A Mesoproterozoic (~1.25 Ga) ‘fossilised’ oil column in the Moroak Sandstone of the Beetaloo Sub-basin, NT
Bibliographic record
Abstract
The Beetaloo Sub-basin hosts a large unconventional ‘shale gas’ resource within organic-rich Mesoproterozoic shales of the Velkerri and Kyalla formations; however, little has been done to understand conventional oil charge to the associated sandstone reservoirs. Using Grains containing Oil Inclusions, we show that an ancient ‘fossilised’ oil column once existed at the top of the Moroak Sandstone in the Elliott-1 well. The column had a minimum height of 18.02 m, with a possible paleo–oil–water contact at the base of a resistive zone on logs at ~1348 m and a change in core colour. Fluid inclusion oil is entrapped in quartz cement and is inferred to be a light oil of >42°API gravity from its near-blue fluorescence colour. Post-oil solid bitumen is still present in the reservoir sandstone, and we assert that this helped to retard the crystallisation of quartz cement that elsewhere occluded porosity. From burial history models that utilise a refined source rock maturity evaluation method, we claim this to be the remnant of Australia’s oldest yet known conventional oil accumulation at ~1.25 Ga. Analogous bituminous paleo-reservoirs from the North China Craton, dated at 1327 ± 2 Ma, were likely sourced from similar oil-prone cyanobacterial shales that formed during their shared connection with the North Australian Craton on the ancient supercontinent Nuna during the Mesoproterozoic.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".