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Lookup NU author(s): Professor Mohamed Rouainia
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2025. The Author(s).The East Coast Basin (ECB) is a complex, active convergent margin located on the North Island of New Zealand, where variable but commonly very high overpressures occur in Cretaceous to Pleistocene stratigraphy. Using a consistent set of sediment physical properties and a single value for tectonic compression, a multi-1D hydro-mechanical modeling approach was employed to evaluate the primary controls on overpressure and porosity across a 40 km section of the ECB. The 1D hydro-mechanical models simulated the geological histories of five key wells across the ECB and investigated overpressure generated by burial disequilibrium compaction and tectonic compression. Present-day overpressure is associated with tectonic compression within the last 3 million years due to the subduction of the Pacific Plate beneath the Australian Plate; this has generated up to 18 MPa of overpressure at a depth of 2,000 m. Burial disequilibrium compaction contributed up to 4 MPa at the same depth. Whilst erosive events can lead to the dissipation of overpressure, the effects of all but the most recent erosive event are masked and overprinted by subsequent sedimentation. In some areas and in specific parts of the stratigraphy, overpressure appears to dissipate through lateral fluid flow. Throughout a complex geological history including several episodes of burial, tectonic compression and erosion, critical state soil mechanics models suggest that mechanical changes in mudstones and fine-grained carbonates occur almost entirely through compaction rather than dilation (shear).
Author(s): Calderon Medina EE, Obradors-Prats J, Aplin AC, Jones SJ, Rouainia M, Crook AJL
Publication type: Article
Publication status: Published
Journal: Journal of Geophysical Research: Solid Earth
Year: 2025
Volume: 130
Issue: 10
Online publication date: 04/10/2025
Acceptance date: 22/09/2025
Date deposited: 27/10/2025
ISSN (print): 2169-9313
ISSN (electronic): 2169-9356
Publisher: John Wiley and Sons Inc
URL: https://doi.org/10.1029/2024JB030585
DOI: 10.1029/2024JB030585
Data Access Statement: Well and seismic data are available at the New Zealand Petroleum and Minerals Online Exploration Database(NZPAM) and the New Zealand Crown Research Institute (GNS). Supporting Information S2, which include stables and information on the hydro-mechanical models' settings and results, is published in the Durham University research data repository (Calderon, 2025)
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