Table of Contents
How was the continental margin formed?
Convergent continental margins develop when two crustal plates collide. When an ocean plate collides with a less dense continental plate a marginal basin forms between the island arc and the continent.
What is continental margin in geology?
continental margin, the submarine edge of the continental crust distinguished by relatively light and isostatically high-floating material in comparison with the adjacent oceanic crust. It is the name for the collective area that encompasses the continental shelf, continental slope, and continental rise.
What happened along the margins of the continental crust?
Active continental margins are typically narrow from coast to shelf break, with steep descents into trenches. Convergent active margins occur where oceanic plates meet continental plates. The denser oceanic crust of one plate subducts below the less dense continental crust of another plate.
Which of the following are found along subduction zones?
Three main features are associated with subduction zones.
- Oceanic Trenches. Oceanic trenches are formed at subduction zones.
- Volcanic Arcs. Volcanic arcs form parallel to subduction zones.
- Earthquakes. Earthquakes occur along the subduction zone.
- Other Subduction Features.
What processes are most important in determining the physical features of continental margins?
What processes are most important in determining the physical features of continental margins? Suggest at least one process for each feature (shelf, slope, rise). Sedimentation, tectonic activity, wave action, erosion, ice ages, gravity flows (turbidites or river-like features that cut submarine canyons), etc. 5.
Which features may be found within a continental margin?
Major Continental Margin Features
- Continental shelf. This is very shallow water, and underlain by continental crust.
- Continental slope. This is much steeper than the shelf, usually about 3° but ranging from 1-10°.
- Continental rise.
- Abyssal plains.
Is the west coast of Africa a passive margin?
Passive margins define the region around the Arctic Ocean, Atlantic Ocean, and western Indian Ocean, and define the entire coasts of Africa, Australia, Greenland, and the Indian Subcontinent.
What causes continental margin volcanoes?
This area where plates converge and one plate is driven below the other is called a subduction zone. This contributes to the earthquakes and volcanic activity that we see associated with active continental margins.
What cuts through the continental margins?
The Bering Canyon north of the Aleutian Islands in the North Pacific Ocean is an example. It cuts through the continental margin for more than 255 miles (410 kilometers) and is the longest canyon in the world.
What geologic features form at subduction zones?
The main features of subduction zones include ocean trenches, volcanoes, and mountains. Earthquakes also happen as a result of these collisions. When two continental plates collide, the land is broken and pushed upwards, creating mountain ranges.
What is subduction in geology?
Subduction occurs when an oceanic plate runs into a continental plate and slides beneath it.
What kind of faults are found in the continental crust at a passive margin?
Beneath passive margins the transition between the continental and oceanic crust is a broad transition known as transitional crust. The subsided continental crust is marked by normal faults that dip seaward.
Is West Africa an active continental margin?
Abstract. The West African region is bounded by a passive continental margin confined to a steadily subsiding zone. It covers sedimentary basins that extend to the deep-water areas of the Atlantic Ocean; they are the Gulf of Guinea, Cuanza-Cameroonian, and Namibian basins.
Why is the West Coast an active margin?
The other type of margin is modeled after the U.S. West Coast. This margin is sometimes characterized as an “active” margin because it is on the leading edge of the North American plate. Margins along plate boundaries are mountainous with narrow shelves, steep slopes and rugged topography.
What is a subduction zone and where does it occur?
The subduction zone is the place where two lithospheric plates come together, one riding over the other. Most volcanoes on land occur parallel to and inland from the boundary between the two plates.
What is subduction zone in geology?