U-Pb geochronology of granitoids from northern Morocco: a two-step tale for the evolution of the Variscan domain in NW Africa
Bibliographic record
Abstract
<p>The Variscan belt in NW Africa represents an intraplate orogen, which mainly developed from Late Carboniferous (ca. from the Bashkirian: 323–315 Ma) to the end of Cisuralian (283–273 Ma), in response to the closure of an oceanic domain between NW Gondwana and Laurentia. The orogenic events were accompanied by an important magmatic activity, distributed across the whole northern Morocco, north of the South Meseta Fault Zone which separates the Meseta domain in the north from the Anti-Atlas domain to the south, where no magmatic activity was recorded at that time. Moreover, an older magmatic phase occurred during the Late Devonian-Early Carboniferous however the associated geodynamic context remains under debate.</p><p>In northern Morocco, existing geochronological results for these magmatic activities are mainly obtained using Rb-Sr methods (whole rock or on different minerals). However, recent U-Pb datings on different massifs in Morocco have revealed older ages. Therefore, Rb-Sr ages should be considered with caution.</p><p>In this contribution, we present new U-Pb geochronological data (LA-ICP MS on zircons) for several plutonic massifs of northern Morocco from the Western (Jebilet) and Eastern Meseta. In the later, we provide new datings on 3 magmatic facies in the High Moulouya massif, but also for the Boudoufoud, Beni Snassen, Tanncherfi, Zekkara and Merguechoum massifs. These new data reinforce the idea that two main magmatic events must be properly separated in northern Morocco. First, a clear Early Carboniferous event, possibly beginning as soon as the end of Late Devonian, is recorded within both Western and Eastern Meseta, and this magmatic event ends at around 330 Ma. Afterwards, from ca. 310–305 Ma to ca.280–275 Ma, the second magmatic event is also expressed across both Western and Eastern Meseta. While this second magmatic event is clearly related to the Variscan orogenic events, the unclear geodynamic context for our new Early Carboniferous ages allows the re-opening of the discussion about the « Eovariscan » phase in NW Africa. Finally, these two magmatic phases are compared to the magmatic records from West Europe Variscan belt.</p>
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".