In this study we combine observations and analytical data from large-scale (10–100s of m-thick and 100 m 2 -extensive), siliciclastic and carbonate MTD/MTCs belonging to the Oligocene – Miocene foredeep and wedge-top suc-cessions of the Northern Apennines and the Paleocene – Eocene Friuli basin of the northwestern Dinarides (Italy and Slovenia), to discuss the deformation processes critical to the emplacement of submarine landslides. We focus on the identification of meso-scale structures, used as diagnostic kinematic indicators of local paleo-transport directions. These structures, represented by linear-planar and complex-shaped elements such as tabular shear zones and detached slump-type folds, are the product of ductile-plastic deformation developed at relatively low-confining pres-sure that involves water-saturated, un-to poorly-lithified sediments, along with liquefaction/fluidization processes. Their final appearance is thus mainly controlled by the mechanical-rheological behavior of deformed sediments, and eventually by tectonic fabrics inherited from deeper structural levels of deformation. Due to this parallelism these structures have been termed and classified accordingly. They reflect strain partitioning due to differential movements within the slide mass, which is in turn controlled by the overall landslide typology. Due to the parallelism with classified tectonic structures and structural associations, we have thus redefined and classified accordingly meso-scale kinematic indicators in ancient MTD/MTCs. Geophysical imaging of modern seafloor surface and subsurface provide the gross morphology, areal extent and overall internal character of single mass transport deposits (MTDs) and composite mass transport complex (MTCs), outlining their importance in practical terms, such as offshore hydrocarbon exploration/production and coastal geohazard assessment/evaluation (see e.g. Kawamura et al. 2012). Con-versely outcrop studies on exhumed " fossil " analogues, allow analyses on the internal deformation mechanisms from micro-to map-(i.e. seismic) scale (see e.g. Lucente and Pini 2003; Alonso et al. 2006; Yamamoto et al. 2009; Ogata et al. 2012). Although scientific drilling provides crucial insights on the anatomy of modern MTD (see e.g. Strasser et al. 2011), the available data are still too punctual, and costly to provide a comprehensive source of information, especially on meso-scale structures, which record the main trace of mass transport-related deformation processes. We here focus on the meso-scale, syn-sedimentary structures, which spatial-geometric relationships are considered to record the strain direction achieved during and/or immediately after the slide body deposition. Such structures represent impor-tant kinematic indicators that can be integrated to unravel the local paleo-transport direction and the internal deformation processes of the slide mass. In this paper we analyze some ancient, seismic-scale MTDs/MTCs analogues, exhumed in the Oligo-cene – Miocene foredeep and wedge-top sedimentary successions of the Northern Apennines, and the Paleocene – Eocene Friuli basin of the northwestern Dinarides (Fig. 46.1a–c; Italy and Slovenia), expanding punctual observations to a broader and more general picture. The systematic occurrence of the described features in basically all the investigated siliciclastic and carbonate examples justifies this effort.
|Name||Advances in Natural and Technological Hazards Research|
- Exhumed mass transport deposits
- Kinematic indicators
- Soft-sediment deformation
- Syn-sedimentary structures