Nuna (continent)

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Nuna was a concept for a hypothetical geological continent that is said to have existed 1.7 to 1.8 billion years ago. The main components are the Canadian Shield and Greenland as well as Fennoscandia and the Eastern European Platform (i.e. the later Baltica ). It is therefore virtually identical in scope to the original conception of the hypothetical geological continent of Nena . However, the concept of Nuna has since been greatly expanded, and Nuna is equated in more recent works with the global supercontinent Columbia .

Naming

The concept of a geological continent Nuna was proposed by Paul F. Hoffman in 1997. The name Nuna is derived from an Inuit word that denotes the land that borders the northern oceans.

Components

According to Paul F. Hoffman 1997, Nuna consists essentially of the central North American cratons ( slave kratons , superior kratons , Hearne kratons and Wyoming kratons including Greenland (Rae and Nain complex) and most of the later Baltica ). It is thus significantly smaller than the hypothetical supercontinent Columbia, with which it is often equated. Hoffman, however, discusses whether Nuna was just part of a much larger supercontinent.

Nuna as a geological continent

According to Paul Hoffman's imagination, Nuna is said to have formed around 1700 to 1800 million years ago. The formation thus falls during the period in which, according to other plate tectonic models, the supercontinent Columbia is said to have formed. In today's literature, Nuna is therefore often equated with the hypothetical continent Columbia, since Paul Hoffman formulated the assumption that Nuna could only have been part of a supercontinent that preceded Rodinia . The concept of a hypothetical continent Nuna is therefore no longer taken into account in the "current" reconstructions.

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literature

  • Dwight C. Bradley: Passive margins through earth history. Earth-Science Reviews , 91: 1-26, Amsterdam 2008 ISSN  0012-8252
  • Paul F. Hoffman: Tectonic Genealogy of North America. In: Ben A. van der Pluijm and Stephen Marshak (Eds.) Earth Structure An Introduction to Structural Geology and Tectonics. Pp. 459-464, WCB / McCraw-Hill, Boston, Mass., 1997.
  • John JW Rogers and M. Santosh: Supercontinents in Earth History. Gondwana Research , 6 (3): 357-368, Osaka 2003 ISSN  1342-937X .

Individual evidence

  1. ↑ Bradley, p. 22