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We document the tectonic and metamorphic evolution of thrust nappes of the eastern island of Elba. The area exposes a natural cross section of the Northern Apennines hinterland, from the metamorphic basement units to the overlying continent- and ocean-derived nappes. We integrated mapping, analysis of structures and microstructures, and the interpretation of drill core logs with lithostratigraphic, metamorphic, and geochronological constraints, producing a novel geological map of eastern Elba (1:5'000 scale). We show that the area experienced polyphase Oligocene - Pliocene contractional tectonics marked by in-sequence and out-of-sequence thrusting accompanied by folding and overprinted by faulting in the Pliocene. Magmatism occurred during contraction with post-magmatic thrusting ultimately coupling HP-LT and LP-HT units. Drill core logs allow for the first time the reconstruction of the N-dipping character of the Zuccale Fault, which represents the youngest (late Miocene - early Pliocene) large-scale structure in the area. [ABSTRACT FROM AUTHOR]

The E‐vergent Northern Apennines formed by Oligocene‐Miocene convergence and westward subduction of Adria beneath Europe. Extension ensued in the Mid‐Late Miocene reflecting lower plate roll‐back and causing opening of the back‐arc Northern Tyrrhenian Sea. Post‐orogenic extension is commonly advocated as the main driver of the exhumation of the belt's inner domain high‐pressure/low‐temperature (HP‐LT) rock units. The Acquadolce Subunit of the Eastern Elba nappe stack contains HP‐LT rocks recording peak blueschist conditions of 1.5–1.8 GPa at 320°C–370°C loosely dated to the Oligocene‐Early Miocene. It is sandwiched by two Late Miocene, out‐of‐sequence top‐to‐the E thrusts between Jurassic LP serpentinites on top and HT–LP contact metamorphosed marbles at its base. We document widespread W‐verging ductile asymmetries within the Acquadolce Subunit, which correspond to top‐to‐the W extensional shearing for the nappe stack current orientation. This allowed for early syn‐orogenic exhumation from blueschist‐ to greenschist‐facies conditions, wherein coeval W‐directed extension at the top of the exhuming units acted synchronously with E‐directed thrusting at their base causing exhumation by extrusion in an overall contractional setting. The basal, E‐vergent thrusting is, however, challenging to document as the wedge has since been reworked by Late Miocene, E‐verging compressive tectonics, contact metamorphism, and later extension, obliterating much of the evidence supporting exhumation by extrusion during the early stages of wedge build‐up. Syn‐orogenic exhumation by extrusion from deep structural levels within the orogenic wedge is a viable mechanism to account for other exhumed HP‐LT units in the inner part of the belt. Key Points: Syn‐orogenic extrusion is proposed as a viable mechanism for the exhumation of HP‐LT rock units of the Northern Apennines;The Acquadolce Subunit of the Eastern Elba nappe stack was exhumed by upward extrusion within an actively shortening orogenic wedge;Middle Miocene extension shaped the upper Northern Apennines orogenic wedge but did not contribute to the early exhumation of HP rocks. [ABSTRACT FROM AUTHOR]

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The paper deals with the idea, design and implementation of unconventional one-of-a-kind Micropiles Tripods Shields (MTS) intended to break and decelerate moderately rapid earthflows surges in the track zone of the Sassi Neri landslide (Nure Valley, Northern Apennines, Province of Piacenza, Italy). The MTS are inspired to floating anchors and "chevaux de fries" used in wartime. The basic elements are tripods of 193 mm diameter steel micropiles laid out at triangle, driven into the stable bedrock and emerging some meters aboveground. Each tripod consists of a vertical upslope central pile and two lateral oblique piles, linked by two transversal beams and connection plates aboveground. Multiple tripods are spaced along transversal rows to form Micropiles Tripods Shields (MTS) to advancing earthflows. The design of MTS has been based on field investigations such as boreholes and geophysics, that indicated a limited thickness of landslide deposits in the track zone where MTS have been installed. The forces resulting from active earthflows fronts have been estimated both with geotechnical and hydraulic computations. The analysis of vertical and transversal forces as well as bending moments acting on a single tripod versus the characteristic resistances was carried out using a bi-dimensional scheme with finite-elements software Plaxis, that indicated that the stress levels were compatible with the structural resistance of the tripods. The construction of MTS took place in 2018, involving working site preparation with partial lime-treatment of the surficial layers, underground micropiles drilling and installation, aboveground micropiles welding, tripods completion with connection beams and plates. Some tripods have been instrumented with load cells for monitoring earth pressures against micropiles, electric transducers for groundwater monitoring next to the piles, tiltmeters for tripods rotations and a total station for slope and tripods movements monitoring. Results show that the acceleration of slope movements corresponds to a generalized increase of pore water pressure at all the monitored tripods and to temporary slight tilting of the tripods which has so far being fully recovered when the landside slowed down and pressure decreased. This pioneering application indicates that once the characteristics of the earthflows are carefully considered, the depth to the bedrock in the installation zone is limited, and the logistical conditions in the field during construction are adequate, the MTS can be taken into consideration as a possible unconventional solution to break down and control moderately rapid earthflows. [ABSTRACT FROM AUTHOR]

This dataset article contains petrographic and mineral-glass chemical data of igneous rock clasts from Early Oligocene Aveto-Petrignacola Formation (APF; Northern Italy). Methods for obtaining the dataset include optical microscopy, scanning electron microscopy and electron probe microanalysis. The APF volcanic rocks are basalts, basaltic andesites, andesites, dacites and rhyolites. Rare gabbroic cumulate nodules complete the dataset. Basalts are porphyritic, with calcic plagioclase (An72–92Ab7–27Or0–1), ferroan enstatite (En59–68Fs29–37Wo3–4) and augite (En38–39Fs18–20Wo41–44) phenocrysts, in a hypocrystalline groundmass made up of bytownite (An71–85Ab14–28Or1), augite (En37–38Fs19Wo43–44), ferroan enstatite (En62–68Fs30–35Wo1–4) and rare pigeonite (En46–50Fs37–42Wo7–17). The basaltic andesites are porphyritic to glomeroporphyritic with phenocrysts of zoned plagioclase (An44–67Ab32–55Or1), orthopyroxene, Mg-rich augite (En38–42Fs15–17Wo43–45), rare pargasite to edenite amphibole (Mg# 69–59) and very rare biotite in a hypocrystalline to holohyaline groundmass. Andesites are highly porphyritic with phenocrysts of plagioclase (An47–79Ab20–52Or0–1), pargasite to magnesio-hornblende (Mg# 72–67), Mg-rich augite (En43–46Fs12–17Wo41–43), subordinate ferroan enstatite (En68–74Fs23–29Wo3–4), biotite (Mg# 53) and Ti-magnetite (Usp29–41). Dacites (massive lavas and ignimbrites) are porphyritic, with phenocrysts and phenoclasts of plagioclase (An33–79Ab20–62Or0–4), calcic amphibole (Ti-pargasite, Mg-hornblende and edenite; Mg# 81–46), biotite (Mg# 67–56), very rare Mg-rich augite (En41–42Fs16–18Wo40–43) and resorbed quartz in hypohyaline to holohyaline groundmass with a dense mat of anhedral quartz, labradorite-andesine (An36–66Ab33–61Or1–4) and rare anorthoclase (An22Ab66Or12). Rhyolitic compositions have been found both as volcanic clasts (massive lava and ignimbrites) with andesine to oligoclase phenoclasts (An25–38Ab61–71Or1–4), quartz, biotite (Mg# 55–53) and Ti-magnetite (Usp18–77), and as interstitial glasses (residual melt drops) in other APF volcanic rocks. The cumulate nodules are olivine-gabbro and amphibole-gabbro/gabbronorite with a mineral paragenesis dominated by plagioclase (An41–73Ab26–57Or1–3), olivine (Fo68–72), Mg-rich augite to ferroan diopside (En41–45Fs12–15Wo42–45; Mg# 79–74), ferroan enstatite (En65–74Fs24–33Wo2–3; Mg# 76–68), magnetite (Usp15–28) and titanian pargasite (Mg# 67–65). The main cumulus phases are plagioclase, olivine and pyroxene, while intercumulus/postcumulus phases are titanian pargasite and magnetite. The dataset can be used to compare petrographic features and chemical compositions of calc-alkaline rocks emplaced in other subduction-related settings. Above all, it can represent a useful contribution in solving the problem linked to the identification of a hidden Early-Oligocene source of the thick volcaniclastic APF succession in the Alpine-Apennine belt geodynamic evolution.

Nine sections from the "Limestones and marls with Rhaetavicula contorta" Auctt. (Norian-Rhaetian) of the Tuscan Nappe in eastern Liguria and northwestern Tuscany, have been examined for their stratigraphic and sedimentological characteristics. The results obtained have been integrated with data pertaining to the previously studied Pania di Corfino section. Two formations were identified and studied in detail: that of Pania di Corfino and that of La Spezia. Where present, the Pania di Corfino Formation accounts for the lower portion of the sections. It consists mainly of thick beds and massive layers of dolomites, dolomitic limestones and limestones. Thinly-bedded dark limestones appear less frequently, while layers rich in clay are rare. The top of the formation is surely of Rhaetian age, in some sections, as indicated by the presence of Triasina hantkeni Majzon; in the others, it is Norian-Rhaetian. The age of the bottom portion can be regarded as Norian-Rhaetian in all the sections; the presence of considerably thick deposits beneath the established Rhaetian layers in some sections, however, suggests an Early Rhaetian or even Late Norian age. The depositional environment of the Pania di Corfino Formation may be envisaged as an epicontinental carbonate platform with predominantly restricted water circulation on which fine carbonate sediments are deposited beneath the wave base; features suggesting a tidal flat are rare. The environment of deposition was, for brief periods only, that of a platform with open circulation in which the effects of wave-motion were prominent; features strictly relatable to a true platform edge have not been found.

The Monte Piano — Blsmantova sequence (Middle Eocene — Late Miocene) in the Northern Apenmnes represents a new sedimentary cycle after the tectonic phase of the Early—Middle Eocene. This phase principally affected the structural Units of Ligurian domain. This sedimentary sequence (the postorogenic Ligurian Sequence), shows evidence of the progression of the Apennine orogenesis mainly through the development of unconformities of regional extension. In fact, this new sedimentary cycle began after the definitive closure of the Ligurian ocean (Oceanic stage) and sedimentation continued durIng the subsequent development of a collisional margin (Ensialic stage) between the European and African Adriatic plates. The stratigraphic and structural features of the Apenmne margin between Tresinaro Valley and Lavino Valley are described brteflv in this paper. Moreover, the contact between the Ranzano Formation and the Antognola Formation, parts of the postorogenic Ligurian Sequence, is discussed in terms of the micropaleontologica] data obtained from three stratigraphical sections situated In the lower valley of the Secchia River. The contact coincides with an unconformity that is marked by a biostratigraphical hiatus. In fact, foraminifera] associations indicate that the top of the Ranzano Formation is attributable to Zone PI 8 (Lower Oligocene) and that the base of the Antognola Formation is already attributable to Zone P 21 (Upper Oligocene). There was no evidence of the presence of Zone PI 9/20. The chronological range of the hiatus is estimated as 2.4 to 1 0 Ma, depending upon the chronological scale adopted and the exact position of the "top" of the Ranzano Formation and the base of the Antognola Formation. On the basis of the stratigraphic relations existing among the various units of the postorogenic Ligurian Sequence outcropping in the studied area and on the basis of the data collected on the contact between the Ranzano Formation and Antognola Formation, it is clear that the hiatus is attributable to submarine erosion of a part of the turbiditic deposits of the Ranzano Formation, which are affected by pronounced tectono—sedimentary phenomena. The tectonic movements developed in the Ligurian domain in a per10d preceding the deposition of the Antognola Formation. They are thus contemporary with the beginning of the deposition of the Macigno in the Tuscan paleogeographical domain.

The 1:10,000 geological map of the San Colombano hill covers 60 km2 in the Po Plain, south of Milan. The new and the historical surface geological data-sets are managed by a GeoDB aiming to contribute to re-interpret the Quaternary evolution at the Po Plain-Northern Apennine border. On the hill, the Calabrian shallow marine San Colombano Fm. unconformably overlies the truncated deeper-marine Miocene formations, up-thrusted by the external fronts of the Apennine Emilian Arc during Mio-Pliocene. Late Pleistocene alluvial units rest in unconformity above the marine succession both on the uplifted hilltop and on the surrounding plain. Fault-related offset of Late Pleistocene units, stratigraphic and morpho-structural evidences (facets, relic surfaces and drainage patterns), document the Quaternary tectonic history. Early to Middle Pleistocene ongoing thrust-folding at the northernmost buried reaches of the Emilian Arc was followed by Latest Pleistocene-Holocene transtension, possibly relating to the NNE striking Pavia-Casteggio lateral ramp.

The Mt. Cusna ridge, located in the Northern Apennines (North Italy), is a mountain area of relevant geological interest for the interaction through time of distinct geomorphic processes, acting since the end of the Last Glacial Maximum. A geomorphological map at the 1:10,000 scale was produced to characterise the main landforms and processes identifiable on the ridge. From this, a detailed reconstruction of the Holocene landscape history of the area is drawn. After deglaciation, at the end of the Pleistocene, glacial and periglacial processes left wide deposits and barren surfaces. Slope and running water processes acted cyclically on the landscape through phases of stronger slope denudation and landslide activation followed by stability periods. These processes are related to the main climatic changes recorded for the N Apennines during the Holocene. Since the Late Holocene, the impact of human communities may have played a prominent role as an agent of landscape modification.

The investigated mantle bodies from the External Ligurians (Groppo di Gorro and Mt. Rocchetta) show evidences of a complex evolution determined by an early high temperature metasomatism, due to percolating melts of asthenospheric origin, and a later metasomatism at relatively high temperature by hydrothermal fluids, with formation of rodingites. At Groppo di Gorro, the serpentinization and chloritization processes obliterated totally the pyroxenite protolith, whereas at Mt. Rocchetta relics of peridotite and pyroxenite protoliths were preserved from serpentinization. The rodingite parageneses consist of diopside ​+ ​vesuvianite ​+ ​garnet ​+ ​calcite ​+ ​chlorite at Groppo di Gorro and garnet ​+ ​diopside ​+ ​serpentine ​± ​vesuvianite ​± ​prehnite ​± ​chlorite ​± ​pumpellyite at Mt. Rocchetta. Fluid inclusion measurements show that rodingitization occurred at relatively high temperatures (264–334 ​°C at 500 ​bar and 300–380 ​°C at 1 ​kbar). Garnet, the first phase of rodingite to form, consists of abundant hydrogarnet component at Groppo di Gorro, whereas it is mainly composed of grossular and andradite at Mt. Rocchetta. The last stage of rodingitization is characterized by the vesuvianite formation. Hydrogarnet nucleation requires high Ca and low silica fluids, whereas the formation of vesuvianite does not need CO 2 -poor fluids. The formation of calcite at Groppo di Gorro points to mildly oxidizing conditions compatible with hydrothermal fluids; the presence of andradite associated with serpentine and magnetite at Mt. Rocchetta suggests Fe3+-bearing fluids with f O 2 slightly higher than iron-magnetite buffer. We propose that the formation of the studied rodingite could be related to different pulses of hydrothermal fluids mainly occurring in an ocean-continent transitional setting and, locally, in an accretionary prism associated with intra-oceanic subduction. Image 1 • Three rodingite occurrences from the Northern Apennine ophiolites are investigated. • Pyroxenites and peridotites are the involved protoliths. • Hydrogarnet, diopside and vesuvianite are the main rodingite mineral phases. • Rodingite-forming processes occurred through a multistage evolution. • Minerals and fluids are traced by reaction path modelling and activity diagrams. [ABSTRACT FROM AUTHOR]

Finite strain analyses were performed on a deformed metaconglomerate from the Calamita Unit in the Island of Elba. The Calamita Unit is a synkinematic contact aureole that was shaped by Late Miocene contractional deformation coeval with high‐temperature metamorphism. The metaconglomerate occurs as an L‐tectonite in the footwall of a major thrust, entirely surrounded by S‐tectonites developed in schistose rocks. Object lineations, defined by the preferred orientation of clasts, trend subparallel to the stretching lineations in the associated rocks. Quartz microstructures registered ductile deformation of clasts by grain boundary migration to bulging recrystallization, suggesting temperature decrease during deformation. Rf/ϕ analyses were carried out on three metaconglomerate samples using quartzite clasts as markers. The finite strain data show that the metaconglomerates are strongly deformed in the constrictional field with K values between ~3 and ~7. The constrictional deformation registered by the metaconglomerate with respect to the surrounding metapelites, which likely deformed under plane strain, can be interpreted as the result of flow partitioning in rheologically heterogeneous sequences during deformation. These results suggest the presence of significant strain gradients in the Calamita Unit, strictly associated with heterogeneously distributed ductile shear zones. [ABSTRACT FROM AUTHOR]

We map the High Sillaro Valley, in the Northern Apennines of Italy. Here the Ligurian wedge overthrust the foredeep deposits of the Marnoso Arenacea formation – MA. The overthrusting occurred through a shear zone with components derived from the frontal part of the Ligurian wedge and interpreted as a tectonic mélange (Sestola-Vidiciatico Tectonic unit - SVU) here subdivided into two different subunits structurally independent one from the other. In the area, the Visignano chaotic body (VIS) constitutes an intercalation within the Serravallian-Tortonian MA and derives, as the SVU, from the frontal part of the Ligurian wedge. We performed a detailed investigation of the components of the VIS that helps to better define the architecture of the frontal part of the Ligurian wedge and to constrain the timing of the deformation phases affecting this portion of the Northern Apennines during the middle-late Miocene. [ABSTRACT FROM AUTHOR]

The Punta Bianca Unit (NW Italy) is a continent-derived metamorphic unit that experienced underthrusting and later exhumation in the hinterland sector of the Northern Apennines fold-and-thrust belt. We present a novel 1:5000 scale geological map that aims to illustrate the polyphase tectonic evolution of the Punta Bianca Unit and its relationships with non-metamorphic units. The geologic data presented in the map are coupled with the structural analysis of the main tectonic elements, lithostratigraphic, finite strain and microstructural data that allow to highlight the tectonic history of the study area. In particular, we recognized that the Punta Bianca Unit underwent an early phase of underplating (D1), followed by syn-orogenic exhumation to shallow crustal levels and coupling with the overlying Tuscan Nappe (D2), and nappe stacking/refolding (D3). Low-angle semibrittle (D4) and high-angle brittle (D5) faulting affected both the Punta Bianca Unit and the Tuscan Nappe during the latest stages of deformation. [ABSTRACT FROM AUTHOR]

We provide new evidence of the preservation of 34S-enriched signals in methane seep-impacted sediments from two onshore Miocene outcrops located in the northern Apennines (Italy). Selected outcrops include methane-derived authigenic carbonates (MDAC) with δ13C composition between − 42.3 and − 18.2‰. MDACs contain chemosynthetic clams and abundant pyrite indicative of formation close to or within a shallow sulfate-methane transition zone (SMTZ). This study aims to evaluate the relative contributions of background organic matter mineralization and anaerobic oxidation of methane (AOM) to sulfate consumption and to gain insight into the transport process (i.e., diffusion, advection) controlling the depth of the SMTZ. Host sediments were investigated by CHN elemental analysis coupled with total sulfur (TS) and sulfur isotopic measurements on bulk samples. Total organic carbon (TOC) measurements reveal a consistent and low amount of organic carbon (TOC< 0.5%), with no notable difference between the underlying turbidites and the stratigraphic intervals hosting the MDACs. The TS/TOC ratio of most samples is well above the baseline value of deposition under normal marine conditions, suggesting the excess TS here is due to enhanced sulfate reduction. The samples show bulk δ34S values commonly enriched (> 0‰ and up to + 17.1‰), which is characteristic of sulfides precipitated in association with AOM. We propose that advection of methane-rich fluids was responsible for maintaining the shallow depth of the studied paleo-SMTZs. AOM at paleo-SMTZ positions in the investigated seep-impacted sediments resulted in excess bicarbonate and sulfide production, favoring solid-phase MDAC and iron sulfide precipitation. [ABSTRACT FROM AUTHOR]

The presence of a set of well-known turbidite successions, deposited in progressively E-migrating foredeep basins and subsequently piled up with east vergence, makes the Northern Apennines of Italy paradigmatic of the evolution of deepwater fold-and-thrust belts. This study focuses on the early Apenninic collisional stage, early Miocene in age, which led to the accretion of the turbidites of the Trasimeno Tectonic Wedge (TTW), in the central part of the Northern Apennines. Based on the interpretation of previously unpublished seismic reflection profiles with new surface geology data and tectonic balancing, we present a detailed tectonic reconstruction of the TTW. In the study area, the TTW is characterized by a W-dipping shaly basal décollement located at a depth of 1–5 km. The tectonic wedge is c. 5 km thick at its central-western part and tapers progressively eastwards to c. 1 km. The total shortening, balanced along a 33 km long cross-section, is c. 60 km, including 20 km (40%) of internal imbrication, c. 23 km of horizontal ENE-wards translation along the basal décollement and c. 17 km of passive translation caused by the later shortening of footwall units. Deformation balancing, constrained through upper Aquitanian – upper Burdigalian (c. 21–16 Ma) biostratigraphy, provides an average shortening rate of c. 8.6 mm a–1. Internal shortening of the TTW shows an average shortening rate of c. 4 mm a–1 for this period. [ABSTRACT FROM AUTHOR]

Temperature changes affect crackmeters monitoring on a daily and a seasonal basis. This is due to rock mass thermal dilatancy and to instrumental matters. The consequent widening closing cycles can mask small irreversible displacements that might be precursors of rock failures. Recently, Weber et al. (Cryosphere 11:567–583, 2017) have proposed a linear fit method between temperature and fracture opening in order to compute the irreversibility index as a metrics to rank irreversible displacements. However, such an approach requires temperature sensors coupled to crackmeters. In order to overcome these limits, we propose an alternative method for deriving a normalised Z-score irreversibility index. It is based on sinusoidal wave fit of cracks opening time series only; thus, it does not require temperature monitoring. The methodology has been tested using data recorded by a wireless sensor network installed at La Pietra di Bismantova rock slab composed of 14 crackmeters and thermometers monitoring potentially unstable rock masses. A comparison of results obtained using the method of Weber et al. (Cryosphere 11:567–583, 2017) and the sinusoidal approach shows that the latter is much less sensitive to the duration of the moving window used to derive the irreversibility index, making it a much more flexible tool for indexing irreversible displacements over short time periods. Moreover, as rapid high–magnitude temperature changes can also be the causal factor of irreversible displacements, their statistical relation with peaks of the Z-score irreversibility index has been investigated. Results have shown that, depending on which crack is examined, correlations between irreversibility peaks and antecedent extreme temperature variations are more or less relevant. In conclusion, we believe that the Z-score sinusoidal wave fit irreversibility index (ZSFI) can represent a useful metrics for indexing irreversible displacements in unstable blocks using crackmeters' datasets affected by temperature cycles at the daily and seasonal scale. [ABSTRACT FROM AUTHOR]

Copyright of Atti della Società dei Naturalisti e Matematici di Modena is the property of Societa dei Naturalisti e Matematici di Modena and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plagioclase peridotites are an important marker of the shallow geodynamic evolution of the lithospheric mantle at extensional settings. Based on low- pressure experiments, a recent study by Fumagalli et al. (2017) defined and calibrated a geobarometer for peridotitic bulk compositions, based on the Forster- ite-Anorthite-Ca-Tschermak-Enstatite (FACE) pressure-sensitive equilibrium. The Suvero plagioclase-bearing peridotites, on which the FACE geobarometer was calibrated, are primarily associated to plagioclase pyroxenites. Assuming that the pyroxenites record the same Pressure-Temperature evolution than the plagioclase peridotites, they represent ideal candidates to test the applicability of the FACE geobarometer on pyroxenitic compositions. As documented in the plagioclase peridotites, the pyroxenites are characterized by the development of fine-grained neoblastic assemblages, indicative of partial recrystallization under plagioclase-facies conditions. Chemical zonations in these neoblastic mineral aggregates suggest equilibration stages at variable pressure and temperature and allowed to document two re-equilibration stages corresponding to the onset of plagioclase-facies recrystallization (830-850°C, 6.9-8.1±0.5 kbar) and a shallower colder re-equilibration (770-790°C, 5.8-5.9±0.5 kbar), respectively. The decompressional evolution reported for pyroxenitic bulk compositions is consistent with the exhumation history documented in the associated Suvero peridotite, although at slightly higher equilibrium pressures (~ 1 kbar). Remarkably, the much lower XCr in pyroxenites reflects in lower Cr incorporation in pyroxenes and, consequently, in significantly higher Ca-Tschermak activity in clinopyroxene that might introduce the systematic pressure overestimation by FACE geobarometer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spatial patterns of landslide events in the N-Apennines chain during the Holocene. • Lower Holocene: landslide events towards the chain interior; Upper Holocene: outwards. • Middle Holocene: most of the landslide events in a 8.5 km belt in the chain interior. • Landslide events reflect changes in atmospheric circulation pattern in the Holocene. • Lithologies and topography for locating landslides with old-dating organic remnants. In this work we examine the spatial and temporal distribution of radiocarbon dates from landslides on the NE-facing side of the Northern Apennines during the Holocene, focusing on the region's associated vegetation and climatic changes. We also propose a method for identifying areas and landslides that may contain very old organic materials for future research in the region. This analysis was based on a principal component analysis (PCA) on 5255 grid cells measuring 1 km2 each, overlaid on the study area. These grid cells incorporated variables derived from the terrain characteristics, including underlying lithologies and topographic features. Our findings reveal that, during the upper Holocene, the last dated events of recurrent and single-event landslides occurred first closer to the coldest and wettest territories once occupied by the glacier termina during the Last Glacial Maximum (LGMgt). Subsequently the last dated events occurred at distances greater than 30 km from the LGMgt, towards the mountain chain's margin. Conversely, at the beginning of the Holocene, an opposite pattern emerged, with landslide events occurring towards the chain interior. These spatial patterns were consistently observed when considering also the entire dataset of 87 dates for landslide events. During the middle Holocene, we observed that the recurrent landslides were primarily concentrated within a narrow belt 8.5 km from the LGMgt. Furthermore, higher rates of landslide activity were associated with the 4.2 ka BP event and persisted until approximately 2.0 ka BP, indicating a correlation with wet and cool periods. In conclusion, these spatial patterns in landslide events can be linked to changes in precipitation patterns and dominant atmospheric circulation in the mountain belt occurred since the beginning of the Holocene. [ABSTRACT FROM AUTHOR]

Lead and zinc hydrothermal mineralizations associated with late Oligocene-early Miocene sedimentary rocks (sandstones and marls) were found and investigated for the first time in the Northern Apennines (Northern Italy, province of Reggio Emilia). The mineralizations are located in a structurally complex area involved in the tectonic events forming the Northern Apennines chain. They are stratabound mineralizations mainly in the form of sub-vertical veins, suggesting a strong structural control. The ore minerals are sphalerite and galena (rare chalcopyrite), the gangue minerals are carbonates, barite and quartz, in different proportions in the three investigated sites (Busana, Casalino, Casenove). On the basis of microthermometric data on fluid inclusions in ore and gangue minerals, the ore-forming fluids belonged to an aqueous system containing Na-, Mg-, Ca-chlorides and/or carbonate and had a relatively high salinity, mainly in the range 11–17 wt% NaCl equivalent. The trapping temperatures were relatively high (142–231 °C range), suggesting basins characterized by anomalous geothermal gradients. The sphalerite composition reveals different FeS contents and different Zn/Cd ratios in the three sites. The δ34S values of the ore minerals vary from −7.98/−10.98 ‰ in Busana to 4.38/6.85 ‰ in the other two sites. The barite in Casalino has values of δ34S = 25.56 ‰ and δ18O = 13.81 ‰. The sphalerite composition and the isotopic data suggest complex interactions of the basin fluids involving crossed sediments, evaporite rocks, organic matter, as well as mixing between fluids and Jurassic marine waters. On the basis of their geological, petrographic-mineralogical and geochemical features, these mineralizations can be considered Alpine- or Irish-type MVT mineralizations. • The Pb-Zn-hydrothermal mineralization are hosted in sedimentary rocks • They are in the form of sub-vertical veins suggesting a strong structural control • The ore-forming fluids had high salinity and high temperature • Sulfur derives from evaporites or Jurassic marine water reduced by bacterial action • These are post-depositional/ syn -diagenetic Alpine- or Irish-type MVT mineralizations [ABSTRACT FROM AUTHOR]

Messinian pre-evaporitic seep carbonates outcropping in the Tuscan-Romagna area share a common upward stratigraphic trend: massive seep carbonates rich in large lucinids, modiolids and planktonic foraminifera pass upward to horizontally laminated carbonates free of macrofauna and foraminifera. A transitional macrofauna-free facies marks the passage in some sections, sometimes with faint lamination. Thin section petrography, SEM-EDS analyses, and X-ray diffraction revealed a high textural and mineralogical variability between the studied sections and facies. In general, the upward facies transition is associated with a switch from massive packstone/grainstone with complex carbonate mineralogy to laminated mudstone microfacies with monomineralic, mostly dolomitic, carbonate composition. The δ13C values of all facies indicate domination of methane-derived carbon, thus demonstrating a methane-charged sedimentary setting with precipitation of authigenic carbonates induced by anaerobic oxidation of methane. The transitional and laminated facies contain several structures typical of microbial sediments, such as peloids, filamentous features, clotted micrite, fibrous cement, and frequent fenestrae; web-like structures are remnants of cyanobacterial mats and resemble Entophysalidaceae thriving at the bottom of the Messinian sea. The distinctive depositional and biotic switch (abrupt disappearance of macrofauna and planktonic foraminifera, predominance of dolomite over calcite, absence of aragonite, presence of horizontal lamination) reflects important environmental changes taking place in the basin. The rise of δ18O from the massive, through transitional, to the laminated facies suggests either a drop of bottom-water temperature or an increase of salinity. Nevertheless, other paleoenvironmental changes must have co-occurred in order to account for the dramatic facies shift observed. We hypothesize that this change could reflect the development of water-column stratification with respect to both salinity and oxygen concentration shortly before the Messinian Salinity Crisis. • Seep carbonates preceding the Messinian evaporites record the transition from marine to stressed evaporitic conditions. • The transition from seep massive to laminated carbonates is marked by loss of macrofauna and dolomite prevailing over calcite. • Microbial fabrics in Messinian seep-carbonates indicate that cyanobacterial communities were crucial in arbonate formation. • The δ18O rise from massive,to laminated facies reflects either a drop of bottom water temperature or a rise of salinity. [ABSTRACT FROM AUTHOR]

Groundwater management of alluvial aquifers facing the northern Italian Apennines is an important issue that is becoming more complicated due to ongoing climate changes and increased water demands. The large groundwater withdrawals, coupled with an overall worsening of the water quality, require detailed knowledge of the recharge mechanisms of these aquifers that can be useful for further adaptation measures. We have focused our attention on a selected alluvial fan in which 49 slug injections of hyperconcentrated solutions of NaCl allowed river discharges to be estimated in seven different hydraulic sections. Consequently, losses from the streambed were assessed for the six river reaches along with the corresponding uncertainties in the estimates. The study confirms the suitability of such tests for identifying sectors in which streambed losses are promoted and for quantifying the total recharge conveyed to underlying aquifers. In addition, it has been demonstrated that the total streambed losses can be further linked to river discharges in any gauge upstream of the alluvial fan thanks to linear regression. Once obtained, the latter makes monitoring groundwater recharge by stream losses in real time possible if a permanent measurement device (such as the common telemetry used for river discharge monitoring) is available.

A detailed geological map at 1:50,000 scale of the Marecchia Valley and adjoining areas (Northern Apennines, NA, Italy) is presented here. The Marecchia Valley represents a geological ‘unicum’ for the NA and it has been the focus of scientific debate for a long time, due to the occurrence in the area of the ‘Coltre della Val Marecchia (CVM)’, a complex stack of allochthonous and semi-allochthonous units emplaced in a foredeep basin during the Late Miocene to Early Pliocene. In order to clarify the geological evolution for this area, the lithostratigraphic relationships and the tectonic framework have been studied, allowing better understanding of the complex relationships between tectonics and sedimentation. The main result has been a new evolutionary framework for this sector of the orogen during the Late Miocene-Early Pliocene. Several new findings about the geological-structural setting and stratigraphy, result from the geological map presented here. These are overall supported by stratigraphic and tectonic evidence, which suggest time and modes of the CVM allochthonous emplacement within the Messinian-early Pliocene foredeep successions. Relationships between the allochthonous and autochthonous formations allowed recognition of two different bodies in the CVM, gravitationally emplaced following different trajectories and timing.

The geological map of Piemonte Region (Italy) is a graphic representation of the geology of the region, grounded on a large geodatabase, that can be also browsed as an interactive scalable map (GeoPiemonte Map) using a WebGIS application. The Map, produced at 1:250,000 scale, is the first original release of the ‘GeoPiemonte Map’ project. The geological data represented on the map derive from a thorough revision of available geological maps and literature, integrated with unpublished original data. The revision and harmonisation of existing and new data have been based on explicit criteria used for the classification of geologic units and their representation on the Map. These criteria firstly aimed at providing a lithostratigraphic, hierarchic subdivision of Piemonte geologic units and describing them using shared concepts and vocabularies, consistent with IUGS Descriptive Standards for the Geosciences.

On 25 October 2011, the eastern Liguria (Vara Valley and Cinque Terre area) and northwestern Tuscany (Magra Valley) were affected by an extreme rainstorm (almost 600 mm/24 h) that caused floods, thousands of shallow landslides, 13 casualties and damage to villages and infrastructure. This study aims at analysing the main features of the 25 October 2011 shallow landslides occurred in the Pogliaschina Torrent basin (25 km2 wide, Vara Valley), in order to investigate the influence of specific predisposing factors (land use, geological and structural setting, plan and profile curvature, slope angle and aspect) on landslide occurrence. For this purpose, both a landslide inventory map and a geology map (scale 1:10,000) were prepared. In addition, a database including the main geological, geomorphological, structural and land use features of the landslide source areas was implemented. The relationship between landslide source areas and the main predisposing factors was evaluated through spatial and statistical analysis.

During the Spring of 2011, we studied the bird community in an area of Val Borbera, in the province of Alessandria (NW Italy). In the study area, situated at an altitude between 655 and 1700 m a.s.l., we conducted 110 points count ten minutes each in four microhabitats (agricultural areas, shrubs, forests, and prairies). In total, we surveyed 72 species, of which 51 were passerine and 21 non passerine. The most abundant species were Sylvia atricapilla, Phylloscopus collybita, Apus apus, and Turdus merula. In the agricultural areas, we detected a total of 50 species (Sylvia atricapilla, Parus major, Turdus merula were the most abundant). In the shrubs, we detected 30 species (Sylvia atricapilla, Parus major, Fringilla coelebs, Phylloscopus collybita, Turdus merula, Erithacus rubecula were the most abundant). In the forest areas, we found 45 species (Sylvia atricapilla, Parus major, Fringilla coelebs, Phylloscopus collybita, Turdus merula, Erithacus rubecula were the most abundant), and in the prairies, we detected 48 species (Alauda arvensis, Anthus campestris, Sylvia atricapilla, Turdus merula, Anthus trivialis, Sylvia communis were the most abundant). Compared to the other macro habitats, the agricultural areas have a significantly high abundance and richness in species, which highlights the importance of the agricultural mosaics in the Piedmont and mountain areas. The data which has been collected so far confirms the important role of this area, given the presence of some species which are rare at a regional scale.

This paper presents the first pedoanthracological study carried out on two mountains of the Northern Apennines, Monte Cimone, and Corno alle Scale, where the results provided new palaeoenvironmental data. The pedoantracological sampling followed an elevation gradient from the current timberline to the highest possible elevation, also adapted to the geomorphological characteristics of the study areas. Based on radiocarbon datings (16 at Monte Cimone and 9 at Corno alle Scale), the soil charcoal fragments provided data about the vegetation dynamics and plant landscape reconstruction, primarily indicating the Late Holocene. The landscape over the last 3000 years appears very similar to the current one with very small altitudinal variations of the timberline and treeline. The present study shows a lack of radiocarbon dates for the Middle Holocene and two hypotheses are discussed to explain this finding. Data suggest that past fires were locally linked to periods of climate optimum and possibly with the management of natural resources (especially animal grazing) by human societies. Some questions concerning the absence of Abies alba, today only present as plantation and normally associated with Fagus sylvatica at these latitudes, are discussed. [ABSTRACT FROM AUTHOR]

The architecture of foreland basins and the resulting distribution of clastic sediments are related to the constant interplay between tectonics and sedimentation. Specifically, basin floor modifications strongly influence dimensions, continuity and connections of sand‐size and fine‐grained deposits. Given the increasing need to identify deep potential reservoir deposits, the large‐scale definition of clastic porous targets and their seals is a matter of interest for oil and gas industry. Here, we present the reconstruction of the Po Plain and Northern Adriatic Foreland Basin (with an extent of ca. 40,000 km2) and its Pliocene–Pleistocene evolution, as an example of a sedimentary clastic system controlled by strongly non‐cylindrical foreland geometry. The study is based on the basin‐scale mapping of six unconformity‐bounded sequences, performed by interpreting a dense network of seismic lines and correlating well‐log data. This provides a three‐dimensional model of the step‐by‐step evolution of the basin and a description of the sediment dispersal pattern. We found that the basin records the change from a continuous (cylindrical) to highly fragmented (non‐cylindrical) foredeep geometry during Late Pliocene. In the Northern Apennines case, the main factors driving the development of a non‐cylindrical geometry are mainly related to inherited inhomogeneity in the downgoing block linked to its Mesozoic extensional faulting, and the relative orientation of these lineaments with respect to the direction of orogen migration. During the late Pliocene–Pleistocene the two directions progressively became close to parallel, and the Northern Apennines system reacted changing from a cylindrical to a non‐cylindrical state. [ABSTRACT FROM AUTHOR]

We present the results of geological and structural investigation documenting the interaction between hydrothermal fluids and host rock leading to a vein-type ore mineralization at shallow crustal depths (<7 km) in the mining district of the eastern Island of Elba (Italy). Sulfide- and iron-rich veins and breccia in addition to minor massive iron-ore bodies form the mineralized system. Structural mapping and analysis of vein systems, fractures, faults and associated fault rocks as well as fracture opening modes show that the main factors controlling the formation and distribution of the mineralization are lithology, deformation style and deformation intensity. Their interplay led to a positive feedback between the evolution of pore pressure through time, strain localization and the resulting mineralization. Inversion of fault and vein data defines an E-W extensional stress field at the time of faulting, which favoured fluid ingress and pervasive flow within the porous host sandstone, interstitial sulfide precipitation and reduction of the primary bulk porosity. Subsequently, cyclic channelized fluid flow during repeated fluid ingresses caused extensive veining and numerous episodes of breccia formation. • Vein-type ore mineralization developed in upper crust during crustal extension. • Deformation and lithology controlled the circulation and distribution of fluids. • Faults, fractures and veins data inversion indicates extensional stress field. • Initial pervasive flow reduced the bulk porosity of host rock. • Cyclic channelized flows aided by faulting lead to veins, breccia and ore deposits. [ABSTRACT FROM AUTHOR]

• A revised surface heat flow map of a sector of the Northern Apennines is presented. • The map is constrained by logs from 174 wells drilled for geothermal and hydrocarbon exploration purposes. • The results confirm that the 70 mW m−2 isoline corresponds to a major tectonic boundary of the region. A revised surface heat flow map of a sector of the Northern Apennines is presented, constrained by recently available thermal and petrophysical logs from 174 wells drilled for geothermal and hydrocarbon exploration purposes. The borehole temperatures have been corrected for drilling, inclination, and palaeoclimate effects. The corrected temperature data, combined with petrophysical parameters for each individual formation, have been used to derive shallow geotherms (down to a maximum depth of 8 km), which have yielded site-specific heat flow values. These values, once corrected for palaeoclimatic topographic and erosion/sedimentation effects, have been contoured by a kriging procedure to obtain the heat flow map. The map shows a clear distinction between a western zone (the Tyrrhenian Domain) of high heat flow (>150 mW m−2), with closely spaced heat flow isolines, and an eastern zone (the Adriatic Domain) of relatively low (<70 mW m−2), spatially uniform heat flow. The boundary between the two zones is roughly parallel to the axis of the Apennines. Five crustal geotherms (extending to the Moho) and the corresponding rheological profiles confirm that the 70 mW m−2 isoline corresponds to a major tectonic boundary, across which the thermal, structural, and seismic properties of the lithosphere go through a significant change. [ABSTRACT FROM AUTHOR]

Among living cetaceans, dwarf and pygmy sperm whales (Kogia) are the only members of the family Kogiidae, regarded as diminutive and elusive relatives of the great sperm whale Physeter. Kogiids are known as fossils by several skulls, teeth, and ear bones from Neogene deposits of the Northern Hemisphere and Peru. We report on a fossil kogiid specimen collected at Sant'Andrea Bagni (northern Italy) from Zanclean marine mudstone; these deposits also yielded a rich deep-water elasmobranch assemblage depicting the presence of Atlantic-derived psychrospheric waters. The kogiid specimen, consisting of a partial cranium, one detached tooth, one vertebra, and one fragmentary rib, is here referred to Pliokogia apenninica gen. et sp. nov. Pliokogia is mostly characterised by a long and dorsally flattened rostrum and by the presence of two well-distinct fossae on the right side of the supracranial basin, including an elongated peripheral maxillary fossa on the posterior portion of the right maxilla. Our phylogenetic analysis recovers Pliokogia as a member of the subfamily Kogiinae, which includes Kogia, Koristocetus, Nanokogia, and Praekogia. A low temporal fossa and the absence of dental enamel suggest that, like extant Kogia, Pliokogia was a suction feeder. Since living kogiids do not inhabit the Mediterranean waters, and considering that they feed on deep-water prey in open-sea areas, the association of Pliokogia with a psychrospheric elasmobranch assemblage with Atlantic affinities is noteworthy. Indeed, in early Pliocene times, the Gibraltar connection was controlled by estuarine dynamics, thus allowing the entrance of deep-water organisms (including the putative prey of Pliokogia) in the Mediterranean Basin. The subsequent abandonment of the Mediterranean Sea by kogiids might therefore be related to the definitive establishment of the present-day antiestuarine circulation at Gibraltar, which likely led to a limited deep nutrient supply and resulted in the strong depletion of most Mediterranean deep-water ecosystems. [ABSTRACT FROM AUTHOR]

Mud volcanism is known to be strictly linked to tectonic structures, since they have the ability to trap hydrocarbon and other fluids, and eventually induce them to migrate from a deep reservoir (e.g. sited into an anticline core, where large overpressures may be generated), to the surface. A central theme is how fluids can migrate upward, and which is the role in this process of near structures (i.e. structures directly controlling the mud volcano system) and far structures (i.e. faults located far away from the mud volcano system). In this study, we investigate the role of both types of structures in the genesis and evolution of mud volcanoes. In particular, we investigate six mud volcano case studies from the Emilia-Romagna and Marche Pede–Apennine margin, in Italy, through integration of fieldwork, interpretation of available seismic reflection profiles and aerial photos. The results of these analyses support an intimate link of the investigated mud volcanoes with anticline structures. We discuss two different fluid migration settings, particularly (i) mud volcanoes emplaced on outcropping anticlines, and (ii) mud volcanoes located on top of buried structures, discerning when fluids are likely to exploit anticline-related fracture sets, or secondary structures and porosity. Finally, we speculate on how far structures, via the seismic triggering, may play a role in the occurrence of historical eruption of some of the investigated mud volcanoes. [ABSTRACT FROM AUTHOR]

Among natural hazards, mud volcanoes can damage property and infrastructures and affect hillslope evolution at different spatial and temporal scales. The results of 10-year-long multidisciplinary investigations performed on a Roman-age archaeological site, La Rovina di Montegibbio, are presented, showing a peculiar example of mutual interplay between human settlement and geological forcing in the mud-volcanic environment. The site (350 m a.s.l.) lies at the termination of the upper Secchia River catchment, near the town of Sassuolo (Modena Province). Here, a 4-km-long mud volcano belt borders the Apennines chain front, comprising one of the most prominent mud volcanoes of Italy (Salsa di Montegibbio), and the still-active chain hinge tectonics gives origin to gas and oil seeps. Based on geological, geoarchaeological, palaeobotanical, geochemical, geophysical records and analytical data, we unravel the onset, the evolution and the abandonment of the settlement in relation to the existence of a previously unknown mud volcano, belonging to the larger Montegibbio mud volcano system. The damages affecting the Roman-age buildings record the ground deformations in the context of mud volcano tectonics. In particular, the pattern of faults set buried under the archaeological site is shown and compared with that of the main mud volcano conduit. At least two Roman-age eruptive episodes have been recorded, whose ejected muds are geochemically characterized. The first recorded eruption must be regarded as the reason for the initial location and function of the sacred ancient settlement. The final site abandonment was because of subsequent severe ground deformations affecting the hillslope as a consequence of mud volcano activity. [ABSTRACT FROM AUTHOR]

Background and aims - The detailed analysis of algae and cyanoprokaryotes in a heterogeneous group of spring habitats (including all the different typologies) of the northern Apennines (Emilia-Romagna Region, Italy) revealed a new Amphora species in a small mountain flowing spring with low conductivity, and a new Halamphora species in a large, inland-saline (Triassic gypsum), fast flowing spring (Poiano spring). The present study aims to describe in detail these two new species found in contrasting spring types. Methods - This study is based on light microscopy (both fresh -for plastids - and prepared materials) and scanning electron microscopy observations, as well as a thorough morphological, physical, chemical, and biological characterization of the habitats. Key results - Amphora eileencoxiae sp. nov. is most similar to A. vetula (and allied taxa), and is characterized by the outline with acutely rounded, moderately ventrally bent ends, by the dimensions, and by the welldefined, semi-elliptic dorsal area. Halamphora poianensis sp. nov. is most similar to H. gasseae but differs by the higher stria density, the clearly ventrally bent ends, and the strongly developed dorsal raphe ledge. Conclusions - This is a contribution to the knowledge of the genera Amphora and Halamphora in mountain springs in understudied geographic areas and inland-saline springs, the species communities of which are likely insufficiently explored. [ABSTRACT FROM AUTHOR]

Abstract We present new field data from three outcrops of Miocene methane-derived authigenic carbonates in the foredeep of the northern Apennines that contain chemosynthetic fauna and record a long history (∼1 Ma) of shallow fluid seepage linked to seafloor anaerobic oxidation of methane. The studied outcrops show similar features in terms of carbonate morphology, facies, spatial distribution and lateral and vertical contacts with the enclosing sediments. Methane-derived carbonates occur in two structural positions: 1) on the slope of the accretionary wedge in hemipelagites draping buried thrust-related anticlines, and 2) at the leading edge of the deformation front in the inner foredeep, within fault-related anticlines standing above the adjacent deep seafloor as intrabasinal ridges. We compare fossil seeps with two extensively investigated modern analogues: the Hikurangi Margin, offshore New Zealand and Hydrate Ridge, on the Cascadia margin, offshore the U.S.A. These analogues share a similar compressive structural setting and are marked by the presence of variably extensive and voluminous methane-derived carbonate bodies and chemosynthetic fauna on the present-day seafloor. The comparison allows us to propose a model for the evolution of fluid seeps on thrust-related ridges. At the deformation front, uplift and geometry of the anticlinal ridges are controlled by the growth of splay faults, mostly blind, connected to the basal detachment, favoring the migration of fluids toward the incipient anticline. Fold development generates extensional stresses in the hinge zone of the anticline, promoting the development of normal faults; fluid migration pathways and seafloor seeps shift from the forelimb toward the crest of the ridge as the structures evolve. In the slope setting, far from the deformation front, thrust faults and extensional faults in buried anticlines remain the main fluid migration pathways to sustain seepage at the seafloor. After reaching a mature stage within the wedge, the structure is less active and buried in the slope environment of the evolved prism. Highlights • We provide summary of recurring features at seep outcrops in the northern Apennines. • Fossil seeps are compared with analogues from modern compressive settings. • The onset and evolution of seeps are linked to the development of anticlinal ridges. • We propose a new evolutionary model for seeps on accretionary ridges. [ABSTRACT FROM AUTHOR]

A detailed characterization of outcrop fracture networks in the turbiditic flysch sequence of the Monte Venere Formation (Northern Apennines) together with in situ measurements of rock strength using the Schmidt hammer provided important insights into the sequence of deformation and the slope stability conditions. The inferred sequence of structure formation from oldest to youngest is bedding-parallel cleavage, veins and normal faults, joints, and strike-slip faults (sheared joints). Alteration halos around fractures (joints, splay joints, strike-slip faults, and some normal faults) point out that these structures were conductive to meteoric water during uplift and erosion in the Holocene. Calcite-filled veins without alteration halos are considered local barriers to fluid flow and diffusion. Bedding thickness controls rock fracturing characterization parameters in the Monte Venere Formation. Reactivation in shear of pre-existing structures, however, causes the formation of splay joint clusters that locally increase fracture density contributing to degrade the mechanical strength of the rock. These localized clusters are apparent in detailed outcrop maps but they are usually not detected by the rock fracturing characterization parameters. Our data also imply that the presence of bedding-parallel cleavage is more important than layer thickness in controlling the rock compressive strength and ultimately the peak shear strength along a potentially sliding surface. This study takes closer look at landslide formation in a sloped flysch sequence under Mediterranean climate conditions and allowed to consider a conceptual model for landslide occurrence in which structural discontinuities and meteoric water flow through fracture networks are main triggering factors. [ABSTRACT FROM AUTHOR]

Earthflows are a flow-like movement of plastic clayey soils characterized by long periods of slow motion (at rates averaging a few meters per year or less) alternated with short periods of rapid surges at high velocity (up to meters per hour). During rapid surges, most earthflows move over a long distance with a fluid-like behavior. Although the generation of flow-type failures is an important issue for hazard assessment, our knowledge is limited by the difficulty of monitoring the process in the field. This has led to different explanations for rapid earthflows including high pore-pressure generation along the basal slip surface, pervasive shearing, or material fluidization. One key question is whether or not earthflows can fluidize through remolding and water entrainment. If this occurs, the material can change from plastic to fluid as the soil moisture increases, causing the landslide to move as a viscous flow; if not, the material remains in a plastic state and, as suggested by many authors, the flow-like morphology shown by earthflows would result by distributed internal shears rather than real mass flow. In this study, we provide the first answer to this question by measuring the shear stiffness of four large active earthflows in the Northern Apennines of Italy. Shear stiffness was measured using two geophysical techniques, the multichannel analysis of surface waves (MASW) and the passive refraction microtremors (ReMi). Measurements were carried out just a few days after the mobilization of the landslides and repeated in the following 2-3 years to evaluate the change of elastic properties with time. Field data show that soon after the mobilization, earthflows are characterized by very low values of shear stiffness (about 5-15 MPa), typical of soft clay soils with the high-void ratio. Shear stiffness then increases 4-5 times in the following months (up to 40-60 MPa) as the earthflows slow down and the material consolidates. These data indicate that during a rapid movement, earthflows undergo a dramatic increase of porosity and water content that probably drive the transition from a solid to a fluid-like state. [ABSTRACT FROM AUTHOR]

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