Endeavour Copper-Gold Porphyry Deposits, Northparkes, New South Wales: Intrusive History and Fluid Evolution
Bibliographic record
Abstract
Four economic porphyry copper-gold deposits, Endeavour 22, 26, 27, and 48, occur within the Late Ordovician \nGoonumbla Volcanic Complex of central-west New South Wales, Australia. Together these deposits \nhave a combined ore reserve of 63.6 million metric tons (Mt) at 1.1 percent copper and 0.5 g/t gold. Mineralization \nis centered in narrow, pipelike quartz monzonite porphyry (QMP) intrusive complexes. \nWe have recognized at least nine intrusive phases within the Endeavour deposits. These are, in order of emplacement, \nas follows: a premineral equigranular monzodiorite; early-mineral, equigranular to weakly porphyritic \nbiotite quartz monzonite (BQM) stocks and dikes; synmineral K-feldspar QMP (K-QMP) pipes and \ndikes; late-mineral augite-biotite–K-feldspar QMP (KA-QMP) intrusions and biotite QMP (B-QMP) dikes; and \npostmineral basaltic trachyandesite dikes, augite monzonite porphyry dikes, and basaltic dikes. \nEarly-stage biotite-magnetite and propylitic alteration of the host volcanic rocks and K-feldspar alteration of \nthe BQM occurred at each deposit during the intrusion of the BQM stocks and early-mineral B-QMP dikes. \nTransitional-stage unidirectional solidification textures and other related anisotropic textures formed mostly \nduring the emplacement of K-QMP and KA-QMP intrusions. Main-stage sulfide mineralization at all four deposits \nis spatially and temporally associated with the K-QMP and, to a lesser extent, KA-QMP intrusions and \ntheir associated K-feldspar and sericite-hematite alteration assemblages, and is characterized by multiple generations \nof stockwork and sheeted quartz, K-feldspar, bornite, chalcopyrite, and gold-bearing veins. Late-stage \nsericite-quartz-copper-sulfide-carbonate-hematite alteration and vein assemblages formed prior to the emplacement \nof the postmineral intrusions. Weak to moderate postmineral propylitic alteration assemblages were \nthe last alteration event related to the QMP intrusive complexes. Intrusive activity and associated biotite alteration \noccurred between 446 and 437 Ma, based on 40Ar/39Ar analyses of biotite and hornblende. \nBased on microthermometric analyses of fluid inclusions from early-, transitional-, main-, and late-stage \nveins, the Endeavour deposits formed at depths between 1,000 and 1,700 m below the paleosurface, with a \nlithostatic pressure regime prevailing throughout the early, transitional, and main stages and near-hydrostatic \npressures during the late-stage sericitic events. The first three stages were dominated by high-temperature \n(460°–>550°C) magmatic-hydrothermal brines with salinities of ~55 to 60 wt percent NaCl ± KCl equiv. Although \nthe late-stage fluids were cooler (350°–400°C) and less saline (~40 wt % NaCl equiv), their compositions \nare consistent with the magmatic-hydrothermal origin indicated by previous oxygen and hydrogen isotope \nstudies, confirming that the Endeavour porphyry deposits are representatives of the orthomagmatic end member \nof the porphyry continuum.
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".