Workshop for Scientific Drilling in the Indian Ocean Crust & Mantle. May 13th to 16th, 2015 Woods Hole MA, USA
Bibliographic record
Abstract
The Workshop for Scientific Drilling in the Indian Ocean Crust and Mantle was held May 13-‐16, 2015 at the Woods Hole Oceanographic Institution, bringing together 60 scientists from Australia, Canada, China, France, Germany, Great Britain, Italy, Japan, the Netherlands, Poland, Portugal and the United States. The meeting was co-‐sponsored by IODP China and the United States Scientific Support Program. Forty-‐four half hour talks were given, with an extensive overview of the tectonics, geophysics, geochemistry, and biogeochemistry of the principal regional interest, the SW Indian Ridge (SWIR). Two new and one scheduled drilling proposal were presented and reviewed. Twelve 30-‐minute discussion sessions provided time for audience input, resulting in specific workshop recommendations as outlined below. The SW Indian Ridge (~14) mm/yr is the best-‐studied ultra slow end-‐member for seafloor spreading. In addition to the unique tectonics of ultra slow spreading, the crust ranges from near zero to some of the thickest ocean crust measured far from a mantle hotspot. Thus, it is a unique laboratory for the study of lithospheric accretion. Unlike faster spreading ridges, the mantle is directly exposed over approximately a quarter of the seafloor formed along it. Mantle peridotite is a highly reactive substrate for water -‐ rock interaction compared to the basaltic crust at faster spreading ridges. This may have significant implications for the global carbon budget. The workshop was particularly timely as it coincided with planning for the 2016 to 2020 2nd International Indian Ocean Expedition. The meeting reviewed plans for the first leg of the SloMo Project (Slow Spreading Ridge Moho). This allowed an exchange between the expedition science party and the community on operation plans and objectives for drilling there, and for forming collaborations between ship and shore-‐based scientists. A review of existing Atlantis Bank surveys identified needed site survey data, including new surveys based on recent state-‐of-‐the-‐art seismic experiments to characterize the internal structure of the crust, as well as constrain the nature and variability of Moho. Near-‐bottom high-‐resolution bathymetric surveys are also needed to constrain the tectonic evolution of the Atlantis Bank Core Complex are needed. Presentations of seismic, bathymetric, submersible, biologic, and geochemical data were made for the Dragon Flag hydrothermal area (49°40’E) and the Dragon Bone Amagmatic Segment (53°E). The former represents the early stages of seafloor massive sulphide (SMS) formation, where shallow drill holes can establish the basic pattern of hydrothermal circulation during SMS formation, which is obscured by long episodic cycles of hydrothermal circulation at older deposits such as TAG. Local exposure of mantle peridotite at Dragon Flag adjacent to the thick crust of the volcanic segment to the east and the non-‐transform discontinuity to the west is an opportunity to explore the nature of the transition from basaltic to ultramafic outcrops along axis. Drilling mantle peridotite at the Dragon Bone Segment would compare mantle from two adjacent extreme melting environments. It was agreed, though, that additional survey data; particularly near-‐seafloor bathymetric mapping, is needed for both sites prior to a preliminary drilling proposal. A proposal was presented for drilling ‘smooth seafloor’ at 64°30'E on the SW Indian Ridge, which represents the magma-‐starved end-‐member of ultra-‐slow spreading ridges. This region lacks the characteristic roughness of most slow spread ocean crust, and crustal rock is virtually absent over large regions with the mantle directly exposed to the seafloor. Moreover, this represents another extreme mantle environment whose geochemistry should contrast sharply to the Dragon Flag and Dragon Bone areas. Based on the existing iii magnetic, seismic, geologic and bathymetric surveys, the consensus was that this was an important objective for lithosphere drilling, and that it is ready for a pre-‐proposal to IODP.\n
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.004 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.159 | 0.064 |
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".