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Exploration Strategies
Geophysical exploration relies on surveys focussed at specific target types which take advantage of physical contrasts in magnetic susceptibility, conductivity, resistivity, chargeability, density, porosity, velocity, etcetera.
A well designed survey takes into account the physical contrasts of a specific target type as well as the actual setting and geometry of the expected target. Of these, depth to target is an important consideration and and may greatly affect the survey design to improve the chances for successful target definition.
Living Sky Geophysics Inc. can help improve chances for success by creating simple forward EM and Resistivity models to aid in survey selection and design.
Multiple targeting vectors will increase the probability of successful uranium exploration in the Athabasca Basin environment. The classic uranium unconformity mineralization model consists of a number of geophysical characteristics
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Aphebian Meta-Pelitic environment = relative magnetic low.
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Graphitic conductor = EM anomaly
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Reactivated basement / sandstone structure = Magnetic structural anomaly (maybe).
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Fluidising hydrothermal events = alteration halo (predominantly low resistivity with the exception of silicification = high resistivity - this would be expected to be very probably brecciated and structurally disrupted by reactivation events which would = low resistivity anomaly).
At Living Sky Geophysics Inc., our geophysical exploration strategy for uranium follows a simple set of processes:
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Use available potential field data (magnetic and gravity) to provide a basis for structural analysis
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Significant double or triple points (combination of magnetic, andor gravity, and airborne EM surveys) would then be the focus areas for DC-Resistivity. Sandstone rocks located immediately above the unconformity displaying low resistivity values may indicate areas of structural disruption, and potentially areas that could reflect basement and sandstone alteration zones affected by reactivation events related to uranium mineralization.
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Focused ground EM survey over areas with sandstone rock located immediately above the unconformity displaying low resistivity values to accurately delineate the basement conductor.
Positive results, identification of resistivity anomalous regions along the strike of the conductor trace, provide the location(s) for focused ground EM surveys which then provide better locations of the conductor across the strike of the airborne conductor trace. We believe this approach will provide improved vectoring to the highest priority drill targets while reducing the time drilling along less prospective portions of otherwise lengthy conductor traces.
2. GOLD & PRECIOUS METALS
Magnetic and IP/Resistivity surveys remain the geoiphysical techniques of choice for these commodies. the normal proceedures are to carry out 2D surveys. Inverting the 2D surveys in 3D can aid greatly in focussing targets and getting very coherent plan maps of actual depths or elevations.
LSGI is experienced and proficient at pre-processing IP/Resistivity data and inverting (with topography) in 2D and 3D with M. H. Loke's RES2DINV and RES3DINV software.
Base metal camps, including deep prospects (600m plus) have unique challenges, including exceptionally deep and conductive targets to deal with. New SQUID and Fluxgate technologies for surface and borehole applications will certainly improve the detection and resolution of these types of targets.
LSGI is experienced and capable of modeling and interpreting Airborne, Ground and borehole data to aid in drill targeting of prospective areas.
The search for diamonds requires techniques that appear to be area specific. Potential fields are normally part of the targeting techniques. Interpretations are usually customised to search for and detect anomaly shapes and sizes relating the the target area distribution of known kimberlites. Techniques which have proved usefull include magnetics, gravity and resistivity (both ground and air based).
Economic concentrations of REE-bearing minerals are generally hosted in, or associated with, alkaline igneous rocks and carbonatites. They are generally circular and can be identified by imagery, even in deeply weathered or highly vegetated terrains. They also tend to cluster along linear belts such as the Kapuskasing structural zone in Ontario. Airborne magnetic, radiometric, and gravity surveys can also be used to delineate host rocks. Because many carbonatite complexes are surrounded by mafic alkaline rocks, they often show up as a magnetic bull’s eye combined with a gravity low and ringed by a gravity high. Geochemical prospecting is also an effective tool because most REE minerals are heavy and resistant.
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