Tectonics and geochemistry of the Amina Formation: record of the primitive caribbean island-arc in the Cordillera Central, Dominican Republic
Bibliographic record
Abstract
Located in the NW Cordillera Central, the Lower Cretaceous Amina Fm comprises a sequence of volcanic protoliths variably deformed and metamorphosed. The deformation was heterogeneous and consisted in N- to NW-directed regional ductile oblique shearing, which produces a penetrative plano-linear Sp-Lp fabric of mylonitic characteristics and a macrostructure consistent in thrust-nappe stack inclined to the SW. The sin-Sp metamorphism was in the low-T greenschist and locally prenhite-pumpellyte facies conditions. Combined detailed mapping, geochemistry and Sr-Nd isotopic studies have shown that the Amina Fm include four mafic protoliths and an additional felsic one: island arc tholeiites, Ti and LREE-depleted island arc tholeiites, boninites, calc-alkaline basalts and low-K rhyolites. The source for these rocks was a variably depleted mantle, overprinted by a subduction zone component. There are strong geochemical, isotopic and petrogenetic similarities between the Amina and Maimón Fm protoliths and the Los Ranchos Fm volcanic rocks, which imply that the first group of rocks is the tectonometamorphic equivalent of the second. All of these rocks have the typical characteristics of intra-oceanic island-arc igneous suites and so, all together they represent the formation and development of the primitive Caribbean island arc in Hispaniola during the Aptian-Albian. The regional geochemical maps and transverses of selected trace elements for the three formations ensemble suggests a location for the related subduction zone, to the W, NW and N of the current position of the Amina-Maimón domain.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".