Africa - Europe collision or pull-apart?
(...The dynamics of the African - European plates are extensional; plate
collision is a myth.)
| The African plate is pulling away from Europe, trailed by the collapse of the Alpine cordilleras, which is collapsing north (Alps and Carpathians) as well as south (Greece). |
Map base courtesy of Unesco.
(Un-cut
version)
Fig1. Geological map of the Mediterranean region with palaeo-basins delineated by excision. Collapse of the diapiric rise of the Alpine -Anatolian - Zagros Mountain Belt along its southern front bears on adjacent crust which is pushed downwards (red arrowpoints, southwards), giving the parallel contours of basinal shorelines (white areas). The northeasterly offset of the Mediterranean and Saudi basins reflects different levels of adjustment across deep crustal transform analogues (Red arrowpoints = mountain belt collapse analogues, 1. Greek Islands; 2. Shib Ku). Effects of crustal loading due to diapiric collapse are also apparent on the nothern side of the fold belt, shown by the equivalent shapes of the Caspian Sea and Saudi Arabia / Iraq, and of the Black Sea with the Western Mediterranean.
Plate collision, in which drifting continents colide and rumple the crust, is a fundamental tenet of Plate Tectonics. Africa colliding with Europe to crumple up the Alps and India colliding with Central Asia to crumple the Himalyas have been cited as definitive examples ever since I was at school. Trouble is, the Mediterranean basin, which lies in between Africa and Europe (and the Ganges plain between India and the Himalayas) is extensional. That's an oversight almost as bad as not noticing that the Earth is round and rotates! So now it seems the jury is out about 'colliding'. There are as many saying that Africa has yet to collide with Europe (in the future) as there are saying that it already did (in the past)
Plate tectonics has modified the basic concept of a century ago to frame it in the context of 'conveyor belts' (convection cells) in the mantle which piggie-back the continents around and rumple them up when they collide. With the advent of seismic tomography however the goalposts are changing (again). 'Conveyor belts' carrying plates around are now considered invalid; it is supposedly the plates themselves (i.e., mantle with crust on top - if any) which define the convection. Now it is (supposedly) not the upwelling convection that drives the system, but the downgoing (subducting) slabs! The USGS (image below) needs a new power source!
So much for the model, but what about THE GEOLOGY, that plate tectonics conveniently neglects in all of this? The geology of the Mediterranean region is manifestly NOT primarily compression, but rather diapirism and extension, which are locked as corollary expressions of expansion,which has pushed the surface of the Earth up and outwards from the centre, causing the shallow inland seas to drain off the continents and fill the developing oceans. In the Eurasian region, the Mediterranean, Black, Caspian, and Aral Seas remain as remnants of these inland waterways. Together with their trans-Atlantic equivalents of the Mexican Gulf and the Caribbean, these seas remain in the ambital 'hinge region' about which the Pangaean Earth dilated to accommodate the extrusion of the Pacific..
Fig.2. Dilations of the Mediterranean region shown in 1. diapiric uplift of the Alpine - Himalayan mountain belt (= the 'tail ' of Pacific extrusion) (the 'loopy' shapes of the belt represent polar elements of uplift within the overall linearity; 2. marginal basins of the Mediterranean and Red Seas and the Persian Gulf to the south; Black and Caspian seas to the North plus their palaeo-extents as partly depicted in Fig.1 above ( yellow dashed line = proximal shoreline, white dashed line = distal shoreline); 3. offsets on deep subcrustal transform analogues. Red 'arrows' = direction of mountain belt collapse. (The Greek Islands are a good example of gravitational 'loop collapse') See alsoThe so-called 'collision' of Africa with Europe is a century-old myth that gains no support from the concept of plates. All major structures of the region - the collapsing southern front of the mountain belt in the Mediterranean, the palaeobasins of Libya and Saudi Arabia, the dilation of the Red Sea, and the deep transform structures that segment them - are linked as integrated expressions of the same extension-in-torsion of global dynamics that have accelerated the rupture of the entire Earth's crust for the last 200m years, the evidence for which is manifest yet ignored by plate tectonicists. Africa is simply not colliding with Europe as plate tectonics asserts. Rather a single 'plate' (namely the Earth's crust) is pulling apart, and Africa is separating from Europe on the same mantle structure as is developing the Indian Ocean spreading ridge (Fig.2) The linear continuity of spreading, and the matching of crustal segments, could not be clearer.The study of offlap of the exhumed sedimentary basins and related structures of North Africa and the Middle East has been the business of the oil industry for well nigh a century, as well as the focus of much geopolitical upheaval. So there's a lot known about it, and extension is clearly written in the field evidence. Yet plate tectonics would set this aside as irrelevant when compared to the 'grand idea' of continental collision. The fanciful notion of a rumpled tablecloth as an analogy for mountain building, linked to continental collision by convection (another fanciful notion based on imagined mantle properties related to the difference in heat between the inside and outside of the Earth) is about the size of the 'evidence'. This obvious contradiction between the empirical field evidence (extension) and the fanciful model of convection (compression) apparently presents no dichotomy for plate tectonics however. The solution is simple: both must apply - first one then the other, with as many repeats as necessary to accord with interpretation. This best effort of plate tectonics to squeeze the square peg of extension into the round hole of compression has earned it the derisory label of 'squeezebox' or 'accordion' tectonics - as many wheezes and gasps as necessary to make any noise at all. For obvious reasons industry has no interest in publicising a synthesis which would correct this error. Indeed it must laugh (all the way to the bank) in the face of the non-empirical, fanciful, geology-as-convection tectonic model based on "an-Earth-divided-into- a-series-of-plates", when the large-scale evidence is plainly otherwise - a single plate in dilational, torsional disruption.
(One plate - in dilational, torsional disruption.)
(... the USGS hypes it up as
the deep heat of plate tectonics)
