Thallium isotopes as indicators of ore mineralization at the Zn-rich sediment-hosted massive sulfide TL Deposit, British Columbia, Canada
Bibliographic record
Abstract
Few studies have focused on the application of the Tl isotopic system for geochemical exploration. We report <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> 205 Tl values of rock samples from the TL Deposit, British Columbia, Canada – a sediment-hosted massive sulfide (SHMS) deposit with characteristics of a Broken Hill-type deposit – and investigate relationships with major and trace element geochemistry. Maps generated using Tl isotope and trace element data indicate that <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> 205 Tl values can potentially be used to fingerprint ore mineralization at the TL Deposit. The sources of Tl and other metals (Ag, Pb, Zn) are assessed using Tl isotope data. Measured <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> 205 Tl values exhibit positive correlations with Pb, sedimentary exhalative metal index (Zn + 100*Pb + 100*Tl), and the redox proxy, U/Th, and negative correlations with Be, Cd, Ce, La, Ni and Th. Individual lithologies have distinct Tl isotopic compositions. Metal-rich heavily altered samples have relatively high <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> 205 Tl values (−5.0 to −2.5 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> -units) reflecting the euxinic conditions of the global Paleoproterozoic ocean and hydrothermal influence. Samples with lower <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> 205 Tl values (−15 to −7.6 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> -units) reflect a combination of their mineralogy (phyllosilicate minerals such as biotite and clinochlore), Tl from sediments reflecting the Tl isotopic composition of modern seawater, and possible low-temperature alteration processes. Samples with high Pb and Ag contents have high <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> 205 Tl values, indicating a hydrothermal origin of these metals, whereas Zn is highest in samples with low <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> 205 Tl values, indicating a low-temperature or sedimentary origin. Thallium isotopes, paired with conventional geochemical data, show promise as a useful tool for exploration of SHMS deposits with Broken Hill-type characteristics. Supplementary material: Major, minor and trace element contents of samples and reference materials, blank values, correlation coefficient values, and XRD patterns are available at https://doi.org/10.6084/m9.figshare.c.6370671 Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".