Petrogenesis of Cenozoic mafic–ultramafic alkaline lavas from the Tigris volcanic field, NE Syria
Bibliographic record
Abstract
Abstract Mafic–ultramafic Quaternary lava flows form the Tigris volcanic field (covering 1750 km2) at the northeastern tip of Syria and extend into Turkey. This volcanic field occurs between the Euphrates graben and the Bitlis–Zagros collision suture that forms the boundary between the Arabian and Eurasian plates. The rocks are made up of labradorite, clinopyroxene, olivine and opaque phases. The Tigris lavas are compositionally restricted to basanites and alkali basalts, having a narrow range of major element compositions (SiO2, 42.2–48.2 wt%; MgO, 5.7–9.0 wt%, with Mg numbers ranging from 0.51 to 0.62; TiO2, 1.7–3.2 wt%), and are alkaline in nature. The rocks are enriched in HFS elements such as Zr (119–231 ppm), Nb (14–43 ppm) and Y (17–22 ppm). The REE patterns are strongly fractionated ((La/Yb)N= 10.6), indicative of a garnet-bearing source. The143Nd/144Nd isotopic compositions range from 0.512803 to 0.512908, and87Sr/86Sr from 0.70327 to 0.70403 (εNd= 3.2–5.3) suggesting strong affinities to ocean island basalts. Modelling using a variety of mantle source materials and different degrees of partial melting indicates that the magma was produced by a small degree of batch partial melting (F = 1.5%) of a primitive, garnet-lherzolite fertile mantle source. The overall petrological/chemical nature supports this interpretation. Shear heating at the base of the lithospheric mantle of the northern boundary of the Arabian plate, caused by a change in plate motion as the Arabian plate moved in a more easterly direction during the Plio-Quaternary, could represent a possible source of the heat necessary for partial fusion and magma generation. Adiabatic decompression and melting represents a more likely process for the generation of the Tigris magma. Elemental ratios such as K/P (4.6), La/Ta (12), La/Nb (0.90), Nb/Y (1.22) and Th/Nb (0.09) indicate that the magma was subjected to minimal crustal contamination.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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 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".