studiot Posted February 11, 2023 Posted February 11, 2023 Quote Turkey earthquake fault lines mapped from space https://www.bbc.co.uk/news/science-environment-64603521 2
exchemist Posted February 11, 2023 Posted February 11, 2023 (edited) 2 hours ago, studiot said: https://www.bbc.co.uk/news/science-environment-64603521 Yes, I presume each dot is a movement measurement and the colour shows how much, though not the direction. Here's a map that makes clearer what plates are involved and the plate boundary faults: The EAF is the East Anatolian Fault (the North one, NAF, can also be seen), where the earthquakes took place. The Arabian and African plates are pushing broadly North and the Anatolian plate is being squeezed between them and the Eurasian plate like a pip, sideways, to the West. I was interested to see a converging margin marked, which accounts for the curious catlike shape of Cyprus, with a "tail" pointing off to the North East, i.e. towards the earthquake fault. There seem to be some slight trenches in the sea bed around it. In the bottom centre of the map the DSFZ, the Dead Sea Fault Zone, can be seen extending Southward. This links up with the Gulf of Aqaba, the Red Sea and the African Rift Valley. Edited February 11, 2023 by exchemist 1
studiot Posted February 11, 2023 Author Posted February 11, 2023 2 minutes ago, exchemist said: The EAF is the East Anatolian Fault (the North one, NAF, can also be seen), where the earthquakes took place. The Arabian and African plates are pushing broadly North and the Anatolian plate is being squeezed between them and the Eurasian plate like a pip, sideways, to the West. I was interested to see a converging margin marked, which accounts for the curious catlike shape of Cyprus, with a "tail" pointing off to the North East, i.e. towards the earthquake fault. There seem to be some slight trenches in the sea bed around it. Thanks +1
sethoflagos Posted February 11, 2023 Posted February 11, 2023 20 minutes ago, exchemist said: I was interested to see a converging margin marked, which accounts for the curious catlike shape of Cyprus, with a "tail" pointing off to the North East, i.e. towards the earthquake fault. There seem to be some slight trenches in the sea bed around it. Cyprus has one of the world's best exposed ophiolite sequences (uplifted oceanic crust), the Troodos Ophiolite. Quote The Troodos mountains are known worldwide for their geology and the presence of an undisturbed ophiolite sequence, the Troodos Ophiolite. These mountains slowly rose from the sea due to the collision of the African and European tectonic plates, a process that eventually formed the island of Cyprus. The slowing and near-cessation of this process left the rock formations nearly intact, while subsequent erosion uncovered the magma chamber underneath the mountain, allowing a viewing of intact rocks and petrified pillow lava formed millions of years ago, an excellent example of ophiolite stratigraphy. The observations of the Troodos ophiolite by Ian Graham Gass and co-workers was one of the key points that led to the theory of sea floor spreading. 1
exchemist Posted February 11, 2023 Posted February 11, 2023 32 minutes ago, sethoflagos said: Cyprus has one of the world's best exposed ophiolite sequences (uplifted oceanic crust), the Troodos Ophiolite. Oh yes the Troodos mountains. I recall reading about oceanic crust/upper mantle being exposed there. It seems there is as yet no consensus as to how it is that bits of this denser material end up on the surface, rather than being subducted. https://en.wikipedia.org/wiki/Ophiolite
sethoflagos Posted February 11, 2023 Posted February 11, 2023 1 hour ago, exchemist said: Oh yes the Troodos mountains. I recall reading about oceanic crust/upper mantle being exposed there. It seems there is as yet no consensus as to how it is that bits of this denser material end up on the surface, rather than being subducted. https://en.wikipedia.org/wiki/Ophiolite The ophiolites I've personal experience of, the Lizard complex and Ballantrae complex are pre-Mesozoic (associated with the Hercynian and Caledonian orogenies respectively) and extensively altered. But some of the rocks are absolutely gorgeous, especially the serpentinites.
exchemist Posted February 12, 2023 Posted February 12, 2023 (edited) 10 hours ago, sethoflagos said: The ophiolites I've personal experience of, the Lizard complex and Ballantrae complex are pre-Mesozoic (associated with the Hercynian and Caledonian orogenies respectively) and extensively altered. But some of the rocks are absolutely gorgeous, especially the serpentinites. Wasn't the Hercynian the one that gave rise to the metamorphic rocks of Brittany? I looked up serpentine. It is apparently a metamorphic, hydrous mineral with principal composition (Mg,Fe)₃Si₂O₅(OH)₄. There is actually even something called Lizardite, named after The Lizard in Cornwall, which is up at the mostly Mg end of the range of composition. A lot of these minerals seem to be green, I presume due to the presence of Fe²⁺ - one would not generally expect Mg compounds to be coloured. A lot of serpentine type minerals seem to cleave easily in either one or two planes, the latter giving rise to the asbestos family. I don't think I've ever seen serpentine. Perhaps it's time I took another trip to the Geological section of the Natural History Museum. They have specimens of just about everything there and the geology section is quiet and peaceful, as all the beastly school parties focus on the dumbed down, pop-sci dinosaur and earthquake exhibits😆! Some of the minerals are very beautiful. Edited February 12, 2023 by exchemist
sethoflagos Posted February 12, 2023 Posted February 12, 2023 58 minutes ago, exchemist said: Wasn't the Hercynian the one that gave rise to the metamorphic rocks of Brittany? Yes, though the full belt can be traced from the Algarve to Bohemia (see https://en.wikipedia.org/wiki/Variscan_orogeny)
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