Wednesday, July 19, 2017 - 19:00
Newgrange Hotel, Bridge Street Navan
SQUEEZING THE GEOLOGY FROM YOUR MAGNETICS – TALES FROM THE PINE CREEK GEOSYNCLINE & AMADEUS BASIN, AUSTRALIA’
Magnetic data is ubiquitous in the mineral and hydrocarbon exploration game, but most magnetic datasets remain under-interpreted, with commonly less than half of the geological content extracted. More value can be achieved by appropriate (and targeted) data processing and imaging, and (most importantly) giving adequate time to the interpretation phase. The keys to a successful interpretation are: Select scales of processing and interpretation to maximise geological understanding. Customise data processing and enhancement to match the project. Carefully integrate the geology with the magnetics.
The first two points will be briefly reviewed before looking at the more demanding task of 'squeezing the geology' out of the data. Two case studies are presented to highlight the critical third point, with demonstration of a systematic methodology from initial capture of the most objective parts of the geology within the magnetics, to interpretation of the more subjective geological elements (structure, alteration, lithological assemblages etc.) and final integration with existing geological data. Whilst the first part of the interpretation phase is relatively straightforward, integration with existing geology is typically time consuming, and often frustrating; there are however few 'automated' shortcuts. The Golden Dyke Dome district of the Palaeoproterozoic Pine Creek Geosyncline provides an excellent case study in the benefit of careful integration of a small amount of magnetic data (only 385 line-km over 70 km2) with an area of good exposure and good mapping. The final interpretation map significantly enhances understanding of the interplay between key structures and mineralisation in the district.
Not every geological terrain has good magnetic expression or good exposure (and mapping!) — But applying (and adapting) the same methodology will maximise the geological robustness of any interpretation. The Amadeus Basin (central Australia) shows a good case study of interpreting geology at different levels within a magnetically-subdued sedimentary basin.