifera biostratigraphy correlation has been applied successfully as a geological tool for establishing the paleoenvironmental conditions during the deposition of siliciclastic and carbonate strata in the Eastern Amazon coastal basins. In this region, previously interpreted tectonic compartments represented by the Marajó Basin and Bragantina Platform were the main sites of siliciclastic and carbonate sedimentation influenced by Late Paleogene-Neogene transgressive–regressive events. In the subsident Marajó basin, a siliciclastic estuary was developed, supplied by the Cratonic Amazon River. The transcontinental river did not influence the Bragantina region to the East, allowing the implantation of a shallow carbonate platform. These Neogene segments require further sedimentological, stratigraphic, and paleontological studies to define these limits. The use of foraminifera content has been considered an important tool to assist in this differentiation, providing a paleoenvironmental and paleoecological reconstruction model. This work used qualitative and quantitative analyses integrating several diversity indices, complementing the R-mode cluster and the correlation of planktonic and benthic (P/B) ratios. The similarity in faunal diversity indicated that these siliciclastic and carbonate units represented by the Marajó and Pirabas formations are chronocorrelated. Marajó Formation is interpreted as a restricted, suboxic, marginal marine environment (lagoons/mangroves) with variable salinity and abundance of the species as Cribroelphidium williamsoni, Ammonia tepida, and A. beccari. In contrast, the Pirabas Formation was deposited in a brackish, oxic, and carbonate platform characterized by Cibicidoides subhaidingerii, Cibicides pachyderma A. beccarii, and Cassidulina laevigata species. These foraminifera assemblages confirm the previous stratigraphic and paleoenvironmental interpretations providing new insights into understanding the Late Paleogene-Neogene evolution of the Eastern Amazonia Coast.

Gamma-radiation levels outdoors in Great Britain based on K, Th and U geochemical data

Gamma-rays from naturally occurring radionuclides are a major component of background radiation. They are an important tool for geology and are also important for radiation protection. In this paper we use over a quarter of a million geochemical measurements of concentrations of potassium, thorium and uranium in soils and in stream sediments to estimate outdoor gamma-ray dose rates across Great Britain. The soil concentrations are generally at a depth of 5–20 cm with some at 35–50 cm. Soil measurements will give spatially relatively precise estimates, but as soil data are not available for much of Scotland, stream sediment data are used there. Kriging methods are used to estimate surface concentrations of K, Th and U and dose rates are imputed from these concentrations. Our results are compared with measurement surveys of both outdoor and indoor gamma-ray dose rates. Recently there has been interest in exploring the carcinogenic risks of low dose radiation by investigating associations between childhood cancer rates and doses from natural background gamma radiation. To achieve adequate statistical power, such studies must be so large that it is impractical to assess exposures by direct measurements in the homes of study subjects. Instead the exposures must be modelled. The results presented here will be an important input to such work.

Differences between soil and air temperatures: Implications for geological reconstructions of past climate

AbstractAmong quantities of interest in paleoclimate, the mean annual air temperature, Ta, directly over the surface looms prominently. Most geologic estimates of past temperatures from continental regions, however, quantify temperatures of the soil or other material below the surface, Ts, and in general Ta < Ts. Both theory and data from the FLUXNET2015 data set of surface energy balance indicate systematic dependences of temperature differences ΔT = Ts − Ta and also of Bowen ratios—ratios of sensible to latent heat fluxes from surface to the atmosphere—on the nature of the land-surface cover. In cold regions, with mean annual temperatures ≲5 °C, latent heat flux tends to be small, and values of ΔT can be large, 3–5 °C or larger. Over wet surfaces, latent heat fluxes dominate sensible heat fluxes, and values of both ΔT and Bowen ratios commonly are small. By contrast, over arid surfaces that provide only limited moisture to the overlying atmosphere, the opposite holds. Both theory and observation suggest the following, albeit approximate, mean annual values of ΔT: for wetlands, 1 °C; forests, 1 ± 1 °C; shrublands, 3–4 °C; savannas, 3.5 °C < ΔT < 5.5 °C; grasslands, 1 °C where wet to 3 °C where arid; and deserts, 4–6 °C. As geological tools for inferring past land-surface conditions improve, these approximate values of ΔT will allow geologic estimates of past mean annual surface temperatures, Ts, to be translated into estimates of past mean annual air temperatures, Ta.

ІДЕНТИФІКАЦІЯ ТА АНАЛІЗ СТРУКТУРНО-ТЕКТОНІЧНИХ ОСОБЛИВОСТЕЙ ТЕРИТОРІЇ НА ОСНОВІ ЛІНЕАМЕНТНОГО АНАЛІЗУ: ПРИКЛАДИ ГЕОМОДЕЛЮВАННЯ ДЛЯ ТЕРИТОРІЇ КАНАДСЬКОГО ТА УКРАЇНСЬКОГО ЩИТІВ

Nowadays, rare earth elements (REEs), which belong to the group of rare metals, are considered worldwide to be strategic critical raw materials and are extremely important for the economic development of any country. Various methods and approaches are used for prospecting and exploration of deposits of these critical metals; among which the methods of 3D geological modeling are currently prioritized, which allow a comprehensive analysis of the structural features of potentially promising areas as well as individual deposits. One of the methods used for REE exploration is structural mapping combined with geological terrain analysis, including structural lineament analysis. The latter is considered an important geological tool for identifying the primary and secondary structural and tectonic features of our study areas of investigation. The objectives of the present research work are: 1) to identify structural lineaments within two studied areas – the Alces Lake area (Northern Saskatchewan, Canadian Shield) and the Western Azov region (Azov block of the Ukrainian Shield) using automated and manual approaches, 2) to compare the results obtained for both areas, and 3) to discuss interpretation/conclusions over the overall suitability of the method for the exploration purposes. In the current research, we conducted the extraction and geospatial analysis of linear features and their tectonic interpretation. During the modeling process, remote sensing and geostatistical methods were used to analyze topographic, geological and geophysical data. As a result, the main structural lineament trends for the two studied areas were identified and structural-tectonic criteria for the formation and localization of deposits of rare earth elements were determined/proposed.

Deep borehole disposal of intermediate-level waste

Abstract. Around the world, deep borehole disposal is being evaluated for intermediate-level waste (ILW), high-level waste (HLW), spent nuclear fuel (SNF), separated plutonium waste and some very high specific activity fission product waste. In Australia, long-lived ILW from research reactors and radiopharmaceutical production represents the principal waste stream that requires deep geologic disposal. Whilst the Australian government has not yet made a decision on its preferred strategy for ILW disposal, deep borehole disposal of small volumes of ILW would be a more cost-effective and modular solution compared to a conventional geologic disposal facility (GDF). CSIRO, ANSTO and SANDIA have created an international partnership to execute a full-scale borehole research, development and demonstration (RD&D) project in Australia. The project will demonstrate the technical feasibility of the long-term safety of borehole disposal in deep geological formations. The execution of this project could also demonstrate options for nuclear waste disposal that would reduce proliferation risks, potentially up to the termination of compliance with international safeguards requirements. The RD&D includes demonstration of surface handling and waste/seal emplacement capabilities, basic research on foundational science areas, and full-scale field testing in both a deep characterization borehole and a larger-diameter (0.7 m or 27.5 inch) 2000 m deep demonstration borehole. The multi-barrier system designed for such a deep disposal borehole concept places much less reliance on engineered barriers at the disposal zone to achieve safety as compared to a conventional GDF. It rather relies on geological features for waste containment. The concept being explored uses disposal containers with primary waste packages, such as vitrified waste canisters, inside; to be both cost effective and fit for purpose, such a container could have a mild steel-based structural component with copper coating. A critical review of six coating technologies showed that cold spray has the greatest advantages, such as minimal porosity and compressive residual stress. The RD&D has delivered novel enabling tools that assist with site screening, borehole design and post-closure safety assessments. For instance, an automated geological fault mapping and meshing tool was developed that assists with ranking the suitability of potential disposal sites based on proximity to faults. New codes were developed for better representation of fault zones in 2D/3D numerical flow and transport models, while also being more efficient to execute. Post-closure safety assessments tested the sensitivity of long-term safety with respect to disposal depth, rock permeability and sorption. Heat transport calculations explored the sensitivity of temperature evolution within the borehole to parameters such as heat load, borehole depth, geothermal gradients and rock thermal conductivity. For verification of host rock tightness while also demonstrating the absence of recent groundwater, a new noble gas analytical facility has been established for measuring rare noble gases in mineral fluid inclusions as indicators of very old pore fluids.

Automatic Asbestos Control Using Deep Learning Based Computer Vision System

The paper discusses the results of the research and development of an innovative deep learning-based computer vision system for the fully automatic asbestos content (productivity) estimation in rock chunk (stone) veins in an open pit and within the time comparable with the work of specialists (about 10 min per one open pit processing place). The discussed system is based on the applying of instance and semantic segmentation of artificial neural networks. The Mask R-CNN-based network architecture is applied to the asbestos-containing rock chunks searching images of an open pit. The U-Net-based network architecture is applied to the segmentation of asbestos veins in the images of selected rock chunks. The designed system allows an automatic search and takes images of the asbestos rocks in an open pit in the near-infrared range (NIR) and processes the obtained images. The result of the system work is the average asbestos content (productivity) estimation for each controlled open pit. It is validated to estimate asbestos content as the graduated average ratio of the vein area value to the selected rock chunk area value, both determined by the trained neural network. For both neural network training tasks the training, validation, and test datasets are collected. The designed system demonstrates an error of about 0.4% under different weather conditions in an open pit when the asbestos content is about 1.5–4%. The obtained accuracy is sufficient to use the system as a geological service tool instead of currently applied visual-based estimations.

Prehistoric landscapes, humans and ostriches: highlighting geoarchaeological issues in the Tapi Basin of Maharashtra (west-central India) – a multidisciplinary approach

Abstract The formal beginning of geoarchaeology in India can be traced back to 1863 when the first palaeolith was documented and collected by Robert Bruce Foote in Tamil Nadu and later described in a detailed geological context. Today, various geological tools such as geospatial analytical tools are available to provide extra mileage to geoarchaeological investigations. They supplement field evidence and enable researchers to display, manipulate, and model geological data and the associated archaeological evidence. The present paper attempts to summarize the current status of understanding of the Quaternary geoarchaeology of the Tapi River basin in west-central India. The aspects considered include geomorphology, landform evolution, morphometric parameters, relationships between climate and basin evolution and Palaeolithic and Mesolithic evidence. This present study uses Landsat imagery, locational data, Survey of India topographic sheets and Shuttle Radar Topography Mission data in ArcGIS software. The study is the first comprehensive attempt to summarize the issue of prehistoric human adaptations (dominated mainly by Late Pleistocene evidence) through changing environments, with an assumption that the two occurred in synchronization. Another assumption is that the reported lithic and fossil sites and the surrounding areas have preserved signatures of original landforms and sedimentary contexts. Through these perspectives and visual integration of topography, drainage networks and Landsat image parameters in a Geographic Information System platform, along with other variable field inputs, a testable hypothetical model of the Quaternary evolution of Central Tapi valley is proposed. Additionally, an accelerator mass spectrometry (AMS) date of 47 145 cal BP for a newly discovered ostrich eggshell fragment from Sakegaon near Bhusawal is presented and its palaeoanthropological implications are discussed. Altogether, our observations from the study area, such as an expansion of land use from the Acheulean onwards, signatures of arid phases and the oldest reported ostrich eggshell, warrant further detailed multidisciplinary research. An in-depth understanding of the first-to-last occurrences of ostriches in the region and comprehensive picture of their pan-South Asian distribution in general will help address the issue of prehistoric human adaptations through changing environments.

Method of Comparable Values: A New Approach for Efficient Exploration Target Selection in Small-Scale Mining

Small-scale mining is an important source of income for many communities worldwide. However, many small-scale mining enterprises lack good management and mining practices and the limited funds available for exploration are often allocated inefficiently. This paper introduces a method of comparable values: a practical, low-cost and effective method for prioritization and selection of exploration targets in small-scale mining. The proposed method combines local geological mapping with a geological uncertainty assessment tool that indicates the risk associated with geological uncertainty for each target. By properly selecting exploration targets, small-scale miners can reduce the project risks and maximize the value resulting from investment that is more effective in exploration. The method of comparable values was applied to a small-scale project in a block of six manganese-rich claims in the state of Bahia, Brazil. The proposed method resulted in proper target selection with a time reduction of 50% and a cost savings of 76% when compared with those of traditional geological mapping work.

TouchTerrain—3D Printable Terrain Models

TouchTerrain is a simple-to-use web application that makes creating 3D printable terrain models from anywhere on the globe accessible to a wide range of users, from people with no GIS expertise to power users. For coders, a Python-based standalone version is available from the open-source project’s GitHub repository. Analyzing 18 months of web analytics gave us a preliminary look at who is using the TouchTerrain web application and what their models are used for; and to map out what terrains on the globe they chose to 3D print. From July 2019 to January 2021, more than 20,000 terrain models were downloaded. Models were created for many different use cases, including education, research, outdoor activities and crafting mementos. Most models were realized with 3D printers, but a sizable minority used CNC machines. Our own experiences with using 3D printed terrain in a university setting have been very positive so far. Anecdotal evidence points to the strong potential for 3D printed terrain models to provide significant help with specific map-related tasks. For the introductory geology laboratory, 3D printed models were used as a form of “training wheels” to aid beginning students in learning to read contour maps, which are still an important tool for geology.

A revised orientation-based correction method for SfM-MVS point clouds of outcrops using ground control planes with marks

Structure-from-Motion/Multiview Stereo (SfM-MVS) point cloud has the potential to display objects and to generate corresponding digital elevation model (DEM) and orthomosaic, from which geometric parameters such as the orientations, shapes, and sizes can be derived, thus making it a promising tool for structural geology. High-precision coordinates of ground control points (GCP) are commonly used for SfM-MVS point cloud correction, but the coordinate measurement depends on expensive and heavy equipment, and more importantly, there is uncertainty of the Global Position System (GPS) signal in some environments. A potential alternative correction method is to use orientations from outcrops, although this method still requires further optimization. This study aims to improve this orientation-based method using ground control planes (GCPL) and test its effectiveness through geometric analysis and simulation experiments, and the improved schemes are as follows: using a single pair of nonparallel planes, using a single horizontal plane with linear orientation marks, and using a single inclined plane with a strike mark. The GCPL method requires a few orientations, and its accuracy is sufficient for fieldwork. It greatly simplifies the field investigation and improves the applicability of SfM–MVS in environments with unavailable GPS signals or with rigid body rotations for GPS imprecision.

Fault modelling, seismic sequence evolution and stress transfer scenarios for the July 20, 2017 (MW 6.6) Kos–Gökova Gulf earthquake, SE Aegean

The July 20, 2017, MW 6.6 Kos–Gokova Gulf earthquake occurred offshore, near Bodrum of Turkey and Kos of Greece. It was one of the strongest in the broader area during the last many decades causing two deaths, many injuries and extensive damages. We investigated the evolution of the seismic sequence using seismological and geological tools. The aftershock sequence was relocated mainly in order to define the geometry of the main seismic source, depicting a NNW-dipping fault plane. It also revealed significant clustering, associated with other nearby faults, and asymmetric spatio-temporal evolution. Along with morphotectonic analysis on Kos Island, and other published seismological information (e.g. focal mechanisms), we modelled the seismic source of the mainshock, as well as the one of the strongest aftershocks (August 8, MW 5.3). We applied the Coulomb failure criterion in order to investigate the effect of the mainshock on the strongest aftershock, and the rest of the sequence as well. Using the same method, we also investigated the stress changes of both strongest shocks for the prevailing E–W-trending normal faults in this area. Among other conclusions and implications, we deduce that the prevailing tectonic setting of the Gokova Gulf consists of roughly E–W-striking normal faults forming inner horsts and grabens.

Recent Advances in Geomathematics in Croatia: Examples from Subsurface Geological Mapping and Biostatistics

Geomathematics is extremely important in geosciences, particularly in the geology. The key for any geomathematical analysis is the definition of a typical model to be applied for further prognosis, either through deterministic or stochastic approaches. The selection of the appropriate procedure is presented in this paper. Two different geomathematical subfield datasets were used in subsurface geological mapping and palaeontology and different biostatistics applications, representing important geomathematical subfields in the Croatian geology. The different subsurface interpolation methods tested, validated and recommended for application were used to obtain the best possible outcome in reservoir modelling, in the cases with small datasets. Cross-validation may be chosen as the main selection criteria, applied to the Croatian part of the Pannonian Basin System (CPBS). Recent advances in biostatistics applied in palaeontology and case studies from Croatia are also presented, where biometric studies are of significant importance in fossil biota. Data, methods and problems in geosciences are vast subjects, and address a wide spectrum of fundamental science. Because geology includes subsurface and surface geology, and very different datasets regarding variable and number of data, we have chosen here two representative case study groups with original samples from Northern Croatia. Subsurface mapping has been presented on limited petrophysical datasets from the Northern Croatian, Miocene, hydrocarbon reservoirs. Biostatistics have been presented on very different samples, allowing us to achieve paleoenvironmental reconstructions of the size of relevant fossils, such as dinosaurs or other species and their paleoenvironments. All examples highlight examples of the valuable application of geomathematical tools in geology. The results, cautiously validated and correlated with other, non-numerical (indicator, categorical) geological knowledge, are of enormous assistance in creating better geological models.

Development of open source Web-GIS platform for three-dimensional geologic modeling and visualization

An Open Source Web-GIS platform for Geologic Voxel (Geo-Vox) modeling and visualization, has been developed. Geo-Vox provides a comprehensive framework by integrating GIS, relational database, open geospatial standards-compliant web mapping engine, 2-D and 3-D rendering libraries for geologic modeling. Free and Open Source Software for Geoinformatics (FOSS4G) stack comprising of GRASS GIS, PostgreSQL, MapServer, OpenLayers and three.js JavaScript 3-D library have been used to implement the system. Geo-Vox overcomes several limitations of solid modeling by construction of model based on an intuitive logical relation between geologic units and boundary surfaces. Two-dimensional visualization allows rendering of horizontal and vertical sections at user-defined planes. The voxel model can also be exported in a format amenable for rendering as 3-D solid model. Geo-Vox is unique, in that, (a) logics used to create the model are easily comprehensible to geologist (b) offers high degree of interoperability (c) leverages FOSS4G stack to implement a comprehensive geologic modeling tool that is hitherto unavailable. The functionality of Geo-Vox is demonstrated using data derived from published geologic map. The results confirm the potential of Geo-Vox to provide an interoperable and scalable framework for delivery of value-added geological information for a variety technical and societal needs.

Anisotropy of Full and Partial Anhysteretic Remanence Across Different Rock Types: 2—Coercivity Dependence of Remanence Anisotropy

AbstractMagnetic fabrics are powerful tools in structural geology and tectonic studies, because they provide a fast and efficient measurement of mineral alignment, which helps interpret a rock's (de)formation history. The magnetic fabric of remanence‐carrying minerals provides useful information when these grains record different deformation stages than the bulk minerals in a rock. When rocks contain several subpopulations of remanence‐carrying minerals, each of these potentially displays a distinct fabric. This can lead to complex remanence anisotropies, being a superposition of all subpopulations' individual anisotropies. Characterization of partial remanence anisotropies has been used to investigate changes in fabric with grain size. However, most studies still report one bulk remanence anisotropy tensor per sample, and it remains to be determined how commonly different populations of remanence‐carrying grains reflect different subfabrics. Based on a large sample collection including 93 specimens from different lithologies, we have investigated the coercivity dependence of anisotropy of (partial) anhysteretic remanent magnetization A(p)ARM. We find that the principal directions, degree, and shape of A(p)ARM are generally dependent on the coercivity window used to impart the anhysteretic remanent magnetizations (ARMs). Depending on the carrier minerals and their fabrics, ARM anisotropy can either increase or decrease when the ARMs are applied over larger coercivity windows. Additionally, the coercivity fraction that dominates the ARM anisotropy is not always the coercivity fraction that acquires the strongest mean ARM. This illustrates the complexity of characterizing remanence anisotropy, and highlights the importance of carefully choosing experimental parameters in A(p)ARM determination for both magnetic fabric and anisotropy correction studies.