Geochemistry of the Lower Cretaceous Chaswood Formation, Nova Scotia, Canada: provenance and diagenesisGeological Survey of Canada Contribution 20080004.
Bibliographic record
Abstract
The fluvial Chaswood Formation records a complex history of tectonic reactivation of basement horsts and shedding of clastic sediment. Previous mineralogical studies indicate sources from both local and more distant basement rocks of the Appalachians. Because such mineralogical studies identify only particular source rocks, the geochemistry of 60 samples from a complete section through the Chaswood Formation in borehole RR-97-23 was investigated to determine the character of bulk sediment supply. The detrital signature is partially obscured by diagenetic processes that caused concentration of K, P, Sr, and U at three regional unconformities. The elements Ti (in ilmenite and its alteration products), Zr (in zircon), Th, and Y are largely controlled by the abundance of heavy minerals in the rocks. Ilmenite is the dominant first-cycle heavy mineral, whereas much of the zircon is of polycyclic origin; therefore, the Ti/Zr ratio is a guide to the proportion of first-cycle sediment supply from crystalline basement. High Cr, Sr, and Ni/Co ratio in mudstones appear related to supply from weathered mafic crystalline basement. Three cycles of sediment supply are recognized, each overlying a regional unconformity. These reflect uplift of horsts that resulted first in shedding of readily eroded Carboniferous sandstones, then rapid erosion of crystalline basement and, finally, greater supply of deeply weathered regolith. This study provides a template for interpreting more distal sediments in the Scotian Basin, where the direct effects of source-area tectonics are not recorded in the stratigraphic succession.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".