Polygonal Faults In The Austin Chalk: Invariance Of Scale From Mud Cracks To Polygons With Implications Of Structural, Geomorphic And Isotopic Data On Polygonal Fault Geometry And Origin.

The Cretaceous Austin Chalk contains large numbers of fractures and normal faults whose orientations have been attributed to either regional stresses (e.g., the Balcones fault trend) or, by analogy with the mudrocks, to polygonal faulting resulting from compaction. In this study, we present geomorphic data, field study, and stable isotope data to support that the majority of these faults in North Texas are polygonal. Field-measured fault orientations suggest randomly distributed fault strikes, indicating a polygonal fault structure. Using geomorphologic data (topographic and DEM data) on stream orientations suggests that the polygonal fault patterns are best reflected in the headwater (1st or 2nd order) streams. The higher-order streams tend to reflect the down-dip direction of the chalk. Furthermore, to simulate the formation of polygonal faults, desiccation of ooze-like muds to produce mud cracks generates polygonal patterns with cracks having orthogonal, Y, non-orthogonal, and crossing intersections. Preliminary results suggest a compositional dependence for the distribution of intersection types and a relationship between thickness and polygonal area. Fault asperity, striated calcite veins, and host-rock chalk samples have δ18O values of -9.5 \u3c δ18OPDB 18O Inoceramid -2.6 \u3c δ18

Rock fractures analysis using Structure from Motion technology: new insight from Digital Outcrop Models

Fractures are one of the most important features of the rocks of the upper crust since they strongly influence their physical and chemical behavior and reflect their tectonic history. For this reason, fracture study plays a key role in different branches of the geosciences. Notwithstanding, the quantification of the features and parameters describing fractures could be unsatisfactory using the standard field techniques because they are mainly based on direct-contact methodologies that are affected by errors, as orientation bias and trace censoring, and scarce representativeness, due to the limited possibility of acquiring information of outcrops partially or totally inaccessible. Recently new remote sensing technologies, such as Terrestrial Laser Scanner (TLS) and Digital Photogrammetry (DP), can help to overcome these limitations. Whereas TLS could be very expensive and difficult to use in geological study, DP permits to obtain similar results in an easier way due to cheaper and lighter equipment and more straightforward procedures. Moreover, DP becomes even more useful when combined with Unmanned Aerial Vehicle (UAV) because permits to acquire digital images from positions inaccessible to humans, allowing to analyze geological objects from points of view previously unimaginable. The images acquired from the ground and/or by the UAV can be then processed using different digital algorithms, such as Structure from Motion (SfM), that permit to create 3D model of the studied outcrop. In geosciences, the 3D model representing the surface of the outcrop is often called Digital Outcrop Model (DOM). Despite DOMs can be really useful in different branches of geosciences, their applications are quite well limited because the procedures of their development and sampling/analysis are scarcely analyzed in literature. It is important to highlight that whereas the UAV-based SfM approach is fairly discussed in literature for simple flat areas, is scarcely treated for application to near vertical and not-planar slopes. Moreover, the validity of some procedures of fracture sampling on 3D model, with special regards to the automatic ones, that have been recently presented in literature, is not well treated for real cases of study. The scarce knowledge about these approaches could cause different troubles to the scientific-users: from the application of avoidable time-consuming routine, to the acquisition and interpretation of erroneous data. This research aims to contribute to the scientific knowledge of the use of digital photogrammetry for fractured rock mass analysis, creating and defining new approaches and procedures for the development, analysis and application of DOMs. Here, a workflow for the fracture analysis of steep rocky outcrops and slopes using the 3D DOM is presented. In particular, the following steps are discussed: (i) image acquisition; (ii) development of 3D model; (iii) sampling of DOM; (iv) quantification and parametrization of the 3D measures; (v) application of the 3D quantitative data and parameters to different case of study. Four different cases of study were selected to validate the proposed method: the upper Staffora Valley and Ponte Organasco (Northern Apennines, Italy), Ormea (Ligurian Alps, Italy), and Gallivaggio (Western Alps, Italy) cases of study. However, this methodology could not completely replace the 'direct-contact' field activity, because some information as roughness, infilling and aperture of fractures cannot be measured satisfactory, and because, where possible, field control measures to validate the 3D data are necessary. However, this methodology could be considered as a new necessary procedure for rock-fracture studies because it allows to overcome the inevitable errors of the ground-based traditional methodology and because the DOMs are always available for the analysis, promoting data sharing and comparison, two fundamental principles on which science have and will have to be basedFractures are one of the most important features of the rocks of the upper crust since they strongly influence their physical and chemical behavior and reflect their tectonic history. For this reason, fracture study plays a key role in different branches of the geosciences. Notwithstanding, the quantification of the features and parameters describing fractures could be unsatisfactory using the standard field techniques because they are mainly based on direct-contact methodologies that are affected by errors, as orientation bias and trace censoring, and scarce representativeness, due to the limited possibility of acquiring information of outcrops partially or totally inaccessible. Recently new remote sensing technologies, such as Terrestrial Laser Scanner (TLS) and Digital Photogrammetry (DP), can help to overcome these limitations. Whereas TLS could be very expensive and difficult to use in geological study, DP permits to obtain similar results in an easier way due to cheaper and lighter equipment and more straightforward procedures. Moreover, DP becomes even more useful when combined with Unmanned Aerial Vehicle (UAV) because permits to acquire digital images from positions inaccessible to humans, allowing to analyze geological objects from points of view previously unimaginable. The images acquired from the ground and/or by the UAV can be then processed using different digital algorithms, such as Structure from Motion (SfM), that permit to create 3D model of the studied outcrop. In geosciences, the 3D model representing the surface of the outcrop is often called Digital Outcrop Model (DOM). Despite DOMs can be really useful in different branches of geosciences, their applications are quite well limited because the procedures of their development and sampling/analysis are scarcely analyzed in literature. It is important to highlight that whereas the UAV-based SfM approach is fairly discussed in literature for simple flat areas, is scarcely treated for application to near vertical and not-planar slopes. Moreover, the validity of some procedures of fracture sampling on 3D model, with special regards to the automatic ones, that have been recently presented in literature, is not well treated for real cases of study. The scarce knowledge about these approaches could cause different troubles to the scientific-users: from the application of avoidable time-consuming routine, to the acquisition and interpretation of erroneous data. This research aims to contribute to the scientific knowledge of the use of digital photogrammetry for fractured rock mass analysis, creating and defining new approaches and procedures for the development, analysis and application of DOMs. Here, a workflow for the fracture analysis of steep rocky outcrops and slopes using the 3D DOM is presented. In particular, the following steps are discussed: (i) image acquisition; (ii) development of 3D model; (iii) sampling of DOM; (iv) quantification and parametrization of the 3D measures; (v) application of the 3D quantitative data and parameters to different case of study. Four different cases of study were selected to validate the proposed method: the upper Staffora Valley and Ponte Organasco (Northern Apennines, Italy), Ormea (Ligurian Alps, Italy), and Gallivaggio (Western Alps, Italy) cases of study. However, this methodology could not completely replace the 'direct-contact' field activity, because some information as roughness, infilling and aperture of fractures cannot be measured satisfactory, and because, where possible, field control measures to validate the 3D data are necessary. However, this methodology could be considered as a new necessary procedure for rock-fracture studies because it allows to overcome the inevitable errors of the ground-based traditional methodology and because the DOMs are always available for the analysis, promoting data sharing and comparison, two fundamental principles on which science have and will have to be base

Big Data Computing for Geospatial Applications

The convergence of big data and geospatial computing has brought forth challenges and opportunities to Geographic Information Science with regard to geospatial data management, processing, analysis, modeling, and visualization. This book highlights recent advancements in integrating new computing approaches, spatial methods, and data management strategies to tackle geospatial big data challenges and meanwhile demonstrates opportunities for using big data for geospatial applications. Crucial to the advancements highlighted in this book is the integration of computational thinking and spatial thinking and the transformation of abstract ideas and models to concrete data structures and algorithms

Multiple data set integration and GIS techniques used to investigate linear structural controls in the southern Powder River Basin, Wyoming

Lineaments in the Powder River Basin were mapped and categorized from Landsat TM imagery, a Digital Elevation Model (30 m), and Digital Line Graph (DLG) hydrology files. A GIS program was written using DLG information to eliminate those lineaments that were within 20° of roads and railroads. The DLG and DEM information was further used to stratify the topographic lineaments into slope-breaks, ridge-tops, or valleys. Rose diagrams created for each class of lineaments give important clues on the timing of their formation. The major northwest and northeast trends that these lineaments follow appear to correspond with those identified by previous works. Comparisons with subsurface data suggests that the concentration of lineaments is strongly coincident with gravity and magnetic highs and lows, possibly representing the surface expression of basement-rooted structure. Lastly, the location many reservoirs in the basin also coincide with higher concentration of lineaments over gravity and magnetic highs.;This project was partially funded by the Schumaker Fund, donated by Dr. and Mrs. Robert Schumaker. Also, supplemental funding was given by the American Society for Photogrammetry and Remote Sensing. I would like to thank all of those involved in supporting both of these funds. Their donations has made it possible for continuing research of GIS and geology

Ghana airborne geophysics project in the Volta and Keta Basin : BGS final report

This report describes the work undertaken by BGS between November 2006 and March 2009 in collaboration with Fugro Airborne Surveys Pty Ltd on an airborne geophysical survey and ground reconnaissance mapping of the Volta River and Keta Basins, Ghana. The project was supported by the EU as part of the Mining Sector Support Programme, Project Number 8ACP GH 027/13. The initial contract duration was three years, but this was extended by five months to account for acquisition of gravity data by another project. Some parts of Ghana have been airborne surveyed as part of the Mining Sector Development and Environmental Project, co-funded by the World Bank and the Nordic Development Fund, but no work was carried out on the Volta River and Keta basins, which together form a major portion of the Ghanaian territory. The approximate areas covered by the surveys are estimated at 98,000 km² for the satellite imagery and the airborne geophysics, except for the Time Domain Electromagnetic (TDEM) survey which was limited to 60,000 km². The main beneficiary of this project is the Geological Survey Department, GSD. The work enhanced its geological infrastructure and its personnel received hands-on training on modern geological mapping technology. Indirect beneficiaries were the mining and exploration companies that can follow up the reconnaissance work with detailed exploration work. The project was conducted in five phases, and this document reports on the BGS input to Phase 1, 4 and 5, with no inputs required in Phases 2 and 3: • Phase1: geological outline through Radar and optical satellite imageries. • Phase 2: airborne geophysical survey over the two basins for magnetics and Gamma Ray spectrometry (Fugro survey). • Phase 3: airborne electromagnetic and magnetic geophysical survey of specific areas, following the completion and interpretation of phase 2, using fixed wing time domain technology (Fugro survey). • Phase 4: interpretation of the combined geology and geophysics. • Phase 5: production of factual and interpretation maps. The full list of BGS products is outlined in Table 1 below, while Jordan et al. (2006) describe the products delivered on schedule in Phase 1

Personal Wayfinding Assistance

We are traveling many different routes every day. In familiar environments it is easy for us to find our ways. We know our way from bedroom to kitchen, from home to work, from parking place to office, and back home at the end of the working day. We have learned these routes in the past and are now able to find our destination without having to think about it. As soon as we want to find a place beyond the demarcations of our mental map, we need help. In some cases we ask our friends to explain us the way, in other cases we use a map to find out about the place. Mobile phones are increasingly equipped with wayfinding assistance. These devices are usually at hand because they are handy and small, which enables us to get wayfinding assistance everywhere where we need it. While the small size of mobile phones makes them handy, it is a disadvantage for displaying maps. Geographic information requires space to be visualized in order to be understandable. Typically, not all information displayed in maps is necessary. An example are walking ways in parks for car drivers, they are they are usually no relevant route options. By not displaying irrelevant information, it is possible to compress the map without losing important information. To reduce information purposefully, we need information about the user, the task at hand, and the environment it is embedded in. In this cumulative dissertation, I describe an approach that utilizes the prior knowledge of the user to adapt maps to the to the limited display options of mobile devices with small displays. I focus on central questions that occur during wayfinding and relate them to the knowledge of the user. This enables the generation of personal and context-specific wayfinding assistance in the form of maps which are optimized for small displays. To achieve personalized assistance, I present algorithmic methods to derive spatial user profiles from trajectory data. The individual profiles contain information about the places users regularly visit, as well as the traveled routes between them. By means of these profiles it is possible to generate personalized maps for partially familiar environments. Only the unfamiliar parts of the environment are presented in detail, the familiar parts are highly simplified. This bears great potential to minimize the maps, while at the same time preserving the understandability by including personally meaningful places as references. To ensure the understandability of personalized maps, we have to make sure that the names of the places are adapted to users. In this thesis, we study the naming of places and analyze the potential to automatically select and generate place names. However, personalized maps only work for environments the users are partially familiar with. If users need assistance for unfamiliar environments, they require complete information. In this thesis, I further present approaches to support uses in typical situations which can occur during wayfinding. I present solutions to communicate context information and survey knowledge along the route, as well as methods to support self-localization in case orientation is lost

Advanced Location-Based Technologies and Services

Since the publication of the first edition in 2004, advances in mobile devices, positioning sensors, WiFi fingerprinting, and wireless communications, among others, have paved the way for developing new and advanced location-based services (LBSs). This second edition provides up-to-date information on LBSs, including WiFi fingerprinting, mobile computing, geospatial clouds, geospatial data mining, location privacy, and location-based social networking. It also includes new chapters on application areas such as LBSs for public health, indoor navigation, and advertising. In addition, the chapter on remote sensing has been revised to address advancements

The structural setting of the Canaã dos Carajás region and Sossego-Sequeirinho deposits, Carajás – Brazil

The Carajás Terrane in the Amazon Craton hosts Precambrian Cu-Au deposits with resources larger than 100 million tonnes of ore (e.g. Igarapé Bahia-Alemão, Cristalino, Sossego, 118 and Salobo). This thesis examines at a local scale, structural aspects of the Sossego and Sequeirinho deposits, located in the Archaean granite-gneiss basement of the Canaã dos Carajás region, the boundary between the Carajás and Rio Maria Granite Greenstone Terranes. The study focuses on the understanding of the processes, controls and styles of two regionally representative Archaean IOCG examples and also investigates the tectonic framework and structural evolution of the Canaã dos Carajás region. Primary data comprises traditional methods of field mapping and structural analysis, microscopic investigation, combined with modern digital mapping, lineament and particles size analysis. The principal aims of the study include: (1) identification of crustal scale regional lineaments and their relationship with mineral deposits; (2) a new tectonic framework and structural model for the Canaã dos Carajás region; and (3) description and interpretation of the structural framework of the Sossego and Sequeirinho mines. The most prominent crustal scale lineaments in the Carajás Terrane comprise early WNW-ESE sets that configure the regional structural trend and mark the basement-cover assemblage contact, and relatively late NE-SW lineaments. Higher lineament frequencies and density were observed in the cover assemblage domain and coincide with numerous lineament intersections. Mineral occurrences and deposits are clustered and spatially associated with domains of higher lineaments density and areas where major lineaments intersect. Then, there is a spatial relationship between major lineaments and the occurrence of mineral deposits. The Canaã dos Carajás region comprises Archaean TTG gneisses, lens shaped amphibolite bodies, 2.7 Ga. syn-tectonic alkali granitoids and 1.88 Ga. isotropic granites. These rocks display widespread heterogeneous, anastomosing WNW-ESE and NE-SW foliation sets, related steeply dipping ductile shear zones associated with steep-to-moderately plunging mineral lineations. The nature and geometry of the ductile fabrics are compatible with a bulk pure-shear dominated transpression with partitioning of strain intensity with shortening and extensional directions oriented at approximately near horizontal (~020° Az) and near vertical respectively. Microstructures in quartz and feldspar indicate deformation at metamorphic conditions compatible with middle to upper amphibolite facies (~650-700°C), overprinted by deformation at middle to upper greenschist facies conditions (~400-500°C). The Canaã dos Carajás region represents part of an original granite-greenstone terrane that has undergone substantial reworking during a late sinistral transpressional deformation. The reworking took place at c.a. 2.7 Ga, coeval with syn-tectonic sub-alkaline magmatism. The basement comprises intensely deformed rocks uplifted from the lower-to-middle crust, deformed under high amphibolite facies conditions and later affected by localised deformation at greenschist facies conditions. The structural framework of the Sossego and Sequeirinho deposits comprises regional WNW-ESE structures (foliations and shear zones) offset by NE-SW sinistral faults. Sequeirinho is hosted along a NE-SW sinistral fault, associated with a positive magnetic anomaly. It comprises an “S” shaped tabular orebody whose tips are hosted by sub-vertical WNW-ESE sheared and foliated granitoids and schists. These are linked by a NE-SW sinistral fault zone containing mineralized breccias. Sossego comprises a sub-circular, vertical, pipe-like orebody with a central breccia body surrounded by a stockwork array of sulphide veins, faults and shear zones. Tensile and shear veins show single or composite mineral fillings consistent with episodic vein opening, with a progressive change in hydrothermal fluid composition during time. The Sossego breccias show high clast angularity, characteristic of immature explosion breccias, whilst the Sequeirinho breccias display rounded fragments with low angularity, typical of mature breccias whose particle fragmentation was dominated by wear and attrition during subsequent slip along a fault zone. Microstructures in quartz and feldspar indicate that the deformation at Sossego and Sequeirinho initially took place under low-to-middle (300-400°C) and middle-to-upper (400-500°C) greenschist facies, respectively. Latter overprinted by brittle-ductile structures and veins containing lower-temperature minerals formed between 170-250°C. The rocks in the area of the mines record deformational processes that initially took place under the viscous regime (>15km), represented by mylonites and ultramylonites. Progressive exhumation, possibly synchronous with regional transpressional thickening led to conditions compatible with the frictional-viscous transition with intense fluid activity, with mineralization