Azores Triple Junction
Coordinates: 39°26′N 29°50′W / 39.44°N 29.83°W 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]
References
- Notes
- ↑ DeMets, Gordon & Argus 2010, The Azores microplate, pp. 24–25
- Sources
- da Silva Fernandes, R. M. (2004). Present-Day Kinematics at the Azores-Gibraltar Plate Boundary as Derived from GPS Observations (PDF). Delft University Press. ISBN 9040725578. Retrieved 22 October 2016.
- DeMets, C.; Gordon, R. G.; Argus, D. F. (2010). "Geologically current plate motions" (PDF). Geophysical Journal International. 181 (1): 1–80. doi:10.1111/j.1365-246X.2009.04491.x. Retrieved 19 October 2016.
- Tectonics of the Azores