accretionary wedge

(redirected from accretionary prism)
Related to accretionary prism: volcanic arc, Passive margin

accretionary wedge

or

accretionary prism

n
(Geological Science) geology a body of deformed sediments, wedge-shaped in two dimensions or prism-shaped in three dimensions, that has been scraped off the surface of the oceanic lithosphere as it moves downwards beneath a continent or island arc. The sediments are added to the continental edge
References in periodicals archive ?
Development of Omans Offshore Block 18 in the North Sohar Basin between the Batinah coast and the Makran Accretionary Prism.
There is a probable presence of an overthrust wedge beneath the Sarawak shelf, which could be interpreted as a sliver of the Rajang Group accretionary prism.
The 14 papers here offer new data and results on sedimentology, stratigraphy, biostratigraphy, tectonics, and kinematics for the Zagros fold belt in Iran and the adjacent Makran accretionary prism.
Genetically related "Bathymodiolus" populations also occur on the Barbados Accretionary Prism (BAP) and have been referred to as "Bathymodiolus" sp.
Anggadiredja, Deputy Chairman of BPPT, stated: "This survey is designed to investigate deep geological structures of the accretionary prism in the western part of the Padang and Bengkulu waters.
A second pair of holes has been drilled into the Cascadia accretionary prism, where over 2 kilometers of sediments are being scraped off the subducting Juan de Fuca plate along the west coast of North America, and slowly compressed into rock.
The figure on page 96 shows seismic reflection and drilling data for the Nankai accretionary prism, where coring penetrated the incoming sedimentary sequence completely, transecting the frontal thrust, the decollement zone (zone of detachment that separates accreted and underthrust sediments), and underthrust deposits to the ocean basement.
Engineering and drilling challenges identified at COSOD I (Conference on Scientific Ocean Drilling) in 1981 and met in the first two years of operation include carbonate reefal sequencing (Bahamas, Leg 101), high-latitude drilling (Baffin Bay, Leg 105), ridge-crest drilling (Mid-Atlantic Ridge, Leg 106), and accretionary prism sequencing (Barbados Transect, Leg 110).
Where sediments are thick, most of them are scraped off onto the leading edge of the overriding plate, like snow piling up on a plow blade, forming an accretionary prism.
High-stress regime characteristics include a large accretionary prism, large shallow earthquakes, a wide range in the composition of the igneous rocks, and a shallow-dipping subducting slab.
Our initial installations were quite successful, and we and our growing group of CORK collaborators have gone on to deploy similar instrumentation in a total of 11 sites (see map opposite) in three representative types of seafloor hydrological environments: spreading centers, where new seafloor is spreading outward from mid-ocean ridges (ODP Holes 857D and 858G), young mid-ocean ridge flanks (395A, 1024C, 1025C, 1026B, 1027C), and accretionary prisms, where sediments scraped off descending seafloor plates accumulate in front of overriding plates, like debris in front of a locomotive's cowcatcher (889C, 892B, 948D and 949C).
Individual topics include interaction between normal faults and pre-existing thrust systems in analogue models; analogue and numerical modeling of accretionary prisms with a decollement in sediments; and the relation between effective friction and fault slip rate across the northern San Andreas fault system.