Azores Triple Junction

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The Azores Triple Junction

Coordinates: 39°26′N 29°50′W / 39.44°N 29.83°W / 39.44; -29.83 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 Straits of Gibraltar. It is classed as a R-R-R triple junction, 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. 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 boundary.[1]


  1. ^ DeMets, Gordon & Argus 2010, The Azores microplate, pp. 24–25