Economic Geology Models 1. Geochemical Exploration and Metallogenic Studies, Northern Chile
Bibliographic record
Abstract
Research was initiated in 1998 on geo-chemical methods of exploration for copper porphyry deposits buried under thick, lithified piedmont gravel cover in the Atacama Desert, Chile. Early data suggest that mineralized, saline groundwater has been episodically forced up through fracture zones to the surface during earthquakes, creating geochemical anomalies above ore deposits. Follow-up research supported by the Canadian Mining Industry Research Organization (CAMIRO) examined the composition of both groundwater and surface anomalies, confirming a link between the two. Further work suggests that the geo-chemical anomalies are the surface expression of a process common to the metallogenic evolution of many deposits. Porphyry intrusion and hypo-gene mineralization are controlled by faults, and are followed by supergene enrichment in a semi-arid climate. After burial by Miocene gravels, the climate changed to hyper-arid; estimates of the onset of hyperaridity vary from mid-Miocene (11–14 Ma) to Pliocene (~3–5 Ma). Since then, saline dewatering of the basement along long-lived faults has converted the original super-gene copper oxide assemblage, formed in equilibrium with meteoric water and lacking atacamite, to one containing atacamite [Cu2Cl(OH)3], the copper mineral especially associated with northern Chile. This interpretation is supported by studies showing that the salinity of fluid inclusions in atacamite is similar to that of local groundwater and that atacamite is considerably younger than the co-existing supergene alteration. SOMMAIRE La recherche decrite ici et initiee en 1998 visait a mettre au point des meth-odes d'exploration de gisements de porphyres cupriferes enfouis sous d'epaisses couches lithifiees de graviers dans le desert d'Atacama au Chili. Des donnees preliminaires indiquent que des eaux souterraines salines mineralisees ont ete poussees episodiquement jusqu'a la surface, a travers des zones de fractures, a l'occasion de seismes, creant ainsi des anomalies au-dessus de gisements mineraux. Une recherche subsequente appuyee par la Canadian Mining Industry Research Organization (CAMIRO) qui a porte sur la composition de l'eau souterraine et des anomalies de surface, a permis de confirmer l'existence d'un lien entre les deux. Les resultats de travaux subsequents permettent de croire que ces anomalies geochimiques sont l'expression en surface d'un processus commun a l'evolution metallogenique de nombreux gisements. L'intrusion porphyrique et la mineralisation hypogene sont tributaires de failles, auxquelles s'est ensuite ajoute un enrichissement supergene sous climat semi-aride. Apres l'enfouissement au Miocene par des graviers, le climat est devenu hyper-aride; selon les estimations le climat serait devenu hyperaride entre le Miocene moyen (11-14 Ma) et le Pliocene (~3-5 Ma). Depuis, l'assechement des eaux salines du socle le long de failles persistantes a entraine une conversion de l'assemblage original d'oxydes de cuivre supergene - lequel s'etait forme en etat d'equilibre en milieu d'eau meteorique et qui etait depourvu d'atacamite - en un assemblage contenant de l'atacamite [Cu2Cl(OH)3], ce mineral de cuivre typique du Chili du nord. Cette interpretation est corrobore par des etudes montrant que la salinite des inclusions fluides dans l'atacamite est semblable a celle de l'eau souterraine locale et que l'atacamite est significativement plus jeune que l'alteration supergene coexistante.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.014 | 0.001 |
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".