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May 20 3 tweets 2 min read Twitter logo Read on Twitter
Geo-#giroditalia2023 - Stage 14. After a refreshing dip into the Alps, the Peloton is quickly returning to the safe shores of Adria. When Adria was pushed over Europe to form the Alps, the Alps pushed back, deforming northern Adria and making the Southern Alps (Dolomites). https://en.wikipedia.org/wi...
The riders will cross the 'Ivrea Body', which is a special geological region: it offers a rare glimpse into the deep Earth! The Alps jacked up northern Adria, and now we can see rocks of the mantle below that is normally at least 30 km deep, impossible to reach by drilling! https://sjg.springeropen.co...
By the way, did you know that the northern Adria margin did not originally form next to the Alps region: in the supercontinent Pangea, the Po Plain was next to...Pau, in Southern France! So back then, today would have been a Pyrenean stage...had the Pyrenees already existed then. https://www.geologist.nl/st...

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More from @geotdf

May 19
Geo-#giroditalia2023 - Stage 13. Today, we recommend the entire peloton to join the grupetto and look around: the Giro organization prepared a fantastic geological excursion! The race will lead from Adria to the 'Penninic Front' of the Central Alps, a former subduction zone! https://www.sciencedirect.c...
The Alps are piled-up rock packages of a few km thick that were offscraped from the European plate that subducted below Adria. The riders will cross remnants of two oceanic basins (the blue colors) and a small continent (the 'Brianconnais', in orange). https://www.sciencedirect.c...
Before these remnants were folded up in the Alps, they covered an area of hundreds of kilometers wide, and we will ride in sequence from Adria to the Piemonte-Ligurian ocean, to the Briançonnais continent, to the Valais Ocean, and end on the slope of Europe! https://www.sciencedirect.c...
Read 4 tweets
May 18
Geo-#giroditalia2023 - Stage 12. The peloton is leaving the Apennines, will race over Adria again, and then enters the Alps today. The difference between these mountain belts is not just geographical: geologically, they're entirely different beasts! But it's a complex geometry! https://www.researchgate.ne...
As we saw last week, the Apennines formed because Adria, the continent that underlies the Adriatic Sea and that is part of the African Plate, subducted below Europe and its sediments were offscraped. In the Alps, however, it's the opposite: Europe subducted below Adria.
So for most of the day, the peloton races over the African Plate again, which in in the morning is a downgoing plate and in the afternoon an overriding plate. Sounds like an ancient Roman riddle, right? The transition is a geological mess called the 'Ligurian Knot' https://www.researchgate.ne...
Read 4 tweets
May 17
Geo-#giroditalia2023 - Stage 11. The peloton is going to race through an ocean today! We've reached the Ligurian 'ophiolites', the oceanic lithosphere remains below which the northern Apennines were offscraped and stacked up, which you may see as the black rocks along the race. https://www.sciencedirect.c...https://www.travelinggeolog...
Geologically, oceans, are not bodies of water, but the crust type that forms by magmatism at mid-ocean ridges. Continents continue into the sea as shelf and slope, and only then the ocean starts. The Apennines are shelf and slope rocks, the 'Ophiolites' are oceanic crust rocks. http://geoverse.co.uk/2000/...
The shelf and slope of the Northern Apennines became in the Jurassic separated from the shelf of Iberia and Corsica by an ocean: the Piemonte-Ligurian Tethys, that was connected to the Atlantic Ocean. This ocean opened between ~160-140 Ma ago. https://www.sciencedirect.c...
Read 5 tweets

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