Permeability, electrical, and thermal properties of sulfide, sedimentary, and basaltic units from the Bent Hill area of Middle Valley, Juan de Fuca Ridge
Bibliographic record
Abstract
Permeability, electrical resistivity, and thermal conductivity measurements were performed on samples from the Bent Hill area of the Middle Valley on the northern Juan de Fuca Ridge. Thermal conductivity measurements were also made on samples from the Trans-Atlantic Geotraverse (TAG) hydrothermal area in the Mid-Atlantic Ridge for direct comparison with previous studies and the Middle Valley results. Electrical resistivity and permeability measurements were made as a function of confining pressure on 15 samples comprising different lithologic compositions found in the Bent Hill area. The effect of pressure on electrical resistivity values is relatively small and the observed frequency dependence is highly controlled by the sulfide content in these rocks. Permeabilities are in the 10–16–10–20 m2 (0.1–100 μD) range. Although permeability does not recover in samples that undergo significant permanent deformation, the elastic permeability dependence on confining pressure is relatively small. Permeability correlates with porosity. Permeability anisotropy correlates with the presence of oriented sulfide veins with increased flow parallel to the veins. Thermal conductivity measurements made on 41 samples from Middle Valley and 9 samples from the TAG area show systematic variations due to changes 1Iturrino, G.J., Davis, E., Johnson, J., Groschel-Becker, H., Lewis, T., Chapman, D., and Cermak, V., 2000. Permeability, electrical, and thermal properties of sulfide, sedimentary, and basaltic units from the Bent Hill area of Middle Valley, Juan de Fuca Ridge. In Zierenberg, R.A., Fouquet, Y., Miller, D.J., and Normark, W.R. (Eds.), Proc. ODP, Sci. Results, 169, 1–42 [Online]. Available from World Wide Web: . [Cited YYYY-MM-DD] 2Borehole Research Group, LamontDoherty Earth Observatory of Columbia University, Route 9W, Palisades NY 10964-8000, USA. iturrino@ldeo.columbia.edu 3Geological Survey of Canada, GSC Pacific Sidney Subdivision, Pacific Geoscience Centre, PO Box 6000, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada. 4New England Research Inc., 76 Olcott Drive, White River Junction VT 05001, USA. 5Division of Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Causeway, Miami FL 33149, USA. 6Department of Geology and Geophysics, University of Utah, 135 South 1460 East, Salt Lake City UT 84112-0111, USA. 7Geophysical Institute, Czech Academy of Science, 141-31 Praha 4, Czechoslovakia. Date of initial receipt: 3 January 1999 Date of acceptance: 14 February 2000 Date of publication: 31 August 2000 Ms 169SR-115 G.J. ITURRINO ET AL. PROPERTIES OF SULFIDE, SEDIMENTARY, AND BASALTIC UNITS 2 in composition and a weak relationship with porosity for sedimentary samples from Middle Valley. A comparison between the divided-bar and the half-space needle-probe methods of measuring thermal conductivity shows good agreement for the Leg 169 measurements unlike previous results from Legs 139 and 158. The discrepancies observed in earlier studies seem to be related to the long times used in the older measurements for the optimal T vs. ln(t) data interval. The apparatus used during Leg 169 was smaller, sampled a smaller volume of core, and in high conductivity material was not influenced by boundary effects.
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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 | 0.001 |
| 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) | 0.000 | 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".