AGS_Information :

Metadata_ID : 8541 Metadata_Parent_ID : 9 Metadata_Create_Date : 2025-10-09 Metadata_Create_Time : 01:53:38 PM Metadata_Last_Update_Date : 2026-02-24 Metadata_Last_Update_Time : 01:20:52 PM Custodian : Arif Rabbani Physical_Location : Recommended_Action : Keep as is Reason_For_Keeping : Business_Resumption_Plan_Record_Category : Important Record_Retention_Category : Official Contact_For_Contents : Arif Rabbani Contact_For_Distribution : Jamie Warren Contact_For_Metadata : Jamie Warren

Identification_Information :

Citation :

Citation_Information :

Originator : Alberta Energy Regulator Originator : Alberta Geological Survey Originator : Hassan, H. Originator : Harms, P. Publication_Date : 2026 Title : Estimating the Curie Point Depth (CPD) Isotherm in Alberta Using Aeromagnetic Data Geospatial_Data_Presentation_Form : document
Series_Information :

Series_Name : Special Report Issue_Identification : SPE 130

Publication_Information :

Publication_Place : Edmonton, Alberta, Canada Publisher : Alberta Geological Survey

Other_Citation_Details : ISBN: 978-1-4601-5745-9 Online_Linkage : N:\InfoStore\Publications\SPE\PDF\SPE_130.pdf

Description :

Abstract : The Alberta Geological Survey (AGS) contracted Multiphysics Imaging Technology, 4th Resource Corp., and GEOSEIS Inc. to estimate the Curie point depth (CPD) isotherm across Alberta using aeromagnetic data. The CPD represents the depth at which crustal rocks reach approximately 580°C, the temperature at which ferromagnetic minerals lose their magnetization. Mapping this thermal boundary provides a regional proxy for crustal heat distribution, geothermal gradients, and mantle-derived heat flow, supporting geothermal resource evaluation and tectonic studies.Residual magnetic intensity (RMI) grids were compiled from high-resolution airborne magnetic surveys acquired by the AGS (2021–2024), and supplemented with lower-resolution datasets from the Geological Survey of Canada and the U.S. Geological Survey. The RMI grid was subdivided into 660 overlapping 160 by 160 km windows, spaced at 40 by 40 km intervals between centroids. Of these, 417 windows fall within Alberta, providing dense spatial sampling for spectral analysis. Fast Fourier transform (FFT) power-spectrum analysis was applied to each window, and CPD was estimated using both centroid and fractal spectral methods. The results were interpolated to produce a continuous provincial grid.The CPD estimates range from approximately 8 to 30 km, with a mean depth of 23 ±4 km. Shallow CPD values occur beneath the Rocky Mountain fold-and-thrust belt, whereas deeper values characterize the Rae and Hearne cratons. Intermediate depths are observed along the Snowbird tectonic zone. From these CPD results, geothermal gradients (average of 26 ±5°C/km) and heat-flow values (48 to 149 mW/m²) were derived, indicating elevated thermal conditions in southwestern Alberta. These estimates are consistent with borehole-based measurements and global heat-flow compilations, though they exclude radiogenic heat contributions from granitic rocks.A complementary three-dimensional (3D) inversion of Bouguer gravity data was conducted to estimate Mohorovičić discontinuity (Moho) depths, which range from 35 to 46 km. A moderate negative correlation (r ≈ –0.70) between CPD and Moho depth suggests that thicker crustal regions may retain heat due to low thermal conductivity, resulting in shallower thermal isotherms above a deeper lithosphere.This work was completed under the Mineral Grant provided by the Government of Alberta dated June 22, 2021. Purpose : CPD estimation from aeromagnetic data supports the assessment of deep lithospheric thermal gradients and conductive heat flow, which is valuable for geothermal exploration. Supplemental_Information :

Time_Period_of_Content :

Time Period Information :

Single Date/Time :

Calendar_Date : 2025

Currentness_Reference : Publication date

Status :

Progress : Complete Maintenance_and_Update_Frequency : None planned

Spatial Domain :

Bounding Coordinates :

West_Bounding_Coordinate : -120 East_Bounding_Coordinate : -110 North_Bounding_Coordinate : 60 South_Bounding_Coordinate : 49

Keywords :

Theme :

Theme_Keyword_Thesaurus : ISO 19115 Topic Category Theme_Keyword : aeromagnetic Theme_Keyword : curie point depth Theme_Keyword : geology Theme_Keyword : geothermal Theme_Keyword : geothermal gradient Theme_Keyword : heat flow Theme_Keyword : moho depth Theme_Keyword : precambrian Theme_Keyword : spectral analysis

Place :

Place_Keyword_Thesaurus : ISO 19115 Topic Category Place_Keyword : alberta Place_Keyword : canada

Access_Constraints : Public Use_Constraints : Acknowledgement of the Alberta Energy Regulator / Alberta Geological Survey as the originator/source of this information is required as described in the Open Government License - Alberta.
Point_of_Contact :

Contact_Information :

Contact_Organization_Primary :

Contact_Organization : Alberta Geological Survey Contact_Person : AGS Information Manager

Contact_Position : AGS Information Manager
Contact_Address :

Address_Type : mailing and physical Address : Alberta Energy Regulator Address : 2nd Floor, Twin Atria Building Address : 4999-98 Avenue NW City : Edmonton State_or_Province : Alberta Postal_Code : T6B 2X3 Country : Canada

Contact_Voice_Telephone : (780) 638-4491 Contact_Facsimile_Telephone : (780) 422-1459 Contact_Electronic_Mail_Address : AGS-Info@aer.ca Hours_of_Service : 8:00 a.m. to 12:00 p.m. and 1:00 p.m. to 4:30 p.m.

Data_Quality_Information :

Attribute_Accuracy :

Attribute_Accuracy_Report : Depth to the bottom of magnetic sources (Curie point depth) was estimated using centroid and fractal spectral methods, yielding consistent results between approximately 8 km and 30 km, with a mean of about 23 km. Derived geothermal gradient and heat-flow maps were produced using identical parameters and methods. Attribute accuracy reflects internal consistency between the two CPD methods and their coherence with Bouguer gravity–derived Moho trends.

Logical_Consistency_Report : All datasets (Residual Magnetic Intensity, Bouguer gravity, Curie point depth from centroid and fractal methods, and derived geothermal gradient and heat-flow maps) were processed using consistent projection parameters (Alberta 10 TM, NAD83 / WGS84). The merged aeromagnetic grid integrates high-resolution AGS surveys with lower-resolution national datasets to ensure continuous coverage. FFT-based spectral computations were applied on uniformly sized 160 × 160 km overlapping windows. Consistency was maintained through: Common projections and coordinate referencing for all grids. Standardized window size and analysis methods. Comparison of CPD and Bouguer gravity–derived Moho surfaces for coherence. No projection or gridding inconsistencies were identified. Completeness_Report : The dataset provides near-complete aeromagnetic and gravity coverage of Alberta, supplemented by lower-resolution national data in boundary and mountain areas. A total of 660 overlapping 160 × 160 km windows, spaced 40 × 40 km apart, were analyzed. Of these, 417 lie within Alberta, ensuring comprehensive spatial representation of Curie Point Depth and derived geothermal parameters.
Positional_Accuracy :

Horizontal_Positional_Accuracy :

Horizontal_Positional_Accuracy_Report : Horizontal accuracy reflects aeromagnetic survey parameters: flight-line spacing 400–800 m, tie lines 1.2–2.5 km, and terrain clearance 120–200 m. All data share a common projection (Alberta 10 TM, NAD83 / WGS84).

Vertical_Positional_Accuracy :

Vertical_Positional_Accuracy_Report : Vertical precision reflects spectral and inversion method limitations. Curie Point Depth values have a mean uncertainty of ± 3–4 km. The Bouguer-derived Moho surface is internally consistent with CPD results; no further quantitative error analysis was performed.

Lineage :

Process_Step :

Process_Description : The Alberta Geological Survey (AGS) contracted Multiphysics Imaging Technology, 4th Resource Corporation, and GEOSEIS Inc. to estimate the Curie Point Depth (CPD) isotherm across Alberta using aeromagnetic data. Residual magnetic intensity (RMI) grids were compiled from high-resolution airborne magnetic surveys acquired by AGS between 2021 and 2024, supplemented with lower-resolution datasets from the Geological Survey of Canada and the U.S. Geological Survey. The RMI grid was subdivided into 660 overlapping 160 × 160 km blocks, and Fast Fourier Transform (FFT) power spectrum analysis was applied. CPD was estimated using both centroid and fractal spectral methods, and the results were interpolated across the province. Source_Used_Citation_Abbreviation : IAM 013 Process_Date : 2025

Data_Quality_Information : Magnetic data were corrected for the International Geomagnetic Reference Field (IGRF) before spectral analysis. Processing included dataset merging, FFT-based spectral analysis, and gridding by minimum-curvature interpolation. All datasets share consistent spatial referencing and methodology. No additional filtering, external validation, or independent QA were performed.

Spatial_Data_Organization_Information : Spatial_Reference_Information : Entity_and_Attribute_Information :
Distribution_Information :

Distributor :

Contact_Information :

Contact_Organization_Primary :

Contact_Organization : Alberta Geological Survey Contact_Person : AGS Information Manager

Contact_Position : AGS Information Manager
Contact_Address :

Address_Type : mailing and physical Address : Alberta Energy Regulator Address : 2nd Floor, Twin Atria Building Address : 4999-98 Avenue NW City : Edmonton State_or_Province : Alberta Postal_Code : T6B 2X3 Country : Canada

Contact_Voice_Telephone : (780) 638-4491 Contact_Facsimile_Telephone : (780) 422-1459 Contact_Electronic_Mail_Address : AGS-Info@aer.ca Hours_of_Service : 8:00 a.m. to 12:00 p.m. and 1:00 p.m. to 4:30 p.m.

Distribution_Liability : The Alberta Energy Regulator / Alberta Geological Survey (AER/AGS) licenses this information under the Open Government License - Alberta. Any references to proprietary software in our documentation, and/or any use of proprietary data formats in our releases, do not constitute endorsement by the AER/AGS of any manufacturer's product.

Metadata_Reference_Information :

Metadata_Date : 20260224
Metadata_Contact :

Contact_Information :

Contact_Organization_Primary :

Contact_Organization : Alberta Geological Survey Contact_Person : AGS Information Manager

Contact_Position : AGS Information Manager
Contact_Address :

Address_Type : mailing and physical Address : Alberta Energy Regulator Address : 2nd Floor, Twin Atria Building Address : 4999-98 Avenue NW City : Edmonton State_or_Province : Alberta Postal_Code : T6B 2X3 Country : Canada

Contact_Voice_Telephone : (780) 638-4491 Contact_Facsimile_Telephone : (780) 422-1459 Contact_Electronic_Mail_Address : AGS-Info@aer.ca Hours_of_Service : 8:00 a.m. to 12:00 p.m. and 1:00 p.m. to 4:30 p.m.

Metadata_Standard_Name : FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version : FGDC-STD-001-1998 Metadata_Time_Convention : local time Metadata_Access_Constraints : none Metadata_Use_Constraints : none