Late-Holocene atmospheric lead deposition in the Peruvian and Bolivian Andes
Bibliographic record
Abstract
The analysis of lead (Pb) in lake-sediment cores is a useful method to reconstruct local histories of Pb pollution. Here, we use Pb concentration profiles from lake sediments to reconstruct local trajectories of pre-Colonial smelting from three metallurgical centres in the South American Andes: the Morococha mining district, Peru; the Bolivian Altiplano around Lake Titicaca; and the silver-mining centre of Potosí, Bolivia. The earliest evidence for Pb enrichment from smelting is on the Altiplano beginning ~AD 400, coincident with the rise of the pre-Incan Tiwanaku and Wari Empires. Coeval with the collapse of these Empires ~AD 1000, there is a dramatic decrease in Pb pollution on the Altiplano, suggesting metallurgical activity was closely tied to the Tiwanaku state. In contrast, metallurgy at Morococha, Peru and Potosí, Bolivia began ~AD 1000—1200, likely as the result of the diaspora generated by the collapses of Tiwanaku and Wari. The independent chronologies of these records suggest asynchronous metallurgical activity between mining centres, and local-scale control of mineral resources. Following Inca conquest of the Andes ~AD 1450, strong increases in Pb are noted at all three study sites, suggesting an increase in silver production to meet Inca imperial demand. Following Hispanic conquest (AD 1532), large increases in Pb pollution are noted at Morococha and Potosí, only to be superseded by industrial development. The records presented here have implications for the reconstruction of Andean prehistory, and demonstrate the sensitivity of lake sediment geochemistry to pre-Colonial smelting activity. The technique has much potential for exploring the timing and magnitude of pre-industrial metallurgy in the New World.
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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 | 0.001 | 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) | 0.000 | 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 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".