  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
