Wopmay orogen revisited: Phase equilibria modeling, detrital zircon geochronology, and U-Pb monazite dating of a regional Buchan-type metamorphic sequence
Bibliographic record
Abstract
Research Article| November 09, 2017 Wopmay orogen revisited: Phase equilibria modeling, detrital zircon geochronology, and U-Pb monazite dating of a regional Buchan-type metamorphic sequence Marc R. St-Onge; Marc R. St-Onge † 1Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada †marc.st-onge@canada.ca Search for other works by this author on: GSW Google Scholar William J. Davis William J. Davis 1Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Marc R. St-Onge † 1Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada William J. Davis 1Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada †marc.st-onge@canada.ca Publisher: Geological Society of America Received: 20 Mar 2017 Revision Received: 30 Jun 2017 Accepted: 28 Sep 2017 First Online: 09 Nov 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2017 Geological Society of America GSA Bulletin (2018) 130 (3-4): 678–704. https://doi.org/10.1130/B31809.1 Article history Received: 20 Mar 2017 Revision Received: 30 Jun 2017 Accepted: 28 Sep 2017 First Online: 09 Nov 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Marc R. St-Onge, William J. Davis; Wopmay orogen revisited: Phase equilibria modeling, detrital zircon geochronology, and U-Pb monazite dating of a regional Buchan-type metamorphic sequence. GSA Bulletin 2017;; 130 (3-4): 678–704. doi: https://doi.org/10.1130/B31809.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The internal metamorphic-plutonic zone of the middle Paleoproterozoic Wopmay orogen, northwestern Canadian Shield, exposes an oblique section through a prograde Buchan-type metamorphic sequence. New petrographic, petrologic, and geochronologic analyses of pelite and quartz arenite samples from the eastern margin of the internal zone quantify the evolving conditions and timing of metamorphism and enable the discriminant evaluation of competing tectonic models. Study of fabric development and mineral growth relationships indicates that prograde metamorphism occurred late within a craton-verging, crustal-shortening ("Calderian") deformation event. Phase equilibria modeling was used to calculate pressure-temperature (P-T) path segments and determine peak conditions from andalusite-muscovite grade at ∼3.3 kbar and 575 °C to sillimanite–K-feldspar ± granitic leucosome grade at ∼4.8–6.2 kbar and 670–745 °C. In situ monazite geochronology indicates that thermal peak metamorphic conditions were reached between 1878.6 ± 6.5 Ma and 1872 ± 9 Ma. Ages of detrital zircon within quartz arenite across the width of the metamorphic sequence document a diagnostic easterly Slave craton–Thelon tectonic zone derivation that links the metasedimentary rocks, including those previously considered to be "exotic" in a proposed tectonic klippe model for the internal zone, to the adjacent craton. Integration of these results with observations on the relatively low state of strain and the bracketing of a common (single) metamorphic field gradient for all garnet-bearing mineral zones confirm that the latter have preserved their prograde isogradic continuity from time of formation, and that the leading edge of a tectonic klippe consisting of rocks exotic to the Coronation margin does not traverse the study area. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 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".