The joint use of imagery and topographic data for inferring bauxite deposits in a Karst landscape
Conventional methods of bauxite orebody delimitation in Jamaica have relied on the use of topographic maps, where closed contour lines in Jamaicas karst landscape (where all bauxite deposits are found), were used to infer the presence of potential deposits when conducting pre-field exploration activities. This was especially true in past decades, prior to the availability of airborne imaging and detailed topographic modeling. Most of Jamaicas orebody maps have been created using these conventional methods, and when these are used to make modern decisions, especially when using modern GIS technologies, they often create a false picture as to the actual state of current reserves. The closed-contour mapping methodology fails to consider the fact that most of Jamaicas deposits are superficially located on slightly-tilted limestone plateaux. Also, depending on the scale of the topographic maps used, delineation of the orebodies themselves may either over-estimate or under-estimate the actual area of the deposit, which has significant implications on volume estimations. Jamaica has begun to incorporate a combination of infra-red satellite imagery and detailed topographic modeling to surmount this problem. Due to the inherent nature of Jamaicas karst landscape, depressions (with bauxite infill) have distinctly different spectral properties than the surrounding hills (with little soil cover), largely owing to the different vegetation profiles that develop on each. These are easily identified using infra-red imagery, and can be simply delimited using supervised classification methods. Three-dimensional topographic modeling also assists in the delineation of the depressions, especially where landscapes may be altered by eforestation for cultivation or urbanization.These methods serve to assist in field exploration, where potential deposits viability can be confirmed or rejected, based on drill ing results, which will determine the depth of the deposit, as well as geochemical quality. This paper will present the results of large-scale exercises conducted in Jamaica using this method, and compares this with past estimates, as well as with post-mining data to confirm this methods accuracy.
Parris Lyew-Ayee Jr Parris A. Lyew-Ayee
Mona Geolnformatics Institute,University of the West Indies Jamaica Bauxite Institute
国际会议
XVIII International Symposium of ICSOBA(第18届国际铝土矿、氧化铝及铝工业学术年会)
郑州
英文
100-109
2010-11-25（万方平台首次上网日期，不代表论文的发表时间）