The Sukari Gold Deposit, Egypt: Geochemical and Geochronological Constraints on the Ore Genesis and Implications for Regional Exploration
Bibliographic record
Abstract
Abstract The Sukari gold deposit (>15 Moz Au) in the Eastern Desert of Egypt is hosted by a deformed granitoid stock (Sukari tonalite-trondhjemite intrusion) and mainly occurs as a network of crosscutting sulfide-bearing quartz (± carbonate) veins and intensely sulfidized-silicified-sericitized wall rock. Emplacement of the Sukari intrusion into a tectonized Neoproterozoic accretionary complex was controlled by a system of NE- to NNE-trending oblique faults that are related to a deep-seated positive flower structure. A robust genetic model has been hampered by the poorly understood relationships between gold mineralization and host rocks. In this study, zircon U-Pb ages of three samples from the Sukari intrusion define a crystallization age of ~695 ± 2 Ma. In contrast, hydrothermal sericite from the ore zone yields an 40Ar/39Ar age of ~625 ± 3 Ma, which coincides with the onset of major sinistral transpression in the region. Features including sigmoidal morphology of gold quartz veins and abundant subhorizontal tension gashes alongside widespread brecciation and recrystallization suggest that quartz veining occurred during renewed shortening and exhumation through the brittle-ductile transition. Petrographic and micro-X-ray fluorescence (µXRF) studies indicate that disseminated gold and sulfides, commonly associated with sericite and carbonate alteration, are mostly confined to stylolitic bands in the quartz veins. Oscillatory and sector zoning patterns, irregular As-rich bands, and truncations between early- and late-genetic pyrites reflect variations in temperature and mechanism of ore deposition, demonstrated by variable As/S and Co/Ni ratios in the different pyrite generations. Laser ablation-inductively coupled plasma-mass spectrometry analysis pinpoints the covariance of gold and arsenic contents in pyrite, but free milling gold inclusions in microfractures consistently have a mercury-bearing electrum composition, depicting different ore formation stages. Ore fluids with δ34SH2s values of –1.9 to –3.0‰, modeled from gold-associated pyrite and arsenopyrite assemblages with nearly identical δ34S values, suggest a likely single source of sulfur. Alternatively, multisourced sulfur could have extensively mixed and equilibrated by fluid reaction with carbonaceous wall rock. Gold deposition was triggered by abrupt changes in fluid pH and fO2. As an implication for future exploration, sites of maximized strain gradients adjacent to granitoid bodies along extensive transpression zones in the district could be highly prospective targets, particularly where imprinted by sericite-carbonate ± graphite alteration.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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 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".