Absolute geomagnetic paleointensities obtained from the Americas’ presumably oldest pottery
Bibliographic record
Abstract
Abstract We carried out a detailed rock-magnetic and absolute paleointensity investigation on well-dated, presumably the oldest American pottery from northern Colombia (around 4000 B.C.) The study aims to contribute to the reconstruction of Earth’s Magnetic Field strength fluctuations in the southern hemisphere, improving extremely incipient archaeomagnetic database for the Caribbean region through comprehensive rock-magnetic and archaeointensity analysis of Puerto Chacho pottery (Lat: 10° .110 N, Long: 75° .455 W). Essentially Ti-poor titanomagnetite and some fractions of hematite are main magnetic carriers of apparently pseudo-single-domain state. Individual intensities obtained from Puerto Chacho archaeological site vary from 8.7 ± 0.5 to 27.3 ± 1.2 μT, which corresponds to the Virtual Axial Dipole Moments (VADM) values between 2.2 ± 0.1 and 6.8 ± 0.3 1022 Am2. The mean Puerto Chacho’s intensity determined for all twenty-three accepted values is 17.1 ± 6.2 μT, corresponding to the mean VADM of 4.2 ± 1.5 1022 Am2. These values are significantly lower compared to nearby San Jacinto paleointensities (Goguitchaishvili et al. in Phys Earth Planet Interiors 31:107061, 2023), considered belonging older archaeological periods. Moreover, the absolute intensity values obtained from the Puerto Chacho pottery yielded relatively low values compared to those derived from three available global field prediction models SHA.DIF.14 K, CALS10k.1b and ArchKalmag.14 K and existing data obtained from previously published studies from Colombia and surrounding areas. A bootstrap analysis of available age distributions and updated radiocarbon calibration values indicate that absolute age intervals for Puerto Chacho are younger, which may explain the difference between the intensity values. The time interval between 6000 and 5000 BP was probably characterized by some drastic variations of the Earth’s magnetic Field strength. Although many studies have recently become available, no conclusions may be drawn about the regional fluctuations of the geomagnetic field strength.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".