Magmatic evolution and genesis of the giant Reko Diq H14-H15 porphyry copper-gold deposit, District Chagai, Balochistan-Pakistan
Bibliographic record
Abstract
Reko Diq porphyry Cu-Au-Mo deposit in the western Chagai belt, Pakistan, is one of the world’s largest porphyry ore deposits, containing a global resource of 5,900 million metric tons @ 0.41 % Cu and 0.22 g/t Au. The Reko Diq volcanic complex hosts a cluster of eighteen porphyry centers within a NW trending, ~10-long mineralized corridor bounded by the Drana Koh fault system to the north and Tuzgi fault to the south. The western porphyry complex at Reko Diq is linked to a distinct tectono-magmatic event of middle-late Miocene (12.9-11.9 Ma) age, which formed four economic porphyry Cu deposits and remains the focus of this study. The Reko Diq western porphyry deposits are spatially and temporally associated with a series of medium-K calc-alkaline granodiorite and quartz-diorite intrusions forming H79, H15, H14 and H13 deposits, which are spatially distributed from north to south. High Sr/Y and low Y adakitic signature and petrochemical variations in the intrusive rocks suggest normal basalt-andesite-dacite-rhyolite magmas derived from a tholeiitic to calc-alkaline suite arc magma with significant upper crustal interaction. Combination of U-Pb-zircon and Re-Os-molybdenite geochronology and zircon mineral chemistry suggests that a short lived (~1 Ma) fractionated magmatic-hydrothermal system with sustained mafic recharge and efficient hydrothermal fluid flow was involved in the formation of the giant H15 and H14 porphyry deposits. Much of the high-grade (up to 2.0 % Cu and 1.5 g/t Au) Cu-Au mineralization is associated with intense hydrothermal potassic alteration and early quartz “A-type” veins in the early-mineral granodiorite and intra-mineral quartz-diorite intrusions and adjacent host rocks. The main ore-stage potassic alteration is typically associated with high temperature, hypersaline magmatic-hydrothermal fluids. Fluid inclusions with co-existing vapor and brine suggest a boiling phase of two immiscible fluids responsible for the copper ore precipitation. The intensity of potassic alteration and Cu-Fe-sulfide mineralization decreases with the emplacement of late-mineral and late-barren stage quartz-diorite intrusions forming a low grade core in H15 and H14 porphyry deposits. The decline in Cu-Au grades with time is interpreted as a manifestation of the underlying magma chamber depleted in metals and volatiles.
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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 | 0.001 | 0.001 |
| 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".