Role of oceanic plateaus in the initiation of subduction and origin of continental crust
Bibliographic record
Abstract
Research Article| July 01, 2008 Role of oceanic plateaus in the initiation of subduction and origin of continental crust Rajeev Nair; Rajeev Nair 1Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar Thomas Chacko Thomas Chacko 1Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar Geology (2008) 36 (7): 583–586. https://doi.org/10.1130/G24773A.1 Article history received: 29 Jan 2008 rev-recd: 31 Mar 2008 accepted: 04 Apr 2008 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Rajeev Nair, Thomas Chacko; Role of oceanic plateaus in the initiation of subduction and origin of continental crust. Geology 2008;; 36 (7): 583–586. doi: https://doi.org/10.1130/G24773A.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 SocietyGeology Search Advanced Search Abstract Archean tonalite-trondhjemite-granodiorite (TTG) magmatic suites represent the oldest coherent pieces of felsic continental crust. We present results of long-duration dehydration-melting experiments on amphibolites to show that melting depths of >48 km are required to have sufficient garnet in the residuum for generating the degree of heavy rare earth element (REE) depletion documented in Early Archean TTG. This depth constraint is inconsistent with early crust evolution models that posit melting at the base of oceanic plateaus or oceanic crust to explain the origin of Early Archean continental crust. Alternative explanations for this early crust, e.g., subduction models, are problematic in that they do not readily provide a mechanism for initiation of subduction in a hotter Archean Earth. We hypothesize that intraoceanic subduction systems in the Archean originated due to gravitational instabilities produced by compositional and density contrasts between converging oceanic plateau and normal oceanic lithosphere. Our model differs from earlier models of subduction initiation in that subduction of oceanic lithosphere occurs through the 'hot' mantle residuum (protomantle lithosphere) at the base of newly formed oceanic plateau crust. Under a high Archean geothermal gradient, subducted oceanic crust would melt to produce TTG. This model explains the origin of subduction systems, TTG, TTG–mafic and/or ultramafic magma association, stabilization of continental crust, and the broadly coeval formation of cratons and their lithospheric roots. 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 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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.000 | 0.002 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
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".