Journal of Structural Geology 163 (2022) 104711 Available online 29 August 2022 0191-8141/© 2022 Published by Elsevier Ltd. Evidence for Triassic contractional tectonics in the Northern Dolomites (Southern Alps, Italy) Eugenio Carminati a, * , Carlo Doglioni a, b a Dipartimento di Scienze della Terra, Sapienza Universit` a di Roma, Rome, Italy b INGV, Istituto Nazionale di Geofsica e Vulcanologia, Rome, Italy A R T I C L E INFO Keywords: Triassic Folding Thrusting dolomites Olistholith ABSTRACT The occurrence of Middle Triassic extensional and strike-slip tectonics has been widely recognized in the Do- lomites and is supported by stratigraphic evidence. Contrarily, the recognition of Triassic contractional tectonic structures is less straightforward because such structures were heavily superimposed by Neogene Alpine shortening. In this work we provide a detailed analysis of a top-class outcrop displaying a syn-sedimentary Middle Triassic extensional fault that displaces a coeval sedimentary m´ elange containing an olistholith of Lower Triassic rocks, characterized by Triassic contractional structures (folds, axial plane cleavage, joints, local thrust faults orna- mented with slickenfbers and associated with forced folds). In particular, integrating geological feld mapping and structural analyses, structural analyses on a 3D virtual outcrop model and microstructural analyses, we demonstrate that: 1) the orientation of tectonic structures in the olistholith is at odd with that of regional structures, implying that deformation occurred prior to deposition of the melange; 2) folds and small-scale thrusts in the olistholith developed in lithifed rocks, pointing to the existence of Middle Triassic fold and thrust tectonics. In summary, the tectonic structures in the analyzed olistholith represent an outstanding, possibly unique, example of fully preserved, practically frozen, Middle Triassic contractional structures. 1. Introduction Since the XIX century the Dolomites, owing to their spectacular landscapes and outcrops, are a worldwide reference area for the re- lationships between magmatism, sedimentation, and tectonics (e.g., Von Richthofen, 1860; Hansel, 1878; Ogilvie-Gordon, 1902, 1903; Varda- basso, 1929, 1930; Leonardi, 1967). Although a Middle Triassic tectono-magmatic event is well known from nearly two centuries (e.g., Von Richthofen, 1860; Vardabasso, 1930), the geodynamic and tectonic framework for this event, associated with fast subsidence but also with local uplift, is far from being unravelled (e.g., Lustrino et al., 2019 and discussion therein). Petrographic data point to an “orogenic” character (typical of oceanic subduction) of the Dolomites Triassic magmatic rocks (Garzanti 1985; Castellarin et al., 1988), while structural data rather indicate extensional and strike-slip tectonics with local transtensional or transpressional deformation (Doglioni, 1983, 1984a,b; Castellarin et al., 1998a,b,c; Caputo et al., 1999) in a rifting (Beltran-Trivin˜ o et al., 2016; Brandner et al., 2016) or aborted rifting (Bechstadt et al., 1977) scenario. Much of the debate stems from the diffculty to constrain Middle Triassic tectonics, since Triassic faults in the Dolomites are frequently reactivated by Alpine contractional deformation and can be mainly recognized from differences in thickness or facies of sediments (Gianolla et al., 1998, 2008; Bosellini et al., 2003). Middle Triassic syn-sedimentary tectonics, including both contrac- tional and extensional structures, were described in different papers some 40 years ago for the Arabba-Varda-Livinallongo (AVL in the following) (Bosellini et al., 1982a; Doglioni, 1982) and adjoining (e.g., Pisa et al., 1980; Doglioni, 1984b, 1987) areas, but no later studies were done to discuss in detail such structures. Middle Triassic syn-sedimentary tectonics and contractional tectonics have always puzzled Dolomites geologists. Mesoscale folds and doublings in the area and in the Dolomites in general were differently interpreted and ascribed to thrust or transpressional tectonics (e.g., Doglioni, 1987) or gravity tectonics and soft sediment deformation induced by diapirism (e. g., Castellarin et al., 1998b). In this work we propose a reappraisal of Middle Triassic tectonics in * Corresponding author. Dipartimento di Scienze della Terra, Sapienza Universit` a di Roma, P.le Aldo Moro 5, I-00185, Roma, Italy. E-mail address: eugenio.carminati@uniroma1.it (E. Carminati). Contents lists available at ScienceDirect Journal of Structural Geology journal homepage: www.elsevier.com/locate/jsg https://doi.org/10.1016/j.jsg.2022.104711 Received 9 May 2022; Received in revised form 18 August 2022; Accepted 23 August 2022