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20 pages, 7798 KiB

Open AccessArticle

Plio–Quaternary Structural Evolution of the Outer Sector of the Marche Apennines South of the Conero Promontory, Italy

by Mario Costa, Jessica Chicco, Chiara Invernizzi, Simone Teloni and Pietro Paolo Pierantoni

Geosciences 2021, 11(5), 184; https://doi.org/10.3390/geosciences11050184 - 24 Apr 2021

Cited by 9 | Viewed by 3856

Abstract

Some new results and preliminary remarks about the Plio–Quaternary structural and evolutionary characteristics of the outer Marche Apennines south in the Conero promontory are presented in this study. The present analysis is based on several subsurface seismic reflection profiles and well data, kindly [...] Read more.

Some new results and preliminary remarks about the Plio–Quaternary structural and evolutionary characteristics of the outer Marche Apennines south in the Conero promontory are presented in this study. The present analysis is based on several subsurface seismic reflection profiles and well data, kindly provided by ENI S.p.A. and available on the VIDEPI list, together with surface geologic–stratigraphic knowledge of Plio–Quaternary evolution from the literature. Examples of negative vs. positive reactivation of inherited structures in fold and thrust belts are highlighted. Here, we present an example from the external domain of the Marche Apennines, which displays interesting reactivation examples from the subsurface geology explored. The study area shows significant evolutionary differences with respect to the northern sector of the Marche region previously investigated by the same research group. The areal distribution of the main structures changes north and south of the ENE–WSW oriented discontinuity close to the Conero promontory. Based on the old tripartite classification of the Pliocene, the results of this work suggest a strong differential subsidence with extension occurring during the Early Pliocene and principal compressive deformation starting from the Middle Pliocene and decreasing or ceasing during the Quaternary. The main structure in this area is the NNW–SSE Coastal Structure, which is composed of E-vergent shallow thrusts and high-angle deep-seated normal faults underneath. An important right-lateral strike–slip component along this feature is also suggested, which is compatible with the principal NNE–SSW shortening direction. As mentioned, the area is largely characterized by tectonic inversion. Starting from Middle Pliocene, most of the Early Pliocene normal faults became E-vergent thrusts. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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35 pages, 19015 KiB

Open AccessArticle

Kinematics of Deformable Blocks: Application to the Opening of the Tyrrhenian Basin and the Formation of the Apennine Chain

by Eugenio Turco, Chiara Macchiavelli, Giulia Penza, Antonio Schettino and Pietro Paolo Pierantoni

Geosciences 2021, 11(4), 177; https://doi.org/10.3390/geosciences11040177 - 14 Apr 2021

Cited by 4 | Viewed by 3691

Abstract

We describe the opening of back-arc basins and the associated formation of accretionary wedges through the application of techniques of deformable plate kinematics. These methods have proven to be suitable to describe complex tectonic processes, such as those that are observed along the [...] Read more.

We describe the opening of back-arc basins and the associated formation of accretionary wedges through the application of techniques of deformable plate kinematics. These methods have proven to be suitable to describe complex tectonic processes, such as those that are observed along the Africa–Europe collision belt. In the central Mediterranean area, these processes result from the passive subduction of the lithosphere belonging to the Alpine Tethys and Ionian Ocean. In particular, we focus on the opening of the Tyrrhenian basin and the contemporary formation of the Apennine chain. We divide the area of the Apennine Chain and the Tyrrhenian basin into deformable polygons that are identified on the basis of sets of extensional structures that are coherent with unique Euler pole grids. The boundaries between these polygons coincide with large tectonic lineaments that characterize the Tyrrhenian–Apennine area. The tectonic style along these structures reflects the variability of relative velocity vectors between two adjacent blocks. The deformation of tectonic elements is accomplished, allowing different rotation velocities of lines that compose these blocks about the same stable stage poles. The angular velocities of extension are determined on the basis of the stratigraphic records of syn-rift sequences, while the rotation angles are obtained by crustal balancing. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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50 pages, 83282 KiB

Open AccessEditor’s ChoiceArticle

Constraining the Passive to Active Margin Tectonics of the Internal Central Apennines: Insights from Biostratigraphy, Structural, and Seismic Analysis

by Giovanni Luca Cardello, Giuseppe Vico, Lorenzo Consorti, Monia Sabbatino, Eugenio Carminati and Carlo Doglioni

Geosciences 2021, 11(4), 160; https://doi.org/10.3390/geosciences11040160 - 1 Apr 2021

Cited by 17 | Viewed by 5211

Abstract

The polyphase structural evolution of a sector of the internal Central Apennines, where the significance of pelagic deposits atop neritic carbonate platform and active margin sediments has been long debated, is here documented. The results of a new geological survey in the Volsci [...] Read more.

The polyphase structural evolution of a sector of the internal Central Apennines, where the significance of pelagic deposits atop neritic carbonate platform and active margin sediments has been long debated, is here documented. The results of a new geological survey in the Volsci Range, supported by new stratigraphic constraints from the syn-orogenic deposits, are integrated with the analysis of 2D seismic reflection lines and available wells in the adjacent Latin Valley. Late Cretaceous syn-sedimentary faults are documented and interpreted as steps linking a carbonate platform to the adjacent pelagic basin, located to the west. During Tortonian time, the pelagic deposits were squeezed off and juxtaposed as mélange units on top of the carbonate platform. Subsurface data highlighted stacked thrust sheets that were first involved into an initial in-sequence propagation with top-to-the-ENE, synchronous to late Tortonian foredeep to wedge-top sedimentation. We distinguish up to four groups of thrust faults that occurred during in-sequence shortening (thrusts 1–3; about 55–60 km) and backthrusting (thrust 4). During Pliocene to recent times, the area has been uplifted and subsequently extended by normal faults cross-cutting the accretionary wedge. Beside regional interest, our findings bear implications on the kinematic evolution of an orogenic wedge affected by far-traveled units. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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28 pages, 149108 KiB

Open AccessArticle

Lifecycle of an Intermontane Plio-Pleistocene Fluvial Valley of the Northern Apennines: From Marine-Driven Incision to Tectonic Segmentation and Infill

by Massimiliano Ghinassi, Mauro Aldinucci, Valeria Bianchi, Andrea Brogi, Enrico Capezzuoli, Tsai-Luen Yu and Chuan-Chou Shen

Geosciences 2021, 11(3), 141; https://doi.org/10.3390/geosciences11030141 - 18 Mar 2021

Cited by 6 | Viewed by 2902

Abstract

Downcutting and infill of incised valley systems is mostly controlled by relative sea-level changes, and studies on valley-fill successions accumulated independently from relative sea-level or lake-level oscillations are limited. This study focuses on the Plio-Pleistocene evolution of a fluvial drainage system developed in [...] Read more.

Downcutting and infill of incised valley systems is mostly controlled by relative sea-level changes, and studies on valley-fill successions accumulated independently from relative sea-level or lake-level oscillations are limited. This study focuses on the Plio-Pleistocene evolution of a fluvial drainage system developed in Southern Tuscany (Italy) following a regional marine forced regression at the end of Piacentian. Subsequent in-valley aggradation was not influenced by any relative sea-level rise, and valley morphological and depositional history mainly resulted from interaction between sediment supply and tectonic activity, which caused segmentation of the major valley trunk into localized subsiding depocenters separated by upwarping blocks. Fluvial sedimentation occurred until late Calabrian time, when the major river abandoned that valley, where minor fluvio-lacustrine depocenters allowed accumulation of siliciclastic and carbonate deposits. The present study demonstrates that the infill of the valley was not controlled by the forcing that caused its incision. Accumulation of the fluvial succession is discussed here in relation with localized, tectonic-controlled base levels, which commonly prevent from establishing of a clear downdip stratigraphic correlations. Chronological reconstruction of the study depositional dynamics provides solid constrains to frame them in the tectono-sedimentary evolution of the Northern Apennines. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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30 pages, 21785 KiB

Open AccessArticle

Burial-Deformation History of Folded Rocks Unraveled by Fracture Analysis, Stylolite Paleopiezometry and Vein Cement Geochemistry: A Case Study in the Cingoli Anticline (Umbria-Marche, Northern Apennines)

by Aurélie Labeur, Nicolas E. Beaudoin, Olivier Lacombe, Laurent Emmanuel, Lorenzo Petracchini, Mathieu Daëron, Sebastian Klimowicz and Jean-Paul Callot

Geosciences 2021, 11(3), 135; https://doi.org/10.3390/geosciences11030135 - 13 Mar 2021

Cited by 19 | Viewed by 3703

Abstract

Unravelling the burial-deformation history of sedimentary rocks is prerequisite information to understand the regional tectonic, sedimentary, thermal, and fluid-flow evolution of foreland basins. We use a combination of microstructural analysis, stylolites paleopiezometry, and paleofluid geochemistry to reconstruct the burial-deformation history of the Meso-Cenozoic [...] Read more.

Unravelling the burial-deformation history of sedimentary rocks is prerequisite information to understand the regional tectonic, sedimentary, thermal, and fluid-flow evolution of foreland basins. We use a combination of microstructural analysis, stylolites paleopiezometry, and paleofluid geochemistry to reconstruct the burial-deformation history of the Meso-Cenozoic carbonate sequence of the Cingoli Anticline (Northern Apennines, central Italy). Four major sets of mesostructures were linked to the regional deformation sequence: (i) pre-folding foreland flexure/forebulge; (ii) fold-scale layer-parallel shortening under a N045 σ₁; (iii) syn-folding curvature of which the variable trend between the north and the south of the anticline is consistent with the arcuate shape of the anticline; (iv) the late stage of fold tightening. The maximum depth experienced by the strata prior to contraction, up to 1850 m, was quantified by sedimentary stylolite paleopiezometry and projected on the reconstructed burial curve to assess the timing of the contraction. As isotope geochemistry points towards fluid precipitation at thermal equilibrium, the carbonate clumped isotope thermometry (Δ₄₇) considered for each fracture set yields the absolute timing of the development and exhumation of the Cingoli Anticline: layer-parallel shortening occurred from ~6.3 to 5.8 Ma, followed by fold growth that lasted from ~5.8 to 3.9 Ma. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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30 pages, 9659 KiB

Open AccessArticle

Stratigraphic and Tectonic Setting of the Liguride Units Cropping Out along the Southeastern Side of the Agri Valley (Southern Apennines, Italy)

by Giacomo Prosser, Giuseppe Palladino, Dario Avagliano, Francesco Coraggio, Eleonora Maria Bolla, Marcello Riva and Daniele Enrico Catellani

Geosciences 2021, 11(3), 125; https://doi.org/10.3390/geosciences11030125 - 9 Mar 2021

Cited by 10 | Viewed by 3072

Abstract

This paper shows the main results of a multidisciplinary study performed along the southeastern sector of the Agri Valley in Basilicata (Southern Italy), where Cenozoic units, crucial for constraining the progressive evolution of the Southern Apennine thrust and fold belt and, more in [...] Read more.

This paper shows the main results of a multidisciplinary study performed along the southeastern sector of the Agri Valley in Basilicata (Southern Italy), where Cenozoic units, crucial for constraining the progressive evolution of the Southern Apennine thrust and fold belt and, more in general, the geodynamic evolution of the Mediterranean area are widely exposed. In particular, we aimed at understanding the stratigraphic and tectonic setting of deep-sea, thrust-top Cenozoic units exposed immediately to north of Montemurro, between Costa Molina and Monte dell’Agresto. In the previous works different units, showing similar sedimentological characteristics but uncertain age attribution, have been reported in the study area. In our study, we focussed on the Albidona Formation, pertaining to the Liguride realm, which shows most significant uncertainties regarding the age and the stratigraphic setting. The study was based on a detailed field survey which led to a new geological map of the area. This was supported by new stratigraphic, biostratigraphic and structural analyses. Biostratigraphic analysis provided an age not older than the upper Ypresian and not younger than the early Priabonian. Recognition of marker stratigraphic horizons strongly helped in the understanding of the stratigraphy of the area. The study allowed a complete revision of the stratigraphy of the outcropping Cenozoic units, the recognition of until now unknown tectonic structures and the correlation between surface and subsurface geology. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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30 pages, 173941 KiB

Open AccessEditor’s ChoiceArticle

The Gavorrano Monzogranite (Northern Apennines): An Updated Review of Host Rock Protoliths, Thermal Metamorphism and Tectonic Setting

by Andrea Brogi, Alfredo Caggianelli, Domenico Liotta, Martina Zucchi, Amalia Spina, Enrico Capezzuoli, Alessandra Casini and Elena Buracchi

Geosciences 2021, 11(3), 124; https://doi.org/10.3390/geosciences11030124 - 8 Mar 2021

Cited by 11 | Viewed by 4860

Abstract

We review and refine the geological setting of an area located nearby the Tyrrhenian seacoast, in the inner zone of the Northern Apennines (southern Tuscany), where a Neogene monzogranite body (estimated in about 3 km long, 1.5 km wide, and 0.7 km thick) [...] Read more.

We review and refine the geological setting of an area located nearby the Tyrrhenian seacoast, in the inner zone of the Northern Apennines (southern Tuscany), where a Neogene monzogranite body (estimated in about 3 km long, 1.5 km wide, and 0.7 km thick) emplaced during early Pliocene. This magmatic intrusion, known as the Gavorrano pluton, is partially exposed in a ridge bounded by regional faults delimiting broad structural depressions. A widespread circulation of geothermal fluids accompanied the cooling of the magmatic body and gave rise to an extensive Fe-ore deposit (mainly pyrite) exploited during the past century. The tectonic setting which favoured the emplacement and exhumation of the Gavorrano pluton is strongly debated with fallouts on the comprehension of the Neogene evolution of this sector of the inner Northern Apennines. Data from a new fieldwork dataset, integrated with information from the mining activity, have been integrated to refine the geological setting of the whole crustal sector where the Gavorrano monzogranite was emplaced and exhumed. Our review, implemented by new palynological, petrological and structural data pointed out that: (i) the age of the Palaeozoic phyllite (hosting rocks) is middle-late Permian, thus resulting younger than previously described (i.e., pre-Carboniferous); (ii) the conditions at which the metamorphic aureole developed are estimated at a temperature of c. 660 °C and at a depth lower than c. 6 km; (iii) the tectonic evolution which determined the emplacement and exhumation of the monzogranite is constrained in a transfer zone, in the frame of the extensional tectonics affecting the area continuously since Miocene. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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22 pages, 8200 KiB

Open AccessArticle

Timing of Contractional Tectonics in the Miocene Foreland Basin System of the Umbria Pre-Apennines (Italy): An Updated Overview

by Francesco Brozzetti, Daniele Cirillo and Lucina Luchetti

Geosciences 2021, 11(2), 97; https://doi.org/10.3390/geosciences11020097 - 19 Feb 2021

Cited by 5 | Viewed by 2892

Abstract

A large dataset of lithostratigraphic and biostratigraphic data, concerning the Early-Late Miocene turbidite succession of the Umbria pre-Apennines, is presented and analyzed. The data come from the study of 24 sections that are representative of all the main tectonic units cropping out between [...] Read more.

A large dataset of lithostratigraphic and biostratigraphic data, concerning the Early-Late Miocene turbidite succession of the Umbria pre-Apennines, is presented and analyzed. The data come from the study of 24 sections that are representative of all the main tectonic units cropping out between the front of the Tuscan allochthon and the Umbria-Marche calcareous chain. The sections have been dated using quantitative calcareous nannofossil biostratigraphy and, wherever possible, they were correlated through key-beds recognition. Such a multidisciplinary approach allowed us to reconstruct the evolution of the Umbria foredeep over time and to unveil the chronology of compressive deformations by defining: (i) the onset of the foredeep stage in each structural unit, (ii) the age of depocenter-shifting from a unit to the adjacent one, (iii) the progressive deactivation of the western sector of the foredeep due to the emplacement of allochthon units, and (iv) the internal subdivisions of the basin due to the presence of foreland ramp faults or thrust-related structures. A further original outcome of our study is having brought to light the Late Burdigalian “out-of-sequence” reactivation of the Tuscan allochthon which bounded westward the foredeep, and the subsequent protracted period of tectonic stasis that preceded the deformations of the Umbrian parautochthon. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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24 pages, 7707 KiB

Open AccessArticle

Reconsidering the Variscan Basement of Southern Tuscany (Inner Northern Apennines)

by Enrico Capezzuoli, Amalia Spina, Andrea Brogi, Domenico Liotta, Gabriella Bagnoli, Martina Zucchi, Giancarlo Molli and Renzo Regoli

Geosciences 2021, 11(2), 84; https://doi.org/10.3390/geosciences11020084 - 12 Feb 2021

Cited by 12 | Viewed by 2712

Abstract

The Pre-Mesozoic units exposed in the inner Northern Apennines mostly consist of Pennsylvanian-Permian successions unconformably deposited on a continental crust consolidated at the end of the Variscan orogenic cycle (Silurian-Carboniferous). In the inner Northern Apennines, exposures of this continental crust, Cambrian?-Devonian in age, [...] Read more.

The Pre-Mesozoic units exposed in the inner Northern Apennines mostly consist of Pennsylvanian-Permian successions unconformably deposited on a continental crust consolidated at the end of the Variscan orogenic cycle (Silurian-Carboniferous). In the inner Northern Apennines, exposures of this continental crust, Cambrian?-Devonian in age, have been described in Northern Tuscany, Elba Island (Tuscan Archipelago) and, partly, in scattered and isolated outcrops of southern Tuscany. This paper reappraises the most significant succession (i.e., Risanguigno Formation) exposed in southern Tuscany and considered by most authors as part of the Variscan Basement. New stratigraphic and structural studies, coupled with analyses of the organic matter content, allow us to refine the age of the Risanguigno Fm and its geological setting and evolution. Based on the low diversification of palynoflora, the content of sporomorphs, the structural setting and the new field study, this formation is dated as late Tournaisian to Visean (Middle Mississippian) and is not affected by pre-Alpine deformation. This conclusion, together with the already existing data, clearly indicate that no exposures of rocks involved in the Variscan orogenesis occur in southern Tuscany. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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18 pages, 4192 KiB

Open AccessArticle

New Chronological Constraints from Hypogean Deposits for Late Pliocene to Recent Morphotectonic History of the Alpi Apuane (NW Tuscany, Italy)

by Ilaria Isola, Francesco Mazzarini, Giancarlo Molli, Leonardo Piccini, Elena Zanella, Giovanni Zanchetta, Russell Drysdale, John Hellstrom, Jon Woodhead, Adriano Roncioni, Flavio Milazzo, Diego Pieruccioni and Eleonora Regattieri

Geosciences 2021, 11(2), 65; https://doi.org/10.3390/geosciences11020065 - 2 Feb 2021

Cited by 5 | Viewed by 2396

Abstract

A sedimentary sequence of fluvial deposits preserved in the Corchia Cave (Alpi Apuane) provides new chronological constraints for the evolution of the cave system and the timing and rate of uplift of this sector of the Alpi Apuane since the late Pliocene. Supported [...] Read more.

A sedimentary sequence of fluvial deposits preserved in the Corchia Cave (Alpi Apuane) provides new chronological constraints for the evolution of the cave system and the timing and rate of uplift of this sector of the Alpi Apuane since the late Pliocene. Supported by magnetostratigraphic analysis performed on fine-grained fluvial deposits, and by radiometric dating of speleothems, we suggest that the deposition of fluvial sediments occurred between ~1.6–1.2 Ma. This implies that the host volume of rock was already located close to the local base level, adding key information about the recent tectonic evolution of the Alpi Apuane. A few before ~1 Ma, an erosive phase occurred due to the base-level lowering, followed by continuous speleothem deposition since at least 0.97 Ma. From that time, Monte Corchia uplifted at a maximum rate of ~0.5 mm/year, which is consistent with isostatic uplift mainly driven by erosional unloading. The petrographical study of the fluvial deposits highlights the presence of material derived from the erosion of rocks that today are absent in the cave’s catchment area, suggesting a different surface morphology during the Early Pleistocene. This study highlights the potential of cave sediments as archives for reconstructing the uplift history of mountain ranges. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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19 pages, 10967 KiB

Open AccessArticle

Miocene Seep-Carbonates of the Northern Apennines (Emilia to Umbria, Italy): An Overview

by Stefano Conti, Claudio Argentino, Chiara Fioroni, Aura Cecilia Salocchi and Daniela Fontana

Geosciences 2021, 11(2), 53; https://doi.org/10.3390/geosciences11020053 - 28 Jan 2021

Cited by 10 | Viewed by 2997

Abstract

The natural emission of methane-rich fluids from the seafloor, known as cold seepage, is a widespread process at modern continental margins. The studies on present-day cold seepages provide high-resolution datasets regarding the fluid plumbing system, biogeochemical processes in the sediment, seafloor seepage distribution [...] Read more.

The natural emission of methane-rich fluids from the seafloor, known as cold seepage, is a widespread process at modern continental margins. The studies on present-day cold seepages provide high-resolution datasets regarding the fluid plumbing system, biogeochemical processes in the sediment, seafloor seepage distribution and ecosystems. However, the long-term (hundreds of thousands to millions of years) evolution of cold seepage remains elusive. The identification and study of outcrop analogous now exposed on land represent a valuable method for better understanding the effects of geological processes and climate forcing on the development of cold seepage systems. Here, we provide an overview on Miocene seep-carbonate deposits of the northern Apennines (from Emilia to the Umbria-Marchean sector, Italy), based on decades of field research integrated with detailed sedimentological and geochemical investigations. We report a total of 13 seep-carbonate outcrops, which formed in three different structural settings of the paleo-accretionary wedge corresponding to wedge-top basins, outer slope and intrabasinal highs at the deformational front. We discuss the recurring lithostratigraphic occurrence of seep deposits and the main compositional features (carbonate facies, carbon and oxygen stable isotopes) in order to interpret the seepage dynamics, duration and infer the contribution of methane-rich fluids released by paleo-gas hydrates. The datasets presented in this study represent a valuable complete record of cold seepage spanning ~12 Myr, that can be used to better understand factors controlling the regional-scale spatial and temporal evolution of cold seepage systems at modern active continental margins. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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23 pages, 15466 KiB

Open AccessEditor’s ChoiceArticle

Structural and Stratigraphic Setting of Campagna and Giffoni Tectonic Windows: New Insights on the Orogenic Evolution of the Southern Apennines (Italy)

by Stefano Vitale, Ernesto Paolo Prinzi, Maria Monda, Francesco D’Assisi Tramparulo and Sabatino Ciarcia

Geosciences 2020, 10(10), 405; https://doi.org/10.3390/geosciences10100405 - 10 Oct 2020

Cited by 3 | Viewed by 2987

Abstract

We present a structural study on the tectonic windows of Giffoni and Campagna, located in the western sector of the southern Apennines (Italy). We analyzed thrusts, folds, and related minor deformation structures. Here, a major in-sequence E-verging thrust fault juxtaposes Meso-Cenozoic successions of [...] Read more.

We present a structural study on the tectonic windows of Giffoni and Campagna, located in the western sector of the southern Apennines (Italy). We analyzed thrusts, folds, and related minor deformation structures. Here, a major in-sequence E-verging thrust fault juxtaposes Meso-Cenozoic successions of the Apennine Platform (Picentini Mts unit) and the Lagonegro-Molise Basin (Frigento unit). However, out-of-sequence thrusts duplicated the tectonic pile with the interposition of the upper Miocene wedge-top basin deposits of the Castelvetere Group. We reconstructed the orogenic evolution of these two tectonic windows, including five deformation phases. The first (D1) was related to the in-sequence thrusting with minor thrusts and folds, widespread both in the footwall and the hanging wall. A subsequent extension (D2) has formed normal faults crosscutting the D1 thrusts and folds. All structures were subsequently affected by two shortening stages (D3 and D4), which also deformed the upper Miocene wedge top basin deposits of the Castelvetere Group. We interpreted the D3–D4 structures as related to an out-of-sequence thrust system defined by a main frontal E-verging thrust and lateral ramps characterized by N and S vergences. Low-angle normal faults were formed in the hanging wall of the major thrusts. Out-of-sequence thrusts are observed in the whole southern Apennines, recording a crustal shortening event that occurred in the late Messinian–early Pliocene. Finally, we suggest that the two tectonic windows are the result of the formation of an E–W trending regional antiform, associated with a late S-verging back-thrust, that has been eroded and crosscut by normal faults (D5) in the Early Pleistocene. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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26 pages, 17807 KiB

Open AccessArticle

The Capo Castello Shear Zone (Eastern Elba Island): Deformation at the Contact between Oceanic and Continent Tectonic Units

by Caterina Bianco

Geosciences 2020, 10(9), 361; https://doi.org/10.3390/geosciences10090361 - 10 Sep 2020

Cited by 1 | Viewed by 3468

Abstract

Low-grade mylonitic shear zones are commonly characterized by strain partitioning, with alternating low strain protomylonite and high strain mylonite and ultramylonite, where the shearing is most significant. In this paper the capo Castello shear zone is analyzed. It has developed along the contact [...] Read more.

Low-grade mylonitic shear zones are commonly characterized by strain partitioning, with alternating low strain protomylonite and high strain mylonite and ultramylonite, where the shearing is most significant. In this paper the capo Castello shear zone is analyzed. It has developed along the contact between continental quartzo-feldspathic, in the footwall, and oceanic ophiolitic units, in the hangingwall. The shear zone shows, mostly within the serpentinites, a heterogeneous strain localization, characterized by an alternation of mylonites and ultramylonites, without a continuous strain gradient moving from the protolith (i.e., the undeformed host rock) to the main tectonic contact between the two units. The significance of this mylonitic shear zone is examined in terms of the dominant deformation mechanisms, and its regional tectonic frame. The combination of the ultramafic protolith metamorphic processes and infiltration of derived fluids caused strain softening by syntectonic metamorphic reactions and dissolution–precipitation processes, leading to the final formation of low strength mineral phases. It is concluded that the strain localization, is mainly controlled by the rock-fluid interactions within the ophiolitic level of the Capo Castello shear zone. Regarding the regional setting, this shear zone can be considered as an analogue of the initial stage of the post-collisional extensional fault, of which mature stage is visible along the Zuccale fault zone, a regional structure affecting eastern Elba Island. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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25 pages, 11073 KiB

Open AccessEditor’s ChoiceArticle

Late Miocene-Early Pliocene Out-of-Sequence Thrusting in the Southern Apennines (Italy)

by Stefano Vitale, Ernesto Paolo Prinzi, Francesco D’Assisi Tramparulo, Claudio De Paola, Rosa Di Maio, Ester Piegari, Monia Sabbatino, Jacopo Natale, Pasqualino Notaro and Sabatino Ciarcia

Geosciences 2020, 10(8), 301; https://doi.org/10.3390/geosciences10080301 - 6 Aug 2020

Cited by 16 | Viewed by 4092

Abstract

We present a structural study on late Miocene-early Pliocene out-of-sequence thrusts affecting the southern Apennine orogenic belt. The analyzed structures are exposed in the Campania region (southern Italy). Here, thrusts bound the N-NE side of the carbonate ridges that form the regional mountain [...] Read more.

We present a structural study on late Miocene-early Pliocene out-of-sequence thrusts affecting the southern Apennine orogenic belt. The analyzed structures are exposed in the Campania region (southern Italy). Here, thrusts bound the N-NE side of the carbonate ridges that form the regional mountain backbone. In several outcrops, the Mesozoic carbonates are superposed onto the unconformable wedge-top basin deposits of the upper Miocene Castelvetere Group, providing constraints to the age of the activity of this thrusting event. Moreover, a 4-km-long N-S oriented electrical resistivity tomography profile, carried out along the Caserta mountains, sheds light on the structure of this thrust system in an area where it is not exposed. Further information was carried out from a tunnel excavation that allowed us to study some secondary fault splays. The kinematic analysis of out-of-sequence major and minor structures hosted both in the hanging wall (Apennine Platform carbonates) and footwall (Castelvetere Group deposits and Lagonegro-Molise Basin units) indicates the occurrence of two superposed shortening directions, about E-W and N-S, respectively. We associated these compressive structures to an out-of-sequence thrusting event defined by frontal thrusts verging to the east and lateral ramp thrusts verging to the north and south. We related the out-of-sequence thrusting episode to the positive inversion of inherited normal faults located in the Paleozoic basement. These envelopments thrust upward to crosscut the allochthonous wedge, including, in the western zone of the chain, the upper Miocene wedge-top basin deposits. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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26 pages, 12224 KiB

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The Alps-Apennines Interference Zone: A Perspective from the Maritime and Western Ligurian Alps

by Fabrizio Piana, Luca Barale, Carlo Bertok, Anna d’Atri, Andrea Irace and Pietro Mosca

Geosciences 2021, 11(5), 185; https://doi.org/10.3390/geosciences11050185 - 25 Apr 2021

Cited by 7 | Viewed by 3389

Abstract

In SW Piemonte the Western Alps arc ends off in a narrow, E-W trending zone, where some geological domains of the Alps converged. Based on a critical review of available data, integrated with new field data, it is concluded that the southern termination [...] Read more.

In SW Piemonte the Western Alps arc ends off in a narrow, E-W trending zone, where some geological domains of the Alps converged. Based on a critical review of available data, integrated with new field data, it is concluded that the southern termination of Western Alps recorded the Oligocene-Miocene activity of a regional transfer zone (southwestern Alps Transfer, SWAT) already postulated in the literature, which should have allowed, since early Oligocene, the westward indentation of Adria, while the regional shortening of SW Alps and tectonic transport toward the SSW (Dauphinois foreland) was continuing. This transfer zone corresponds to a system of deformation units and km-scale shear zones (Gardetta-Viozene Zone, GVZ). The GVZ/SWAT developed externally to the Penninic Front (PF), here corresponding to the Internal Briançonnais Front (IBF), which separates the Internal Briançonnais domain, affected by major tectono-metamorphic transformations, from the External Briançonnais, subjected only to anchizonal metamorphic conditions. The postcollisional evolution of the SW Alps axial belt units was recorded by the Oligocene to Miocene inner syn-orogenic basin (Tertiary Piemonte Basin, TPB), which rests also on the Ligurian units stacked within the adjoining Apennines belt in southern Piemonte. The TPB successions were controlled by transpressive faults propagating (to E and NE) from the previously formed Alpine belt, as well as by the Apennine thrusts that were progressively stacking the Ligurian units, resting on the subducting Adriatic continental margin, with the TPB units themselves. This allows correlation between Alps and Apennines kinematics, in terms of age of the main geologic events, interference between the main structural systems and tectonic control exerted by both tectonic belts on the same syn-orogenic basin. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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31 pages, 17606 KiB

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Active Fault Systems in the Inner Northwest Apennines, Italy: A Reappraisal One Century after the 1920 Mw ~6.5 Fivizzano Earthquake

by Giancarlo Molli, Isabelle Manighetti, Rick Bennett, Jacques Malavieille, Enrico Serpelloni, Fabrizio Storti, Tiziano Giampietro, Aurelien Bigot, Gabriele Pinelli, Serena Giacomelli, Alessio Lucca, Luca Angeli and Lorenzo Porta

Geosciences 2021, 11(3), 139; https://doi.org/10.3390/geosciences11030139 - 18 Mar 2021

Cited by 12 | Viewed by 4857

Abstract

Based on the review of the available stratigraphic, tectonic, morphological, geodetic, and seismological data, along with new structural observations, we present a reappraisal of the potential seismogenic faults and fault systems in the inner northwest Apennines, Italy, which was the site, one century [...] Read more.

Based on the review of the available stratigraphic, tectonic, morphological, geodetic, and seismological data, along with new structural observations, we present a reappraisal of the potential seismogenic faults and fault systems in the inner northwest Apennines, Italy, which was the site, one century ago, of the devastating Mw ~6.5, 1920 Fivizzano earthquake. Our updated fault catalog provides the fault locations, as well as the description of their architecture, large-scale segmentation, cumulative displacements, evidence for recent to present activity, and long-term slip rates. Our work documents that a dense network of active faults, and thus potential earthquake fault sources, exists in the region. We discuss the seismogenic potential of these faults, and propose a general tectonic scenario that might account for their development. Full article

(This article belongs to the Special Issue The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present)

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