Myths and recent progress regarding the Argille Scagliose, Northern Apennines, Italy

Abstract

Argille scagliose (scaly clay) is a geological term first used in 1840 to describe rocks in the Northern Apennines of Italy. The term was originally created to stress the mesoscopic scaliness of a type of rock that commonly outcrops in this area. The rock is also typified by a chaotic assemblage of blocky components that are embedded within the scaly matrix. Before the advent of plate tectonic concepts, the extreme complexity of these rocks posed an extreme challenge to interpret with then-standard concepts of deposition processes in sedimentary basins. Similar rocks were recognized in many other mountain belts, thus the term became widely used. At the same time, the emphasis of the term changed from a description of the matrix to a term with multiple, intensely debated, genetic associations. Only after the discovery of plate tectonics was it accepted that these rocks are formed at subduction boundaries, and that the multiple types of embedded blocks can have an origin from both slope-instabilities within an accretionary prism, and from tectonic reworking/deformation processes near the base of an active accretionary prism. This paper reconstructs the scientific evolution of thinking about argille scagliose during the years when it was one of the supreme challenges to sedimentary geologists. The often strong debate between competing hypotheses for the origin of these rocks led to many myths that still outcrop in the geological literature. We explore why this happened, the apparent future of modern research on chaotic rocks in the Apennines and other fossil accretionary prisms, and what is and should productively remain from the long geological controversy over argille scagliose.

Mechanisms and processes of stratal disruption and mixing in the development of mélanges and broken formations: Redefining and classifying mélanges

“…This definition implies that the term mélange can be used only, at least in part, as a synonym of complex (see Salvador, 1994). However, the controversial definition of complex, as a lithodeme subunit (NACSN, 2005), suggests a mostly tectonic origin of its contacts (see also Pasquarè et al, 1992;Vannucchi and Bettelli, 2010). The term complex, however, is also a formal lithostratigraphic term, defining any rock body that is characterized by complicated deformation patterns and bounded by primary (i.e.…”

“…Yet, the debate and discussions on the mélange concept continue after nearly four decades of extensive studies of mélanges and related rock units around the world (Silver and Beutner, 1980;Raymond, 1984;Rast and Horton, 1989;Wakabayashi and Dilek, 2011). We refer the reader to Hsü (1968), Cowan (1974Cowan ( , 1985, Raymond (1984), Suzuki (1986), Rast and Horton (1989), Pini (1999), Şengör (2003), Camerlenghi andPini (2009), Festa et al (2010a), Vannucchi and Bettelli (2010), Wakabayashi and Dilek (2011) and Ogata et al (2012b) for various discussions on the conflicting uses of the term mélange.…”

“…3C) (e.g., Pini, 1999;Vannucchi and Bettelli, 2010), part of the Argille Varicolori and "Flysch Rosso" (Figs. 3A and 3B) in the Central-Southern Apennines (Festa et al, 2010a(Festa et al, , 2010bVezzani et al, 2010), the Costal Range mélange of Hikurangi margin, and the Esk Head (Fig.…”

Jurassic syn-rift and Cretaceous syn-orogenic, coarse-grained deposits related to opening and closure of the Vahic (South Penninic) Ocean in the Western Carpathians – an overview

“…For re cent com pre hen sive re views of lit er a ture sources, termi nol ogy, as so ci a tions and pro cesses re lated to mass-trans port de pos its, or mélanges in gen eral, the reader is rec om mended espe cially to pa pers by Mutti et al (2009), Camerlenghi and Pini (2009), Fes ta et al (2010a, Vannucchi and Bettelli (2010) and Pini et al (2012), and to the ref er ences quoted therein.…”

Origin and assessment of deep groundwater inflow in the Ca' Lita landslide using hydrochemistry and in situ monitoring

“…Moving towards the middle-front portion of the wedge, the SV and LU units can be considered impermeable (Vannucchi and Bettelli, 2010). Starting from the 1950s, the LU has been subjected to several drilling campaigns for intensive hydrocarbon investigations, whose results are collected inside the national VIDEPI Project database (UNIMIG, 2007).…”