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Azores Triple Junction

Coordinates: 39°26′N 29°50′W / 39.44°N 29.83°W / 39.44; -29.83
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39°26′N 29°50′W / 39.44°N 29.83°W / 39.44; -29.83

The Azores Triple Junction

The Azores Triple Junction (ATJ) is a geologic triple junction where the boundaries of three tectonic plates intersect: the North American plate, the Eurasian plate and the African plate. This triple junction is located along the Mid-Atlantic Ridge (MAR) amidst the Azores islands, nearly due west of the Strait of Gibraltar. It is classified as an R-R-R triple junction of the T type (for its shape), as it is an intersection of the Mid-Atlantic Ridge running north–south and the Terceira Rift which runs east-southeast.

The spreading rate along the MAR does not change abruptly at the ATJ, instead decreasing from 22.9±0.1 mm/yr at 40°N to 19.8±0.2 mm/yr at 38°N. This means the ATJ is not a simple triple junction where three tectonic plates meet at a point. The transitional range of spreading rates instead indicates the presence of a microplate, commonly referred to as the Azores Microplate, although the observed behaviour can also be explained in terms of a diffuse boundary.[1] Its northern boundary intersects the MAR between 39.4°N and 40.0°N and its southern between 38.2°N and 38.5°N. The microplate moves about 2 mm/yr east-northeast along its Nubian (African plate) boundary.[2]

References

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Notes

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  1. ^ F.O. Marques, J.C. Catalão, C.DeMets, A.C.G. Costa, A. Hildenbrand (2013). "GPS and tectonic evidence for a diffuse plate boundary at the Azores Triple Junction" (PDF). Earth and Planetary Science Letters. 381: 177–187. Bibcode:2013E&PSL.381..177M. doi:10.1016/j.epsl.2013.08.051.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ DeMets, Gordon & Argus 2010, The Azores microplate, pp. 24–25

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