|Titre||Increased mineral exploration efficiency through integration of novel mapping approaches, improved dispersal models, and field-based portable XRF analyses|
|Auteur||Lesemann, J -E; Cummings, D I; Hooke, R B; Kerr, D; Kjarsgaard, B A; Knight, R; Parkinson, W; Russell, H A J; Sharpe, D R|
|Source||39th Annual Yellowknife Geoscience Forum, abstracts of talks and posters; par Fischer, B J; Watson, D M; Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume vol. 2011,
2011 p. 107-108|
|Séries alt.||Secteur des sciences de la Terre, Contribution externe 20110221|
|Réunion||Yellowknife Geoscience Forum; Yellowknife; CA; Novembre 14-17, 2011|
|Document||publication en série|
|Sujets||prospection minière; dépôts glaciaires; exploration de dépôts glaciaires; techniques de cartographie; profils de dispersion; dispersion des sédiments; télédétection; géologie économique; géologie des
dépôts meubles/géomorphologie; géophysique; Cénozoïque; Quaternaire|
|Programme||Diamands, GEM : La géocartographie de l'énergie et des minéraux|
|Liens||Online - En ligne |
|Résumé||(disponible en anglais seulement)|
Drift prospecting has a long and storied history in Canada. Although the current prospecting methodology (mapping from aerial photographs, field verification,
geochemical and indicator mineral sampling, etc.) has proven successful in the past, it remains a time-consuming and expensive endeavour. As well, physical processes governing mineral dispersal are poorly-constrained by data and do not properly
integrate modern notions of how sediment is eroded, transported and deposited beneath glaciers.
A three-stage framework for improving prospecting methodologies is outlined below. This framework integrates the unrealized potential of digital
datasets for quickly producing surface geology maps with improved dispersal models, and field-based measurements.
1) Remote Predictive Mapping (RPM) techniques provide a rapid cost efficient method to map the glacial geology and landforms to
establish a framework for further exploration. Within this RPM scheme, identification of surface materials is refined by integrating automated landform recognition (eskers, streamlined landforms), to improve inferences of surface materials. This
initial stage helps to focus further mapping and sampling efforts by quickly identifying potential areas of exploration.
2) Improved representation of subglacial processes and resulting dispersal patterns is achieved through development of a
process-based dispersal model emphasizing basal freeze-on mechanisms (including its variants associated with various scales of subglacial meltwater production and drainage) as first-order controls on sediment dispersal. This model helps constrain
length scales of dispersal and, when integrated with a surface materials map, provides a useful tool to further target exploration and sediment sampling efforts. Dispersal patterns extracted from the Kimberlite Indicator and Diamond Database (KIDD)
are used to evaluate this technique. In addition, improved understanding of ice sheet hydrology leads to the recognition of a process continuum between the genesis of some tills and glaciofluvial sediments. Consequently, this work also aims to
improve understanding of the transport vectors from till to eskers, and the downflow dispersal, and indicator mineral concentration in eskers.
3) To further support this work and also to improve sample design efficiency work is being completed to
compare various analytical methods of till matrix geochemistry and its relationships to indicator minerals. Use of portable x-ray fluorescence (pXRF) devices allows for rapid field-based analysis of the matrix (sand-silt-clay fraction) portion of
till samples. These data may help further target indicator mineral sampling locations by highlighting relationships between till matrix geochemistry and indicator minerals in surrounding till. Comparison of pXRF data with lithium
metaborate/tetraborate fusion and dilute nitric digestion (total digestion), 4-acid digestion, and aqua-regia analyses indicate the success of this approach and the high potential for improving sampling efficiency while reducing costs associated with
collecting, shipping and processing field samples. Improved understanding of the relationship between till matrix geochemistry and indicator minerals also helps to better understand transport vectors to eskers.