Geological Case Study Research Articles

Geology and inquiry-based learning. The case of sliding rocks

ABSTRACT This paper is a proposal to develop inquiry-based learning (IBL) as a methodological approach to learn science. I outline the characteristics of this methodology, which is based on an initial challenge that has not a unique answer. Here we have a complete experience to carry out IBL in a geological case study. Starting with the question presented by the teacher (the mysterious sliding rocks phenomenon in Death Valley), a) students must individually produce hypotheses about the cause of the movement, b) interpret data, previously prepared by the teacher, c) discuss in small group and, finally, d) give an answer. This experience can be extended with modelling and scientific communication activities, as proposed by the author. The experience was performed with 17-year-old students. During the performance, data analysed were collected, showing that IBL allows the development of some scientific skills that discursive methods obstruct or difficult, such as the formulation of multiple hypotheses, the selection of required data and group discussion.

Auto-labelling entities in low-resource text: a geological case study

Studies on named entity recognition (NER) often require a substantial amount of human-annotated training data. This makes technical domain-specific NER from industry data especially challenging as labelled data are scarce. Despite English as the surface language, technical jargon and writing conventions used in technical documents render the low-resource language challenges where techniques such as transfer learning hardly work. Relieving labour intensive annotations using automatic labelling is thus an important research topic, seeking ways to obtain labelled data quickly and consistently. In this work, we propose an iterative deep learning NER framework using distant supervision for automatic labelling of domain-specific datasets. The framework is applied to mineral exploration reports and produced a large BIO-annotated dataset with six geological categories. This quality-labelled dataset, OzROCK, is made publicly available to support future research on technical domain NER. Experimental results demonstrated the effectiveness of this approach, further confirmed by domain experts. The generalisation ability is verified by applying the framework to two other datasets: one for disease names and the other for chemical names. Overall, our approach can effectively reduce annotation efforts by identifying a much smaller subset, that is challenging for automatic labelling thus requires attention from human experts.

Spatial change of precipitation in response to the Paleocene-Eocene thermal Maximum warming in China

The Paleocene-Eocene Thermal Maximum (PETM), a transient greenhouse climate interval associated with a huge release of carbon to the ocean-atmosphere system ~56 million years ago, provides a geological case study for the effect of rapid global warming on regional hydroclimate. Here we reconstruct carbon isotope discrimination (△) of C3 plants across the PETM in the Fushun and Nanyang Basins of China. The △ values present remarkable increase at both sites but with greater magnitude in the Fushun Basin during the PETM, which is explained as a response to regional precipitation. Quantitative estimate of mean annual precipitation based on the △ values suggests that East Asian continent generally became wetter with relatively more precipitation occurring at higher latitudes in response to the PETM warming. Our results support the prediction that continuous anthropogenic warming will lead to a wetter climate in East Asia with relatively more precipitation in higher-latitude lands.

Paleo-depth of fossil faults estimated from paleostress state: Applications from the Alps and the Apennines (Italy)

Estimating the paleo-depth of a fossil fault usually requires the application of complex and highly specialized techniques. We propose a new method, that is based mainly on field data and simplifies the process: - calculation of the reduced stress tensor (with four variables) through inversion of fault-slip data; - calculation of the complete stress tensor (i.e., the two remaining unknowns) using the friction and the rupture laws; - estimation of the paleo-depth. The friction law is defined by the lower boundary of the cloud of points in the Mohr space represented by inherited faults. This operation fixes the abscissa origin of the Mohr diagram. To calculate the rupture law, we estimate both intact rock and outcrop quality parameters and need pairs of conjugate faults. Their dihedral angle fixes a point on the Mohr circle, where the rupture law has to be tangent, thus defining the scale of the axes and the values of the principal stresses. To define the paleo-depth, we estimate the average density of overlying rocks and the hydraulic conditions (i.e. the pore pressure).Testing of this workflow in three well-constrained geological case studies proved its promising reliability, showing a good agreement with independent stratigraphic and structural evidence.

On the genetically meaningful decomposition of grain-size distributions: A comparison of different end-member modelling algorithms

End-member modelling algorithms extract valuable information from grain-size distribution datasets, such as provenance, transport and sedimentation processes, which can subsequently be used to reconstruct past climate variability. Twenty years ago, Weltje (1997) published the algorithm EMMA, first applied to unmixing of grain-size distribution datasets in Prins and Weltje (1999a). In recent years, a range of new non-parametric algorithms developed specifically for unmixing of these datasets has become available. We evaluate whether the new algorithms as well as the original EMMA produce genetically meaningful results. We use artificial datasets and a published dataset from a geological case study. Experiments with the artificial datasets demonstrate that some algorithms are more appropriate for the unmixing of grain-size distribution data than others. Furthermore, the “geologically feasible” number of end members determined by the algorithms depends on the criteria for a statistical goodness of fit and does not necessarily correspond to the true number of end members in a dataset. Our study indicates that when an incorrect number of end members are modelled the shape and modal position of the end member grain-size distributions may deviate. Thus, end-member modelling should be used cautiously and in tandem with geological background information.

Wide area lithologic mapping with ASTER thermal infrared data: Case studies for the regions in/around the Pamir Mountains and the Tarim basin

After the authors have proposed the mineralogical indices, e.g., Quartz Index (QI), Carbonate Index (CI), Mafic Index (MI) for ASTER thermal infrared (TIR) data, many articles have been applied the indices for the geological case studies and proved to be robust in extracting geological information at the local scale. The authors also have developed a system for producing the regional map with the indices, which needs mosaicking of many scenes considering the relatively narrow spatial coverage of each ASTER scene. The system executes the procedures very efficiently to find ASTER data covering a wide target area in the vast and expanding ASTER data archive. Then the searched ASTER data are conditioned, prioritized, and the indices are calculated before finally mosaicking the imagery. Here in this paper, we will present two case studies of the regional lithologic and mineralogic mapping of the indices covering very wide regions in and around the Pamir Mountains and the Tarim basin. The characteristic features of the indices related to geology are analysed, interpreted and discussed.

DIRECT IMAGE-TO-GEOMETRY REGISTRATION USING MOBILE SENSOR DATA

Adding supplementary texture and 2D image-based annotations to 3D surface models is a useful next step for domain specialists to make use of photorealistic products of laser scanning and photogrammetry. This requires a registration between the new camera imagery and the model geometry to be solved, which can be a time-consuming task without appropriate automation. The increasing availability of photorealistic models, coupled with the proliferation of mobile devices, gives users the possibility to complement their models in real time. Modern mobile devices deliver digital photographs of increasing quality, as well as on-board sensor data, which can be used as input for practical and automatic camera registration procedures. Their familiar user interface also improves manual registration procedures. This paper introduces a fully automatic pose estimation method using the on-board sensor data for initial exterior orientation, and feature matching between an acquired photograph and a synthesised rendering of the orientated 3D scene as input for fine alignment. The paper also introduces a user-friendly manual camera registration- and pose estimation interface for mobile devices, based on existing surface geometry and numerical optimisation methods. The article further assesses the automatic algorithm’s accuracy compared to traditional methods, and the impact of computational- and environmental parameters. Experiments using urban and geological case studies show a significant sensitivity of the automatic procedure to the quality of the initial mobile sensor values. Changing natural lighting conditions remain a challenge for automatic pose estimation techniques, although progress is presented here. Finally, the automatically-registered mobile images are used as the basis for adding user annotations to the input textured model.

DIRECT IMAGE-TO-GEOMETRY REGISTRATION USING MOBILE SENSOR DATA

Abstract. Adding supplementary texture and 2D image-based annotations to 3D surface models is a useful next step for domain specialists to make use of photorealistic products of laser scanning and photogrammetry. This requires a registration between the new camera imagery and the model geometry to be solved, which can be a time-consuming task without appropriate automation. The increasing availability of photorealistic models, coupled with the proliferation of mobile devices, gives users the possibility to complement their models in real time. Modern mobile devices deliver digital photographs of increasing quality, as well as on-board sensor data, which can be used as input for practical and automatic camera registration procedures. Their familiar user interface also improves manual registration procedures. This paper introduces a fully automatic pose estimation method using the on-board sensor data for initial exterior orientation, and feature matching between an acquired photograph and a synthesised rendering of the orientated 3D scene as input for fine alignment. The paper also introduces a user-friendly manual camera registration- and pose estimation interface for mobile devices, based on existing surface geometry and numerical optimisation methods. The article further assesses the automatic algorithm’s accuracy compared to traditional methods, and the impact of computational- and environmental parameters. Experiments using urban and geological case studies show a significant sensitivity of the automatic procedure to the quality of the initial mobile sensor values. Changing natural lighting conditions remain a challenge for automatic pose estimation techniques, although progress is presented here. Finally, the automatically-registered mobile images are used as the basis for adding user annotations to the input textured model.

Effect and quantitative evaluation of CO2 derived from organic matter in coal on the formation of tight sandstone reservoirs

Tight reservoirs are widely distributed, especially in coal measure strata. Identification of the densification mechanism of the tight sandstone reservoirs is critical in effectively exploring and exploiting tight gas/oil resources. In this study, the gas formation from type III organic matter in coal was kinetically modeled for the whole diagenetic stage, from the shallow buried biogas generation stage to the deep buried thermal gas generation stage. The results demonstrated that during hydrocarbon formation, quantities of non-hydrocarbon gases, such as CO2, were generated. The proportion of CO2 is about 50%–70% of that of the C1–5, which far exceeds the CO2 content (0–5%) in the natural gas in the sedimentary basins. Geological case study analysis showed that a considerable part of the “lost” gaseous CO2 was converted into carbonate cement under favorable environments. Under the ideal conditions, the volume of the carbonate cement transformed from total CO2 generated by 1 m3 coal (Junggar Basin Jurassic, TOC 67%) can amount to 0.32 m3. Obviously, this process plays a very important role in the formation of tight sandstone reservoirs in the coal measures. Our results also show that the kinetic generation processes of C1–5 and CO2 are asynchronous. There are two main stages of CO2 generation, one at the weak diagenetic stage and the other at the over-mature stage, which are different from large-scale multi-stage hydrocarbon gas generation. Therefore, we can understand the mechanism of tight gas charging by determining the filling time for a tight gas reservoir and the key period of CO2 generation. Further analysis and correlation studies of a specific region are of great significance for determining the mechanism and modeling gas charging in tight reservoirs. It should be noted that the formation of tight sandstone reservoirs is the combined result of complex organic-inorganic and water-rock-hydrocarbon interactions. The details of spatial and temporal distributions of the carbonate cement derived from the organic CO2, which combines with metal ions (Ca/Mg/Fe) in the formation water, should be further investigated.

CLOSE RANGE HYPERSPECTRAL IMAGING INTEGRATED WITH TERRESTRIAL LIDAR SCANNING APPLIED TO ROCK CHARACTERISATION AT CENTIMETRE SCALE

Abstract. Compact and lightweight hyperspectral imagers allow the application of close range hyperspectral imaging with a ground based scanning setup for geological fieldwork. Using such a scanning setup, steep cliff sections and quarry walls can be scanned with a more appropriate viewing direction and a higher image resolution than from airborne and spaceborne platforms. Integration of the hyperspectral imagery with terrestrial lidar scanning provides the hyperspectral information in a georeferenced framework and enables measurement at centimetre scale. In this paper, three geological case studies are used to demonstrate the potential of this method for rock characterisation. Two case studies are applied to carbonate quarries where mapping of different limestone and dolomite types was required, as well as measurements of faults and layer thicknesses from inaccessible parts of the quarries. The third case study demonstrates the method using artificial lighting, applied in a subsurface scanning scenario where solar radiation cannot be utilised.

Facets of Luminescence for Dating

ABSTRACT The aim of this article is to introduce luminescence dating and relate it to luminescence and Raman spectroscopy of minerals. The physical bases of luminescence signals used in dating and their relationships to other radiation-induced luminescence and Raman signals are briefly reviewed. The manner in which these signals are applied to evaluate luminescence ages is described. Archaeological and geological case studies from the author's experience are used to illustrate potentialities and issues related to different contexts, techniques, and materials.

D. Beerling 2007. The Emerald Planet. How Plants Changed Earth's History. xvi + 288 pp. Oxford, New York: Oxford University Press. Price £14.99 (hard covers). ISBN 9780 19 280602 4.

In most books dealing with the history of life, fossil plants comprise the fuzzy backdrop to a zoological drama of ‘hopeful monsters’. At best, they may be permitted to give a static performance and mumble through a few disjointed lines. That’s why David Beerling’s new book – which brings plants onto centre stage – is so refreshingly novel. Through three hundred well written pages and seven geological case studies, Beerling emphasizes plants as a dynamic agent in the Earth’s system, simultaneously shaping the …

The application of geography markup language (GML) to the geological sciences

GML 3.0 became an adopted specification of the Open Geospatial Consortium (OGC) in January 2003, and is rapidly emerging as the world standard for the encoding, transport and storage of all forms of geographic information. This paper looks at the application of GML to one of the more challenging areas of automated geography, namely the geological sciences. Specific features of GML of interest to geologists are discussed and then illustrated through a series of geological case studies. We conclude the paper with a discussion of anticipated geological web services that GML will enable. GML is written in XML and makes use of XML Schema for extensibility. It can be used both to represent or model geographic objects and to transport them across the Internet. In this way it serves as the foundation for all manner of geographic web services. Unlike vertical application grammars such as LandXML, GML was intended to define geographic application languages, and hence is applicable to any geographic domain including forestry, environmental sciences, geology and oceanography. This paper provides a review of the basic features of GML that are fundamental to the geological sciences including geometry, coverages, observations, reference systems and temporality. These constructs are then employed in a series of simple geological case studies including structural geological description, surficial geology, representation of geological time scales, mineral occurrences, geohazards and geochemical reconnaissance.

Variation in apatite fission-track length measurement: implications for thermal history modelling

Predictive thermal history modelling using apatite fission-track (FT) data is dependent on an algorithm to describe the time and temperature dependency of FT annealing which, in turn, relies on the empirical determination of FT length as a measure of the annealing process. Assessment of variation in FT length measurement is poorly described, with few comparisons between analysts and little interlaboratory standardisation. Using apatites of various compositions containing induced tracks annealed to differing degrees, this study has assessed variation in horizontal confined track-length measurement for a variety of procedural conditions. Replicate analysis by a single observer is typically within 3% but increases inversely with track length. Comparison between observers on the same samples shows significant, generally nonsystematic variation between observers; for a complex length distribution variation is ∼12%. Sources of variation are identified as: (a) variation from track revelation, including etching, track-in-track (TINT) vs. track-in-cleavage (TINCLE) measurement and use of 252Cf irradiation to produce additional etching channels; (b) bias in measurement, including equipment, analytical procedures, and sample size; and (c) observer bias, principally differences in and consistency of personal technique. 5 M HNO 3 is preferred to weaker etchants: although more anisotropic, tracks are better defined, permitting more rigorous measurement, while c-axis parallel sections (where 2 π/4 π geometry is better defined) are more easily identified. For all but the longest length distributions, TINCLEs are significantly longer than TINTS, with few short TINCLEs at high angles; measurement of TINCLEs effectively masks the anisotropy of annealing. 252Cf irradiation is effective in increasing the number of TINTs sampled and measured. Variation between values measured for unirradiated and Cf-irradiated aliquots does not exceed that found for a single analyst, although a slight systematic shift to longer lengths for Cf-irradiated samples is seen. As reported by other workers, track-length distributions are anisotropic, anisotropy increasing with annealing level. Track angle exerts a major influence on measured length, summing affects from annealing and etching anisotropies with observer bias. Track angle should be accommodated within the annealing algorithm. It is recommended that similar track revelation, observation and measurement conditions are used for the analysis of field samples as are used in annealing experiments, and subsequently employed in numerical models to predict thermal history. A parallel argument can be advanced for using samples of similar composition. Further, we recommend that the FT community should seek as a matter of some urgency a programme of interlaboratory comparison of track-length measurement using standard apatite samples containing artificial length distributions typifying various levels of complexity. Such comparisons would provide a more rigorous baseline for thermal history prediction in geological case studies.

FISSION TRACK THERMOCHRONOLOGY: APPLICATION TO CONTINENTAL RIFTING OF SOUTH-EASTERN AUSTRALIA

Over the last five to ten years, apatite fission track analysis has developed into a sophisticated technique for studying the low-temperature thermal history of rocks. It has particular utility in oil exploration because its temperature range of sensitivity, about 20° to 125°C, overlaps the oil generation window. Whereas older fission track thermal history approaches relied solely on the sample fission track age, the new interpretive approaches use sample age, single grain age and track length data. They also emphasise the analysis of systematic variations in data patterns in sequences of samples, such as samples from various depths in a well. Laboratory study of the thermal annealing of fission tracks and compilation of fission track data from geological case studies has greatly improved our understanding of apatite fission track systematics, allowing considerably more detailed interpretations of thermal histories.Application of apatite fission track analysis to the rifted continental margins of south-eastern Australia shows that rifting and separation of Australia from Antarctica and the Lord Howe Rise were accompanied by at least 1.5-3 km of uplift and erosion along the Tasman Sea and Bass Strait coasts. Uplift and erosion were much less 100 km or so inland. This shows that the uplift of the south-eastern Australian margins was caused by the continental rifting process, the same process that initiated major subsidence in the sedimentary basins in Bass Strait. The consistent fission track data patterns around south-eastern Australia suggest a generally similar tectonic setting for the Tasman Sea and Bass Strait parts of the margin. Lister et al. (in press) propose that the Tasman part of the margin is an upper plate type of margin that formed above a west-dipping detachment zone. The fission track data suggest that the Bass Strait part of the margin may also be of upper plate type.

Computer analysis of lithostratigraphic data derived from geotechnical records

Summary The database GEOSHARE is used to demonstrate some practical applications of a geotechnical database and illustrate the potential benefits of establishing a national computer database of site investigation records. GEOSHARE is an easy to use (menu driven) system in which data of only a purely factual nature is stored. The data storage system is designed to accommodate the complete range of site investigation records in forms that are merely transcripts of the originals. Flexible report and graphic display procedures are described. Three geological case studies are discussed to demonstrate the value of computer analysis of the stored data to the engineer.

841124 Engineering geological case studies of tunnelling and deep excavations in Malaysia : Tan, B K Proc International Symposium on Engineering Geology and Underground Construction, Lisbon, 1983V1, P1.25–1.33. Publ Lisbon: SPG, 1983

841124 Engineering geological case studies of tunnelling and deep excavations in Malaysia : Tan, B K Proc International Symposium on Engineering Geology and Underground Construction, Lisbon, 1983V1, P1.25–1.33. Publ Lisbon: SPG, 1983

Engineering geological case study of the site investigation and design of a major trunk road cutting in carboniferous rocks : Buist, D S; Burnett, A D; Sanders, M K Q J Engng Geol, V11, N2, 1978, P161–176

Engineering geological case study of the site investigation and design of a major trunk road cutting in carboniferous rocks : Buist, D S; Burnett, A D; Sanders, M K Q J Engng Geol, V11, N2, 1978, P161–176

Engineering geological case study of the site investigation and design of a major trunk road cutting in Carboniferous rocks

Summary The 7.1 km dual two-lane Unstone-Dronfield By-Pass, Derbyshire, first opened to traffic in 1975, incorporates a 30 m deep rock cut at Monk Wood, excavated in strata of Lower Coal Measures age. Cuttings in similar geological settings elsewhere had resulted in mass slide failures and the measures adopted at Monk Wood to avoid a similar problem are described. The site was complicated by the presence of extensive old workings for coal and ironstone; their treatment is discussed.