Genesis of the Kateba’asu gold deposit, Western Tianshan, China: Constraints from pyrite trace element, sulfur isotope, and quartz H-O isotopes
Bibliographic record
Abstract
The Kateba’asu gold deposit, situated in the Western Tianshan of China, is one of the most significant discoveries in the world-class Tianshan gold belt. The deposit features two distinct mineralization styles. The early, subordinate skarn-type copper–gold mineralization occurs in the contact zone between monzogranite, diorite, and Silurian limestone, composed of garnet, diopside, epidote, chalcopyrite, pyrite, and gold. The later, primary lode-gold mineralization is hosted in the altered monzogranite characterized by pervasive quartz-pyrite-sericite-chlorite-K-feldspar alteration and a well-develped veining systems. Pyrite is the dominant sulfide mineral related to gold mineralization in the Kateba’asu gold deposit, with four types identified: Py0 from the early skarn copper–gold mineralization, and Py1 to Py3 from the later lode-gold mineralization. All types of pyrite are homogeneous and contain very low levels of lattice-bound gold. Py0 is euhedral and fine-grained, with relatively high Cu, Au, Co, and Ni contents, and displays a magmatic sulfur isotopic signature with δ 34 S ranging from 0.8 to 4.3 ‰. Py1 occurs as euhedral to subhedral, coarse-grained crystals within pyrite-quartz veins with higher concentrations of Co and Ni. Py2, which develops in the quartz-pyrite veins, is medium to coarse-grained and contains elevated levels of As, Cu, Zn, and Bi relative to Py1. Py3, found in polymetallic sulfide veins of the main lode-gold stage, is anhedral and medium to fine-grained with higher contents of As, Ag, Cu, Zn, Se, Te and lowest Co and Ni concentrations compared to Py1 and Py2. The positive correlations between Au-Te, Au-Bi, Au-Cu, and Pb-Bi across all pyrite types, along with the presence of visible gold in Py3, indicate that most gold occurs as micro-/nano-sized inclusions and as fissure gold. The δ 34 S values of Py1, Py2, and Py3 (7.6 to 11.8 ‰, 10.1 to 12.6 ‰, and 9.8 to 12.4 ‰, respectively) were attributed to an initial magmatic source and mixed with external sulfur subsequently from the wall rocks. The H and O isotopic compositions (δD H2O = −84.1 to −93.5 ‰; δ 18 O H2O = 1.8 to 6.6 ‰) of quartz from the lode-gold mineralization imply that ore-forming fluids were predominantly of magmatic origin, with a additional contribution from meteoric water. Taken together, a two-episode mineralization model was proposed for the formation of the Kateba’asu gold deposit. The early skarn mineralization stage is associated with the emplacement of diorite during the Early Carboniferous. In contrast, the subsequent lode-gold mineralization, occurring between the Late Carboniferous and Permian periods, represents a overprinted magmatic-hydrothermal gold system potentially linked to a deep-seated magmatic intrusion.
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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 | 0.002 | 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) | 0.001 | 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".