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Three monazite generations were observed in garnet-bearing micaschists from the Schobergruppe in the basement to the south of the Tauern Window, Eastern Alps. Low-Y monazite of Variscan age (321 ± 14 Ma) and high-Y monazite of Permian age (261 ± 18 Ma) are abundant in the mica-rich rock matrix and in the outer domains of large garnet crystals. Pre-...
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Context 1
... Permian monazite (Fig. 5a, f) and those surrounding staurolite (Fig. 9b), show a simple core to rim zoning with a rimward decrease of MnO and CaO (1-0.1 wt. %; 3-0.1 wt. %) and increase of MgO (2.5-4 wt. %; Fig. 10). However, a few of the larger garnet crystals also yield a Mn-enriched core (plateau) with 3-4 wt. % MnO and 1-2 wt. % CaO and MgO (Fig. 11), followed by a rim domain, which is characterized by an abrupt decrease of MnO and increase of CaO and MgO (up to ca. 3-4 wt. %). The composition of the latter rims is similar to the garnet crystals shown in Fig. 10. A narrow retrogressive rim (max. 100-200 lm) is common in all investigated garnet ...
Context 2
... garnet crystals, including those with inclusions of Eo-Alpine and Permian monazite (Fig. 5a, f) and those surrounding staurolite (Fig. 9b), show a simple core to rim zoning with a rimward decrease of MnO and CaO (1-0.1 wt. %; 3-0.1 wt. %) and increase of MgO (2.5-4 wt. %; Fig. 10). However, a few of the larger garnet crystals also yield a Mn-enriched core (plateau) with 3-4 wt. % MnO and 1-2 wt. % CaO and MgO (Fig. 11), followed by a rim domain, which is characterized by an abrupt decrease of MnO and increase of CaO and MgO (up to ca. 3-4 wt. %). The composition of the latter rims is similar to the garnet crystals shown in Fig. 10. A narrow retrogressive rim (max. 100-200 lm) is common in all investigated garnet ...
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The Ötztal Complex is a polymetamorphic Austroalpine basement complex. The Variscan and Eo-Alpine metamorphic events in the central and northern Austroalpine Ötztal Complex (ÖC) and the Schneeberg Complex (SC) were studied by TROPPER & RECHEIS (2003) on a regional scale by means of P-T estimates, based on multi-equilibrium methods. Since these P-T...
Citations
... Moreover, the complex Y (yttrium) distribution within the rims of the type I Mnz supports their metamorphic origin, and the presence of low-Y cores suggests that they formed during the Cenerian stage when Y was incorporated into other mineral phases such as garnet. Subsequently, the crystallization of the high-Y rims (Fig. 9g) implies the presence of Y in the system, which may have been due to reactions involving garnet and plagioclase (Krenn et al. 2012;Wyatt et al. 2022), likely during the successive Carboniferous Variscan metamorphic event. ...
The onset of the Cossato-Mergozzo-Brissago shear zone within the Strona Ceneri Border Zone in the W-Southalpine basement (Italy) and its role in the collapse of the Variscan crust have been the subject of considerable controversy. A set of new petrographic, geochemical and geochronological data from a suite of syn-kinematic migmatitic paragneiss and amphibolites in between the upper and lower crustal sections of the W-Southalpine basement provide new evidence on the thermo-mechanical role played by the middle crust in the evolution of the Permian Southalpine basement. The petrological investigation of these amphibolite-facies rocks and U–Pb ages from monazite crystals, occurring in distinct microstructural positions, provide new P–T-t constraints on the late-Paleozoic tectono-thermal evolution of the Variscan middle crust. The SCBZ units recorded tectonic events from a possible Early Silurian Cenerian (ca. 440 Ma) overprint onto the proto-sedimentary units of the Southalpine basement to the Mid-Permian (ca. 285 Ma) syn-kinematic partial melting event developed close to the CMB shear zone. Phase equilibria modeling is used to constrain the metamorphic conditions recorded by this section of the Variscan basement. Pressure–temperature (P–T) isochemical phase diagrams show that, after the ca. 330 Ma Variscan metamorphic peak at P ≅ 4 kbar and T < 630 °C, the SCBZ paragneiss experienced isobaric heating up to 700–720 °C at ca. 285 Ma, which led to the formation of a syn-kinematic partial melting event coeval to the emplacement of the Mafic Complex in the lower Ivrea-Verbano Zone. These new geochronological and petrological constraints on the SCBZ paragneiss seem to corroborate the hypothesis that the transition from the stage of mature Variscan orogen to the stage of its collapse developed in the Permian, at ca. 285 Ma. Thus, we argue that the orogenic collapse was probably driven by the rheological weakening of the mid-crustal SCBZ units induced by their syn-tectonic partial melting and, ultimately, by the coeval thermal perturbation of the crust due to the intrusion of the mafic igneous suite at the crust-mantle boundary.
... In the Koralpe-Wölz nappe system, Variscan metamorphic ages obtained by Th-U-Pb monazite and Lu-Hf garnet-whole rock dating of metapelite and eclogite lie in the range 335-310 Ma (Krenn et al. 2012;Schulz 2017;Hauke et al. 2019). Gaidies et al. (2006Gaidies et al. ( , 2008 proposed Froitzheim et al. 2008). ...
... The Permian event in the Koralpe-Wölz nappe system is characterized by low-P/ high-T metamorphism and magmatic intrusions, and has been the focus of many geochronological and petrological studies (see summary by Schuster and Stüwe 2008). The majority of pegmatite intrusions and metamorphic rocks within the Koralpe-Wölz nappe system yield ages between 250 and 290 Ma (Krenn et al. 2012;Schulz 2017;Knoll et al. 2018 and references therein;Chang et al. 2023 and references therein). For this metamorphic event a high geothermal gradient of 45 °C/km is proposed (Schuster et al. 2001). ...
... The Permian age in sample WC30 (286.2 ± 12.0 Ma) is slightly older but in line with previous Th-U-Pb monazite ages of 261 ± 18 Ma and 267 ± 9 Ma in the Koralpe-Wölz nappe system (Krenn et al. 2012;Schulz 2017). However, no textural information is available to constrain Permian allanite growth due to the pervasive Eoalpine overprint. ...
We use U–Pb dating of allanite and REE-rich epidote in three polymetamorphosed units from the Eastern Alps to constrain the timing of prograde metamorphism. All three units (Ennstal, Wölz and Rappold Complex) record several metamorphic cycles (Variscan, Permian and Eoalpine) and presently define an Eoalpine (Cretaceous) metamorphic field gradient from lower greenschist to amphibolite facies. For U–Pb data, a method is introduced to test the magnitude of ²³⁰Th disequilibrium and potentially approximate the Th/U ratio of the reservoir out of which allanite and REE-rich epidote grew. We also show that the modelled stability of epidote-group minerals in the REE-free MnNCKFMASH and MnNCKFMASHTO systems and REE-bearing systems is nearly identical. By combining the stability fields of (clino-)zoisite and epidote modelled in REE-free systems with known geothermal gradients for the region, REE-rich epidote growth is constrained to 200–450 °C and 0.2–0.8 GPa during prograde metamorphism. In the Rappold Complex, allanite cores yield a Variscan age of ca. 327 Ma. In the Ennstal and Wölz Complex, allanite growth during the Permian event occurred at ca. 279–286 Ma. Importantly, recrystallized allanite laths and REE-rich epidote overgrowths in samples from all three units yield prograde Eoalpine ages of ca. 100 Ma, even though these units subsequently reached different peak conditions, most likely at different times. This suggests that all units were buried roughly at the same time during the onset of Eoalpine continental subduction. This interpretation leaves room for the model proposing that diachronous peak metamorphic conditions reported for the field gradient may be related to the inertia of thermal equilibration rather than tectonic processes.
... For example, Y-rich monazite domains have been suggested to be plausible targets to use for thermometry (e.g. Viskupic and Hodges 2001;Krenn et al. 2012;Laurent et al. 2018). Y content can also be used to distinguish between different monazite age populations (i.e. ...
The study of magmatic and metamorphic processes is challenged by geological complexities like geochemical variations, geochronological uncertainties, and the presence/absence of fluids and/or melts. However, by integrating petrographic and microstructural studies with geochronology, geochemistry, and phase equilibrium diagrams investigations of different key mineral phases, it is possible to reconstruct pressure-temperature-deformation-time histories. Using multiple geochronometers in a rock can provide a detailed temporal account of its evolution, as these geological clocks have different closure temperatures. Given the continuous improvement of existing and new in-situ analytical techniques, this contribution provides an overview of frequently utilised petrochronometers such as garnet, zircon, titanite, allanite, rutile, monazite/xenotime, and apatite, by describing the geological record that each mineral can retain, and explaining how to retrieve this information. These key minerals were chosen as they provide reliable age information in a variety of rock types and, when coupled with their trace element composition, form powerful tools to investigate crustal processes at different scales. This review recommends best applications for each petrochronometer, highlights limitations to be aware of, and discusses future perspectives. Finally, this contribution highlights the importance of integrating information retrieved by multi-petrochronometer studies to gain an in-depth understanding of complex thermal and deformation crustal processes.
... Owing to the high closure temperature of the isotopic systems (Thöni, 2002;and references therein), these data are considered as garnet formation ages close to the Permian metamorphic peak. Additional microprobe U-Th-Pb ages of monazite and xenotime included in garnet, staurolite or in the matrix fall in the similar range (Gaidies et al., 2008a;Krenn et al., 2012;Li et al., 2021a;Li et al., 2021b;Schulz et al., 2005;Schulz, 2017;Schulz & Krause, 2021). ...
There is an ongoing debate as to whether rare element pegmatite is always related to fractional crystallization of huge fertile granite bodies or whether it can also form directly from limited portions of enriched anatectic melt. In this contribution, we present a case study from the Eastern European Alps, showing the continuous evolution from melt generation in staurolite bearing micaschist to spodumene (LiAlSi2O6) bearing pegmatite. The investigated Austroalpine Unit Pegmatite Province formed during Permian lithospheric extension and all levels of the Permian crust are now accessible in a Cretaceous nappe stack. This nappe stack is mapped in detail, subdivided lithostratigraphically and the internal tectonic structure is well understood. It is clear that the described pegmatites are neither spatially nor genetically related to large fertile granite bodies. A review of geochronological data proofs that emplacement of pegmatite and leucogranite is broadly contemporaneous with high temperature-low pressure metamorphism of the country rocks. Field observations give clear evidence of a genetic link between simple pegmatite, leucogranite, evolved pegmatite and albite-spodumene pegmatite, on the one hand, and the subsolidus or suprasolidus metasediment hosting them on the other hand. These relations are underpinned by geochemical major and trace element investigations on all types of rock and the minerals therein. As source rock an Al-rich metapelite enriched in Li (70-270 ppm) with respect to the average upper continental crust is identified. The main Li-carrier is staurolite with up to 3000 ppm Li. The pegmatite and leucogranite originate in anatectic melts that formed between 0.6-0.8 GPa and 650-750°C, corresponding 18-26 km depth. During melt formation staurolite was consumed by sillimanite forming reactions. Subsequently, the melts were enriched in Li by fractional crystallization of quartz and feldspar during their ascent to higher crustal levels. While simple pegmatite and inhomogeneous leucogranite formed in lower and intermediate levels, evolved and albite-spodumene pegmatite crystallised at high levels at conditions between 0.3-0.4 GPa and 500-570°C, corresponding to about 12 km depth. Based on these data we develop a geochemical model for showing that Li can be transferred from a metasediment into an anatectic melt if staurolite is stable or metastable at the onset of melting. Such a melt can contain between 200 and 1000 ppm Li and the melt can be further enriched with up to 5000 to 10000 ppm Li through fractional crystallization of quartz and feldspar, allowing crystallization of spodumene. Estimated fractionation degrees vary between 81 and 99%, depending on the protolith composition, the melting scenario and the partitioning coefficients. Li-Al-rich metasediments are therefore a rich source of certain rare elements when they first melt. However, the spectrum of elements contained in the melt depends on a wide variety of conditions. This anatectic model provides an alternative explanation for the formation of Li-rich pegmatite if no fertile parent granite can be identified.
... To the north of the Defereggen-Antholz-Vals Line, a polyphase metamorphic evolution is recorded. Carboniferous amphibolite-facies metamorphism was followed by Permian intrusion of pegmatites, succeeded by Cretaceous eclogite-facies metamorphism restricted to the Prijakt Subgroup and a final greenschist-to amphibolite-facies late Alpine metamorphic stage (Schulz et al. 1993Krenn et al. 2012;Hauke et al. 2019). ...
... 336-325 in the Tonale Nappe (Sm-Nd mineral isochron data; Tumiati et al. 2003) and ca. 321-300 Ma in the basement south of the Tauern Window (EPMA Th-U-Pb monazite data; Krenn et al. 2012;Lu-Hf garnet data, Hauke et al. 2019). ...
Abstract
New whole-rock geochemical and coupled U–Pb and Lu–Hf LA-ICP-MS zircon data of metasedimentary rocks of the Austroalpine,
South Alpine and Penninic basement domains are presented, to disentangle the pre-Variscan tectonic evolution
of the proto-Alps. The studied units seem to record distinct stages of protracted Late Ediacaran to Carboniferous tectonosedimentary
processes prior to the Variscan collision. In the case of Austroalpine and South Alpine units, nevertheless,
no major differences in terms of provenance are observed, since most detrital zircon samples are characterized by a major
Pan-African peak. Their detrital zircon spectra record a provenance from the northeastern Saharan Metacraton and the Sinai
basement at the northern Arabian-Nubian Shield, being thus located along the eastern Early Paleozoic northern Gondwana
margin, whereas sources located further west are inferred for the Penninic Unit, which might have been placed close to the
Moldanubian Unit of the Bohemian Massif. In any case, it is thus clear that the Alpine basement remained in a close position
to the Gondwana mainland at least during the Early Paleozoic. The Late Ediacaran to Silurian tectonic evolution, which
includes Cadomian and Cenerian tectonometamorphic and magmatic processes, seem thus to record a continuum related
to a retreating-mode accretionary orogen, with diachronous back-arc basin opening and possibly discrete compressional/
transpressional pulses linked to changes in subduction zone dynamics. On the other hand, it is inferred that the Alpine basement
essentially comprises Pan-African metasedimentary and subordinate metaigneous rocks, possibly with very few Early
Neoproterozoic relics. This basement was significantly reworked during the protracted Paleozoic orogenic evolution, due to
anatexis and/or assimilation by mantle-derived juvenile magmatism.
... Based on a two-point Lu-Hf mineral isochrone of eclogites, Hauke et al. (2019) described a Variscan minimum age of 313 Ma of high-pressure metamorphism, which is overprinted by Cretaceous eclogite facies metamorphism. Variscan and Permian ages of metamorphism are well constrained by microprobe monazite dating (Krenn et al., 2012). Pegmatites postdate Variscan metamorphism and have an age of 265 Ma (Knoll et al., 2018). ...
In all reconstructions published during the last two decades, the Austroalpine and the correlative Southalpine basement units of the Eastern Alps were considered to represent a uniform continental block that split off from the northern Gondwana margin during Early Paleozoic times and collided with microcontinental blocks during the Variscan orogeny in the early Late Carboniferous. Afterwards, these units formed finally the outboard part of the European Variscides adjacent to the Paleotethys Ocean. The combined Austroalpine/Southalpine basement extends to the Western Carpathians, contains Ediacaran and Early Paleozoic ophiolites and magmatic arcs and Devonian passive margin successions and represents a key region for resolving the Late Neoproterozoic to Late Paleozoic tectonic evolution of the basement in the Alpine-Mediterranean Mountain belts. The Austroalpine and Southalpine basement contains well-known fossil-rich Ordovician and Silurian rift and mainly Devonian passive margin successions summarized as the Noric and Carnic domains, which were juxtaposed to amphibolite-grade metamorphic complexes during Early Carboniferous plate collision. In the metamorphic units the following main stages of tectonic evolution are. Two distinct Ediacaran to Cambrian arc systems were recognized, correlating with subduction of the Prototethys (Ran) Ocean. The continental Wechsel Arc stopped its activity during Late Cambrian times, whereas the Silvretta-Gleinalpe Arc was reactivated at the Devonian/Carboniferous boundary during subduction of the Devonian Balkan-Carpathian Ocean. The Prototethyan oceanic crust is preserved in the ophiolitic Upper Neoproterozoic to Middle Ordovician Speik Complex, that was obducted onto the Silvretta-Gleinalpe Arc during Late Ordovician to Early Silurian times. On the other hand, the Noric domain was initially part of the northern Gondwana margin and includes a virtually continuous sedimentary section ranging from the Early Ordovician to earliest Pennsylvanian. It started with an Early to Late Ordovician rift succession with mafic and acidic volcanic rocks related to rifting of parts of the Noric domain from the northern Gondwana margin forming an oceanic basin (Rheic of previous interpretations) in between and back-arc rifting is the likely setting. In both Noric and Carnic domains, Silurian strata were deposited during a tectonically quiet period followed by onset of a second rifting period during Late Silurian times, which resulted in deposition of thick Devonian carbonates heralding the opening of the Balkan-Carpathian Ocean and separation of the Paleo-Adria microcontinent from Gondwana. Late Devonian–Carboniferous plate convergence led to subduction of this oceanic rift followed by subduction of the Paleo-Adria margin underneath the accreted Variscan convergence belt, collision and Late Carboniferous intramontane molasse deposition. However, new data argues that a third ophiolitic belt, the Plankogel ophiolitic mélange, which formed as part of the Paleotethys Ocean during the Devonian and was reactivated as trench during initial consumption of the Paleotethys Ocean during Late Permian–Triassic times. The Middle-Late Triassic plutonic and volcanic rocks of the Southern Alps are considered, in this preliminary model, to represent the magmatic arc associated with Paleotethys subduction.
... The samples analyzed in this study are deformed quartz veins (2-10 cm thick) that were collected within pre-Alpine paragneisses of the Austroalpine Prijakt Nappe of the Eastern Alps, Austria ( Figure 1) (Krenn et al., 2012;Schulz, 1993). This nappe underwent Cretaceous subduction to eclogite-facies conditions at 650°C and 1.9 GPa (Hauke et al., 2019). ...
Using a combination of microstructural, spectroscopic, and geochemical analyses, we investigate how subgrain rotation recrystallization and fluid migration affect Ti concentration [Ti] in naturally deformed quartz veins from the Prijakt Nappe (Austroalpine Unit, Eastern Alps). These coarse‐grained quartz veins, that formed at amphibolite facies conditions, were overprinted by lower greenschist facies deformation to different degrees. During the overprint, subgrain rotation recrystallization was dominant during progressive deformation to ultramylonitic stages. The initial [Ti] (3.0–4.7 ppm) and cathodoluminescence (CL) signature of the vein crystals decrease during deformation mainly depending on the availability of fluids across the microstructure. The amount of strain played a subordinate role in resetting to lower [Ti] and corresponding darker CL shades. Using a microstructurally controlled analysis we find that the most complete re‐equilibration in recrystallized aggregates ([Ti] of 0.2–0.6 p.m.) occurred (a) in strain shadows around quartz porphyroclasts, acting as fluid sinks, and (b) in localized microshear zones that channelized fluid percolation. [Ti] resetting is mainly observed along wetted high angle boundaries (misorientation angle >10–15°), with partial [Ti] resetting observed along dry low angle boundaries (<10–15°). This study shows for the first time that pure subgrain rotation recrystallization in combination with dissolution‐precipitation under retrograde condition provide microstructural domains suitable for the application of titanium‐in‐quartz geothermobarometry at deformation temperatures down to 300–350°C.
... Assemblages with garnet, biotite, muscovite, oligoclase, quartz and lacking staurolite and aluminosilicates were observed. The garnet showed increasing pyrope contents at high grossular contents from [16,[61][62][63]. Aluminosilicates (and Ky, Sill), cordierite-in (Cd+), muscovite-out (Ms-) and staurolite-in and -out (Sta+, Sta-) univariant lines [30]. ...
... Garnet zonations in this pegmatite zone displayed a significant decrease in Ca towards the rims, corresponding to a prograde P-T evolution towards 10 kbar/600 • C followed by a marked decompression to 4 kbar/600 • C (Figure 5c,g). The EPMA monazite dating in the pegmatite zone to the south of the DAV [62] yielded Permian ages at isochrons of 276 ± 18 Ma (sample Sti13) and 271 ± 15 Ma (sample P24, Figure 5j). ...
... The Lu-Hf geochronology of garnet in eclogites allowed to identify major events, one with a 313 Ma minimum age reflecting for Carboniferous metamorphism, and a second event (104-97 Ma) related to a Cretaceous high pressure metamorphism in a Prijakt Subgroup amphibolitised eclogite body [66]. The data confirmed Cretaceous EPMA Th-U-Pb monazite ages in micaschists [62]. Garnets in staurolite and kyanite-bearing micaschists in the vicinity of the amphibolitised eclogites displayed complex zonations [62,64]. ...
Garnet-bearing metapelites in the Helvetic and Austroalpine pre-Mesozoic polymetamorphic basement are characterised by pressure-temperature path segments reconstructed by microstructurally controlled geothermobarometry, and the Th-U-Pb monazite age distribution pattern revealed by the electron probe microanalyser (EPMA). In the Helvetic Aiguilles Rouges Massif and the Austroalpine Oetztal-Stubai basement to the NW an Ordovician-to-Silurian high temperature event preceded a pressure-dominated Carboniferous metamorphism. In the Austroalpine basement units to the south of the TauernWindow, the maximal pressures of the Carboniferous amphibolite-facies metamorphism range from 12 to 6 kbar. The decompressional P-T path segments signal a transition to low pressure conditions. A subsequent high pressure overprint is restricted to the Prijakt Subgroup unit in the Schobergruppe and documented by Cretaceous monazite crystallisation at 88 +- 6 Ma. In the Austroalpine Saualpe basement to the SE, a distinct early Permian metamorphism which started at low pressures of ~4 kbar/500 °C and reached maximal 6 kbar/600–650 °C predated the intrusion of Permian pegmatites. Permian monazite crystallised in line with the intrusion of pegmatites. Corona
microstructures around the Permian monazites indicate retrogression previous to a Cretaceous high pressure metamorphism. That way, pressure-temperature-time paths resolve the spatial and temporal evolution in the polymetamorphic Alpine basement prior to the Tertiary collision.
... | Samples from the southern slope Samples U1 and N1 from the southern slope (Figure 4, Figure S3) show similar U-Pb age, ATE and AFT data as the samples LPF3, I1, E1 and HFM and probably reflect a similar provenance. In the G1 sample, the presence of Eoalpine U-Pb ages (Figure 4, Figure S4) shows that the grains were likely sourced from the Koralpe-Wölz nappe system which experienced Eoalpine metamorphism (Figure 1) (Krenn et al., 2012;Thöni & Miller, 2000). We interpret the differences in AFT, ATE and U-Pb data (Figures 4 and 7, Figure S4, Table 1) between samples G1 and N1 to be related to the redeposition of the AFM south of the Upper Austrian NAFB (Figure 1). ...
The early exhumation history of the Tauern Window in the European Eastern Alps and its surface expression is poorly dated and quantified, partly because thermochronological and provenance information are sparse from the Upper Austrian Northern Alpine Foreland Basin. For the first time, we combine a single-grain double-dating approach (Apatite Fission Track and U-Pb dating) with trace-element geochemistry analysis on the same apatites to reconstruct the provenance and exhumation history of the late Oligocene/early Miocene Eastern Alps. The results from 22 samples from the Chattian to Burdigalian sedimentary infill of the Upper Austrian Northern Alpine Foreland Basin were integrated with a 3D seismic-reflection data set and published stratigraphic reports. Our highly discriminative data set indicates an increasing proportion of apatites (from 6 % to 23 %) with Sr/Y values <0.1 up section and an increasing amount of apatites (from 24 % to 38 %) containing >1000 ppm light rare-earth elements from Chattian to Burdigalian time. The number of U-Pb ages with acceptable uncertainties increases from 40 % to 59 % up section, with mostly late Variscan/Permian ages, while an increasing number of grains (10 % to 27 %) have Eocene or younger apatite fission track cooling ages. The changes in the apatite trace-element geochemistry and U-Pb data mirror increased sediment input from an ≥upper amphibolite-facies metamorphic source of late Variscan/Permian age - probably the Ötztal-Bundschuh nappe system - accompanied by increasing exhumation rates indicated by decreasing apatite fission track lag times. We attribute these changes to the surface response to upright folding and doming in the Penninic units of the future Tauern Window starting at 29-27 Ma. This early period of exhumation (0.3-0.6 mm/a) is triggered by early Adriatic indentation along the Giudicarie Fault System.
... The samples analyzed in this study are deformed quartz veins (2-10 cm thick) that were collected within pre-Alpine paragneisses of the Austroalpine Prijakt Nappe of the Eastern Alps, Austria ( Figure 1) (Krenn et al., 2012;Schulz, 1993). This nappe underwent Cretaceous subduction to eclogite-facies conditions at 650°C and 1.9 GPa (Hauke et al., 2019). ...
