Geological Society of Namibia Talk - 6 March

DR AMANDA STOLTZE (First Quantum Minerals)

TITLE : “DESIGNING, MANAGING, AND INTERPRETING SOILS PROGRAMS”

DATE : 6 MARCH 2015

VENU : AUDITORIUM OF THE GEOLOGICAL SURVEY OF NAMIBIA

TIME : 17H45

Summary

Soil Geochemistry is a proven and commonly used method of prospect scale exploration. Thoughtful design and management of soils programs ensures that the maximum value is obtained from each data set. Important features to consider when designing a soils program are: the regolith profile of the area under investigation, the size of the footprint you are looking for, the final use of the data (lithological information and target generation?), and the time available for the program. Transported sediments will mask underlying geology and mute geochemical anomalies from mineralisation therefore specific techniques maybe used to deal with these terrains but comparing geochemical responses from residual terrains to transported terrains is nonsensical. Spacing of soil samples should be dependent on the footprint of the deposit size sought. There is no point taking extra time and spending extra money if the information you are collecting is not going to add value to a program.

The importance of using internal QAQC in a soils program is also discussed. It’s important to have confidence in your results even if it’s not necessary to report them to a stock exchange, as you will be basing economically significant decisions on results i.e. do we drop the ground, drill a hole or use a different analyses method (extra cost). Checks on the quality of data received are also important as lab issues need to be picked up before interpretation of the data. Finally interpreting the multi-element data can not only identify geochemical targets but can help to generate a more accurate geology map where outcrop is sparse or non-existent.

Many examples from First Quantum Minerals programs around the world will be used to illustrate the points raised in this talk. The programs are from multiple regolith types, climates and are exploring for several deposit types. 

About the Speaker

Amanda Stoltze is a geologist specialising in collecting regional geochemical datasets in green-fields and brown-fields exploration projects. She completed her PhD in 2006 at The Australian National University, Research School of Earth Sciences, looking at the geochemistry of the Wallaby Gold Deposit to determine the source of Au mineralising fluids. After completing her PhD, she made the move to Africa working in Ghana on load gold, then moved into PGE exploration in East Africa and finally into Sediment hosted-Cu and Ni exploration in the Cu Belt of DRC and Zambia. Amanda has worked for First Quantum Minerals for 5 years, initially managing a resource drill program and running an extensive regional soils program in Zambia, but for the last 2 years she has been roaming for the exploration group helping set up geochemical programs. During this time her focus has been to help groups design soils programs that are fit for purpose and ensuring that the quality of the samples and subsequent data is of the best possible level. Recently she has been working on hydrogeochemistry as a district scale direct detection technique.