Low-level fixed-wing flights to image geology of Michigan and Wisconsin
USGS low-level survey will map minerals, hazards
RESTON, VA. — Low-level airplane flights are planned to begin soon over areas of the Upper Peninsula of Michigan and northern Wisconsin using airborne geophysical technology. Data collection for this survey area will start in late May or early June 2025, weather and flight restrictions permitting.
Most of the surveying is expected to be completed by the late autumn of 2025; however, surveying may continue in the spring and summer of 2026 to avoid adverse weather conditions.
The Michigan and Wisconsin flights are part of a national effort to map critical mineral resources needed to drive the U.S. economy and national security, searching below ground and in tailings from old mines. As directed by the Energy Act of 2020, the U.S. Geological Survey has identified 50 critical minerals essential to the U.S. economy and national security, with a supply chain vulnerable to disruption. The USGS partners on this effort with the Michigan Geological Survey, the Wisconsin Geological and Natural History Survey, and many other state geological surveys.
"The USGS Earth MRI program's data for the Upper Peninsula is incredibly valuable. It will significantly enhance our understanding of the U.P.'s complex geology and is crucial for making informed decisions about sustainable land and resource management, and protecting public health in the region," said Sara Pearson, director of the Michigan Geological Survey.
Flights will cover areas within Alger, Baraga, Chippewa, Delta, Dickinson, Gogebic, Houghton, Iron, Keweenaw, Luce, Mackinac, Marquette, Ontonagon, and Schoolcraft Counties in Michigan, as well as Ashland, Florence, Forest, Iron, Marinette, Price, and Vilas Counties in Wisconsin.
The flights will be based out of various Michigan and Wisconsin airports. Flights and landing areas could shift with little warning to other parts of the survey area as necessary to minimize ferrying distances and avoid adverse flying conditions.
The survey will acquire both magnetic and radiometric data across two non-overlapping blocks. Fixed-wing survey aircraft will collect data along closely spaced flight lines at a nominal elevation of about 300 feet (100 meters). Flight lines will be spaced approximately 500 feet apart in the western survey block and 1,300 feet apart in the eastern survey block. The magnetic component of the survey detects variations in the Earth’s magnetic field that reveal subsurface structures up to a few kilometers deep, or about 10,000 feet. Radiometric sensors measure natural low-level radiation to help map the distribution of potassium, thorium, and uranium near the surface.
The survey will use aircraft equipped with an elongated “stinger” mounted to the tail extending backward off the aircraft. The scientific instruments on the aircraft are completely passive, with no emissions that pose a risk to humans, animals, or plant life. No photography or video data will be collected. The data collected will be made freely available to the public on ScienceBase, typically within one year of flight completion. The aircraft will be flown by experienced pilots who are specially trained and approved for low-level flying. The company contracted to fly the survey works with the FAA to ensure flights are safe and in accordance with U.S. law. The surveys will be conducted during daylight hours only.
The new geophysical data will be processed to develop high-resolution two- and three-dimensional representations of bedrock composition and structure to depths more of approximately 10,000 feet (almost 2 miles) below the surface. The survey is funded by the USGS Earth Mapping Resources Initiative and is designed to meet needs related to mineral resource assessments, regional geologic framework and mapping studies, as well as water resource investigations and surficial mapping studies. Additionally, the data and maps are important for improving our understanding of parameters for infrastructure and land-use planning, and potential risks of naturally occurring radon. The MAG and RAD survey is focused on characterizing several major mineral systems, including critical minerals associated with mafic magmatic, volcanogenic seafloor, and porphyry systems. Data from the survey will significantly improve our understanding of the region’s tectonic history.
Figure 1: Fixed-wing survey aircraft with tail stingers and sensors that collect scientific data on geology. (Credit: EON Geosciences Inc.)
The USGS has contracted with Woolpert and EON Geosciences Inc. to collect data.
Funding by the Infrastructure Investment and Jobs Act has facilitated coverage of such a large area.
The survey fits into a broader effort by the USGS, the Michigan Geological Survey, the Wisconsin Geological and Natural History Survey, and other partners, including private companies, academics and state and federal agencies to modernize our understanding of the Nation’s fundamental geologic framework and knowledge of mineral resources. This effort is known as the Earth Mapping Resources Initiative, and it includes airborne geophysical surveys like this one, geochemical reconnaissance surveys, topographic mapping using LiDAR technology, hyperspectral surveys, and geologic mapping projects.