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Record W2085396925 · doi:10.1029/2005je002404

Magnetic minerals in the Martian crust

2005· article· en· W2085396925 on OpenAlex

Why this work is in the frame

A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.

affAt least one author lists a Canadian institution in the pinned OpenAlex snapshot.

Bibliographic record

VenueJournal of Geophysical Research Atmospheres · 2005
Typearticle
Languageen
FieldPhysics and Astronomy
TopicPlanetary Science and Exploration
Canadian institutionsMcGill UniversityUniversity of Toronto
Fundersnot available
KeywordsGeologyCrustMagnetiteBasaltMartianGeophysicsGeochemistryThermoremanent magnetizationMars Exploration ProgramMagnetizationAstrobiologyRemanenceMagnetic fieldPhysicsPaleontology

Abstract

fetched live from OpenAlex

Using rock magnetism and thermal modeling, we evaluate the candidate minerals responsible for strong magnetic anomalies in the Terra Sirenum and Terra Cimmeria regions of Mars' southern highlands. We assume an early global dynamo field similar in strength to the present Earth's field, enduring about 500 Myr after accretion and core formation, and a basaltic crust containing no more than 4–7 weight% of magnetic minerals. Thermal evolution models with a wide variety of initial crustal thicknesses, distributions of radioactive elements, and thermal expansion coefficients all yield similar thermal histories for the crust: warming in the first ∼1000 Myr (due mainly to radioactive heating) followed by monotonic cooling for the remainder of Mars' history. Primary thermoremanent magnetization (TRM) acquired by intrusive and extrusive bodies during the first 500 Myr was in part thermally demagnetized by general crustal warming after the dynamo field disappeared, from 500 to 1000 Myr. The Curie point isotherms around 1000 Myr established the maximum depth of TRM‐bearing crust. Shock and heating due to impacts demagnetized the uppermost ∼10 km of the crust around the same time, resulting in potential magnetic layer thicknesses of 15–20 km for pyrrhotite, 40–50 km for magnetite, and 50–60 km for hematite. Other magnetic phases, such as iron and finely exsolved low‐Ti titanohematite, are possible but less likely in a basaltic crust under oxidizing conditions. The prime candidates, in order of likelihood, are single‐domain magnetite (0.2–0.4 volume% or 0.4–0.8 weight% required), single‐domain pyrrhotite (1–2 volume% or 2–4 weight%), and either multidomain (>15 μm) or 5–15 μm single‐domain hematite or a mixture of both (1.5–3 volume% or 3–6 weight%). A composite source with different combinations of these minerals at different depths is entirely possible. Viscous decay of TRM is difficult to assess without detailed knowledge of the distribution of minerals and blocking temperatures with depth but would increase the amounts of magnetic material required.

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.

Full frame distilled prediction

Teacher imitation

Not 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.

metaresearch head score (Codex)0.001
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.504
Threshold uncertainty score0.541

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0010.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0000.000

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.

Opus teacher head0.036
GPT teacher head0.317
Teacher spread0.281 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it