The development of sophisticated 3D visualization software has made it possible to fully integrat... more The development of sophisticated 3D visualization software has made it possible to fully integrate geological, geochemical, and geophysical data in three dimensional space creating new opportunities to explore data relationships. The advent of inexpensive, multi-element ICP-MS (inductively coupled plasma-mass spectrometry) analysis techniques with low detection limits has led to the identification of zoned element associations and their spatial relations to ore with great efficiency and clarity. Geochemical modeling of down-hole data has advantages in pattern recognition by facilitating the creation of 3D volumes. This is achieved by producing individual element block models using a gridding algorithm to interpolate concentrations between drill holes. The block models provide an effective means of exploring relationships in the down-hole data and integrating this information with other subsurface data (geologic lithology logs, geophysical inversions) and surface data (geochemistry, geology, and geophysics). A key prerequisite for geochemical modeling is the acquisition of down-hole data distributed in a generally systematic fashion along each hole. Some inconsistencies in a geochemical database that need to be addressed prior to modeling include: 1) relative accuracy shifts over time in data reported from a single laboratory or between different laboratories; 2) variable detection limits amongst datasets; 3) mixed partial and total extraction data; 4) special values or zeros representing data below detection limit or missing data; and 5) mixed reporting units. Some applications of 3D geochemistry include: 1) stratigraphic correlation using elements not introduced or significantly redistributed during the mineralizing event; 2) development of a conceptual zonation model of a mineral system; 3) identification of vector criteria for locating high grade mineralization based on zonation relationships; 4) distinguishing proximal from distal signatures; 5) improving vectoring by integrating surface and sub-surface data; 6) improving interpretation of surface data by understanding the effects of surface weathering; 7) locating the bedrock source of anomalies in 3D overburden data; and 8) increasing the understanding of mineral systems and dispersion phenomena. Most of these applications are illustrated using a schematic zonation model for Carlin-type sediment-hosted gold systems in Nevada, U.S.A., a 3D model of the Sleeper low sulphidation gold system in Nevada, and a 3D model of mobile ion dispersion in glacial overburden over the Shoot gold zone, Ontario, Canada. INTRODUCTION The development of sophisticated 3D visualization software over the last 10-15 years has made it possible to fully integrate geological, geochemical, and geophysical data in three dimensional space. This has created new opportunities to identify data relationships that were not easily recognized or illustrated using 2D map presentations. Previously, 3D data relationships have been explored using a surface plan map in conjunction with sets of cross sections and long sections. Each map view, whether plan or section, consisted of a set of maps with each containing certain types of information. A compilation of data relationships was achieved by overlaying the various maps. The integration of surface data has advanced with the development of GIS (Geological Information System) software. This has the advantage of being able to explore data relationships in 2D digital space. Some GIS software has introduced a 3D component for viewing data in the third dimension but it remains essentially a 2D map making tool. Geochemical exploration methods are based on an understanding of the dispersion behaviour of elements in the
The development of sophisticated 3D visualization software has made it possible to fully integrat... more The development of sophisticated 3D visualization software has made it possible to fully integrate geological, geochemical, and geophysical data in three dimensional space creating new opportunities to explore data relationships. The advent of inexpensive, multi-element ICP-MS (inductively coupled plasma-mass spectrometry) analysis techniques with low detection limits has led to the identification of zoned element associations and their spatial relations to ore with great efficiency and clarity. Geochemical modeling of down-hole data has advantages in pattern recognition by facilitating the creation of 3D volumes. This is achieved by producing individual element block models using a gridding algorithm to interpolate concentrations between drill holes. The block models provide an effective means of exploring relationships in the down-hole data and integrating this information with other subsurface data (geologic lithology logs, geophysical inversions) and surface data (geochemistry, geology, and geophysics). A key prerequisite for geochemical modeling is the acquisition of down-hole data distributed in a generally systematic fashion along each hole. Some inconsistencies in a geochemical database that need to be addressed prior to modeling include: 1) relative accuracy shifts over time in data reported from a single laboratory or between different laboratories; 2) variable detection limits amongst datasets; 3) mixed partial and total extraction data; 4) special values or zeros representing data below detection limit or missing data; and 5) mixed reporting units. Some applications of 3D geochemistry include: 1) stratigraphic correlation using elements not introduced or significantly redistributed during the mineralizing event; 2) development of a conceptual zonation model of a mineral system; 3) identification of vector criteria for locating high grade mineralization based on zonation relationships; 4) distinguishing proximal from distal signatures; 5) improving vectoring by integrating surface and sub-surface data; 6) improving interpretation of surface data by understanding the effects of surface weathering; 7) locating the bedrock source of anomalies in 3D overburden data; and 8) increasing the understanding of mineral systems and dispersion phenomena. Most of these applications are illustrated using a schematic zonation model for Carlin-type sediment-hosted gold systems in Nevada, U.S.A., a 3D model of the Sleeper low sulphidation gold system in Nevada, and a 3D model of mobile ion dispersion in glacial overburden over the Shoot gold zone, Ontario, Canada. INTRODUCTION The development of sophisticated 3D visualization software over the last 10-15 years has made it possible to fully integrate geological, geochemical, and geophysical data in three dimensional space. This has created new opportunities to identify data relationships that were not easily recognized or illustrated using 2D map presentations. Previously, 3D data relationships have been explored using a surface plan map in conjunction with sets of cross sections and long sections. Each map view, whether plan or section, consisted of a set of maps with each containing certain types of information. A compilation of data relationships was achieved by overlaying the various maps. The integration of surface data has advanced with the development of GIS (Geological Information System) software. This has the advantage of being able to explore data relationships in 2D digital space. Some GIS software has introduced a 3D component for viewing data in the third dimension but it remains essentially a 2D map making tool. Geochemical exploration methods are based on an understanding of the dispersion behaviour of elements in the
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