Magnetic Exploration Projects in CSIRO 1978 to Now

ASEG Queensland Branch Meeting for March 2016.  Talk to be presented by Phil Schmidt.

After WWII magnetic surveys became common place and airborne magnetic surveys followed quickly.  Seafloor magnetic stripes were a huge driver for magnetic surveys and ironically the correct interpretation of these stripes implicated magnetic remanence.  The magnetic susceptibility of seafloor basalts was ignored.  This was not the case for magnetic surveys over land where magnetic susceptibility was paramount and remanence often ignored.

The importance of remanence in the interpretation of magnetic anomalies was realised in the 1970s and CSIRO began to document cases for the benefit of the minerals exploration industry.  This talk will discuss projects that CSIRO generated over the past 40 years and others that I have developed more recently to enable the potential field properties of magnetic surveys to be fully utilised, rather than treating surveys as mere images.  Projects include differential vector magnetometers, the calculation of the magnetisation vector directly from magnetic anomalies, high-temperature (-197°C!!) SQUID gradiometers for submarine and unexploded ordnance (UXO) detection and the Qmeter field instrument for measuring remanence/induced magnetisation (Q).  A laboratory instrument that is being developed will not only allow remanence and induced magnetisation to be determined but also the anisotropy of magnetic susceptibility (AMS).

About the Speaker:

Phil Schmidt was Chief Research Scientist in geophysics for CSIRO before resigning in 2012. He obtained his BSc (Hons) from the University of New England in 1973, and his PhD in Geophysics from the Australian National University in 1976. After a post-doctoral position in Ottawa with the Earth Physics Branch of the Dominion Observatory (now GSC) he returned to Australia in 1978 to take up a position with CSIRO Mineral Physics to apply rock magnetism to mineral exploration. His research interests include physical properties of rocks, potential fields and the interpretation of magnetic and gravity surveys, palaeomagnetism and its interpretation in terms of Earth history, magnetic instrumentation for surveys and field work such as differential magnetometry, magnetic tensor gradiometry, the Q-meter, a portable device that measures remanent and induced magnetisation of rock and core samples and a two-axis spinner laboratory magnetometer for simultaneously measuring remanence and anisotropy of magnetic susceptibility.

RSVP Megan Nightingale by 5:00pm 26 Feb 2016