Alteration and lithogeochemical characterisation of the Esaase gold deposit in the Paleoproterozoic Birimian Terrane of Ghana
Bibliographic record
Abstract
The Esaase gold deposit is located in the Asankrangwa gold belt and within the Paleoproterozoic Birimian Supergroup of the Kumasi basin. The deposit represents an important example of a structurally controlled turbidite-hosted gold system. Despite its economic significance, the geochemical processes controlling the element mobility during mineralisation remain poorly understood. This study presents an integrated petrographic and mass balance investigation of the Esaase gold deposit to characterise alteration processes and quantify the elemental mass transfer associated with the hydrothermal mineralisation. Petrographic studies revealed two major stages: (I) metamorphic and (II) hydrothermal. Stage II is associated with gold mineralisation. Metamorphic alteration is characterised by fine-grained sericite, chlorite, paragonite, and albite, while hydrothermal alteration is characterised by coarse-grained sericite, chlorite, carbonates, quartz, albite, paragonite, pyrite, arsenopyrite, and traces of chalcopyrite and gold. (Na 2 O/Al 3 O 2 vs. K 2 O/Al 3 O 2 ) Isocon-based mass balance calculations reveal a net mass gain of 16.67%, with significant enrichment in Au, As, Sb, Bi, Pb, Te, Se, Sb, Cr, Ni, and Cu, and marked depletion in Cao without significant changes in K 2 O and Na 2 O. These geochemical trends reflect localised but efficient fluid-rock interaction along structurally controlled hydrothermal pathways. The alteration assemblages are dominated by sericite-chlorite over sericite-albite, as supported by alkali-alumina molar ratios (Na 2 O/Al 3 O 2 vs. K 2 O/Al 3 O 2 ), consistent with alteration haloes surrounding sheeted quartz-carbonate veins. The deposit geology, alteration mineralogy, and lithogeochemistry of the Esaase turbidite-hosted gold deposit are similar to other world-class turbidite-hosted gold deposits, such as Bendigo in Australia, Meguma in Canada, Reefton in New Zealand, and Shangxu in China. This study establishes the quantitative mass balance assessment of the hydrothermal alteration at Esaase, demonstrating how moderate net mass gains reflect structurally controlled fluid flow and mineralisation. The findings provide new constraints on the genetic interpretations and support targeted exploration strategies in the Kumasi basin and similar geological settings.
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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 | 0.001 | 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) | 0.001 | 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".