If you were still wondering about Magnetotellurics (MT) vs Audio-Magnetotellurics (AMT) the following may be of interest.
Ausmex Mining Group (ASX: AMG or 'Ausmex') used MT and AMT with spectacular results during 2018-2019, it is currently looking for copper-gold deposits at Burra in South Australia.
A challenge for the global mineral exploration industry is to identify world-class deposits under thick layers of sedimentary cover. Traditional approaches target the small-scale economic ore deposit, with declining rates of success over past decades. However, an alternative approach is to image deeper parts of the Earth's crust to find a much larger footprint where the metals originated. By finding the deep source mining companies can also map potential pathways through the upper crust to define new prospective areas beneath sedimentary cover. So, rather than looking for the needle, it is better to first identify the haystack.
MT is a passive geophysical tool that is highly sensitive to minor interconnected conducting mineralogy and fluids, and thus is ideal for distinguishing between lithosphere of different degrees of enrichment. Additionally, the sensitivity to these minor phases means that fossil fluid pathways associated with the ascent of mineralising fluids and metals are detectable with MT. Mining companies are specifically looking for a 'plume'.
MT is capable of penetrating the entire lithosphere of the Earth, potentially tens to hundreds of km deep.
AMT is a higher-frequency magnetotelluric technique for shallower investigations (around 1-3 km depth). While AMT has less depth penetration than MT, AMT measurements often take only about one hour to perform and use smaller and lighter magnetic sensors.
As you can see from the diagram below, MT is shown on the LHS and is looking at the 'architecture' of the lithosphere.
AMT is shown on the RHS of the diagram, and is looking at the 'deposit' scale for mineral accumulations.
Ausmex Mining Group (ASX: AMG or 'Ausmex') completed AMT during April 2019 on a previous MT grid (that had been completed during October 2018), with spectacular results around Burra in South Australia. Ausmex said AMT was designed to increase the data resolution from the initial regional 10 km spaced MT survey completed during October 2018 and focus on the surface to 2,000 metre depth, progressing the conductive zone to exploration and drill targets:
Subsequently, Ausmex released a number of ASX releases during August 2019 including the following announcement that confirmed the validity of AMG’s approach of using MT and AMT to identify plumes and structures which originate from the deep conductive structures that lie approximately 20 kms below Burra:
Figures 1-6 in the above ASX release are interesting, it shows you the modelling mining companies can do with the results of AMT.
Cheers
These are only my thoughts and it does not constitute investment advice. Before acting on any information you read and before making any financial or investment decisions, you should always consult your advisor(s) or other relevant professional experts.
