SITE INVESTIGATIONS:RISK ASSESSMENT

962248 Further results on prediction of soil properties from terrain attributes: heterotopic eokriging and regreesion-kriging I. O. A. Odeh, A. B. McBratney & D. J. Chittleborough, Geoderma, 67(3-4), 1995, pp 215-226. Methods involving spatial prediction of soil properties from landform attributes are compared using carefully designed validation procedures. The methods, tested against ordinary kriging and universal kriging of the target variables, include multi-linear regression, isotopic cokriging, heterotopic cokri- ging and regression-kriging models A, B and C. Prediction performance by ordinary kriging and unversal kriging was comparatively poor. Heterotopic cokriging outperformed isotopic cokriging because the former utilised more of the local information from the covariables. The combined regression-kriging methods generally performed well. Both the regression-kriging model C and heterotopic cokriging performed well when soil variables were predicted into a relatively finer gridded digital elevation model (DEM) and when all the local information was utilised. Regression- kriging model C generally performed best and is, perhaps, more flexible than beterotopic eokriging. (from Authors)

962249 2D and 3D analogue modelling of extensional fault structures: templates for seismic interpretation K. R. McClay, Petroleum Geoscience, 1(2), 1995, pp 163- 178. Scaled analogue models provide powerful insights into the progressive evolution of 2D and 3D extensional fault systems and can be used as templates for the interpretation of seismic sections in areas of complex structure and poor seismic resolution. This paper reviews the results of 2D and 3D extensional fault models and compares the structural styles within the models with examples of natural fault systems in both cross-section and in map view. (from Author)

962250 Cost-effective staggered schemes for the numerical simula- tion of wave propagation A. Kamel, P. Sguazzero & M. KAndelan, International Journal for Numerical Methods in Engineering, 38(5), 1995, pp 755-773. The use of elastic wave equations to model the seismic response of an assumed geophysical structure is an invaluable tool to understand complex seismic data. It is a very expensive tool, though, in particular in 3-D, given the huge amount of gridpoints needed to represent accurately the wave fields in domains of practical interest. Large efforts have been made to develop methods for solving accurately the wave equation at an afforable cost. This paper presents a cost- effectiveness analysis of explicit Finite Difference (FD) methods for the numerical integration of the wave equation. (from Authors)

962251 Aplicacion del procesu de imagenes al analisis de datos gravimetricos (Application of image processing to gravity data analysis) J. L. Plata Torres & S. S. Diaz-Sarmiento, Boletin Geologico y Minero, 105(5), 1994, pp 473-483. In this paper impages are prepared from irregularly distrib- uted gravity data developing a new method for testing the validity of the densisty used in the reduction of the Bouguer anomaly. The superposition of three images, with altimetry and Bouguer anomaly at two different densities, of selected range and application of just one basic colour per image, has given the best results to locate topographic correlation anomalies. (from English summary)

962252 Structural interpretation of the Bouguer and aeromagnetic anomalies in central Sinai H. H. Ghazala, Journal of African Earth Sciences, 19(1-2), 1994, pp 35-42.

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A large part of the central Sinai peninsula, covering mainly the EI-Tih and Egma plateaux, was evaluated using geophy- sical data. The Bouguer and aeromagnetie anomaly maps were critically analyzed and correlated to investigate regional tectonism, structural elements and major sedimentary basins characterizing this region. The results should be of help in delineating some exploration concepts of hydrocarbon and groundwater resources. (from Author)

962253 NURE geochemical and geophysical surveys - defining prospective terranes for United States placer exploration A. E. Grosz & P. G. Sehruben, US Geological Survey Bulletin, 2097, 1994, 9 pp, maps. The data outlined a large area in the Coastal Plain province in Virginia and North Carolina, and several areally extensive regions in Idaho and Oregon for Ti-Hf-REE-bearing placer exploration. Evidence for other potential Ti-Hf-REE placer deposits is given for unconsolidated Coastal Plain sediments along the Fall Zone from Virginia to Georgia and for large segments of Montana in areas underlain by stratified marine and continental deposits. Other parts of the conterminous US, particularly in the largely unexplored Central Plains, appear suitable for similar study. (from Authors)

962254 Computer processing in the exploration and evaluation of the Angovia gold deposit B. Tourliere & J. Bobillier, Engineering & Mining Journal, 196(7), 1995, pp 32-35. In 1983 BRGM took out an Exploration License over the YaourC Massif in Cote d'Ivoire and in 1987 discovered the Angovia gold deposit, which included 3.4 mint of open- pittable ore grading 4.3 g/mt gold. GDM, an applied geology software package developed and marketed by BRGM, was used from the very first stages of exploration to process the geochemical survey results and produce anomaly maps. GDM was then used in the field during the evaluation phase for processing the trrenching and drilling results and esti- mating reserves. The use of the GDM software package resulted in significant improvements in productivity, the quality of information, and lower exploration costs. (Authors)

962255 Fractal characters of gold distribution in one ore deposit, Xinjiang, China and their significance Burning Shen & Yuanchao Shen, Science in China, Series B, 38(1), 1995, pp 124-128. Fractal characters of gold distribution in one ore deposit, Xinjiang, China and their geological signif'w.ance are studied. The relationships between fractal dimension and sampling are also discussed. (Authors)

Risk assessment

962256 Risk assessment and technological options for contami- nated sediments - a geochemical perspective U. Forstner, Marine & Freshwater Research, 46(1), 1995, pp 113-127. The effective long-term remediation of contaminated sedi- ments presents a particular challenge, since the large volume and the often diverse range of contaminants in these materials makes many of the traditional remediation techniques uneconomic. Future risk assessments of contaminated sedi- ments should focus on assessing possible chemical changes in the stored sediment (e.g. redox changes and acid production) that could lead in the long term to contaminant remobiliza- tion. Priority needs to be given to the application of new geochemical engineering techniques, including chemical sta- bilization by additives and storage under permanent anoxic conditions, that optimize the long-term chemical stability of contaminated sediments. (from Author)