Geology of the Pikku-Vaiskonselkä differentiated sill in the Kevitsa area, northern Finland
Bibliographic record
Abstract
The Pikku-Vaiskonselk sill, situated in the Kevitsa area, northern Finland, was studied using core logging, field observations, petrography and whole-rock and mineral analysis.The aim of the Master's project was to describe the intrusion and compare it with other layered intrusions in central Finnish Lapland, including the Kevitsa, Satovaara, Rantavaara intrusions, the Lower Suite of the Koitelainen intrusions, and layered sills the ca.2.22 Ga gabbro-wehrlite association.The sample material from the Pikku-Vaiskonselk sill consisted of drillcore samples (drillcores KV300 and KV305) and outcrop samples.Twenty polished thin sections were used in petrographical studies and one polished thin section was used to determine the composition of olivine, clinopyroxene and chromite with electron microprobe micro-analyzer.Whole-rock compositions were measured with the XRF and ICP methods.The Pikku-Vaiskonselk sill is differentiated, consisting of chromite-bearing wehrlite, clinopyroxenite and gabbro.The studied rocks are strongly altered and the primary magmatic minerals of the rocks have been mostly replaced by secondary minerals, with preserved olivine and clinopyroxene being only observed in few outcrops.No significant sulfide mineralization seems to be present in the intrusion.The parental magma composition of the intrusion was not very primitive as shown by the forsterite content (~84.5 mol.%) of olivine.The shape of chondrite-normalized REE patterns suggests that the magma was LREE-enriched.Ratios of incompatible elements in olivine cumulates were used to estimate the character of the parental magma and to compare it with that of other mafic-ultramafic intrusions.The Pikku-Vaiskonselk parental magma had Al 2 O 3 /TiO 2 ratio of ~20 that is higher than in the other intrusions.Also the Zr/TiO 2 ratio in the Pikku-Vaiskonselk parental magma was higher.The Koitelainen Lower Suite olivine cumulates are compositionally closest to the Pikku-Vaiskonselk sill rocks, but have higher CaO/Al 2 O 3 ratios.Al 2 O 3 /TiO 2 ratios in clinopyroxene suggest compositional differences between the Pikku-Vaiskonselk, Kevitsa and the GWA intrusions.The differences in the mineral and whole-rock compositions between the Pikku-Vaiskonselk sill and the other intrusions indicate compositionally different parental magmas.
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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 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".