Notice bibliographique
Résumé
The samples of Si-Fe-Mn oxides were dredged from PACMANUS (Papua New Guinea-Australia-Canada-Manus) hydrothermal field in Eastern Manus Basin. Major, trace and rare earth elements, Sr, Nd and Pb isotopic compositions were analyzed for studying the genesises and geochemical characteristics, and analyzing the ore-forming material sources. Utilizing Si, Fe and Mn concentrations within the end-member PACMANUS hydrothermal fluid, Si-Fe-Mn-H 2 O thermodynamic systems-Pourbaix diagrams were constructed at 300°C and 25°C, respectively. The diagrams illustrated the main Si, Fe and Mn oxides species, precipitating sequences and stability field of each species precipitating from the hydrothermal fluid. Based on microscopic textures, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), typical biogenic filamentous structures were identified. The relationship between biotic and abiotic kinetic mechanism in the formation of Fe oxides and the precipitation mechanism of amorphous silicon were researched. The genesises of the Si-Fe-Mn oxides were complicated. The geochemical characteristics reflected a obvious hydrothermal origin, and diagenetic influence in the later period. However, seawater and volcanic materials did not make a big contribution. Sr and Nd in the hydrothermal Si-Fe-Mn oxides had two end-member sources (seawater and hydrothermal fluid). The seawater contributed a large amount of Sr about 76.7%-83.1% of total amount. Nd was mainly derived from hydrothermal fluid and preserved the hydrothermal signature. Pb isotopic compositions showed minor variability and was mainly derived from local basement rocks. The Pourbaix diagrams showed that the main Si, Fe and Mn oxides species precipitating from the hydrothermal fluid were SiO 2 , Fe(OH) 3 , Fe 3 (OH) 8 , Mn 3 O 4 , and Mn 2 O 3 at 25°C. During mixing of hydrothermal fluid with seawater, SiO 2 precipitated earlier than Fe-Mn oxides because of the lower stability boundary. Then Fe(OH) 2 precipitated first, followed by Fe 3 (OH) 8 and Fe(OH) 3 , and last, small amounts of Mn 3 O 4 and Mn 2 O 3 precipitated. Based on the physico-chemical conditions of PACMANUS hydrothermal fluid, a strict abiotic oxidation rate of Fe 2+ to Fe 3+ was calculated, which was approximately 0.012 g/min. 3.2 kg per year Fe oxides would be deposited in this vent. A mesh-like microenvironment constructed by biogenic filaments ensured adequate Fe 2+ concentration and low oxygen content for the growth of bacteria. Moreover, this structure promoted the deposition of abiotic Si-Fe oxides. The precipitation of amorphous silicon was divided into two stages. In the first stage, amorphous silicon would precipitate on the Fe filaments. When the Fe-Si filaments were crusted, the second stage of precipitation of amorphous silicon began. In this stage, the size of Fe-Si filaments increased and a large amounts of globular rich in Si and Fe precipitating around these filaments.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».