Taconic orogeny
The Taconian orogeny in the Ordovician is the first of several Paleozoic deformation phases in the Appalachians and is considered to be the early phase of the Caledonian orogeny . A deformation event occurring around the same time in the British Isles is called Grampian orogeny .
The Taconian Mountains were formed by the displacement of the volcanic island arc , which was created by the ocean floor spreading of the Iapetus Ocean , onto the craton or continental core of Laurentia. This development is comparable to the current situation in the Japanese Islands on the Pacific Ring of Fire .
On Avalonia and Baltica , the forerunners of modern Europe, only the smallest folds of the lithosphere occurred during this phase of mountain formation .
In the Rhine Ocean , south of Avalonia, Perunica and Armorica, a volcanic chain of islands also arose around 420 mya - the Hun Terrane - which, however, "soon" disappeared again in a deep-sea basin or sedimentary basin in the course of Gondwana’s northern movement . Parts of these islands were raised during the Alpine mountain formation and today form layers in the folds of the central Alps .
The southern major continent of Gondwana and the Asian cratons were geologically calm at that time.
Later (390 mya) the subduction of the Iapetus took place under the continental plates and their collision in the phases of the Acadian , Variscan and then the Alleghenic orogeny .
Individual evidence
- ^ A b W. S. McKerrow, C. Mac Niocaill, JF Dewey: The Caledonian Orogeny redefined. Journal of the Geological Society. Vol. 157, 2000, pp. 1149–1154, doi : 10.1144 / jgs.157.6.1149 (alternative full text access : University of Oxford )