Heavy-Mineral Assemblages In Sandstone Intrusions: Panoche Giant Injection Complex, California, U.S.A.
Bibliographic record
Abstract
Abstract: Excellent exposure from part of the Panoche Giant Injection Complex in the San Joaquin Valley is used to examine provenance characteristics of sandstone intrusions with respect to two parent sandstone units that are known to feed the sand-injection complex. The succession is part of the upper Mesozoic to lower Tertiary Great Valley Group, and was deposited in a deepwater part of an evolving deep-water forearc basin. The section examined is mudstone-dominated, and the sand injection is constrained to have occurred in the Danian. Sandstones in the Dosados Member (Moreno Fm) are identified as the main parent unit on the basis of total heavy-mineral-assemblage compositions and varietal studies of selected minerals (tourmaline, garnet, titanite, apatite, and zircon). Fluidized sand is emplaced in turbulent flow conditions creating high-velocity inter-grain collisions. Evidence of comminution and diminution of minerals that are less hard than quartz is documented using indices for the relative hardness (TAH) and durability (TAD) of heavy minerals. Preferential settling of high-density zircon relative to lower-density tourmaline produces density-controlled variations of zircon:tourmaline upward through the injection complex. Heavy-mineral dissolution occurred in the most permeable sandstone intrusions and is believed to record the effects of mid-Eocene deep weathering, when subtropical climate prevailed in the study area. Detrital heavy-mineral assemblages, which are dominated by titanite and garnet, record erosion of the Sierran metamorphic terrane with mafic and alkaline plutonic rocks. Zircon with U/Pb ages of c. 140–160 Ma and c. 90–110 Ma, consistent with earlier independent analyses, record erosion of Sierran granitoids. On the paleo-seafloor, enrichment of Ca-amphibole and epidote is indicative of Sierran provenance concurrent with sand extrusion. The presence of Na-amphibole in the Uhalde Sandstone supports earlier work that suggested sediment input from obducted seafloor to the west.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 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".