Geophysical surveys are an important tool in a wide range of industries, from archeology and environmental science to mineral exploration and mining. These surveys use various methods to scan the subsurface to reveal information about potential structures and materials that may be of interest.
What are the Limits of Geophysical Surveys?
Like most methods of data collection, there are limitations in geophysical surveys pertaining to variable baselines, interference, and more that may limit the accuracy of the report. While the intent of geophysical surveys is as accurate information as possible, these limitations should be considered in the collection and interpretation of this data. The right partner will be able to work within these limitations to provide quality geophysical reports.
1. Subsurface Variations
One of the fundamental challenges of geophysical surveys is the variation of subsurface materials and structures. Most geophysical surveys rely on detecting physical properties such as electrical conductivity, magnetism, and density. However, the subsurface of a given area is rarely uniform, which means detected variations from the “baseline” in geotechnical properties can sometimes lead to inaccuracies in the results. The variation can result in false anomalies or cause depth estimation errors.
2. Depth Estimation
Accurately determining the depth of subsurface targets can be challenging when using geophysical surveys. Many geophysical methods provide depth estimates, but these estimates can be imprecise, especially in complex geological settings. Geophysical experts have methods for working with these estimates and survey methods to conclude depth measurements more accurately.
3. Environmental Interference
Geophysical surveys can be sensitive to environmental factors such as temperature, humidity, and soil moisture. Changes in these conditions can affect the measurements, leading to data inaccuracies. Additionally, external sources of electromagnetic interference, like power lines or radio waves, can contaminate the collected data and hinder the interpretation process.
4. Limited Resolution
The resolution of geophysical surveys resolution is limited by the wavelength of the signals used. This limitation means that small or shallow subsurface features may go undetected. This is typically less of an issue for mining projects, which are attempting to detect larger-scale deposits and have other methods of geophysical survey intended for outcroppings. However, for archeological applications such as fine-scale archaeological features or detecting shallow buried objects, the resolution of geophysical methods may not be sufficient to provide precise details.
5. Data Interpretation
Interpreting geophysical data is often a complex and iterative process that relies on the expertise of the geophysicist. This interpretation can be subjective and may vary from one expert to another. When selecting a company for geophysical surveys, it is important to select one with significant experience and expertise to ensure the data collection and interpretation methods are as trustworthy as possible.
6. Cost and Time Constraints
Geophysical surveys can be costly and time-consuming, depending on the chosen method and the size of the survey area. Large-scale projects may require significant financial resources and can be time sensitive. This limitation can make it challenging to perform comprehensive geophysical surveys in certain situations.
Final Thoughts
Geophysical surveying is important to the mineral exploration process, helping to provide high-level decision-making as well as detailed information for drilling targets and more. Understanding the limits of geophysical surveys as well as picking the right partner in geophysical expertise can ensure a more successful survey process.
Learn more about Rangefront and our experience with geophysical surveys and more by clicking the “Learn More” button below.
ABOUT THE AUTHOR
BRIAN GOSS
President, Rangefront Mining Services
Brian Goss brings over 20 years of experience in gold and mineral exploration. He is the founder and President of Rangefront, a premier geological services and mining consulting company that caters to a large spectrum of clients in the mining and minerals exploration industries. Brian is also a director of Lithium Corp. (OTCQB: LTUM), an exploration stage company specializing in energy storage minerals and from 2014 to 2017, he fulfilled the role of President and Director of Graphite Corp. (OTCQB: GRPH), an exploration stage that specialized in the development of graphite properties. Prior to founding Rangefront, Brian worked as a staff geologist for Centerra Gold on the REN project, as well as various exploration and development projects in the Western United States and Michigan. Brian Goss holds a Bachelor of Science Degree with a major in Geology from Wayne State University in Michigan.