PhD Arthur Decae 2010 - Ghent Ecology - Universiteit Gent

Origin of the Mediterranean
Questions of origin are always difficult to approach because we have to find a starting point.
In the case of the Mediterranean this is particularly difficult, but we might start from the idea
that the forces that broke-up the ancient super continent Pangaea, some 170 million years ago,
led to the formation of the separate ‘continental plates’ that much later in time, were to form
the Mediterranean. This formation of the Mediterranean finally took place in a gigantic
‘tombola’ of collisions and segregations of fractions of the earths crust (see footnote 7 for
discoveries and discoverers of continental drift and seafloor spreading). The main processes to
be considered here are: (1) the opening of the North Atlantic Ocean and the vanishing of the
ancient Tethys Ocean, (2) the movements of the African and Arabian continental plates, (3)
birth of the Mediterranean Sea. For information on these phenomena I lean heavily on the
following sources: D. Ager’s (1980) celebrated book The Geology of Europe; Rögl &
Steiniger’s (1984) Chapter 10 in Fossils & Climate (Wiley Books) and Rögl’s (1999) short
discussion of the Mediterranean Palaeogeography in Geologica Carpatica.
1. The Atlantic and Tethys Oceans
The formation of the Atlantic Ocean started
near the equator with cracking open the
solid continental block of Pangaea, roughly
at a place where we now find the Caribbean.
A subsequent rapture moved from there to
the southwest to separate North and South
America. A second giant rapture moved
northeast to separate North America from
Africa and Europe. In the process southern
Europe was broken-up in a series of microplates
that formed an archipelago within the
northwestern Tethys Ocean (Fig. 2). It all
must have happened early in Jurassic times,
approximately 170 million years ago
(Pannekoek 1973), when giant dinosaurs
roamed the earth. The rapture of Pangaea
separated the northern continents from one
large southern continent that is here denoted
as Neogondwana 9 . To the east the young
Atlantic Ocean had a seaway connection with
the western parts of the ancient Tethys Ocean.
This inter-oceanic seaway is the location where
the Mediterranean was going to be formed. In
time the Tethys Ocean would be replaced by the
Indian Ocean (late Mesozoic to mid Cenozoic)
Fig. 2 Showing the young Atlantic Ocean (approx.
150myBP) separating the northern from the still
united southern continents and the seaway
connection with the western Tethys. Source:
R.Blakey.ucc.nau.edu/
through the northward movement of the Indo-Australian plate and the rotation of the Arabian
plate away from Africa to close the Atlantic-Tethys connection so shaping the Mediterranean.
9 An earlier separation between northern and southern continental blocks broadly denoted as
Laurasia and Gondwana had existed in the Palaeozoicum (400myBP-350myBP) before the
formation of Pangaea, hence the term Neogondwana for the southern continental block that
originated from the breakdown of Pangaea.