Arrested versus active silica diagenesis reaction boundaries—A review of seismic diagnostic criteria
<p>This paper evaluates previously proposed diagnostic criteria that can be used to determine whether or not there is active migration of the opal-A to opal-CT transition zone (TZ<sub>A/CT</sub>). The criteria are based on the interpretation of 2D and 3D seismic surveys and are the...
| Main Authors: | , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
Wiley
2021
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| Summary: | <p>This paper evaluates previously proposed diagnostic criteria that can be used to determine whether or not there is active migration of the opal-A to opal-CT transition zone (TZ<sub>A/CT</sub>). The criteria are based on the interpretation of 2D and 3D seismic surveys and are therefore geometrical. They involve an assessment of the relationship of the TZ<sub>A/CT</sub> with polygonal fault systems, differential compaction structures and tectonic folds. The most robust evidence for an inactive ‘reaction front’ between opal-A and opal-CT bearing sediments is the discordance of the TZ<sub>A/CT</sub> relative to present-day isotherms. Any of these may be persuasive as diagnostic criteria for the upward arrest of the diagenetic transformation at a regional scale, but actual truncation of the TZ<sub>A/CT</sub> at the modern seabed is definitive for arrested diagenesis. This study argues that diagenetic assessment based solely on a single criterion independently is not reliable as an indicator for the current state of a silica transition. As a conclusion, the analysed seismic/structural criteria should be synthesised to provide a more credible interpretation for silica diagenesis. The use of modern 2D and 3D seismic data for the reconstruction of the diagenetic history of opaline silica bearing sediments offers a new approach to the study of silica diagenesis at a regional scale.</p> |
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