Abstract

A significant part of mélanges recognized in exhumed convergent margins around the world have been recently documented to be chiefly originated from en-mass transport and subsurface remobilization and disruption (i.e., mélanges, from sedimentary and mud-serpentinite diapiric processes and from in-situ fludification-disruption). Tectonic and/or sedimentary processes occurring during subsequent multiple deformational events of convergent margins evolution, commonly overprint and significantly rework the primary (sedimentary or diapiric) mélange fabric, forming polygenetic mélanges. This ultimately complicates their distinction from true tectonic mélanges, masking part of the recorded tectono-sedimentary evolution of the associated convergent margin. The contributions gathered in this thematic collection explore with different methodologies (from field-structural and stratigraphic observations to geophysical analyses) different types of polygenetic mélange, at various scales, around the world. The results conclude that the understanding of this type of mélange may provide crucial insights for a more detailed interpretation of both the evolution of ancient and modern convergent margins, and of processes-mechanisms triggering potential natural hazards (earthquakes and tsunamis). Case studies include the Apennines in the Central Mediterranean region, the Carpathians in Central Europe, and the Nankai Prism in Japan.

Thematic collection: “Polygenetic mélanges: a glimpse on tectonic, sedimentary and diapiric recycling in convergent margins” available at https://www.lyellcollection.org/cc/polygenetic-melanges

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