Fundamental issues in quantitative estimation of mineral resources

Several issues considered to be fundamental in quantitative estimation of mineral resources and selection of mineral targets are addressed. Integration of multiple data sets, either by experts or by statistical methods, has become a common practice in estimation of mineral potential. Several major problems in data integration must be solved to significantly improve mineral resource estimation. Issues related to randomness of mineral endowment, basic statistical tools, exceptionalness of ore, and economic truncation and translation are discussed in the first part of the article. A number of important technical problems in data integration are also identified; they include data compilation, information enhancement, information synthesis, and target selection.     

Geo-/Object-Coding for Local-Change Assessment

Missing availability of reliable and specific landscape data may pose substantial restrictions to successful exploitation of remote sensing data and fast implementation of GIS (Geo-Information Systems). The possibilities to document conditions with high spacial resolution at a given time and to review changing aspects by different disciplines represent opportunities for complex environmental programs.The article covers: geodata acquisition and processing, research, execution, and ergonomical/cognitive aspects. Application in inpenetrable terrain for research, landuse, and engineering requirements proved the feasibility especially in areas with high demand for timely, accurate, and comprehensive surveys.Airborne close-range sensing was developed to survey localities and regions. It is no competition to global-change monitoring and large area are mapping programs possible with remote sensing. Substituting only the bulk of field-work, leaving time for in-depth review in the field or in the office, the system provides a possibility to restudy points of interest.Exploitation of advanced metric cameras, specialized airborne platforms, and spatial overlay, recognition, and discrimination techniques form the backbone of the TOPOGRAMM approach. Multi-sectoral, multi-temporal, multi-spectral survey and processing methods rely basically on enlarged image scales additional to conventional aero-photogrammetry and analytic plotting. Measurements and identification, not primarily interpretation, allow to establish high-fidelity and high resolution geo-frameworks. Focussing on micro- and mesoscales, no emphasis is given to highest geometric accuracy used for geodetic surveys. Drawing near to the object allows extraction of thematical and semantical information, dimensions, and phenomelogy of objects hitherto only singularily available.

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Empirical assessment of obstruction adaptive elevation masks to mitigate site-dependent effects

GPS Solutions - Site-dependent effects are accuracy-limiting factors in static and kinematic GNSS-based positioning applications since they cannot be minimized using differential techniques. In...     

Guided Waves from Sources Outside Faults: An Indication for Shallow Fault Zone Structure?

— Using 3-D numerical modeling of seismic wave propagation we investigate the possibility of generating fault zone (FZ) trapped wave energy from sources well outside a fault. The FZ is represented by a O(200 m) wide vertical low velocity layer in a half space. We find that FZ trapped waves can be excited from sources well outside the fault if (1) the low-velocity structure extemds only to shallow depth and the source is located at greater depth or (2) the structure of the low-velocity zone is such that only the shallow part of the FZ traps energy. FZ trapped waves are not excited from sources well outside a FZ continuous with depth. The results support, in conjunction with recent observational evidence, a model for natural faults with shallow trapping structures rather than ones that span the entire seismogenic zone. This may have implications for fault mechanics as well as for aspects of shaking hazard near faults.     

Glacial isostatic adjustment in Fennoscandia from GRACE data and comparison with geodynamical models

The Earth’s gravity field observed by the Gravity Recovery and Climate Experiment (GRACE) satellite mission shows variations due to the integral effect of mass variations in the atmosphere, hydrosphere and geosphere. Several institutions, such as the GeoForschungsZentrum (GFZ) Potsdam, the University of Texas at Austin, Center for Space Research (CSR) and the Jet Propulsion Laboratory (JPL), Pasadena, provide GRACE monthly solutions, which differ slightly due to the application of different reduction models and centre-specific processing schemes. The GRACE data are used to investigate the mass variations in Fennoscandia, an area which is strongly influenced by glacial isostatic adjustment (GIA). Hence the focus is set on the computation of secular trends. Different filters (e.g. isotropic and non-isotropic filters) are discussed for the removal of high frequency noise to permit the extraction of the GIA signal. The resulting GRACE based mass variations are compared to global hydrology models (WGHM, LaDWorld) in order to (a) separate possible hydrological signals and (b) validate the hydrology models with regard to long period and secular components. In addition, a pattern matching algorithm is applied to localise the uplift centre, and finally the GRACE signal is compared with the results from a geodynamical modelling. The GRACE data clearly show temporal gravity variations in Fennoscandia. The secular variations are in good agreement with former studies and other independent data. The uplift centre is located over the Bothnian Bay, and the whole uplift area comprises the Scandinavian Peninsula and Finland. The secular variations derived from the GFZ, CSR and JPL monthly solutions differ up to 20%, which is not statistically significant, and the largest signal of about 1.2 Gal/year is obtained from the GFZ solution. Besides the GIA signal, two peaks with positive trend values of about 0.8 Gal/year exist in central eastern Europe, which are not GIA-induced, and also not explainable by the hydrology models. This may indicate that the recent global hydrology models have to be revised with respect to long period and secular components. Finally, the GRACE uplift signal is also in quite good agreement with the results from a simple geodynamical modelling.     

Modeling abiotic production of apparent oxygen utilisation in the oligotrophic subtropical North Atlantic

Apparent oxygen utilisation is potentially biased by abiotic, physical processes. Using a coupled 3-D circulation-oxygen model, this potential is quantitatively estimated for a region in the eastern subtropical North Atlantic, called the Beta Triangle, where an inconsistency exists between observational estimates of high carbon export from the euphotic zone, based on oxygen utilisation rates in the thermocline (Jenkins 1982), and those of low nutrient supply to the euphotic zone (Lewis et al. 1986, 2004). Our results indicate that in the upper ocean, the Jenkins (1982) estimate is indeed biased high by approximately 10% due to abiotic processes feigning respiration, thus contributing to the apparent inconsistency. Vertical integration, however, yields an abiotic fraction of less than 3%, so the apparent observational discrepancy can not be resolved.Responsible Editor: Franciscus Colijn