The bedrock of Hymittos, Attic peninsula, Greece, exposes a pair of low-angle crustal-scale ductile-then-brittle detachment faults. The uppermost detachment fault separates sub-greenschist facies phyllite and marble of a Pelagonian Zone hanging wall, from greenschist facies metasedimentary schist, calc-schist, and marble correlated to the Cycladic Blueschist Unit. A second, structurally lower detachment fault subdivides the metamorphic rocks of the Cycladic blueschist unit footwall into middle and lower units. There is a marked step in metamorphic grade between the sub-greenschist facies uppermost package, and the middle-to-upper greenschist facies middle and lower packages. A suite of new white mica 40 Ar/ 39 Ar and zircon (U-Th)/He dates indicates accommodation of deformation along these faults occurred from the late Oligocene to the late Miocene with both faults active during the middle Miocene. The structures have clear top-S/SSW kinematics determined from flanking folds, sigmoids, shear bands, stair-stepping of strain shadows on porphyroclasts, and SCC' fabrics. The ductile-to-brittle deformation of the structures, morphology of the massif, and the increase in metamorphic grade suggest these low-angle structures are part of a major, crustal-scale extensional complex, located at the northwest end of the West Cycladic Detachment System, that accommodated Miocene bivergent exhumation of Attic-Cycladic metamorphic core complexes in the central Aegean. Taken together, the above data suggest that multiple coeval detachment branches may form in areas with high strain gradients to accommodate the mechanically necessary termination of Cycladic-style detachment systems.

At the northwestern margin of the Gurktal Alps (Eastern Alps), Eoalpine (Cretaceous) thrusting of carbonaceous material (CM) bearing metasediments formed a very low- to low-grade metamorphic nappe stack above higher-grade metamorphic basement nappes. Sedimentary burial as well as progressive metamorphism transformed the enclosed CM to anthracite, metaanthracite and semigraphite. In a kinematically well-constrained section at the northwestern frontal margin of the nappe stack, this transformation has been investigated by vitrinite reflectance measurements and Raman spectroscopy of carbonaceous materials (RSCM). Automated, interactive fitting of Raman spectra estimates the metamorphic peak temperatures in a complete section through the upper part of the Upper Austroalpine unit. A RSCM trend indicates a temperature profile of ca. 250–600 °C. The top part of the gradient is reconstructed by one-dimensional thermal modeling. The certainty of ca. ± 25 °C at a confidence level of 0.9 resembles the data variability within a sample location. Due to the large calibration range, the method is able to reconstruct a thermal crustal profile in space and time. The study highlights the versatility of RSCM, which characterizes almost 250 Ma of a complex and polyphase tectonic history. RSCM data characterize the Variscan metamorphic grade in nappes now imbricated in the Eoalpine nappe stack. They additionally constrain a numerical model which emphasizes the significance of an increased thermal gradient in a continental margin towards the western Neotethyan ocean during Permo-Triassic lithospheric extension. It finally characterizes the Eoalpine metamorphic gradient during nappe stacking and a significant metamorphic jump related to exhumation and normal faulting.

Dating low‐grade metamorphism is challenging since such rocks commonly lack suitable target minerals for acquiring pressure–temperature–time–deformation (P–T–t–d) data. Herein a new geochronological method termed ‘bulk inclusion dating’ is applied to a chloritoid‐bearing schist from the Staufen‐Höllengebirge Nappe (SHN, Austroalpine Unit, Eastern Alps, Austria) for which Cretaceous metamorphism is imprecisely constrained. Thermodynamic modelling of the phase relations and mineral chemistry predicts the stability of the equilibrium assemblage in a P–T field between 450–490℃ and 0.5–0.7 GPa, which agrees with peak temperature constraints ~490℃ derived from Raman spectroscopy of carbonaceous material. Chemical zoning of, and the zonation of inclusions within, chloritoid confirm porphyroblast growth at these conditions. High‐resolution imaging reveals thousands of minute (length: 0.1–3 µm), euhedral micro‐zircon crystals included in chloritoid porphyroblasts and in the matrix. The morphological and microstructural characteristics of micro‐zircon as well as the crystal size distributions indicate that it nucleated and grew at greenschist facies conditions most likely from a Zr‐saturated fluid. In situ laser ablation inductively coupled plasma mass spectroscopy bulk inclusion dating of metamorphic zircon in the chloritoid rim using a laser spot diameter of 120 μm yields a U–Pb age of 116.7 ± 9.1 Ma (MSWD: 1.5, n: 79). We interpret zircon precipitation and progressive coarsening coeval with chloritoid growth during prograde metamorphism and thus link the age to the late prograde part of the P–T evolution. The contribution of other U‐bearing phases (apatite, epidote, rutile) does not significantly disturb the U–Pb age. The data provide clear evidence for Early Cretaceous metamorphism in the SHN and indicates that metamorphism started at least 20 m.y. before the formation of eclogites in the Austroalpine Unit. The method introduced here allows integration between metamorphic conditions and age constraints in low‐grade metamorphic rocks and opens up new potential applications in petrochronology.

<p>In low-grade metamorphic units, precise thermobarometric and geochronologic data are often ambiguous or entirely lacking, thus complicating the temporal interpretation of metamorphism and hampering the identification of complex polymetamorphic histories. We present new P-T-t-D data from samples collected in two Austroalpine nappes exposed in the Eastern Alps, Austria: the structurally upper greenschist-facies Schöckel Nappe (“Graz Paleozoic,” Drauzug-Gurktal Nappe System) and the structurally lower amphibolite-facies Waxenegg Nappe (Koralpe-Wölz Nappe System). Although polymetamorphism was previously inferred from garnet zonation indicating multiphase growth in the Waxenegg Nappe, the timing of metamorphism is poorly resolved and only limited geochronology exists in the Schöckel Nappe.</p><p>Detailed petrographic investigations revealed that the chloritoid-bearing phyllite and micaschist of the Schöckel Nappe contain allanite that occasionally show partial replacement by small (<10 µm) monazite and thorite. Large (up to 500 µm) monazite exhibiting distinct core-rim chemical zoning were observed in the garnet-bearing micaschist of the Waxenegg Nappe. Careful documentation of the microstructural phase relations, thermodynamic modeling in the MnCNKFMASHT system, Raman spectroscopy of carbonaceous matter and in-situ LA-ICPMS U-(Th)-Pb dating of the accessory phases allow us to reconstruct a first metamorphic imprint at ~560°C and 4 kbar in the Waxenegg Nappe at c. 270 Ma (Permian event). Overprinting occurred at ~540°C and 8-10 kbar at c. 90 Ma (Eo-Alpine event). In the Schöckel Nappe, peak metamorphic conditions of ~470°C and 3-4 kbar existed during the Permian event at c. 260 Ma and the Eo-Alpine event in the upper part of the nappe did not exceed lower to middle greenschist-facies conditions.</p><p>Our results provide unequivocal evidence for Permian metamorphism in the Schöckel Nappe, which was hitherto unknown in this part of the Austroalpine Unit. Moreover, it demonstrates that the main metamorphic signature in this unit occurred during the Permian event and that the Eo-Alpine overprint is relatively lower grade than previously proposed. Combined with the data from the Waxenegg Nappe, there is an obvious marked increase in the Eo-Alpine peak conditions of ~130°C and 5 kbar across the nappe contact with higher grade in the footwall compared to the hanging wall. This is consistent with the existence of a major normal fault between the Drauzug-Gurktal Nappe System and the Koralpe-Wölz Nappe System in the easternmost part of the Austroalpine Unit, as already identified in its central and western parts. Modern thermobarometric analytical approaches coupled with high spatial resolution geochronology on accessory minerals is allowing a more thorough assessment of the subtle metamorphic histories recorded in the fundamentally important low-grade units of orogens.</p>

<p>EUGEN (European Geoscience Student Network) is an association that provides a platform for the international exchange between geoscience students in Europe. The network organizes annual meetings which take place during the first week of August. From the first EUGEN meeting in 1996 which was organized in Germany the network looks back on a history of annual meetings held in 13 different countries in Europe.</p><p>During an EUGEN meeting participants are offered to join a scientific program consisting of field trips and evening lectures. Excursions cover a broad range of geoscientific topics and give an introduction to the geology of the host country. Evening lectures give a deeper insight into topics conveyed during excursions and are organized in cooperation with local universities and supporting organizations. Moreover, participants can use this platform to present their Bachelor or Master thesis. In addition to that, activities like the ‘geolympics’ – a geological-sportive team competition – and one cultural daytrip complete the program. To sum up, EUGEN aims to enhance the scientific exchange across all geoscientific disciplines between both geoscience students and graduates. By combining the accompanying program of a scientific conference with the fun atmosphere of a geological field camp, an EUGEN meeting provides the ideal atmosphere for students to acquire international connections and lay the foundations of future professional collaborations. Participation in such a network is especially advantageous for those who are intending to study abroad and to internationalize their professional network.</p><p>EUGEN is a non-profit association which is funded by donations, membership- and participation fees. As such, the network depends on the active participation of committed members in the association. Future challenges comprise finding more and new ways to connect with students from all over Europe in order to increase the diversity of participating counties. Moreover, the association intends to internationalize its organization structure which is at the moment strongly focused on Germany. For the 25<sup>th</sup> anniversary meeting the network goes back to its roots in the Black forest region in Germany. We invite students from all over the world to save the date (3<sup>rd</sup> – 9<sup>th</sup> of August 2020) and join us for an unforgettable experience!</p>