Provenance approaches in polydeformed metasedimentary successions: Determining nearest neighboring cratons during the deposition of the Paleoproterozoic Murmac Bay Group
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Bibliographic record
Abstract
The proximity and positions of cratons constituting the western Canadian Shield prior to and during the Rhyacian Period (2.30–2.05 Ga) are poorly known. In the absence of paleomagnetic data, stratigraphic correlation and detrital zircon isotopic data from sedimentary successions can be used to constrain relative craton positions during their time of deposition. The Murmac Bay Group, a multiply deformed metasedimentary succession located on the Rae craton margin in Canada, provides an opportunity to test hypotheses regarding its nearest cratonic neighbors during deposition. The polydeformed nature of the Murmac Bay Group, however, presents challenges in determining detailed stratigraphic relationships in the upper succession, which lacks distinct marker beds. Provenance analysis from detrital zircon geochronology provides one strategy for overcoming these challenges. Previous U-Pb geochronology indicates the lower succession was deposited <2.32 Ga, and the upper succession was deposited between <2.17 Ga and >1.94 Ga. We provide new U-Pb detrital zircon ages for the upper succession, including a new maximum depositional age at <2.00 Ga. We integrate our new data with published detrital zircon ages and compare them with published and public-domain igneous crystallization ages stored within a large geochronological database to identify potential provenance locations. While there is no known local source for the ca. 2.17 Ga age population, potential 2.17 Ga sources are found on the neighboring Slave craton and Buffalo Head–Chinchaga domain. Geographically, sources for the remaining dominant age populations (e.g., 2.33 Ga) exist either locally, or between the potential sources for ca. 2.17 Ga zircon grains and our study area. Our results support the interpretation that the Rae and Slave cratons were already amalgamated during upper Murmac Bay Group deposition (<2.00 to >1.94 Ga). This provides an important constraint on the timing of Rae-Slave amalgamation.
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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 | 0.000 | 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) | 0.001 | 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 it