Abstract
Natural surface gas seeps provide a significant input of greenhouse gas emissions into the Earth's atmosphere and hydrosphere. The gas flux is controlled by the properties of underlying fluid-escape conduits, which are present within sedimentary basins globally. These conduits permit pressure-driven fluid flow, hydraulically connecting deeper strata with the Earth's surface; however they can only be fully resolved at sub-seismic scale. Here, a novel 'minus cement and matrix permeability' method using three-dimensional X-ray micro-computed tomography imaging enables the improved petrophysical linkage of outcrop and sub-surface data. The methodology is applied to the largest known outcrop of an inactive fluid-escape system, the Panoche Giant Intrusion Complex in Central California, where samples were collected along transects of the 600 to 800 m stratigraphic depth range to constrain porosity and permeability spatial heterogeneity. The presence of silica cement and clay matrix within the intergranular pores of sand intrusions are the primary control of porosity (17 to 27%) and permeability (
Original language | English |
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Pages (from-to) | 2463–2485 |
Number of pages | 23 |
Journal | Sedimentology |
Volume | 69 |
Issue number | 6 |
Early online date | 29 Apr 2022 |
DOIs | |
Publication status | Published - 1 Oct 2022 |
Bibliographical note
AcknowledgementsThis work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 654462 (STEMM-CCS) and the Natural Environment Research Council (CHIMNEY; NE/N016130/1). We also thank the California Bureau of Land Management for facilitating access to the outcrop area. We acknowledge Diamond Light Source (Beamline I13-2; MT18758). We thank Sharif Ahmed, Hans Deyhle, Hector Marin-Moreno, Laurence North, Christina Reinhard, Shashi Marathe, Kaz Wanelik, Andrew Bodey, Matthew Beverley-Smith, Daniel Doran, Richard Pearce and the Diamond Support Scientists at I13-2 for their support. We acknowledge the use of the IRIDIS High Performance Computing Facility, μ-VIS X-Ray Imaging Centre, and the SEM facility at the University of Southampton. We acknowledge and thank the British Ocean Sediment Core Research Facility (BOSCORF). We also thank the FEI Visualization Sciences Group for providing the use of the Avizo 9.3.0 software for µCT image processing. Finally, we would like to sincerely thank Richard H. Worden and Thomas Seers for their constructive comments, which greatly improved the manuscript.
Data Availability Statement
The data set associated with this work is available online at https://doi.org/10.5258/SOTON/D1441. Here we provide the raw and segmented µCT tomographic image data, and the associated image processing files.Keywords
- Cementation
- fluid flow
- permeability
- seal bypass
- sandstone intrusion
- X-ray micro-CT
- GIANT INJECTION COMPLEX
- FORE-ARC BASIN
- INTERNAL STRUCTURES
- FLOW
- EVOLUTION
- RESERVOIR
- INSIGHTS
- DIAGENESIS
- MIGRATION
- FIELD