Azores triple junction
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 Strait of Gibraltar. It is classed 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 boundary.[2]
References
Notes
- ^ 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) - ^ 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". Geophysical Journal International. 181 (1): 1–80. Bibcode:2010GeoJI.181....1D. doi:10.1111/j.1365-246X.2009.04491.x.
- Tectonics of the Azores
External links
| Triple trench | |
|---|---|
| Triple ridge | |
| Triple fault | |
| Trench–trench–ridge | |
| Fault–fault–trench | |
| Ridge–fault–fault | |
| Ridge–trench–fault | |
| See also | |
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