Supercontinents

In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many earth scientists, such as P.F. Hoffman (1999), use the term "supercontinent" to mean "a clustering of nearly all continents". This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times. Using the first definition provided here, Gondwana is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were most recently in proximity to one another. This would classify Pangaea as a supercontinent. According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain.

The following table displays historical supercontinents, using a general definition.

There are two contrasting models for supercontinent evolution through geological time. The first model theorizes that at least two separate supercontinents existed comprising Vaalbara (from ~3600 to 2500 Ma) and Kenorland (from ~2700 to 2450 Ma). The Neoarchean supercontinent consisted of Superia and Sclavia. These parts of Neoarchean age broke off at ~2300 and 2090 Ma and portions of them later collided to form Nuna (Northern Europe North America) (~1750 Ma). Nuna continued to develop during the Mesoproterozoic, primarily by lateral accretion of juvenile arcs, and in ~1000 Ma Nuna collided with other land masses, forming Rodinia. Between ~800 and 700 Ma Rodinia broke apart. However, before completely breaking up, some fragments of Rodinia had already come together to form Gondwana (also known as Gondwanaland) by ~530 Ma. Pangaea formed by ~300 Ma through the collision of Gondwana, Laurentia, Baltica, and Siberia.

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