<sup>87</sup>Sr/<sup>86</sup>Sr of brines from the Fennoscandian Shield: a synthesis of groundwater isotopic data from the Baltic Sea region
Bibliographic record
Abstract
High salinity CaNaCl brines occur in Sweden and Finland. The complex geological history of the Fennoscandian Shield is reflected by the wide range of saline waters whose chemical compositions have been explained by local waterrock interaction, simple evolution of relict sea water, or freezing of sea water during glacial periods. This study deals with the present knowledge of Sr isotopes in groundwater from the Fennoscandian Shield to better constrain the origin of their deep saline component. Two different mixing trends are seen between Äspö Island groundwater and the Baltic Sea. The first trend links the North Sea to rivers through various dilution levels in the Baltic; the second trend is a simple linear relationship through Äspö groundwaters, agreeing with a binary mixing between a Baltic end-member and a highly Sr-concentrated fluid. Strontium isotope compositions are presented for precipitation in Finland and Sweden, the Baltic Sea, and the river waters draining the Fennoscandian Shield, and for groundwaters from several sites in the Fennoscandian Shield. At least six mixing lines between rain-and-snow input and surface waters can be drawn in each region around the Baltic Sea, reflecting a first step of waterrock interaction. A second series of calculated lines links the surface end-members and the deep brines, and defines a range of 87 Sr/ 86 Sr ratios for the deep brines at each site. All sites show a specific 87 Sr/ 86 Sr signature and the large 87 Sr/ 86 Sr variations is site specific. The well-constrained 87 Sr/ 86 Sr signatures in deep brines should correspond to a large, well-mixed, and homogeneous water reservoir.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.003 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".