**Preface to "The Apennines: Tectonics, Sedimentation, and Magmatism from the Palaeozoic to the Present"**

This Special Issue of Geosciences consists of a selection of papers, some of them presented at the International Meeting EGU 2020 in the session: "Apennines tectonics, magmatism and sedimentation: from Permian to Present". This session emphasized the necessity of a multidisciplinary and integrated approach to the study of the Apennines and the related crustal structures.

Papers included in this Special Issue deal with structural, stratigraphic, geochemical and geophysical methods, and cover arguments from local to regional scale, investigating different sectors of the Apennines (Figure 1) and their role from pre-orogenic to late- and post-orogenic stages during belt's evolution.

**Figure 1.** Numbers are the same of the references list, indicating the areas where the papers of this special issue are related. Modified after Google Earth 2018.

The completeness of the information collected in this book, makes it an optimal revision and implementation of the knowledge for the entire Apennines, as also shown by the location of the different study areas, distributed throughout the entire belt.

The geodynamic context is investigated by Turco et al. [1], proposing a reconstruction on the coeval development of the Tyrrhenian Basin and Apennines, from Oligocene to present. This is based on the assumption that different crustal blocks, delimited by shear zones and involved in the tectonic evolution, rotated under the same Eulero pole. Values at the base of this study are interestingly obtained from balanced crustal geological sections and stratigraphic data.

A multidisciplinary approach to unravel the evolution of the Apennines from Cretaceous to present is then presented by Cardello et al. [2]. These Authors deal with central Apennines, with emphasis on thrust evolution and inheritance of extensional structures, a crucial theme in the frame of the Alpine-Apenninic orogeny.

The relationships between Alps and Apennines are faced by Piana et al. [3]. These Authors conclude accounting for the role of a regional Oligocene–Miocene transfer zone which favored the Adria indentation and drastically influenced kinematics and tectono-metamorphic evolution of the involved tectonic units.

Regarding the northern Apennines, a long-lasting issue on the age and evolution of the Paleozoic basement cropping out in Tuscany is discussed by Capezzuoli et al. [4]. The new investigations on palynoflora and sporomorphs, joined with original structural studies, relate these Paleozoic rocks to the Middle Mississippian and exclude their involvement in the Hercynian deformation.

Several contributions are concerned with tectonics and sedimentation relationships in the outer zone of Apennines.

Brozzetti et al. [5] illustrate the Miocene foredeep evolution, providing paleontological, sedimentary, and structural data to constrain the timing and reconstruct the evolution of the compressional deformations in the central part of the northern Apennines.

The same time-span is investigated by Conti et al. [6], discussing the seep-carbonates cropping out in the outer zone of the northern Apennines. These Authors integrate sedimentary, geochemical, and paleontological data, providing a unique dataset for cold seepage systems, with fallouts for the understanding of the modern carbonates, located in comparable tectonic settings.

Costa et al. [7] discuss the relationships between sedimentation and tectonics during the Pliocene–Quaternary in the outermost (i.e., eastern) part of northern Apennines. This work integrates field and geophysical data, and highlights the relationships between negative vs. positive reactivation of inherited structures in this part of the Apennine fold and thrust belt.

A study, reconstructing the burial-deformation history of sedimentary rocks in outer zones of the Apenninic Chain (Cingoli anticline), is then provided by Labeur et al. [8]. The work is based on the combination of geochemical and microstructural analysis, allowing to identify the effects of the regional tectonics from layer-parallel shortening to fold growth.

Three different contributions describing crucial issues in the tectono-stratigraphic evolution of the southern Apennines are also included in this Special Issue.

Based on a multidisciplinary approach involving field mapping, structural geology, biostratigraphy, and geophysical methods, Prosser et al. [9] shed light on the age and structural setting of crucial deposits belonging to the Tethyan oceanic cover (i.e., Albidona formation). Surface geology, coupled with subsurface data, has allowed the Authors to better define the stratigraphic features of the Albidona Formation, and to provide an updated review on the tectonic setting of the well-known Agri Valley.

In the same line of innovation, Vitale et al. [10,11] present two contributions on the inner part of southern Apennines. The Authors analyze compressional deformation structures in several key-areas of the western part of the southern Apennines. A detailed kinematic, structural and stratigraphic approach permitted to define the timing of in- and out-of-sequence thrusts, thus better explaining the relationships among the geological bodies of southern Apennines.

Geological features related to the extensional tectonics affecting the inner zone of the northern Apennines are reported by Bianco [12], who studied a Miocene extensional shear zone, precursor of other regional low angle normal faults. The microstructural study highlighted the role of the strain partitioning and of the fluid assisted deformation during this extensional event.

Inland Pliocene extension is accompanied by magmatism. The relationships between magma emplacement and structures is discussed in Brogi et al. [13], who describe the role of the transfer zones and their internal deformation to favor up flow of magmatic, deep fluids in localized, fracture-controlled, permeable sectors.

Effects of extensional tectonics in recent times are then investigated by Ghinassi et al. [14], who applied a multidisciplinary approach based on stratigraphy, dating analyses and structural geology to depict the tectonic control on fluvial tracks, by studying a key area where one of the main Italian river changed its flow direction.

The morphogenetic stage of the evolution of the inner NW zone of the Northern Apennines is described by Isola et al. [15]. They constrained the uplift of the Alpi Apuane region, joining structural and sedimentological analyses in caves with speleothem dating. Hence, indications for the erosion rate during the Late Neogene uplift of the inner NW Apennines belt is provided.

Finally, Molli et al. [16], one century after the 1920 Mw 6.5 Fivizzano earthquake, presented a reappraisal of the potentially seismogenic faults and fault systems of this sector of the inner northern Apennines, reviewing existing data along with new observations. The result is an integrated approach, leading to a catalog of active faults and a new tectonic scenario accounting for their development.

> **Domenico Liotta, Giancarlo Molli, Angelo Cipriani** *Editors*
