Carbonate Speleothems in the Dry, Inneralpine Vinschgau Valley, Northernmost Italy: Witnesses of Changes in Climate and Hydrology Since the Last Glacial Maximum
Bibliographic record
Abstract
Abstract An interesting association of slope breccia, inactive and active tufa deposits, and speleothems is present in the central Vinschgau Valley, Italy. The occurrence of abundant carbonate cements in fractures and voids of crystalline basement rocks is unexpected considering the fact that this valley is among the driest spots in the entire Alps. Low annual precipitation of 440-530 mm coupled with frequent wind give rise to a semiarid climate and steppe vegetation along the south-facing slopes of the valley. Springs in this area are mostly supersaturated with respect to calcite, and carbonate precipitation occurs locally as tufas and, less well known because of lack of accessibility, as speleothems in the shallow subsurface. The majority of the tufa deposits and speleothems, however, are fossil. Speleothems are composed of low-Mg calcite and calcite-aragonite, respectively. Delicate growth textures including presumable annual lamination caused by pronounced changes in fluorescence intensity are preserved in both calcite and aragonite. Most calcite is a primary precipitate, but small amounts of secondary calcite replacing aragonite are common in most aragonite-bearing samples. The highly radiogenic Sr isotope composition, as well as high concentrations of U, Fe, Sr, and Mg, indicate that the groundwater from which these carbonates precipitated experienced intensive interaction with the host crystalline rocks. The very low tritium concentrations and the lack of a seasonal O isotope variation in modern spring waters, as well as their rather constant hydrochemical composition, also support this suggestion. S isotope data for dissolved sulfate and Ca and Mg sulfate precipitates indicate a sulfide source, i.e., oxidation of sulfide ore minerals in the aquifer, resulting in elevated sulfate and Fe concentrations. Th/U dating of speleothem samples using thermal ionization mass spectrometry yielded ages between 13,710 and 378 yr BP, with most ages falling in the early to middle Holocene. Although no isotopic dates are available for the tufa deposits, field evidence strongly suggests that speleothems, tufa deposits, and carbonate cements in the slope breccia were closely related. We therefore interpret the existence of these terrestrial carbonates as evidence of changes in climate since the middle Holocene. Their presence suggests a higher annual rainfall during the first half of the Holocene, possibly because of enhanced moisture transport from the Mediterranean.
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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) | 0.001 | 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 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".