Solutions For A Complex World:
Geophysical Tools For Lithium Basin Characterization
Article by: Caleb Perez | hydroGEOPHYSICS
The race is on to harness innovative green energy technologies and their clean power. Governments worldwide are forging ahead with determination to transform the energy industry into a resilient, balanced, and sustainable power source. There has been explosive growth in green technology, from wind and solar farms, and electric vehicles, to high-capacity power storage in lithium batteries. To meet global climate targets by 2050, the World Bank estimates that five times more lithium is needed than is currently mined. That is a staggering amount. The need is so great that the U.S. government has declared lithium “essential” to economic security and “critical” to U.S. national security. The challenge to meeting our current and future lithium needs rests on our ability to extract this raw geological material that lies deep within the earth.
To meet global climate targets by 2050, the World Bank estimates that five times more lithium is needed than is currently mined.
Most lithium deposits come from lithium-enriched brines and lithium pegmatites. Lithium is also found in sediments, clays, and many other sources worldwide. As the demand for lithium production and mining continues to rise, developments in geophysical survey techniques help catalyze an environmentally and economically sustainable path forward. Gravimetric (gravity) and Electromagnetic (EM) surveys are two geophysical techniques that can provide critical information in lithium exploration. These methods are quick and cost-efficient to deploy, extremely sensitive, highly consistent, and can efficiently map, estimate, and characterize various geological and geophysical properties of interest.
Gravity and EM are powerful modern tools capable of pinpointing and locating lithium hot spots while assessing and estimating resource size.
Current lithium prospecting relies heavily on geological or geochemical analysis conducted by academic or government sources.
Geophysical methods such as Gravity and EM are powerful modern tools capable of pinpointing and locating hot spots while assessing and estimating resource size. Gravity and EM methods identify the subsurface sedimentary composition, locate and identify structural controls such as faulting, discover the potential depth of groundwater, and determine if the groundwater is brine rich. Brine-rich groundwater has a high potential to host concentrated lithium and makes a great target. Using this technology, we can identify potentially favorable areas for lithium-rich brines and near-surface lithium-rich sediments.
Gravitational pull around the earth varies in space and time. Local variations in density at depth, changing elevation, and other factors cause gravity to fluctuate from place to place. We can understand subsurface structures and hydrological properties by measuring the changes in gravity across the earth’s surface. These characteristics make the gravity method ideal for providing helpful information on subsurface geology. In the case of lithium, gravimetric surveys take advantage of lithium’s uniquely low density by measuring contrasting differences in gravitational fields exerted by materials surrounding lithium deposits. Gravimetric methods can effectively map lithium deposits’ depth, thickness, architecture, and local geologic structure.
A wide range of EM survey methods are available for lithium exploration, including time-domain EM (TEM), audio-frequency magnetotellurics (AMT), and magnetotellurics (MT). The methods are sensitive to variations in electrical properties of subsurface materials and can map regions with enhanced conductivity due to the presence of fluids, metals, or other geologic variations. EM survey methods are often used in lithium exploration to map variations in electrical conductivity to show variations in material features. Such instruments can collect data rapidly to identify and optimize potential drill sites for lithium deposits.
Gravity and EM surveys can be combined, offering flexibility and affordability to easily customize and conduct surveys in almost any terrain and across multiple scales. Gravity surveys are typically independent of terrain, making them reliable and easy to perform over practically any topography. EM is also flexible, encompasses various techniques, and may target different domains or frequencies, and the range of survey depth can span 10’s of meters to multiple kilometers. Gravity and EM surveys are relatively easy to implement, making data collection fast and cost-efficient and providing a superior multi-layered subsurface story and its targets.
If you have a lithium project where gravity and EM could benefit you or your client, consider HGI as your geophysical provider. Applied together, Gravity and EM can identify the subsurface sedimentary composition, locate and identify structural controls such as faulting, determine the potential depth to groundwater, and determine if the groundwater is brine rich and a suitable target for drilling.
About the Author: Caleb Perez | hydroGEOPHYSICS
Caleb Perez is a Field Technician for hydroGEOPHYSICS (HGI), with a background in Physics. He supports staff geoscientists, engineers, and project managers with geophysical surveys using geophysical instrumentation and techniques to measure subsurface geologic properties. Caleb has a working knowledge of electrical resistivity, induced polarization, seismic refraction, and Multichannel Analysis of Surface Waves (MASW).
Before working at HGI, Caleb studied advanced Earth System Science, Geology, Meteorology, and Planetary Science at the University of California, Santa Barbara.
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