Delineating the Tuwu porphyry copper deposit at Xinjiang, China, with seismic-reflection profiling
Bibliographic record
Abstract
Abstract The Tuwu deposit is one of a series of recently discovered porphyry copper deposits in the eastern Tian Shan range of Xinjiang, China. Since its discovery in 1997, more than ten boreholes have been drilled and a suite of geophysical surveys has been acquired to delineate the deposit. As part of the geophysical program, a set of eight seismic reflection profiles was acquired in 2000, followed by a physical rock-property study in 2001. The ores are characterized by slightly higher density (Δρ ∼ 0.1 g/cm 3) and significantly higher P-wave velocity (ΔVP ∼ 1.0–1.5 km/s) than the dioritic host rocks. The seismic surveys used 0.6- to 0.9-kg shallow dynamite sources, with a 24-channel end-on spread and offsets up to 350 m. The orebody and associated igneous layers dip steeply (>45°) toward the south, so careful processing of the seismic data was required. Weak reflections from stratigraphic contacts are visible on most of the profiles, including the top of the intrusion and the base of the orebody. Since the observed reflections include a significant out-of-plane component, we developed a simple 2.5D migration procedure. This method was applied to line drawings of the seismic profiles, providing the basis for delineation of the orebody in three dimensions. Synthetic seismic sections computed using the inferred bounding surfaces of the ore deposit are in reasonable agreement with observed reflections, even for along-strike lines not used to build the model. The ability to verify interpreted reflections using line intersections was critical to the development of our model. The results of this work indicate that seismic methods may be useful as an aid for mapping the flanks of shallow, moderately dipping porphyry copper orebodies and associated strata, particularly for defining the structure of deeper sections of the mineralized zones in advance of drilling.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".