What is the definition of accreted terranes?

Accreted terranes are the blocks of continental fragments and oceanic islands that have collided with a continent and are now permanently attached.

What does accretion zone mean?

Accretion, in geology, is a process by which material is added to a tectonic plate at a subduction zone, frequently on the edge of existing continental landmasses. The added material may be sediment, volcanic arcs, seamounts, oceanic crust or other igneous features.

What is a geological terrane?

A terrane is defined as a fault-bounded block containing rocks that have a distinct geologic history compared with contiguous blocks.

What is accretion in tectonic plates?

Accretion describes the process by which fragments of tectonic plates are added to the continent at a plate tectonic boundary. This can happen at a subduction zone, where material is scraped off of the downgoing plate (see Juan de Fuca plate, above) and added onto the overriding plate (see accretionary wedge, above).

What are the different types of terranes?

The two most likely types of terranes are sections oceanic crust and entire island arcs. Also likely are oceanic plateaus (broad zones of thick oceanic crust in shallow water), ocean islands (such as the islands of Hawaii), and groups of island arcs that have already merged together.

What are accreted terranes made of?

Typically, accreting terranes are portions of continental crust which have rifted off another continental mass and been transported surrounded by oceanic crust, or they are old island arcs formed at some distant subduction zone.

How do we know where an accreted terrane came from?

Isotopes such as strontium-87 provide additional clues about terrane accretion in places where rocks have been buried deeply in the crust, metamorphosed, or melted and recrystallized as granite. Strontium-87 values are much higher in older continental crust than in oceanic and island arc crust.

How does a terrane become part of a continent?

Accretions of terranes. The development of a series of mountain belts along a continent’s margins increases the size of the continent by adding new continental crust (accretion). In most cases, a continent consists of an older core (craton) surrounded by progressively younger rocks.

How does a terrane typically become attached to a continent?

For terrane to become attached to a continent, it typically enters a subduction zone, where it is scraped off the subducting plate and tectonically added to the continent. Through this process of adding terranes along subduction zones, a continent grows.

What is a terrane boundary?

Terranes are defined as fault-bounded fragments whose surface geology differs from that of adjacent areas (e.g., Badarch et al. 2002; Kröner et al. 2010).

What is the difference between terrane and terrain?

is that terrane is (geology) a block of the earth’s crust that differs from the surrounding material, and is separated from it by faults while terrain is (geology) a single, distinctive rock formation; an area having a preponderance of a particular rock or group of rocks.

Where is the suture zone between North America and the accreted terranes?

Location map of the western Idaho suture zone (WISZ) and age traverses across it from the Late Paleozoic and Mesozoic accreted terranes on the south or west to the cratonal terranes of Mesozoic North America on the north and east. The WISZ occurs near the western margin of the Idaho batholith over much of its length.

What area of the US is composed of terranes?

Two of the largest terranes, the Alexander terrane and Wrangellia, found along western British Columbia, southwest Yukon, and eastern Alaska, have long been considered to be exotic to each other and to North America.

What types of terranes have been added to or displaced in California?

List the types of terranes added to or displaced in California. slices of paleozoic, and mesozoic oceanic crust and sediment, mesozoic island arcs, and an accretionary prism. How Did the Continents Join and Split Apart?

What often forms when large terranes and continents collide?

What often forms when large terranes and continents collide? continent movements separated populations of organisms.

What do you think is the reason that there are large faults in places where terranes meet?

What do you think is the reason that there are large faults in places where terranes meet? When a terrane is scraped off a sinking plate, it is put under a lot of pressure. The pressure makes the rock crack. You just studied 14 terms!

What type of fault is the San Andreas Fault?

strike-slip fault

strike-slip fault – a fault on which the two blocks slide past one another. The San Andreas Fault is an example of a right lateral fault.

Why is it called San Andreas Fault?

The San Andreas Fault received its name from Andrew Lawson after the 1906 earthquake. He named it for San Andreas Lake, a (now) man-modified sag pond in San Mateo county through which the fault passes.

Why do earthquakes occur near the San Andreas Fault?

The Pacific Plate (on the west) moves northwestward relative to the North American Plate (on the east), causing earthquakes along the fault. The San Andreas is the “master” fault of an intricate fault network that cuts through rocks of the California coastal region.

What happens if the San Andreas Fault happens?

Narrator: The quake could kill about 1,800 people and leave 50,000 or more with injuries. While people could die from falling debris and collapsed structures, the highest death toll would be from fires.

How many years overdue is the San Andreas Fault?

about 80 years overdue

California is about 80 years overdue for “The Big One”, the kind of massive earthquake that periodically rocks California as tectonic plates slide past each other along the 800-mile long San Andreas fault.

What plate do we live on?

The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores.

What if plate tectonics stopped?

If all plate motion stopped, Earth would be a very different place. The agent responsible for most mountains as well as volcanoes is plate tectonics, so much of the activity that pushes up new mountain ranges and creates new land from volcanic explosions would be no more.

What plates is Death Valley on?

DEATH VALLEY FORMS IN THE MODERN TECTONIC ENVIRONMENT

By about 20 Ma., the Farallon Plate had been consumed, and the Pacific Plate and the North American Plate were forming a strike-slip plate boundary, which we know as the San Andreas Fault.

Where are tectonic plates?

Earth’s thin outer shell is broken into big pieces called tectonic plates. These plates fit together like a puzzle, but they’re not stuck in one place. They are floating on Earth’s mantle, a really thick layer of hot flowing rock.

Why do tectonic plates exist?

For millions of years after the planet accreted, its surface roiled with a molten magma ocean. Once the planet cooled enough for a crust to form, the surface may have looked more like modern-day Venus, with the crust and upper mantle — collectively called the lithosphere — forming a single unbroken plate.

Who gave plate tectonic theory?

meteorologist Alfred Wegener

German meteorologist Alfred Wegener is often credited as the first to develop a theory of plate tectonics, in the form of continental drift.