Bibliographic record
Abstract
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.
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".