The Influence of Bioturbation on Sandstone Brittleness: A Comparative Analysis of Massive Sandstone versus Bioturbated Sandstone (Ordovician Qasim Formation-Saudi Arabia)
Bibliographic record
Abstract
Bioturbation is the reorganization of sediment particles by living organisms, mainly infauna, as they move through and over sediment, feed, and construct dwellings. The biosedimentary structures produced by organisms alter the petrophysical and mechanical properties of the sediment, including porosity, permeability, and brittleness, such that the petrophysical and mechanical properties of bioturbated sedimentary strata commonly differ from that of unbioturbated strata. This directly impacts fluid flow through sedimentary strata. In this study, we investigate the impact of bioturbation on sandstone brittleness through the comparison of seemingly massive sandstone with bioturbated sandstone in the Ordovician Kahfa Member of the Qasim Formation in northwestern Saudi Arabia. Through a series of field observations (sedimentological descriptions and fracture intensity measurements) and laboratory analyses (thin-section petrography, SEM, XRD, XRF, spot permeability and hardness, as well as Vp and Vs measurements) the mechanical properties of bioturbated and unbioturbated sandstone are determined. The results indicate that although both units have moderate to high porosity (17–25%), the bioturbated sandstone units exhibit decreased brittleness (~ 0.2 fractures·m-1) relative to their unbioturbated counterparts (~ 2 fractures·m-1). Young’s Modulus of bioturbated sandstone ranges from 4.0 to 5.7 GPa, while unbioturbated sandstone has much higher moduli, ranging from 15.1 to 17.6 GPa. This decreased brittleness in bioturbated sandstone is attributed to locally enhanced porosity, altered grain size distribution, and the incorporation of clay particles, all of which are associated with bioturbation. These modifications result in a less brittle sandstone and, by extension, a reduction in fracture density. Understanding the role of bioturbation in altering sandstone brittleness is not only significant for geotechnical and geological applications but also holds implications for civil engineering and environmental science. Further research into the specific mechanisms underlying bioturbation-induced changes in sandstone properties is recommended for comprehensive insights into this phenomenon.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".