CSA Global Principal Consultant, Dennis Arne will present on his co-authored paper: “Processing Regional Stream Sediment Data for Mineral Exploration Targeting” at the Resources for Future Generations (RFG2018) Conference between June 16-21, 2018 at the Vancouver Convention Center, British Columbia, Canada.
The paper was developed in consultation with Chris Pennimpede and Eric Grunsky from the CSA Global in Vancouver in 2017.
The RFG 2018 conference is designed to mobilize geoscientists, policy-makers and other stakeholders to explore resource and related sustainability issues.
ABSTRACT:
The interpretation of stream sediment geochemical data for mineral exploration is complicated by the influence of bedrock lithology, the effects of scavenging by secondary Fe and Mn hydroxides, clays and organic matter, and by dilution dependent on the size of the catchment area draining through the sample site. A number of ways have been proposed in the literature to correct for the effects of background variations in lithology, but most are driven by a knowledge of the bedrock geology that may not always be available in reconnaissance exploration programs. We present a new approach for correcting for lithological and scavenging influences that is data-driven. Lithological controls on stream sediment geochemical data are identified by interpreting the results of principal component analysis. Values for elements strongly controlled by lithology are corrected by regression against the relevant component(s). Positive residuals represent elevated geochemical concentrations above what is defined by background bedrock geology. These positive residuals represent samples worthy of further investigation and allow regional data sets to be gridded to reveal trends in elevated metal concentrations above background. The residuals are incorporated in weighted sums models which define geochemical indices using element associations typical for a given mineral deposit type. These models are refined through validation against known mineral occurrences and then levelled by catchment area to define anomalous catchments for follow-up investigation. The selected catchments include not only those that have anomalous raw element values, but also highlight areas with subtle raw data responses that may have been overlooked by previous exploration campaigns. Use of the approach is illustrated through selected examples of high quality geochemical analyses from British Columbia and Yukon.
ABOUT YOUR PRESENTER
Dennis Arne
BSc (Hons) Geology, MSc, PhD, Grad Diploma
Dennis has over (30) years’ experience in exploration in a wide range of environments in both the minerals and the petroleum industries, as an academic, and in geological surveys. In recent years he has been involved as a consultant in the development of exploration programs for precious and base metals exploration in Australia, North America, South America and the Middle East. Specifically, this has included contributing to exploration targeting reviews and understanding gold and base metals mineral systems, the design, management and interpretation of surficial geochemical surveys, the interpretation of lithogeochemical data, the preparation of QA/QC protocols, reviews of geochemical data quality, and contributions to NI43-101 and JORC/Valmin technical reports. He has published extensively in the areas of applied geochemistry, economic geology and thermal history analysis for tectonic and petroleum exploration applications.
