Devonian to Permian intrusions in the Zentralgneis Supersuite of the eastern Tauern Window constrained by U-Pb zircon geochronology and geochemistry

In the course of comprehensive geological mapping, the Geosphere Austria (formerly Geologische Bundesanstalt – Geological Survey of Austria) initiated a systematic geochemical and geochronological characterization of the metamorphic granitoids forming the Zentralgneis Supersuite in the eastern Tauern Window. Three dozens of samples from already defined units (Sonnblick, Siglitz, Romate, Göss, and Hochalm orthogneiss) as well as newly defined units (Säuleck, Kampleck, and Grübelwand orthogneisses) were sampled in four different nappes of the Venediger Nappe-System (Sonnblick, Romate, Hochalm, and Göss nappe). Major and trace element geochemical analyses indicate three groups. Most of the Sonnblick orthogneiss samples, the Siglitz orthogneiss and other non-leucocratic orthogneisses derive from high-K, calc-alkaline granite with a peraluminous and magnesian composition. The analyzed samples classify as I-type (subordinately S-type) granites formed in volcanic arcs and show no negative Eu-anomaly. The Kampleck, Säuleck, and Grübelwand orthogneiss as well as leucocratic orthogneisses derive from high-Si, calc-alkaline granite, aplite and pegmatite, with a peraluminous ferroan composition. This group classifies as S-type granites formed in a within-plate setting and samples show a clear negative Eu-anomaly as well as comparably low Ba and Sr concentrations. The Romate orthogneiss and one analyzed Sonnblick orthogneiss sample derive from shoshonitic, quartz-monzonite to syenite with metaluminous and magnesian composition. This group classifies as syn-collisional A-Type granites and shows no negative Eu-anomaly with comparably high Eu, U and Th concentrations. The three distinguished groups are found in different nappes of the Venediger Nappe System; however, note that single orthogneiss units can host elements of different characteristics. U-Pb zircon geochronology further constrains some of the orthogneiss units. A sample of coarse-grained Sonnblick orthogneiss with an augen microstructure yields a Late Devonian age. An atypical fine-grained Sonnblick orthogneiss with small K-feldspar yields a late Carboniferous age and a Siglitz orthogneiss sample yields an early Carboniferous age. Samples from Kampleck, Säuleck and Grübelwand yield middle Permian ages. Our findings illustrate the complex and long lived intrusion story over 100 Myrs hidden in what is called the Zentralgneis Supersuite. The dominant group corresponding to I-type calc-alkaline plutonism contemporaneous to the Variscan Orogeny took more than 30 Myrs to form. At least in the Sonnblick orthogneiss, this group hosts younger intrusions that remain undefined and unmapped. Later Permian S-type intrusions are for the moment only attested in the Hochalm Nappe. However, based on lithological characteristics these can also be expected in other nappes (e.g. Sonnblick and Göss nappe). Finally, geochronological characterization of the Romate orthogneiss underpins any interpretation of its exotic chemistry. These results stress the importance of combined geochemical and geochronological analyses together with geological mapping for a more comprehensive understanding of the complex geological situation in the eastern Tauern Window

The Serifos Metamorphic Core Complex (Greece) — kinematic investigations of the southern detachment mylonites

The island of Serifos is situated about 100km SSE of Athens in the Aegean Sea and belongs to the Attic-Cycladic massif. The geology of Serifos is largely characterized by a shallow hornblendebiotite granodiorite pluton that intruded in the late Miocene into a previously deformed (under blueschist conditions) sequence mainly consisting of ortho- and paragneisses, calc-silicate marbles, amphibolites and schists. The pluton has a dome-shaped body occupying the central and southern parts of the island (Salemink 1985). The Serifos MCC is the very western continuation of a zone of syn- to post tectonic intrusions younging from the East (Naxos, Paros ?12Ma) to the West (Serifos 9– 8Ma). Whereas the older intrusions in the East show a top to the North geometry, the Serifos MCC has developed a South-directed low-angle detachment fault...conferenc

Late stage evolution of the Serifos Metamorphic Core Complex (Cyclades, Greece)

The island of Serifos is located in the Western Cyclades within the Attic- Cycladic metamorphic belt. It represents the westward continuation of an arcuate belt of Metamorphic Core Complexes with intrusions of late syn-post tectonic intrusions younging from East (e.g. Naxos main activity ca. 12Ma) to West (e.g. Serifos with 9–8Ma). In scientific discussions the dominance of probably continuous extension since ca. 30Ma (e.g. Jolivet & Faccenna, 2000) and the presence of Metamorphic Core Complexes (Lister et al. 1984) is accepted. The speculated roll-back of the subducting plate possibly started due to the slowing down of absolute plate convergence rate between Africa and Eurasia. This model is attractive, because it would also explain the shift from a compressional Andean-type regime to an extensional Mariana-type regime (Jolivet & Faccenna 2000). Contrary to the kinematic directions reported from the Central and Eastern Cyclades, the movement of the hanging wall of the Serifos Metamorphic Core Complex is south directed. The island’s main part is occupied by an undeformed granodiorite. Early granitic intrusions intruded into low-grade M2-crystalline rocks that have been overprinted to as high as amphibolite facies conditions due to contact metamorphism. Parts of these rocks (gneisses and amphibolites) as well as the early intrusions are deformed to mylonites (Grasemann et al. 2004).conferenc

Kinematics and deformation structures in a crustal-scale shear zone on Kea (W. Cyclades, Greece)

It is generally agreed upon that the exhumation of metamorphic rocks in the Aegean is caused by post orogenic extension in the late Oligocene to early Miocene. This extension is in principle largely accommodated by low-angle crustal detachment faulting possibly resulting in the formation of metamorphic core complexes (MCC). Here, we present data from recent structural investigations on the island of Kea in the W. Cyclades, Greece. Our work focussed in the north of the island. Of the ca. 270m total structural thickness that was mapped, the entire section of rocks are highly strained. Exhumation during progressive deformation is recorded by the transition from ductile to brittle/ductile to brittle conditions. The regional characteristics and types of deformation structures vary depending on the protolith and the intensity of strain...conferenc

Extensional crustal-scale shear zones in the Western Cyclades (Kea, Greece)

Intense seismicity and intensely developed active and ancient fault systems are common to the Aegean Region. Extending/ thinning crust involves a complex interplay of (1) Gulf of Corinth riftexpansion, (2) west- and south-ward retreat of the Hellenic Trench, (3) westward impingement of the Anatolian Platen, and/or (4) propagation of the Anatolian Fault system into the Aegean. New geological/structural investigations on Kea (also known as Tzia), in the Western Cyclades reveal a low angle crustal-scale, detachment-type ductile shear zone probably formed during Miocene extension and thinning of the continental crust...conferenc

Vector data map sheet Radenthein-Southeast, NL 33-04-06 SE-Quadrant

Die in dieser Datenpublikation publizierten Daten wurden für die Erstellung des Kartenwerkes Geologische Karte der Republik Österreich, Blatt RADENTHEIN-SÜDOST im Maßstab 1:25.000 verwendet und entsprechen dem aktuellen Wissensstand zum Zeitpunkt des Kartendruckes (November 2019). Die Datengrundlage basiert auf einer umfassenden Basisdatenerhebung im Rahmen der gesetzlich verankerten geologischen Landesaufnahme, welche eine umfangreiche Literaturrecherche, die Geländekartierung, sowie die Probenahme mit wissenschaftlichen Analysen und Messungen beinhaltet.The data provided in this dataset was used printing the Geological Map of Austria, map sheet Radenthein-Southeast on a scale of 1: 25,000. They correspond to the current state of knowledge in November 2019 at the time the map was printed. The dataset is based on a comprehensive collection of basic geological data in the Division of Geological Mapping at the Geological Survey of Austria including literature research, geological mapping and scientific research on rock samples

Vector data map sheet Radenthein-Northeast, NL 33-04-06 NE-Quadrant

Die in dieser Datenpublikation publizierten Daten wurden für die Erstellung des Kartenwerkes Geologische Karte der Republik Österreich, Blatt RADENTHEIN-NORDOST im Maßstab 1:25.000 verwendet und entsprechen dem aktuellen Wissensstand zum Zeitpunkt des Kartendruckes (November 2019). Die Datengrundlage basiert auf einer umfassenden Basisdatenerhebung im Rahmen der gesetzlich verankerten geologischen Landesaufnahme, welche eine umfangreiche Literaturrecherche, die Geländekartierung, sowie die Probenahme mit wissenschaftlichen Analysen und Messungen beinhaltet.The data provided in this dataset was used printing the Geological Map of Austria, map sheet Radenthein-Northeast on a scale of 1: 25,000. They correspond to the current state of knowledge in November 2019 at the time the map was printed. The dataset is based on a comprehensive collection of basic geological data in the Division of Geological Mapping at the Geological Survey of Austria including literature research, geological mapping and scientific research on rock samples

Quantitative kinematic of a frictional viscous low-angle normal fault on Kea (Western Cyclades, Greece)

Lithospheric extension during the Miocene is well documented in the Aegean. Within the Central and Western Cyclades extension has been documented in detail by the formation of Metamorphic Core Complexes and movement along low-angle normal faults (LANFs). Focusing on a hitherto unrecognised main low-angled fault geometry outcropping on northern Kea, this work presents pervasive evidence of top-to-south kinematics

Research update for articles published in EJCI in 2008

Eur J Clin Invest 2010; 40 (9): 770-78