Earth, Molnar 2015 7x

What causes recurring great earthquakes in Chile?

Steady motion of the Nazca Plate toward South America loads strain along the plate boundary until friction fails, causing major earthquakes such as those in 1835 and 2010.

How does plate tectonics affect climate and glaciation?

Plate tectonics shifts continents and opens or closes ocean gateways, changing atmospheric and ocean circulation and influencing climate and glaciation.

What was Gondwanaland and what evidence supports its position?

Gondwanaland was a supercontinent located over the South Pole about 300 million years ago, supported by glacial evidence on modern southern continents.

How do ocean gateways influence thermohaline circulation?

Openings such as the Bering Strait allow ocean circulation patterns that help drive the global thermohaline circulation cycle.

Why does Antarctica remain extremely cold?

The Antarctic Circumpolar Current isolates Antarctica from warm tropical waters and developed after gateways opened 30–35 million years ago.

Why are continental margins important for petroleum formation?

Rifting creates thin continental crust below sea level where sediments and organic material accumulate and mature into oil and gas due to higher heat flow.

How does plate tectonics help modern oil exploration?

Geologists use plate tectonic principles to identify regions likely to contain petroleum resources.

How are ore deposits related to plate tectonics?

Magma and hot fluids at subduction zones and volcanic regions concentrate metals such as copper, gold, and silver into ore deposits.

Why do the Andes contain many major ore deposits?

Subduction-generated magma and mountain uplift expose and erode ore deposits in the Andes.

Why are other planets thought not to have plate tectonics?

Their lithospheres are likely too thick and rigid for subduction, especially on smaller planets that cooled faster than Earth.

What are granite belts and ophiolites evidence of?

They mark ancient subduction zones and sutures where continents collided.

What is an ophiolite?

An ophiolite is a section of oceanic crust and mantle thrust onto a continent during continental collision.

How did plate tectonics change Earth science?

It shifted geology from describing rocks and events to understanding large-scale Earth processes and interactions.

Why was plate tectonics difficult to recognize from the rock record?

Land rock records poorly preserve large-scale tectonic processes such as ocean floor spreading and subduction.

How does basalt form oceanic crust?

Basalt forms when mantle material melts at depths of about 10–30 km beneath the Earth’s surface.