GSV Report 131 - Structural modelling of the Portland Trough using seismic interpretation, gravity inversion and forward modelling: SW Otway Basin.
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Product description:Executive Summary:The Portland Trough is a subsurface structural depression in the far west Victorian Otway Basin. Previous seismic interpretations had identified the structure as relatively young, forming in the Late Cretaceous and Palaeogene, and remaining active into the Neogene. A more recent study of airborne gravity gradiometry data conducted by McLean et al. (2021) suggested that the Portland Trough may be significantly deeper than previously determined and that further modelling may contribute to a better understanding of the subsurface geology of the region. This study integrates a suite of geophysical data and geological modelling methods to investigate the structural evolution of the Portland Trough. To gain further insight into the geological history and tectonic context of the Portland Trough, a novel approach to modelling crustal architecture was implemented. This involved combining seismic interpretation and gravity inversion with a conceptual understanding of modern rift geometries to constrain structurally feasible faults and horizon surface inter-relationships. The results of this work demonstrate that a significant Late Jurassic to Early Cretaceous local depocentre may explain the deeper structures observed from gravity inversion and forward modelling in the Portland Trough. Older, deeper and partially reactivated fault structures are interpreted to account for the substantially thicker sequence of basin sediments and the gravity response that exists over the trough. A new structural feature - the “Deep Portland Trough”, (constrained by the newly interpreted Portland Fault) has been interpreted as an early, syn-rift graben or half graben similar in age, origin and structural context to the Penola Trough to the north. The revised interpretation has implications for energy recovery and storage in the area such as gas and hydrogen storage and geothermal energy potential. Bibliographic Reference: Boyd, M., McLean, M.A. & Cayley, R.A., 2024. Structural modelling of the Portland Trough using seismic interpretation, gravity inversion and forward modelling: South west Otway Basin, Victoria. Geological Survey of Victoria Report 131. Department of Energy, Environment and Climate Action, 38 pp. Download: The downloadable version of this report is supplied as (PDF 15 MB) & Attachment A1 data (ZIP 3.0 GB). Related products:
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