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Geology LibreTexts

Global Tectonic Processes

Structural geology alone is not enough to understand the full picture of how and why continents deform. Interactions with oceanic lithosphere fundamentally influence continental deformation.

Alfred Wegener's theory of continental drift was rejected by many because it lacked a physical mechanism to drive the proposed motions. It was only the discovery of seafloor spreading and subduction that forced scientists to confront the physics to explain these processes.

Orogen: A general term describing a region of continental crust undergoing deformation, usually in response to plate collision, though rifting and strike-slip dominated orogens also exist.

Figure 1: Diagram of Wadati-Benioff zone. Image from the United States Geological Survey.

Image of a Benioff Zone of earthquakes from subducted pacific plate beneath Honshu, Japan. From Hasegawa et al., 1978. Double trend arises from different dewatering reactions in oceanic crust and mantle lithosphere of the plate.


Figure 2: Seismicity cross-section, Kuril Islands subduction zone, 15 November 2006, 8.3 Mw event marked as star. Image used with permission from Wikipedia.