Triple Junction

As Triple Junction (German: triple point; outdated and drilling structure or three-fold structure) is known in geology a point at which meet the boundaries of three tectonic plates. In plate tectonics, a distinction between divergent plate boundaries where the plates move apart and convergent plate boundaries where the plates collide. There are also conservative plate boundaries, where the lithospheric plates slide past each other horizontally. Are as diverse as the combinations of the types of plate boundaries at the triple junctions.

At divergent plate boundaries located mid-ocean ridges form (MOR ). Along this back and thresholds extend grave breaches, where new crust through volcanic activity is formed. The concept of the triple junction was originally developed on the basis of three such plates are drifting apart by W. Jason Morgan, Dan McKenzie and Tanya Atwater. Powered by convection rises to hot mantle material and separates the lithospheric plates from each other. If three mid-ocean ridge of a triple junction go (type ridge - ridge - ridge ), they have each other ideally equal angles of 120 °. Such a situation is shown, for example at the Galapagos Triple Junction, where three oceanic plates, the Pacific Plate, the Cocos and Nazca plate drift apart.

In the event of the breakup of a continental plate initially also forms a triple junction, from which a branch but not later further developed and consummated in a Aulakogen. In the other two grave fractures eventually forms the ocean floor that separates the two new continents. The opening of the Atlantic Ocean between South America and Africa began with a triple junction in present-day Gulf of Guinea. The grave break which did not develop further, now forms the Niger Delta and continues along the partly extinct volcanoes in Cameroon (→ Cameroon line).

Also in the Afar Triangle in East Africa launched three grave breaches together. A road now forms the Red Sea, a second runs north east to the Gulf of Aden, both separate the Arabian plate from the African plate. The third branch is the Rift Valley, but not as rapidly evolving and may terminate in a Aulakogen.