Digital Alteration Mapping
CIM Vancouver 2016
Mrs Anna Fonseca (Principal Consultant - SRK Consulting Canada), Mrs Julia Kramer Bernhard (SRK Consulting Canada)
Hydrothermal alteration mapping differs from conventional bedrock mapping in that it requires the input of a large number of outcrop observations and field tests, including the mineral interpretations from infrared spectroscopic analyses of most outcrops that were visited. This large amount of information is best collected digitally using GPS-bearing handheld devices and mobile GIS in order to efficiently manage the data generated in the field. Besides collecting information on weathering, lithologies, brecciation, samples, field photographs, structures, and stockwork, the alteration mapper must also collect information about the texture and abundance of each alteration mineral that is identifiable in each outcrop, while refraining from using interpretational alteration mineral assemblage names that do not reflect what is being observed in the outcrop. For best results, small, unweathered rock chip samples for infrared spectroscopic analyses must be collected from all outcrops visited. The samples should be analyzed upon return to camp, and the results of the spectral mineral interpretation should be examined and entered in the alteration mapping database in the evening and used to refine the following day’s traverse. This paper discusses common pitfalls in alteration data collection in the field and in infrared spectroscopic data collection and best-practice for alteration mapping digital data management are proposed.