Tracciamento Frenzela 2024: a new tracing test on the Sette Comuni Plateau, Vicenza, Italy

We applied a blind source separation algorithm to the ground displacements time-series obtained from the analysis of continuous GPS stations operating in the Eastern Southern Alps and northern Dinarides. This analysis highlighted both annual common mode component signals and a time-variable, non-cyclic signal characterized by a spatially variable response in the horizontal component. The first signal is well described by loading effects caused by Earth surface water mass redistributions, while the latter one has a temporal evolution that well correlates with the history of cumulated precipitations at monthly time scales and has larger amplitudes in karst areas of the study region. The GPS stations respond to this signal by moving in opposite direction, reversing the sense of movement in time, implying a succession of extensional/compressional strains, with variable amplitudes through time, oriented normal to rock fractures. We focus on the pedemountain front of the Venetian Southern Alps, and test the hypothesis that the succession of horizontal extensions and contractions recorded by the GPS stations are caused by the variation of the water level in hydrologically-connected fractures, whose temporal evolution is guided by water storage variation in the hydrological basin of this area. Having found high correlations between the temporal evolution of water storage variations, modeled by using rainfall-runoff hydrological models, and the deformation signal, we built a bi-dimensional numerical model based on finite-element method, containing the geologic feature of the study area, to understand how water storage variations generate the observed displacements. After testing different sources of deformation, we found that they are best reproduced by a sub-vertical structure corresponding to the backthrust of the Bassano-Valdobbiadene thrust fault. Here, the water accumulates because of the larger permeability of the fractured rock faults, varying its level up to tens of meter and then generating pressure changes that cause the observed displacements.

Deposits from 46 Holocene rock avalanches, with volumes ranging from 1 000 000 m3 to 500 000 000 m3 , have been identified from aerial photographs of the Southern Alps between Arthur's Pass and Mt Cook. The rock avalanches occur mainly in the eastern Southern Alps, in Torlesse Supergroup rocks. Rock avalanches are rare in schist terrain. Rock avalanching is a significant slope process in the Southern Alps. In the last 2000 years, 19 large rock avalanches have moved about 1 000 000 000 m3 of material; equivalent to an areally averaged erosion rate of 100 t/km2 per year, although the material is seldom moved far from its source. Rock avalanche deposits may be a significant sediment source for major rivers in the Southern Alps. The average annual yield of 36 000 t from a rock avalanche in the Jollie River is more than the measured annual sediment yield of the river.

<p>The eastern Southern Alps are part of the deformed leading edge of the Adriatic plate indenting the European plate to the north. Neogene deformation in the eastern Southern Alps is partitioned into three, kinematically linked fold-and-fault systems: (1) The Giudicarie Belt, (2) the Valsugana Thrust System and (3) the external fold-and-thrust systems of the orogenic front, including the strike-slip Schio-Vicenza Fault. We aim to constrain fault kinematics from the Southern Alpine orogenic front to the Northern Giudicarie Fault to better understand deformation of the Adriatic indenter since Miocene time.</p><p>The Giudicarie Belt is a sinistral transverse zone characterized by NNE-oriented faults. Some of these faults originated in the Mesozoic as NNE-SSW trending normal faults, which were inverted during Alpine orogeny. Most of the Mesozoic normal faults are oriented oblique to sub-parallel to the main Neogene shortening direction, which led to strain partitioning between thrust and strike-slip faults. This significant strike-slip component complicates kinematic and structural restoration of geological cross-sections in 2-D because rock units moved into and out of the section trace, distorting in-section shortening estimates.</p><p>To assess lateral variations in shortening and quantify strain partitioning along and across the strike of the Giudicarie Belt, we constructed and balanced a network of closely spaced cross-sections perpendicular to the main structural trend. Seven 2-D NNW-SSE cross-sections from the Northern Giudicarie Fault to the Southern Alpine orogenic front reveal that the amount of Neogene NNW-SSE shortening varies from 11 km in the vicinity of the Adige embayment to 27 km further NE, with most shortening (20 to 26 km) accommodated within the Valsugana and Giudicarie systems. Shortening differs on either side of the Trento-Cles, Schio-Vicenza (4 km difference) and Ballino-Garda (7 km difference) strike-slip faults. These faults are inherited Mesozoic faults that coincide with significant stratigraphic thickness variations, which we constrained along orogen-parallel cross-sections. The SW-NE variation in shortening is inferred to have been taken up by these sinistral strike-slip faults, but also including the Northern Giudicarie Fault, for which we estimate the minimum amount of slip to be 19 km.</p><p>Exposure of Pre-Permian basement in the hanging wall of thrusts indicates a thick-skinned style of deformation. Forward modelling using the MOVE Suite Software indicates that the depth of the detachments within the Pre-Permian basement is no greater than 20 km. A recently located cluster of minor seismic events (2017-2018) within the study area is aligned between 5 and 15 km along the modelled detachments. These earthquake clusters occur within the external fold-and-thrust systems of the orogenic front, suggesting that ongoing shortening is taken up within this system and that the Valsugana and Giudicarie systems are inactive today.</p>

There is anecdotal evidence that increasing densities of Himalayan tahr (Hemitragus jemlahicus) are associated with declining densities of chamois (Rupicapra rupicapra) in the Southern Alps, New Zealand. To examine this phenomenon, densities of tahr and chamois were measured at 53 sites within their sympatric range in the eastern Southern Alps during 1978-1979. In sites where only one species was present, tahr density was significantly higher than chamois density (P=0.032), probably reflecting species differences in sociality. Chamois density was higher in catchments without tahr than in those with tahr (P=0.012). Similarly, tahr density was significantly higher at sites without chamois than at those with chamois (P=0.033). Sites with both species present (termed sympatric) were significantly larger than those with only chamois or tahr (P<0.001). Following the prohibition of aerial hunting of tahr in 1983, 16 of the 17 sites where tahr and chamois were sympatric during 1978-1979 were recounted during 1991-1996. There was a 6-fold increase in the mean density of tahr between the two counts (P=0.001), whereas chamois density had declined significantly (P=0.006). Chamois persisted at only three sites, two of which had the highest chamois densities in 1978-1979. This is evidence that increasing densities of tahr exclude chamois from all but the `best' habitats. We conclude that intensive aerial hunting of tahr during 1967-1983 reduced tahr densities such that chamois could co-exist with tahr.

We present a novel three-dimensional model of compressional wave attenuation (1/QP) for the Eastern and eastern Southern Alps in Europe that includes the eastern part of the Adriatic indenter, termed here the Dolomites Sub-Indenter. Our approach employed waveform data from the SWATH-D network, a dense temporary network operational between 2017 and 2019, as well as selected stations of the larger AlpArray Seismic Network. A spectral inversion method using frequency-independent quality factor QP, was applied to derive 3578 path-averaged attenuation values (t*) from 126 local earthquakes. These were then inverted using the damped least square inversion (local earthquake tomography) for the attenuation structure. The resulting QP model, which builds on and complements a previously calculated 3-D velocity model (VP and VP/VS), exhibits good resolution down to ~ 20 km depth. Several anomalies can be correlated with the distribution of other physical parameters (VP and VP/VS) and regional tectonic features. Notably, the Friuli-Venetian region exhibits the highest attenuation (lowest QP) anomaly, coinciding with low VP values and increased VP/VS. This anomaly is likely associated with a high density of faults and fractures, as well as the presence of fluid-filled sediments along the active thrust front in the eastern segment of the Southern Alps. Another intriguing observation is the low attenuation (high QP) anomaly along the northwestern edge of the Dolomites Sub-Indenter (NWDI), located south of the Periadriatic fault and east of the Giudicarie fault, where seismicity is notably absent. This anomaly coincides with Permian magmatic rocks at the surface and may be a measure of their strength at depth.Graphical

The eastern Southern Alps are located at the northern tip of the Adria microplate, which imposes 2.0–2.5 mm/year of N‐S‐convergence relative to stable Eurasia. We map surface evidence of recent folding/faulting in this area from a 5‐m Digital Elevation Model (DEM). In the eastern part of the belt, observations reveal a 30‐km‐wide zone of active folding composed of at least five growing anticlines. The most recent ones warped the postglacial alluvial surface by &lt;10 m. Combining these findings with published geological and geophysical data allows us to infer that active thrusting occurs along a single deeply rooted thrust, which accommodates the indentation of the Adriatic crust. Resolving the observed pattern of uplift on the inferred fault geometry indicates that NNE‐SSW shortening across the eastern Southern Alps has occurred at a rate of about 1.5 mm/year over the postglacial period. On the other hand, a balanced cross section for the eastern Southern Alps at the scale of the upper crust constrains a minimum of 43 km of finite shortening over the last 14 Ma, yielding a shortening rate of about 3 mm/year, which is 2 times higher than the postglacial shortening rate. This decrease in the shortening rate is associated to the Pleistocene activation of new thrusts that is compatible with a change in the direction of compression. The inferred local change in the kinematics of thrusting during the Pleistocene is consistent with a change from Nubia‐imposed to Adria‐imposed convergence indicating that the fragmentation of the Adriatic promontory could have occurred 1–2 Ma ago.

Oligocene trachytes from the Euganean Hills include various regionally metamorphosed gneissic and granulitic xenoliths. These xenoliths provide the unique opportunity to investigate South Alpine intermediate to deep crustal levels that are not at present exposed in the Eastern Alps. The estimated P – T conditions are in the range of 780–850°C and 0.45–0.55 GPa for a migmatitic gneiss xenolith. Sensitive high-resolution ion microprobe (SHRIMP II) U–Pb analyses on zircon from this xenolith provide concordant ages around 259.7 ± 3.5 Ma, consistent with a proton-induced X-ray emission (PIXE) U–Th–Pb age on monazite of 262 ± 12 Ma. The Sr–Nd–Pb isotopic compositions, and major and trace element data show distinct origins for the different types of xenoliths. Mafic granulite xenoliths have an isotopic signature close to mantle-derived rocks and to Permian gabbroic rocks from the Western Southern Alps. Metapelite xenoliths have high Sr and low Nd initial ratios like those of acid crustal rocks and could possibly represent the source of the crustal component that is dominant in the acid Permian supervolcanoes. The migmatitic xenolith provides the first documented evidence for a Permian thermal event associated with crustal thinning in the Eastern Southern Alps. Here the South Alpine basement escaped most of the Alpine crustal shortening and still preserves most of the original Permian extension under thick Mesozoic cover. Supplementary material: Microprobe analyses of mineralogical phases and Ti-in-biotite geothermometric calculations are available at https://doi.org/10.6084/m9.figshare.c.5032337

Successions that characterize the eastern southern Alps have&#13;\nbeen compared with coeval units drilled in the Alpine foreland&#13;\n(Po and Veneto plains, northernAdriatic Sea). The eastern&#13;\nsouthern Alps are composed of a carbonate platform-plateau,&#13;\ndrowned in the Early Jurassic (Trento platform and plateau);&#13;\na basin formed in the Early Jurassic (Belluno Basin) and a carbonate&#13;\nplatform that lasted from the Jurassic to the Cretaceous&#13;\n(Friuli platform). Integration of stratigraphic and geophysical&#13;\ndata illustrates the extensional architecture of the Alpine foreland&#13;\nsubsurface. At the beginning of the Jurassic, peritidal successions&#13;\nwere widespread everywhere except for the Belluno&#13;\nBasin. A reorganization of the Early Jurassic paleogeography affected&#13;\nthe southern Alps around the Sinemurian–Pliensbachian&#13;\nboundary: the Pliensbachian successions were deposited in the&#13;\ncentral-western areas of the Trento platform whereas, elsewhere&#13;\nin the same platform and in the northern Friuli platform,&#13;\nPliensbachian units are missing, replaced by an unconformity&#13;\nsurface covered by crinoidal sands that have also been&#13;\nfound in the subsurface. The Belluno Basin is recognizable in&#13;\nseismic profiles under the Veneto Plain. Southward (northern&#13;\nAdriatic Sea and Po plain), the basin between the Trento and&#13;\nthe Friuli platforms, here called the “northern Adriatic Basin,”&#13;\npossesses a stratigraphy different from that of the Belluno&#13;\nBasin. The northern Adriatic Basin drowned later, and seismic profiles indicate that it was wider and bounded by groups of&#13;\nsmall synsedimentary faults instead of the major faults displacing&#13;\nthe Belluno Basin. The northernAdriatic Basin can be interpreted&#13;\nas the northeastern extension of the Umbro-Marchean Basin of&#13;\ncentral Italy.

A frost “buzzsaw” mechanism for erosion of the eastern Southern Alps, New Zealand

Most paleotectonic reconstructions assume the indentation of Adria subsequent to the Periadriatic magmatism, after 32-26 Ma. Some consider an even younger (post 14-10 Ma) retrobelt of the Alps. These reconstructions contrast with evidence of a late Cretaceous to Eocene retro-belt in the western Southern Alps, intruded by the Adamello pluton and associated magmatic bodies. Recent work suggest this retro-belt continued eastwards into a relief extending from the Texelgroup towards the Transdanubian Range, allowing detritus to feed the retroforeland basin. In the eastern Southern Alps, remnants of this basin occur in the northernmost sectors, and recent work documented the Late Cretaceous northward flexuring of the Adria foreland.Collectively, these observables confirm the occurrence of a Late Cretaceous retrobelt, subsequently cut in the Oligocene by the Periadriatic Line: the western part of the retro-belt remained in the Southern Alps, whereas, to the east, the Cretaceous double vergent belt was left north of the Periadriatic Line, only leaving the tip of the retro-foreland basin in the Southern Alps. This Eastern Alps Cretaceous belt is well recognized, following the so-called eclogite belt.The Cretaceous retro-belt was sinistrally reworking the Jurassic Giudicarie fault system, finally defining it as first-order transverse range pre-existing the Periadriatic Line. This latter reworked the indented Adria plate in the west, where the crustal doubling prevented any possible deeper source for the Periadriatic magmatism. The lower plate break-off, therefore, seems a very unsuitable hypothesis.

The Southern Alps / K&amp;#257; Tiritiri o te Moana in Aotearoa New Zealand have attracted scientists to study the interactions between climate and tectonics for decades. It has long been argued that tectonic uplift of this orogen is approximately balanced by erosion. The prevailing westerly airflow at the latitudes of the Southern Alps has created a strong orographic effect with precipitation decreasing sharply across the orogen&amp;#8217;s main divide. The signature of this orographic effect is apparent in erosion rates that decrease from west to east, and from the dominant types of erosional processes that operate on either side of the orogen&amp;#8217;s main divide. Most studies quantifying erosion over geologic timescales have focussed on the wetter&amp;#8212;but areally significantly smaller&amp;#8212;side of the orogen. Here, we seek to quantify the Pliocene&amp;#8211;Recent erosion history of the Southern Alps&amp;#8217; much larger and drier eastern side using cosmogenic radionuclides (10Be and 26Al), tracer techniques (U&amp;#8211;Pb) and a grain size analysis on fluvial deposits in the Canterbury region that record concomitant erosion of this mountain range. Cosmogenic radionuclides provide a powerful tool to constrain catchment-scale erosion rates on timescales of 100&amp;#8211;100,000 years, which is the temporal range at which tectonic and climatic forcings overlap and meso-scale stratigraphic architecture is created, thereby offering critical insights into the dynamics between tectonics, climate, and surface processes. Detrital grain U&amp;#8211;Pb analysis of the fluvial deposits will be used to establish the sediment&amp;#8217;s provenance, while a grain size analysis of the river sediments will provide insights into associated past stream dynamics. With this multi-method study, we seek to constrain both spatial patterns and catchment-scale rates of erosion of the eastern Southern Alps, as well as their changes through time and see if erosion has been affected by major climatic shifts during the Pliocene and Pleistocene epochs. Finally, this research will provide a benchmark for assessments of anthropogenically influenced erosion of the eastern Southern Alps. Preliminary results from 10Be and 26Al analyses and dating of fluvial terraces will be presented.

Constraining the timing of tectonic events is of prime importance for the in-depth understanding of the complex evolution of orogenic deformation, particularly in the case of fold-and-thrust belts. In this work, we combined U-Pb dating of tectonic carbonates and K-Ar dating of fault gouges of selected key outcrops along two main thrusts of the Paleogene-Neogene Eastern Southern Alps (ESA), Italy. The ESA are the south-verging fold-and-thrust retrobelt of the Alpine orogen, offering spectacular exposures to study the details of past tectonic processes. However, despite a few published papers regarding the deformation mechanisms of a major thrust in the ESA (the Belluno Thrust), modern, multiscale structural and radiometric studies of fault zones in the ESA are missing, such that detailed reconstructions of the local and regional tectonic evolution through space and time remain only loosely constrained. We focused on the (i) Valsugana Thrust, which is a first-order thrust separating the Dolomites s.s. to the north from the Venetian Pre-Alps to the south, and (ii) the more external Belluno Thrust. We coupled U-Pb dating of tectonic carbonates and X-ray diffraction and K-Ar dating of clay minerals in fault gouges with structural analysis and microtextural characterization. We show that the Valsugana Thrust represents an inherited pre-Alpine structure that (i) registered far field deformation during the Early Cretaceous (K-Ar gouge age of 140 &amp;#177; 32 Ma), (ii) strongly influenced the geometry and kinematics associated with deformation structures during the Alpine orogenesis and (iii) recorded multiple reactivations in Late Cretaceous (K-Ar age of 79.2 &amp;#177; 8.4 Ma and 76.2 &amp;#177; 1.4 Ma), late Miocene (U-Pb age of 9.1 &amp;#177; 0.8 Ma), and Miocene-Pliocene (U-Pb age of 5.3 &amp;#177; 1.6 Ma) times. Radiometric constraints from the Valsugana Thrust attest to remarkable out-of-sequence compressional movements in the inner ESA after the orogenic wave had progressed farther south to the more external Belluno Thrust, whose activity is constrained to the Oligocene by a 30.6 &amp;#177; 5.8 Ma K-Ar gouge age and a 23 &amp;#177; 14 Ma U-Pb syn-tectonic vein age.

Stable isotopic evidence for mixing between metamorphic fluids and surface-derived waters during recent uplift of the Southern Alps, New Zealand

Post-Messinian drainage changes triggered by tectonic and climatic events (eastern Southern Alps, Italy)

The Slovenian Basin (the eastern Southern Alps, Slovenia) formed during the Middle Triassic and lasted until the end of the Mesozoic. The oldest succession belongs to the Ladinian volcanic- and clastics-dominated Pseudozilian Formation, followed by the Carnian Amphiclina Formation, composed of shale, sandstone, subordinately conglomerate and bedded limestone. Several sections were documented by Skaberne et al. (2024) in the southern part of the Tolmin Nappe (subunit of the Southern Alps), but only one succession was logged from more northern parts of the Tolmin Nappe (Gale et al., 2017). Consequently, little is known about Carnian paleotopography of the basin. To augment current knowledge on the lateral differences within the Amphiclina Formation, a succession was logged on the Martinj Vrh hill, structurally situated in the middle part of the Tolmin Nappe. The entire succession is 47.3 m long and ends at the transition to the Norian-Rhaetian Ba&amp;#269;a Dolomite Formation. According to conodont data, this stratigraphic boundary corresponds to the Carnian-Norian boundary. The rocks were analysed using optical microscopy, XRD, and &amp;#956;-EDRF. The outcrop consists of bedded fine-, medium- and coarse-grained sandstone, marlstone, mud-supported conglomeratic breccia, conglomeratic breccia with carbonate cement, and bedded limestone with occasional occurrences of dolomite. Parallel and cross-lamination, load casts, ball and flame structures, scour structures, slumps and synsedimentary faults are present. Limestone is mudstone-wackestone with radiolaria, filament and bioclastic wackestone, echinoderm-intraclastic packstone, filament-peloidal packstone-grainstone, intraclastic-peloid packstone-grainstone, peloidal grainstone, and rudstone. Position within the basinal area cannot be directly determined, although the sedimentary structures suggest that sedimentation took place on the basin slope. Comparison with previously published logs shows that sedimentation within the basin greatly varied and that no clear distinction can be drawn between different parts of the Tolmin Nappe. This is probably due to complex internal topography of the basin.Gale et. al. 2017: Characterization of silicified fossil assemblage from upper Carnian "Amphiclina beds" at Crngrob (central Slovenia). Geologija, No. 60/1, pp. 61&amp;#8211;75.Skaberne et. al. 2024: Middle Triassic deeper-marine volcano-sedimentary successions in western Slovenia. Geologija, No. 67/1, pp. 71&amp;#8211;103.