What are continental collision terranes?

Continental collision terranes are blocks of crust like volcanic island arcs or continental fragments that form elsewhere and later get accreted onto the margins of continents through tectonic plate movements. For instance, ancient island arcs such as the Intermontane terranes formed in the Panthalassa Ocean and docked onto the western edge of North America during the Jurassic. Similarly, terranes like Carolinia originated near Gondwana before migrating across ancient oceans to fuse with Laurentia.

What we know

• The Intermontane terranes were volcanic island arcs that formed in the Panthalassa Ocean during the Triassic period and were later accreted to western North America during the Jurassic. [2]
• Continental collision is a plate tectonics phenomenon at convergent boundaries where a subduction zone is destroyed, mountains are produced, and two landmasses are sutured together. [3]
• The Carolina terrane likely formed as a subduction-related volcanic island arc off the coast of South America before moving across the Iapetus Ocean to dock with Laurentia. [4]
• The Suwannee terrane is a block of continental crust that originated on the edge of Gondwana and now underlies much of Florida, Georgia, and parts of the Carolinas. [5]

Still open

• The exact date of the docking of the Carolina terrane with Laurentia remains unknown, as it could have occurred during the Taconic, Acadian, or Alleghanian Orogenies.

Where to go next

• how it workedHow do tectonic subduction zones operate?
• a case in pointWhat was the Slide Mountain Ocean?
• what followedHow does continental collision build mountain ranges?
• the bigger pictureWhat is the geological history of the Appalachian Mountains?
• whenWhat role did the Iapetus Ocean play in ancient plate tectonics?
• an unexpected connectionHow did parts of South America end up beneath the southeastern United States?Terranes like Carolinia formed originally off the coast of Gondwana and traveled across an ancient ocean before becoming part of the modern North American eastern seaboard.

Sources

• [1]Intermontane Plate (Wikidata Q3391667) · CC0 1.0
• [2]Intermontane terranes · CC BY-SA 4.0
• [3]Continental collision · CC BY-SA 4.0
• [4]Carolina terrane · CC BY-SA 4.0
• [5]Suwannee terrane · CC BY-SA 4.0