Final answer:
An accretionary-wedge complex is formed at convergent plate boundaries from sediments and oceanic crustal material scraped off a subducting plate, contributing to the creation of mountain ranges and significant geological formations.
Step-by-step explanation:
A accretionary-wedge complex is a thick accumulation of sediments and small, tectonic blocks formed of material scraped off a descending, lithospheric plate.
Understanding Accretionary Wedges
An accretionary wedge forms at a convergent plate boundary where one plate is subducting beneath another. This structure is made up of sedimentary material such as turbidite sedimentary deposits and pieces of the oceanic crust, including ophiolites, that get scraped off the subducting plate and accumulate at the edge of the overriding plate. This process can lead to significant geological features, such as the creation of mountain ranges through orogenic events and contributes to the complex stratigraphy observed in these areas.
Example from Geology
The Appalachian/Caledonide Mountains are an example of a mountain range that formed through several orogenic events. These mountains went through phases of uplift and erosion, illustrating the dynamic processes at play in areas with accretionary wedges. The added weight from these geological events affects the lithosphere, leading to formations such as the Persian Gulf basin due to continental collisions.