Early Diagenesis of Carbonates on a Cool-Water Carbonate Shelf, Southern Australia
Bibliographic record
Abstract
Abstract The southern Australian continental margin is an immense cool-water carbonate factory. The high-energy open shelf is blanketed by heterozoan carbonates of both Holocene and late Pleistocene age. Three distinct grain types have been identified and radiocarbon dated. These include (1) relict grains, highly abraded iron-stained intraclasts formed during the intermediate sea-level stands of Marine Isotope Stages 3 and 4, (2) stranded grains, gray and buff-colored abraded biofragments and intraclasts marooned during the sea-level rise associated with Marine Isotope Stage 2, and (3) Holocene grains, unaltered biofragments formed during Marine Isotope Stage 1. Optical, mineralogical, and chemical characterization of grains of each age has revealed pathways of early diagenesis in this realm. Both calcitic and aragonite biogenic grains undergo dissolution. While dissolution of calcitic components is minor and incomplete (relict sediments are predominantly Mg calcite), aragonitic skeletons undergo significant dissolution within ~ 30,000 years. In contrast to early dissolution of aragonite, micritic calcite cement, with ~ 12 mol% MgCO3, is a significant diagenetic phase in these sediments, infilling many stranded and most relict skeletons. Similar cement precipitates between grains, forming small numbers of cemented grain aggregates in most samples. Microprobe and ICP-MS analysis demonstrates Fe oxides, Mn oxides, and associated clay minerals discolor stranded and relict grains, by coating grain surfaces and infesting micropores. Such coatings begin to form on Holocene grains during or soon after formation. The oxides scavenge trace elements including V, Ti, Cr, and REE, altering the elemental compositions of biogenic carbonate.
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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 | 0.000 |
| 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) | 0.005 | 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".