Question

Which plate is subducting beneath the South American Plate? A) Nazca C) North American B) African D) Indo-Australian

Short answer

The Nazca Plate is subducting beneath the South American Plate.

Step-by-step solution

Understanding Plate Tectonics

The process of one tectonic plate moving under another is called subduction. This usually occurs at convergent boundaries where an oceanic plate meets a continental plate. The denser oceanic plate subducts beneath the less dense continental plate.

Identifying the Location

The South American Plate is a continental plate located on the western side of South America. It's important to identify the nearby oceanic plates to determine which one is subducting beneath it.

Recognizing Nearby Oceanic Plates

One of the most significant oceanic plates adjacent to the South American Plate is the Nazca Plate. This plate is smaller and denser compared to the continental South American Plate, making it a candidate for subduction.

Comparing Plate Options

Compare the given plate options: A) Nazca - An oceanic plate adjacent to the South American Plate. B) African - A continental plate not located near the South American Plate. C) North American - A continental plate located to the northwest but not subducting under South America. D) Indo-Australian - A plate located much farther away and not involved in this region's subduction zone.

Concluding the Correct Plate

Based on the geographic proximity and the nature of tectonic interactions, the Nazca Plate is the one that subducts beneath the South American Plate at the Peru-Chile Trench.

Key concepts

Subduction Zone

A subduction zone is an area where two tectonic plates come together, and one moves under the other. This typically happens at convergent plate boundaries. Here, the denser plate, often an oceanic plate, begins to descend into the Earth's mantle beneath a less dense, often continental plate. This process is the driving force behind many significant geological phenomena, such as earthquakes and the formation of mountain ranges.
A classic example of a subduction zone is where the Nazca Plate is subducting beneath the South American Plate. This takes place at the Peru-Chile Trench.

• Creates major geological activity, including earthquakes and volcanoes.
• Drives mountain building, such as the Andes Mountains.

Understanding subduction zones is essential for grasping how the Earth's surface is shaped and how these powerful geological processes impact our planet.

Tectonic Plates

Tectonic plates are immense slabs of the Earth's crust that move over the semi-fluid asthenosphere beneath them. The Earth's crust is divided into several major and minor tectonic plates.
These plates constantly move, albeit very slowly, driven by forces such as mantle convection, gravity, and Earth's rotation.

• Oceanic plates are denser due to their basaltic composition.
• Continental plates are less dense and mostly granitic.

The interactions between tectonic plates are crucial in shaping our planet's landscape. They form mountains, cause earthquakes, and give rise to volcanic activity. When two plates interact, it can result in one subducting under the other, earthquakes occurring from their collision or rubbing past one another, or new crust being formed at divergent boundaries.

South American Plate

The South American Plate is a significant tectonic plate covering the continent of South America and part of the Atlantic Ocean floor. It interacts primarily with the Nazca Plate to the west, where it experiences subduction.
This interaction is responsible for the Andes Mountains' formation and the frequent seismic activity in the region.

• The plate is mostly continental with some oceanic segments.
• Bounded by the Caribbean Plate to the north, and the Scotia Plate to the south.

As it pushes against these smaller plates and the oceanic Nazca Plate, it is continuously reshaping the western coastline of South America, creating one of the most dynamic and complex geological areas on Earth.