How did the Farallon plate fragment over time?

The Farallon plate was a major ancient tectonic plate that underwent fragmentation during its long history of subduction and interaction with other plates. Similar geological processes led to the breakup of its southwestern counterpart, the Phoenix plate, resulting in the creation of smaller tectonic fragments such as the Charcot, Rivera, and Cocos plates. Remnants of this larger tectonic system continue to influence modern boundaries, such as the Juan de Fuca Ridge.

What we know

• The southwestern part of the Phoenix plate fragmented into the Charcot plate during the Late Cretaceous or early Cenozoic, in a process comparable to the fragmentation of the Farallon plate that formed the Rivera and Cocos plates. [2]
• The Juan de Fuca Ridge is a section of what remains from the larger Pacific-Farallon Ridge, which formerly served as the primary spreading center driving the Farallon Plate beneath the North American Plate. [3]
• The Phoenix plate formed a triple junction with the Izanagi and Farallon plates in the Panthalassa Ocean as early as 410 million years ago. [2]

Where to go next

• a case in pointWhat formed the Rivera and Cocos plates?
• how it workedHow does the Juan de Fuca Ridge operate today?
• compared withWhat was the Phoenix plate?
• the bigger pictureWhat is the Pacific Ring of Fire?
• whenWhen did the Pacific plate arise?
• an unexpected connectionHow do ancient tectonic plates connect to Canadian volcanism?The tectonic activity and subduction systems involving plates like the Farallon and Phoenix are part of the broader Pacific Ring of Fire that also shapes modern and ancient volcanism in Canada.

Sources

• [1]Phoenix Plate (Wikidata Q902322) · CC0 1.0
• [2]Phoenix plate · CC BY-SA 4.0
• [3]Juan de Fuca Ridge · CC BY-SA 4.0
• [4]Volcanism of Canada · CC BY-SA 4.0
• [5]Yosemite National Park · CC BY-SA 4.0