Can dolomitic marble be weaker than calcitic marble at lower greenschist-facies conditions? Microstructural analyses of coexisting greenschist-facies calcitic and dolomitic mylonites
Bibliographic record
Abstract
The bedrock of Mt Hymittos, Greece, exposes two parallel Miocene low-angle extensional faults. Strain along the upper detachment is localized in calcitic marble and schist; deformation associated with the lower detachment is accommodated in a >100 m thick package of dolomitic mylonite exhibiting consistent top-to-SW kinematic indicators and pronounced L–S fabrics. Field and geochronometric evidence indicates that both detachments deformed under middle to lower greenschist-facies conditions, where dolomite is predicted to be stronger than calcite. Evidence of preferential strain localization in dolomitic marble under these conditions conflicts with generally expected predictions of mineral and rock strength; microstructural analysis and electron backscatter diffraction were applied to investigate this anomaly. Microstructures in both dolomitic and calcitic marbles record dislocation creep of dolomite and calcite leading to subgrain rotation recrystallization and grain-size reduction of coarse domains (>50 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>μ</mml:mi> </mml:math> m). Grain-size reduction initiated a switch in the dominant deformation mechanism from dislocation creep to diffusion creep in fine-grained dolomite domains. Zener pinning and limited recovery controlled dolomite grain sizes. The crystallographic preferred orientation in calcitic marble indicates that deformation by dislocation creep accommodated grain boundary sliding. Our work suggests that polydeformed dolomitic marble can be weaker than calcitic marble at relatively low temperatures.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot 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.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| 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 teacher head, 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".