Airborne Gravity 2010 - Geoscience Australia

Airborne Gravity 2010
Acquisition and analysis of the 2007-2009
Geoscience BC airborne data
Peter Kowalczyk 1 , Doug Oldenburg 2 , Nigel Phillips 3 , Thi Ngoc Hai Nguyen 4 , and Vicki
Thomson 5
Abstract
1 Geoscience BC Project Team (kowalczyk@geosciencebc.com)
2 University of British Columbia (doug@eos.ubc.ca)
3 Mira Geoscience Advanced Geophysical Interpretation Centre
(nigelp@mirageoscience.com)
4 Mira Geoscience Advanced Geophysical Interpretation Centre
(hain@mirageoscience.com)
5 Mira Geoscience Advanced Geophysical Interpretation Centre
(vickit@mirageoscience.com)
Airborne gravity data have been acquired over a large portion of central British Columbia (BC) by
Geoscience BC (GBC) during a program of regional geoscience data acquisition. The work was
completed over three years in coordination with other regional surveys; primarily geochemistry,
regional helicopter time domain EM traverses, regional and property scale geological mapping and
property scale case studies. Magnetic data from the Natural Resources Canada (NRCan) national
database exist for the survey area and are supplemented by some detailed higher resolution magnetic
data sets. The gravity survey was flown with a line spacing of 2 km. The result is a gridded data set
matched to the approximate 4 km minimum wavelength resolution of the airborne system, both across
and along lines.
The survey was motivated by GBC’s mandate to attract mineral and petroleum investment to British
Columbia. Each tranche of data was released as a standalone product soon after acquisition
concluded. Once released, additional analysis was commissioned by GBC to add value to the new
data, in conjunction with the other geosciences data sets available. These studies included inversion
of the regional gravity, magnetic, and time domain helicopter data followed by an integrated
presentation of the different data sets.
The existence of a large area of Quaternary cover in central BC impedes mineral exploration. This
cover is a mixture of glacial tills and lacustrine-fluvial sediments of variable thicknesses emplaced
during the last ice age. Highly favourable terranes for a number of deposit types are present beneath
the cover. In particular it is prospective for both calc-alkaline and alkaline type porphyry copper
deposits. These are high value deposit types of significant economic interest. The cover sediments
create difficulties identifying areas to focus exploration and the program of airborne work undertaken
in the area was designed to lead exploration companies back into this area of high economic potential.
The GBC data acquisition and subsequent analysis of the data has had a considerable impact on the
level of exploration activity in British Columbia. We are hopeful it will lead to the discovery of new
economic deposits and the commissioning of new mines.
Introduction
In 2007, Geoscience BC (GBC) started a regional program of geoscience data acquisition intended to
stimulate mineral exploration in central British Columbia. Airborne magnetics, helicopter TEM, airborne
radiometrics, airborne gravity, geological mapping, and regional geochemistry were considered. The
airborne survey methods selected were airborne gravity and regional helicopter TEM traverses.
Concurrently, the regional geochemical database was upgraded by both the re-analysis of the
archived sample pulps and the acquisition of new samples to achieve a consistent distribution of
sample sites and a more complete set of elemental analyses. In addition, financial assistance was
provided to improve the geological mapping of the area of interest, and the existing mineral deposit
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