Evolution of a post-Variscan mid-crustal shear zone in relation to the Tethyan rifting (Ivrea-Verbano Zone, Southern Alps)
Bibliographic record
Abstract
In the last decade, studies of rifted margins have benefited from an increasing quantity of high-quality data from several disciplines. The Ivrea-Verbano Zone (IVZ), in the Italian Southern Alps, represents a complete section of middle to lower continental crust, which records both the Variscan and subsequent Alpine Tethys rift-related tectonics (Beltrando et al., 2015; Simonetti et al., 2023).One of the most important structures is the Forno-Rosarolo shear zone (Siegesmund et al., 2008). It is a NE-SW-oriented, subvertical shear zone made of metapelites, amphibolites, calc-silicates and granulites involved in anastomosed proto- to ultra-mylonite layers enveloping weakly deformed lenses. Mylonites formation postdate Variscan metamorphism and deformation and predate Jurassic brittle fracturing and faulting.In present day orientation, the kinematic indicators point to a sinistral sense of shear. Removing the Alpine tilt at high angle of the IVZ, this kinematic points to a former extensional shear zone. Investigations on the mylonitic flow kinematic reveal a non-coaxial deformation characterized by dominant pure shear (between 70 % and 50 %) and minor simple shear. Metamorphic conditions of the wall rocks vary from the upper amphibolite (SE, footwall) to the granulite facies (NW, hanging wall). Within the mylonites, PT estimate from mineral assemblage points to amphibolite facies conditions during deformation (~650 °C and ~5.5 kbar).Such kinematic data and metamorphic conditions allow to constrain the development of the Forno-Rosarolo shear zone mylonitic deformation, together with other similar structures of the IVZ, during the intermediate phase of the Tethyan rift (Beltrando et al., 2015; Simonetti et al., 2023) known as “thinning mode” (Manatschal et al., 2007). This stage was characterized by general shear conditions (pure shear between 70 % and 50 %) suggesting a phase of transition from a symmetric to an asymmetric configuration of rift.Beltrando M., Stockli D.F., Decarlis A., Manatschal G., 2015. A crustal‐scale view at rift localization along the fossil Adriatic margin of the Alpine Tethys preserved in NW Italy. Tectonics, 34, 1927–1951. https://doi.org/10.1002/2015TC003973Manatschal G., Müntener O., Lavier L.L., Minshull T.A., Péron-Pinvidic G., 2007. Observations from the Alpine Tethys and Iberia–Newfoundland margins pertinent to the interpretation of continental breakup. Geol. Soc. Spec. Publ., 282, 291–324. https://doi.org/10.1144/SP282.14Siegesmund S., Layer P., Dunkl I., Vollbrecht A., Steenken A., Wemmer K., Ahrendt H., 2008. Exhumation and deformation history of the lower crustal section of the Valstrona di Omegna in the Ivrea Zone, southern Alps. Geol. Soc. Spec. Publ., 298, 45–68. https://doi.org/10.1144/SP298.3Simonetti M., Langone A., Bonazzi M., Corvò S., Maino M., 2023. Tectono-metamorphic evolution of a post-variscan mid-crustal shear zone in relation to the Tethyan rifting (Ivrea-Verbano Zone, Southern Alps). Journal of Structural Geology, 173, 104896. https://doi.org/10.1016/j.jsg.2023.10489
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.002 |
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; both teacher heads agree on what is shown here.
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".