Trace element contents in white mica and tourmaline from the Panasqueira W-Sn-Cu deposit (Portugal)
Bibliographic record
Abstract
Analyzing the chemical composition of rocks and minerals is an important tool for exploring and understanding mineral resources. Typically, hydrothermal ore deposits are characterized by primary alteration halos. At the world-class Panasqueira W-Sn-Cu deposit, the hydrothermal alteration of the wall rocks produced concentric zones with progressively greater distance from the veins, consisting of a proximal tourmaline-quartz-muscovite zone and a distal muscovite-quartz zone. Panasqueira is a world-class W-Sn-Cu lode-type deposit located in the Castelo Branco district (Beira Baixa, central Portugal). The ore deposit consists of a swarm of sub-horizontal veins associated with a Late-Variscan S-type granite and enclosed by a metasedimentary unit of Late Ediacaran to Early Cambrian age (e.g., Kelly and Rye, 1979; Romão et al., 2013). The veins are mainly composed of gangue quartz, muscovite and minor carbonates, apatite, topaz, topaz, fluorite, tourmaline, rutile, ilmenite, arsenopyrite, sphalerite, pyrite, marcasite, stannite, and pyrrhotite. Mineralization of wolframite, chalcopyrite, and cassiterite is predominantly hosted in veins with minor stringers and lenses of sulfide minerals in the wall rocks (e.g., Kelly and Rye, 1979; Polya, 1989; Polya et al., 2000). Although there is a strong variation in the vein mineralogy, typically, the quartz vein-filling is rimmed by a muscovite selvage up to 4-5 cm thick. The hydrothermal alteration produced a 2 to 30 cm thick tourmaline-rich alteration halo in the metasedimentary host rock (Bussink, 1984). Tourmaline and mica are ubiquitous minerals at Panasqueira W-Sn-Cu and coexist in many other hydrothermal ore deposits worldwide. Both minerals are well-known to host variable amounts of trace elements and to have potential as pathfinder minerals as well as fluid monitors. We analyzed major, minor and trace element contents of altered and unaltered metasediments from the Panasqueira by XRF and ICP-MS and tourmaline and white mica major, minor and trace element compositions by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in previously well-characterized samples from different locations/setting in the mine (greisen, vein-selvages, wall-rock alteration zones, fault zone, and late vugs). The analyzed samples are described by Codeço et al. (2017), Codeço et al. (2019), and Codeço et al. 2020). These studies discuss the chemical (major, minor, and trace elements) and boron-isotopic compositions of tourmaline and white mica, and whole-rock chemistry of altered and unaltered metasediments. Further details on sample description can be found in the folder "2020-002_Codeco-et-al_Samples" and the analytical methods are described in " 2020-002_Codeco-et-al_data-description.pdf". Detailed information about the samples used, the location, and general geological background of the samples, and the analytical method is provided in the data description "2020-002_Codeco-et-al_data-description.pdf ".
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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 | 0.001 | 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".