Brief description
The interpretation of AusAEM airborne electromagnetic (AEM) survey conductivity sections in the Canning Basin region delineates the geo-electrical features that correspond to major chronostratigraphic boundaries, and captures detailed stratigraphic information associated with these boundaries. This interpretation forms part of an assessment of the underground hydrogen storage potential of salt features in the Canning Basin region based on integration and interpretation of AEM and other geological and geophysical datasets. A main aim of this work was to interpret the AEM to develop a regional understanding of the near-surface stratigraphy and structural geology. This regional geological framework was complimented by the identification and assessment of possible near-surface salt-related structures, as underground salt bodies have been identified as potential underground hydrogen storage sites. This study interpreted over 20,000 line kilometres of 20 km nominally line-spaced AusAEM conductivity sections, covering an area approximately 450,000 km2 to a depth of approximately 500 m in northwest Western Australia. These conductivity sections were integrated and interpreted with other geological and geophysical datasets, such as boreholes, potential fields, surface and basement geology maps, and seismic interpretations. This interpretation produced approximately 110,000 depth estimate points or 4,000 3D line segments, each attributed with high-quality geometric, stratigraphic, and ancillary data. The depth estimate points are formatted for Geoscience Australia’s Estimates of Geological and Geophysical Surfaces database, the national repository for formatted depth estimate points. Despite these interpretations being collected to support exploration of salt features for hydrogen storage, they are also intended for use in a wide range of other disciplines, such as mineral, energy and groundwater resource exploration, environmental management, subsurface mapping, tectonic evolution studies, and cover thickness, prospectivity, and economic modelling. Therefore, these interpretations will benefit government, industry and academia interested in the geology of the Canning Basin region.
Lineage
Maintenance and Update Frequency: asNeeded
Statement:
This study interpreted >20,000 line km of 20 km nominally line-spaced AEM conductivity sections, covering an area of ~450,000 km2 to a depth of ~500 m. The AEM data were acquired as part of the AusAEM 02 WA/NT 2019-20 AEM Survey (Ley-Cooper, 2022), and were inverted using Geoscience Australia’s (GA) Layered Earth Inversion
Sample-By-Sample Time Domain Electromagnetics inversion (Brodie, 2015). Horizontal resolution of the conductivity sections is 12.5 m. The vertical resolution varies exponentially with depth, with the cell sizes increasing from 4.0 m at the surface to ~55 m at the bottom cell, ~500 m below the surface. Consequently, the resolvability of fine detail decreases with depth. The depth of investigation (Hutchinson et al., 2010) varies depending on the bulk electrical conductivity, and averages ~250 m across the survey. The depth of signal penetration is estimated to be >500 m in electrically resistive terrain. Refer to Ley-Cooper & Brodie (2020) and Ley-Cooper, Brodie & Richardson (2020) for more details on the AusAEM survey.
This interpretation was undertaken in 2021-22 by The University of Queensland’s (UQ) The Sustainable Minerals Institute, as part of a collaboration between UQ and the National Geological Mapping and Hydrogen Studies modules in GA’s Exploring for the Future program. This study uses methodologies from GA’s multilayered chronostratigraphic AEM interpretation workflow (Wong et al., 2022). Utilisation of this workflow ensures that all stratigraphic unit information is consistent with GA’s Stratigraphic Units Database (https://asud.ga.gov.au), multidimensional exports are in non-proprietary formats, and exports meet the data standards for the EGGS database (Mathews et al., 2020; accessible through GA’s Portal https://portal.ga.gov.au). The workflow used is an evolution of that used in GA’s previous regional AusAEM interpretations (Wong et al., 2020; Wong et al., 2021), with this version having enhanced functionality and capability to capture additional features and attributes.
This interpretation forms part of a study on the salt-related underground hydrogen storage potential of the Canning Basin region by integration and interpretation of AEM and other geoscientific datasets (Connors et al., 2022). A main aim of this work was to interpret the AEM to develop a regional near-surface geological framework. This framework was complimented by the identification and assessment of possible near-surface salt-related structures. Refer to Connors et al. (2022) for further information on the hydrogen storage potential component of this study. This interpretation produced approximately 110,000 depth estimate points or 4000 3D line segments, each attributed with high-quality geometric, stratigraphic, and ancillary data. These points are formatted for and intended to be uploaded to GA’s EGGS database.
Notes
PurposeThis interpretation was produced as part of a study to identify possible near-surface salt-related features to support the exploration of salt features suitable for hydrogen storage in the Canning Basin region (Connors et al., 2022). The interpretation of AEM conductivity sections delineates the geo-electrical features that correspond to major chronostratigraphic boundaries. The chronostratigraphic resolution used was the delineation of the era chronostratigraphic boundaries, specifically the contact between Cenozoic, Mesozoic, Paleozoic, Neoproterozoic, Mesoproterozoic, Paleoproterozoic and Archean stratigraphic units. Non-chronostratigraphy-related interpretations were also collected, such as faults and the base of weathering. The chronostratigraphic and non-chronostratigraphic feature types (in the “TYPE” field) form the parent-level categories in the interpretations. These are the categories that were digitised during the interpretation; they are related to the geometry of each line segment, and are the symbolised categories displayed by the 3D GOCAD objects. All other (child) attributes are attached to the lines or points as ancillary data. Moreover, each interpretation line or point is attributed with interpretation-specific metadata, including geometry, chronostratigraphic relationship, geological contact type, stratigraphy, confidence, basis of interpretation, comments, new observations, interpreter’s details and interpretation date. The geometry data and pixel coordinates allow interpretations to be plotted in multidimensional spaces. Segment and vertex identifiers are provided to maintain polylines when converting between multidimensional spaces. The ground surface elevation directly above each vertex, derived from a digital elevation model acquired during AEM acquisition, is provided (in the “AEM_DEM” field). Chronostratigraphic relationships are captured by the eras of the units above and below the interpretations, which identify if the high-level chronostratigraphic order is continuous or discontinuous. This information is complemented by the contact type field, which describes if contacts are conformable, unconformable, intrusive, faulted, etc. The stratigraphic unit fields capture the stratigraphic unit names and numbers for the units above and below the interpretation (if the interpretation occurs at an era boundary) or the stratigraphic unit name and number of the unit the interpretation occurs within (if the interpretation line occurs entirely within one unit). The interpreter’s confidence levels of the interpretation placement, and for the stratigraphic units occurring in the locations in which they are interpreted, are provided. As the AEM interpretations were performed by integrating the AEM with multidisciplinary datasets, each line or point is attributed with a list of the data types that were used to support the interpretation. A comments field provides further information about the interpretation. A field that captures any new observations made during the interpretation provides insight into features that were previously unknown. The names of the interpreter and the date of the interpretation for each line or point are also provided.Interpretation of potentially newly-discovered geological faults observed in the AEM conductivity sections, and known faults from the integrated supporting information, have been included in the dataset. Where the attitudes of faults were either indiscernible in the conductivity sections or were otherwise unknown, the faults have been interpreted as vertical. This dataset also includes observations of potential salt-related features in the near-surface stratigraphy, such as interpretation of a breccia zone overlying a salt diapir, and areas of disruption to near-surface stratigraphy possibly due to salt movement and/or dissolution.In addition to the data in this data package, this interpretation is also available for visualisation on Geoscience Australia’s Portal
Created: 08 01 2022
Issued: 10 02 2023
text: westlimit=120; southlimit=24; eastlimit=127.5; northlimit=16; projection=GDA94 / MGA zone 51 / projected (EPSG: 28351)
text: uplimit=-1500; downlimit=0; projection=Australian Height Datum / vertical (EPSG: 5111)
Subjects
AFER |
ARF |
Airborne electromagnetics |
Archean |
AusAEM |
Australia’s Future Energy Resources |
Australia’s Resource Framework |
Basins |
Canning Basin |
Cenozoic |
Cover thickness |
Depth to basement |
Diapir |
EFTF – Exploring for the Future |
Electrical and electromagnetic methods in geophysics |
Energy |
Geophysical interpretation |
Groundwater |
Groundwater hydrology |
Hydrogen storage |
Mesoproterozoic |
Mesozoic |
Minerals |
Neoproterozoic |
Paleoproterozoic |
Paleozoic |
Published_External |
Resource geoscience |
Salt intrusion |
Sedimentology |
Stratigraphy (incl. biostratigraphy |
Structural geology and tectonics |
Western Australia |
geoscientificInformation |
sequence stratigraphy and basin analysis) |
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Other Information
Download data package (zip) [13.21 MB]
uri :
https://d28rz98at9flks.cloudfront.net/147597/147597_00_0.zip
Download metadata statement (pdf) [1.1 MB]
uri :
https://d28rz98at9flks.cloudfront.net/147597/147597_01_0.pdf
Identifiers
- DOI : 10.26186/147597
- URI : pid.geoscience.gov.au/dataset/ga/147597
- global : 2b95d02c-ab4b-49a0-b7fb-fc9a3ec31765
