Mélange

In geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. The mélange typically consists of a jumble of large blocks of varied . Large-scale melanges formed in active continental margin settings 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), sedimentary action (such as slumping, gravity-flow, and olistostromal action), or some combination of these. Some larger blocks of rock may be as much as 1 kilometre (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.

Examples include the Franciscan Formation along the Coast Ranges of central and northern California and the Bay of Islands ophiolite complex in Newfoundland. The Gwna Mélange in the UK extends through Anglesey and the Llŷn Peninsula onto Bardsey Island in North Wales. The Northern Palawan melange distributed in Miniloc Island, west coast of Inabamalaki Island, west coast of El Nido; Cudugman Point on Bacuit Bay, in the islands of the Cuyo Group of Islands. It consists of a jumble of various rock types contained in a matrix of grey-green slaty mudstone and siltstone.

...
Wikipedia