PRESERVATION OF MICROBIAL ICHNOFOSSILS IN BASALTIC GLASS BY TITANITE MINERALIZATION
Bibliographic record
Abstract
Glassy volcanic rocks and their metamorphosed equivalents are a recently realized setting in the search for traces of early life on Earth, as revealed by ichnofossils. Numerous authors have demonstrated that the record of microbial colonization of submarine basaltic glass extends to at least 3.5 Ga. Microbes rapidly colonize the glassy surfaces along fractures and cracks exposed to water, producing characteristic granular and tubular bioalteration textures. We present results of a mineralogical study of the materials mineralizing bioalteration structures in oceanic crust samples from the Ontong Java Plateau (OJP), and subaqueously emplaced, formerly glassy, basaltic rocks from the Abitibi greenstone belt (AGB). Previously reported Ca-and Ti-rich material in the OJP tubules was determined to be very fine-grained crystalline titanite (CaTiSiO 5 ) by micro X-ray diffraction (μXRD). Formerly glassy pillow lavas and interpillow hyaloclastites in AGB samples contain tubular and granular structures that also have been preserved by titanite mineralization, as confirmed by μXRD. Titanite mineralization associated with bioalteration in the OJP samples strongly suggests that mineralization of these trace fossils occurred penecontemporaneously with bioalteration. Early precipitation of titanite within the alteration structures enables their preservation in the geological record, potentially for billions of years in the absence of penetrative deformation. Mineralogical identification of titanite by in situ non-destructive μXRD has provided essential phase information, which is complementary to other microscopic and microanalytical data.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| 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".