The geological story of southern Spain
Chapter 2
the break-up of Pangaea and closure of the Tethys Ocean
Beginning around 200 my, Pangea started to break apart.
It began with a crack down the middle, along the line of what was to become the Atlantic Ocean. The rifting started in the central Atlantic, then spread to the southern Atlantic, then along the northern Atlantic - 'unzipping' through the process of Ocean Spreading (see section on Plate Tectonics) with Africa and Eurasia separating from the Americas and new oceanic crust being injected into the widening gap in-between. By 110 my, other parts of Pangea had also split off. Fragments that were to become modern day Antartica, India and Australia parted, with India, along with Africa and Arabia heading northwards, on an inexorable collision course with Eurasia.
The process by which this was happening was 'subduction' along the northern margin of the Tethys (see section on Plate Tectonics). The leading, northern edge of the Indian Plate - made of oceanic lithosphere - was being subsumed beneath Eurasia, gradually closing the Tethys Ocean in the process and dragging the continental crust on the Plate's tailing edge towards inevitable continent-continent collision. And sure enough, beginning as early as the late Cretaceous in some parts, the northern edge of the African, Arabian and Indian continental lithospheres ground into the southern underbelly of Eurasia. The continental portion of the Indian plate hit Eurasia around 50 my forcing Eurasia into and onto India and creating the Himalayas. Although the first impact happened around 50 million years ago, the Indian Plate's momentum has since carried it over 2000km further northwards, and it is still moving today - at about 4 to 5 cm/year.
Before we describe the effects of the Africa-Eurasia collision on the Mediterranean area however, we first need to look at what was happening in the area of southern Spain whilst the Tethys was closing .... Next: the Jurassic / Cretaceous palaeogeography of southern Spain |
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