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Record W2140778824 · doi:10.1190/1.1487055

Mapping remanent magnetization using the local phase

2001· article· en· W2140778824 on OpenAlexaboutno aff
Jeffrey B. Thurston

Bibliographic record

VenueGeophysics · 2001
Typearticle
Languageen
FieldEarth and Planetary Sciences
TopicGeophysical and Geoelectrical Methods
Canadian institutionsnot available
Fundersnot available
KeywordsRemanenceMagnetizationGeologyMagnetometerField (mathematics)PerpendicularPaleomagnetismGeophysicsMagnetic anomalyPhase (matter)GeodesyMagnetic fieldGeometryPhysicsMathematics

Abstract

fetched live from OpenAlex

Abstract For uniformly magnetized 2-D contacts, thin sheets, horizontal cylinders, and dykes, the apparent inclination of the magnetization vector (i.e., the inclination projected into a plane perpendicular to the strike of a 2-D anomaly) can be computed from the difference in the anomaly shapes of the total field and the vertical field. The calculation can be performed using gridded data, resulting in a grid containing estimates of apparent inclination. These estimates take into account varying source–strike direction. This quantity is important for computing source dip wherever the data are likely to be affected by the presence of remanent magnetization. As well, it is useful for input to forward models computed along profiles perpendicular to strike. Further, without knowledge of source dip, the apparent inclination can be used to map the presence of remanent magnetization. This is an aid to geologic mapping, allowing isolated paleomagnetic measurements to be extrapolated over a broad area. Knowing the extent of remanent magnetization can also help indicate how well the reduction to the pole process will work. The method requires both total-field and vertical-field component data. Most modern airborne surveys are conducted with optically pumped magnetometers that record only the total field. To apply the method in these cases requires estimation of the vertical component from the total field using a 2-D Fourier operator, which in turn requires the assumption that the earth's field direction is constant over the study region and the induced field is small compared to the ambient field. This restricts application to areas of several hundred square kilometers. Apparent inclination is estimated from synthetic data computed over a generalized cross-section of the center of the Manicouagan impact structure (Canada) and to measured aeromagnetic data over this structure. The results of the synthetic test indicate that for the northern and southern edges of this source, the method can distinguish the present-day and paleomagnetic fields with the same spatial resolution as the analytic signal has for identifying magnetization boundaries. Application to the airborne data indicates that where the source strikes at high angles to the declination of the present-day field, the estimated apparent inclination is influenced by both the remanent and inducing fields. For other strikes the field is almost entirely remanent or no distinction between the present-day and paleomagnetic fields can be made. As well, the source dip, estimated from the local phase and the estimated apparent inclination, is consistent with previously published results.

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 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)0.000
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: Other design · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.989
Threshold uncertainty score0.550

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.001
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0010.000

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 head0.030
GPT teacher head0.267
Teacher spread0.236 · 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

Classification

machine, unvalidated

Machine predicted; a candidate call from one teacher head, not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designOther design
Domainnot available
GenreEmpirical

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".

Quick stats

Citations6
Published2001
Admission routes1
Has abstractyes

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