A geologic mélange consists of a jumble of large blocks of varied types of rocks. A mélange is a large-scale breccia (rock consisting of angular fragments cemented together). It is a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all different sizes, contained in a fine-grained deformed matrix.
Large-scale mélanges formed in active continental margins generally consist of altered oceanic crustal material and blocks of continental slope sediments in a sheared mudstone matrix.
The mixing mechanisms in such settings may include tectonic shearing forces, ductile flow of a water-charged or deformable matrix (such as serpentinite),
and sedimentary action (such as slumping or gravity-flow).
Some larger blocks of rock may be as much as 1 kilometer (0.62 mi) across. Smaller-scale localized mélanges may also occur in shear or fault zones, where coherent rock has been disrupted and mixed by shearing forces.
For my money, mélange is an beautiful-sounding word for a jumbled mess of lithologies. Sorting out environmental conditions in a mélange is a geological puzzle with well over 1,000 pieces.
Happy sorting and solving all those puzzle pieces!
Steph
Deer and Dear Maizie---Fall in the Rockies:
Large-scale mélanges formed in active continental margins generally consist of altered oceanic crustal material and blocks of continental slope sediments in a sheared mudstone matrix.
The mixing mechanisms in such settings may include tectonic shearing forces, ductile flow of a water-charged or deformable matrix (such as serpentinite),
and sedimentary action (such as slumping or gravity-flow).
Some larger blocks of rock may be as much as 1 kilometer (0.62 mi) across. Smaller-scale localized mélanges may also occur in shear or fault zones, where coherent rock has been disrupted and mixed by shearing forces.
For my money, mélange is an beautiful-sounding word for a jumbled mess of lithologies. Sorting out environmental conditions in a mélange is a geological puzzle with well over 1,000 pieces.
Happy sorting and solving all those puzzle pieces!
Steph
Deer and Dear Maizie---Fall in the Rockies:
