Liquification and soft-sediment deformation in a limestone megabreccia: The Ayabacas giant collapse, Cretaceous, southern Peru

Geomorphologic features related to gravitational collapse: Submarine landsliding to lateral spreading on a Late Miocene–Quaternary slope (SE Crete, eastern Mediterranean)

“…8, 10, and 11). These features are very similar to what is observed, for instance, in the Ayabacas Formation in Peru (Callot et al 2008b). Some significant similarities with the Cretan collapse features are observed in Peru: i) siliciclastic materials were in a plastic state during gravitational collapse, ii) carbonate megablocks were relatively more lithified, and iii) the presence of clay in the matrix of megablocks is also recorded onshore Peru.…”

Distribution and characterization of failed (mega)blocks along salt ridges, southeast Brazil: Implications for vertical fluid flow on continental margins

“…Other possibility is that the more deformed blocks result from squeezing of softer material between less competent strata (Figure 7d). The latter is also supported by published works of onshore fossil MTDs that have documented the presence of both brittle and ductile block deformation occurring close together due to contrasting sediment cementation [Callot et al, 2008;Odonne et al, 2011]. This has also been associated with the block sedimentary composition, but there is no indicator that such could be the case in MTD-A1.…”

“…In fact, the internal deformation in MTD-A1 is likely to be more intense than what is observed on seismic data as faults are also commonly surrounded by subseismic scale damage zones [e.g., Knipe et al, 1998;Zhang et al, 2010]. Outcrop-and corebased studies have also shown the degree of complex brittle and ductile deformation within MTDs and these can replicate at variable scales [Callot et al, 2008]. The development of microfractures is common in these deposits [Tripsanas et al, 2008], especially in higher cohesion sediments.…”

“…When derived from distinct sources, often due to tectonically influenced topographic oversteepening and failure, the components are likely to exhibit both distinct lithogical compositions and bulk deformation styles [e.g., Callot et al, 2008]. As the subseismic deformation often mimics large scale features [Callot et al, 2008], on-land slabs can be used to estimate smaller features present in submarine slide blocks.…”

“…Fractures within rafted blocks commonly develop upon the initial failure [Alves and Lourenço, 2010] but the effects of shear stress during transport must also be considered, regardless of the travel distances, which can either enhance previous fracturing or develop new ones [Alves and Lourenço, 2010;Lucente and Pini, 2003]. This, associated with overpressure along the basal shear zone, favors the formation of clastic injectites propagating upwards either through the heterogeneous MTD matrix or tensile fractures in the block base [Alves and Lourenço, 2010;Butler and McCaffrey, 2010;Callot et al, 2008]. Clastic injectites are particularly important for smaller scale fluid flow within failed strata as they form good fluid conduits which can have higher permeability than their source beds [Odonne et al, 2011].…”