3D Geologic Framework Models

The California Geological Survey (CGS) contracted Terraquest Ltd., to acquire high-resolution airborne magnetic and radiometric data over approximately 30,365 square kilometers in the northern San Joaquin Valley, California. The survey was flown between June 2024 and April 2025 and included 1,052 traverse lines oriented 050º/230º and spaced 300 meters apart and 60 control lines oriented 140º/320º oriented and spaced 3,000 meters apart, for a total of 111,351 line-kilometers of data collection.

The survey was conducted to expand high-resolution geophysical data coverage in California and improve understanding of the geologic framework in the region. Airborne magnetic data can help delineate variations in subsurface geology and geologic structures, while radiometric data provide information about the distribution and composition of rocks and materials at or near the ground surface. Together these datasets support rock identification, geologic and geophysical mapping, and characterization of surface and subsurface geology. The data were collected to support a variety of geologic investigations, including efforts to identify and characterize areas that may be suitable for geologic carbon sequestration.

This data release provides the airborne magnetic and radiometric survey data and associated contractor deliverables. The data are released as collected and processed by the contractor and do not include geologic interpretations by CGS.

Suggested citation:

Gerhardt, A.M., Nakamura, K., Escobar, L., and Coyan, J.A, 2026, Airborne Magnetic and Radiometric Geophysical Survey of a portion of the northern San Joaquin Valley, California, DR 2026-4. California Department of Conservation, California Geological Survey data release,  https://conservation.ca.gov/cgs/publications/data-releases.

Download Links:

• Data Release for Airborne Magnetic and Radiometric Geophysical Survey of a portion of the northern San Joaquin Valley, California (40 MB, PDF)
• Request the data associated with DR 2026-4

The California Geological Survey (CGS) contracted Terraquest Ltd., to acquire high-resolution airborne magnetic and radiometric data over approximately 9,400 square kilometers in the southern San Joaquin Valley, California. The survey was flown between Fall 2022 and Spring 2023 and included 499 east-west traverse lines spaced 250 meters apart and 41 north-south control lines spaced 2,500 meter apart, for a total of 41,783 line-kilometers of data collection.

The survey was conducted to expand high-resolution geophysical data coverage in California and improve understanding of the geologic framework in the region. Airborne magnetic data can help delineate variations in subsurface geology and geologic structures, while radiometric data provide information about the distribution and composition of rocks and materials at or near the ground surface. Together these datasets support rock identification, geologic and geophysical mapping, and characterization of surface and subsurface geology. The data were collected to support a variety of geologic investigations, including efforts to identify and characterize areas that may be suitable for geologic carbon sequestration.

This data release provides the airborne magnetic and radiometric survey data and associated contractor deliverables. The data are released as collected and processed by the contractor and do not include geologic interpretations by CGS.

Suggested citation:

Gerhardt, A.M., Nakamura, K., Escobar, L., and Coyan, J.A., 2026, Airborne Magnetic and Radiometric Geophysical Survey of a portion of the southern San Joaquin Valley, California, DR2026-3. California Department of Conservation, California Geological Survey data release,https://conservation.ca.gov/cgs/publications/data-releases.

Download Links:

• Data Release for Airborne Magnetic and Radiometric Geophysical Survey of a portion of the southern San Joaquin Valley, California (14 MB, PDF)
• Request the data associated with DR 2026-3

By Angela Gerhardt, PG., Kazumi Nakamura, PhD, PG, Lennin Escobar, and Josh Coyan, PhD

The California Geological Survey (CGS) contracted Xcalibur MPH Canada Ltd., to acquire high-resolution airborne magnetic and radiometric data over portions of the Klamath Mountains province in northern California. The survey was flown between October 2023, and May 2024 and included approximately 94,476 line-kilometers of traverse lines spaced 250 meters apart and 9447 line-kilometers of tie lines spaced 2,500 meters apart, for a total of 103,920 line-kilometers of data collection.

The survey was conducted to expand high-resolution geophysical data coverage in California and improve understanding of the geologic framework in the region. Airborne magnetic data can help delineate variations in subsurface geology and geologic structures, while radiometric data provide information about the distribution and composition of rocks and materials at or near the ground surface. Together these datasets support rock identification, geologic and geophysical mapping, and characterization of surface and subsurface geology. The data were collected to support a variety of geologic investigations, including efforts to identify and characterize areas that may be suitable for geologic carbon sequestration.

This data release provides the airborne magnetic and radiometric survey data and associated contractor deliverables. The data are released as collected and processed by the contractor and do not include geologic interpretations by CGS.

Suggested citation:

Gerhardt, A.M., Nakamura, K., Escobar, L., and Coyan, J.A., 2026, Airborne Magnetic and Radiometric Geophysical Survey of the Klamath Mountain geomorphic province in northern California, DR2026-2. California Department of Conservation, California Geological Survey data release, https://conservation.ca.gov/cgs/publications/data-releases.

Download Links:

• Data Release for Airborne Magnetic and Radiometric Geophysical Survey of the Klamath Mountains geomorphic province in northern California (3 MB, PDF)
• Request the data associated with DR 2026-2

by Daniel Boyd, Brian Clements, Kazumi Nakamura, Angela Gerhardt, and Lennin Escobar

PSGM 25-01 represents the Preliminary Subsurface Geologic Model of the south-central San Joaquin Basin. Work on this project spanned from July 2021 to December 2025 and was in part supplemented through USGS STATEMAP funding. The results of this project will help inform methods for future California Geological Survey subsurface geologic mapping projects and support long-term planning and prioritizations of future projects across the state. Future subsurface maps and models will include assessments of potential carbon storage reservoirs to facilitate meeting the state’s carbon goals. PSGM 25-01 is a stratigraphically focused, 3D geologic framework model representing a conceptual interpretation of selected subsurface formations and sequence boundaries within the study area covering approximately 3,600 mi² (9,000 km²) in the Fresno and Bakersfield 1° x 2° Quadrangles of the south-central San Joaquin Basin Province. Products developed for PSGM 25-01 include: ten structure-contour maps (Plates 1A to 1J), nine isochore maps (Plates 2A to 2I), a geodatabase, CSV file, gridded surfaces (Z-Map Plus ASCII, .XML), triangulated surfaces (GOCAD .TS), metadata files, and an executive summary. These subsurface maps are complemented by a surface geologic map of the study area (Gutierrez and others, 2025 - Plate 3), completed concurrently under a separate STATEMAP award.

Download Links:

• Map Plates and Executive Summary (131 MB ZIP, File Request)
• PSGM 25-01 DATA: Subsurface Geology (57 MB, CSV format)
• PSGM 25-01 DATA: Subsurface Geology (9 MB, geodatabase)
• PSGM 25-01 DATA: Surface Geology (9 MB, geodatabase)
• PSGM 25-01 DATA: Subsurface Geological Model triangulated surfaces (124 MB, GOCAD format)
• PSGM 25-01 DATA: Subsurface Geological Model gridded surfaces (5 MB, Z-MAP Plus format)