Which plates collided to form the alps

The Swiss Alps. Tectonic History The Swiss Alps are a mountain range that formed after the break-up of the supercontinent Pangea. During the mesozoic, there was an ocean that separated Europe from Africa called the Tethys Ocean. The subduction of this basin and the collision of Africa with the Eurasian plate is what caused the formation of these mountains. There were two main episodes of orogenisis, one during the Cretaceous causing the formation of the eastern and western Alps, the second during the Tertiary resulting in the formation of the central Alps.

The study mapped Southern Alps ice loss from the end of This will help improve current earthquake risk Under a limited warming scenario, glaciers would lose about two-thirds of These special calcite crystals demonstrate that intensive snowfall Microdiamonds in metamorphic rocks are important minerals because they form in And researchers Over time, while the mountains grew higher the basin floor sank deeper and deeper with the rest of the plate.

A few years ago, however, new geophysical and geological data led ETH geophysicist Edi Kissling and Fritz Schlunegger, a sediment specialist from the University of Bern, to express doubts about this theory. In light of the new information, the researchers postulated an alternative mechanism for the formation of the Alps.

Kissling and Schlunegger pointed out that the topography and altitude of the Alps have barely changed over the past 30 million years, and yet the trench at the site of the Swiss Plateau has continued to sink and the basin extended further north.

This leads the researchers to believe that the formation of the Central Alps and the sinking of the trench are not connected as previously assumed. They argue that if the Alps and the trench indeed had formed from the impact of two plates pressing together, there would be clear indications that the Alps were steadily growing.

That's because, based on the earlier understanding of how the Alps formed, the collision of the plates, the formation of the trench and the height of the mountain range are all linked. Furthermore, seismicity observed during the past 40 years within the Swiss Alps and their northern foreland clearly documents extension across the mountain ranges rather than the compression expected for the bulldozing Adria model.

The behaviour of the Eurasian plate provides a possible new explanation. Since about 60 Ma ago, the former oceanic part of the Eurasian plate sinks beneath the continental Adriatic microplate in the south. By about 30 Ma ago, this process of subduction is so far advanced that all oceanic lithosphere has been consumed and the continental part of the Eurasian plate enters the subduction zone. Over time, while the mountains grew higher the basin floor sank deeper and deeper with the rest of the plate.

A few years ago, however, new geophysical and geological data led ETH geophysicist Edi Kissling and Fritz Schlunegger, a sediment specialist from the University of Bern , to express doubts about this theory. In light of the new information, the researchers postulated an alternative mechanism for the formation of the Alps.

Kissling and Schlunegger pointed out that the topography and altitude of the Alps have barely changed over the past 30 million years, and yet the trench at the site of the Swiss Plateau has continued to sink and the basin extended further north.

This leads the researchers to believe that the formation of the Central Alps and the sinking of the trench are not connected as previously assumed. They argue that if the Alps and the trench indeed had formed from the impact of two plates pressing together, there would be clear indications that the Alps were steadily growing.

Furthermore, seismicity observed during the past 40 years within the Swiss Alps and their northern foreland clearly documents extension across the mountain ranges rather than the compression expected for the bulldozing Adria model.

The behavior of the Eurasian plate provides a possible new explanation. Since about 60 Ma ago, the former oceanic part of the Eurasian plate sinks beneath the continental Adriatic microplate in the south.

By about 30 Ma ago, this process of subduction is so far advanced that all oceanic lithosphere has been consumed and the continental part of the Eurasian plate enters the subduction zone. This theory is plausible because the Alps are mainly made up of gneiss and granite and their sedimentary cover rocks like limestone. Over millions of years, the oceanic plate becomes increasingly curved, practically curling in on itself.

The Eurasian plate as a whole remains stationary. This causes the subducting plate to start exerting a suction effect on the much smaller Adriatic plate, pulling it northwards to the left in the diagram. When this process of subduction is so far advanced that the lighter, continental part of the Eurasian plate enters the subduction zone and begins to collide with the Adriatic microplate, the subduction process slows down.

The buoyant continental part of the Eurasian plate resists being subducted while the previously subducted oceanic part continues to pull downward leading to steepening of the slab and eventually to necking of the plate and the beginning of separation of the upper, lighter crust from the heavier, underlying lithospheric mantle. A decisive moment takes place 30 million years ago when the oceanic part of the subducted plate breaks away.

This reduces its tremendous weight.