HYDROCARBON‐INDUCED DIAGENETIC DOLOMITE AND PYRITE FORMATION ASSOCIATED WITH THE HORMOZ ISLAND SALT DOME, OFFSHORE IRAN
Bibliographic record
Abstract
Hormoz Island, a salt diapir in the eastern Persian Gulf, is dominated by the Infracambrian Hormoz Complex comprising both evaporites (Hormoz Salt) and carbonates, siliciclastics and volcanic rocks. Minerals include black, white and grey dolomites, pyrite, gypsum, anhydrite, apatite and iron oxides. Formation of some of the dolomite crystals is interpreted to be linked to the oxidation of hydrocarbons. The δ13C values of black dolomite crystals range from −0.8 to −2.07‰ VPDB, indicating that little if any of their carbon is derived from hydrocarbon oxidation but that sea water has provided carbon and Mg for dolomite precipitation. The δ18O values for these dolomites range from −9.2 to −15.3‰ VPDB, reflecting a temperature effect on isotopic fractionation. By contrast, δ13C values for white to grey dolomites range from −17.81 to −35.68‰ VPDB, indicating that the carbon may be derived from the oxidation of hydrocarbons. Based on the δ18Odolomite and temperatures obtained from fluid inclusion studies (215°C), the calculated δ18Owater in equilibrium with these dolomites (+2 < δ18Ofluid < +12‰) indicates the involvement of brines evolved via the interaction of seawater with the Hormoz Salt and associated sedimentary rocks. Some of the dolomite may have precipitated from post‐Cambrian seawaters at lower temperatures (ca.100 °C). Thus, the dolomites may have begun to form during deep burial but have also formed during salt diapirism at more shallow depths. Pyrite and native sulphur are interpreted to have formed in reducing conditions where the source of sulphur was H2S produced by the thermochemical reduction of sulphate in the Hormoz Salt evaporites. Heavy δ34S values for the anhydrites (ranging from 28.7 to 30.8‰) and for sulphides (ranging from 17.2 to 23.4‰) preclude a major contribution of sulphur from volcanic sources or from Early Cambrian shales. Pyrites, apatites and dolomites formed at depth within the diapir. It is envisaged that hydrocarbons leaked along the flanks of the Hormoz Island salt dome, resulting in reducing conditions which promoted the formation of diagenetic minerals.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 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".