Mélanges originated from sedimentary processes (sedimentary mélanges) and olistostromes are frequently present in mountain chains worldwide. They are excellent fossil examples of mass-transport complexes (MTC), often cropping out in well-preserved and laterally continuous exposures. In this article we will show the results of the integrated study of fossil MTCs, including sedimentary mélanges/olistostromes, with a focus on the Apennines of Italy. Fossil MTCs, especially the basin-wide ones, are composite and multi-event units involving the entire spectra of mass-transport processes. The down-slope motion of these bodies is enabled by the relative movement of discrete masses, with progressive stratal disruption of rocks/sediment involved and flow transformation. Three kinds of MTC are here distinguished, in which the movements are enabled by 1) shear-dominated viscous flows within a muddy matrix, 2) mud-silt-sandy matrix sustained by fluid overpressure, 3) concentrated shear zones/surfaces with advection of grains and fluid (overpressured basal carpets). These MTC types may represent end-members of a continuum of products and correspond to different kinematics of transport and emplacement and to different relationship with the substratum. These observations should result in a better knowledge of mass-transport processes and bodies, in relation with the basin floor geometry.

Chapter 52. Sedimentary Mélanges and Fossil Mass-Transport Complexes: A Key for Better Understanding Submarine Mass Movements?

Camerlenghi, Angelo
2012

Abstract

Mélanges originated from sedimentary processes (sedimentary mélanges) and olistostromes are frequently present in mountain chains worldwide. They are excellent fossil examples of mass-transport complexes (MTC), often cropping out in well-preserved and laterally continuous exposures. In this article we will show the results of the integrated study of fossil MTCs, including sedimentary mélanges/olistostromes, with a focus on the Apennines of Italy. Fossil MTCs, especially the basin-wide ones, are composite and multi-event units involving the entire spectra of mass-transport processes. The down-slope motion of these bodies is enabled by the relative movement of discrete masses, with progressive stratal disruption of rocks/sediment involved and flow transformation. Three kinds of MTC are here distinguished, in which the movements are enabled by 1) shear-dominated viscous flows within a muddy matrix, 2) mud-silt-sandy matrix sustained by fluid overpressure, 3) concentrated shear zones/surfaces with advection of grains and fluid (overpressured basal carpets). These MTC types may represent end-members of a continuum of products and correspond to different kinematics of transport and emplacement and to different relationship with the substratum. These observations should result in a better knowledge of mass-transport processes and bodies, in relation with the basin floor geometry.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.14083/3692
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