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Lithospheric delamination

12 June 2023

At https://phys.org/news/2023-06-seismic-convey-lithospheric-delamination-mechanism.html … use of  seismic body waves in the South China lithosphere found anomalies which could be interpreted as lithospheric blocks at 90 km below the surface. The assumption is that  plate tectonics is taking place which is used to provide an explanation – they began to delaminate around 180 million years ago, and subsequently sank into the deep mantle. They later floated back up to the high mantle. Lrge scale delamination led ot lithosphere transformation, triggering thinning of the lithosphere, and adiabatic upwelling of asthenosphere. Subsequently, lithosphere extended and overlaying crust melted, forming the magmatic province in South China. Nothing to do with subduction it would seem. Geochemical analysis found that water and heat from the  convective mantle was necessary to trigger delamination. A hotter than normal interior mantle. Now, what could have caused that? The heat formed  granitoid and mafic rocks, as well as metal deposits – so something big was going on, in order to create the magmatic cemetery.

At https://phys.org/news/2023-06-volcanic-tsunami-hazards-santorini-seafloor.html … the eruption of the Thera volcano [Santorini] in the Aegean sent hig amounts of hot volcanic rock and gases across the eastern Mediterranean region. A tsunami battered the coast of Crete. Research at the caldera, using sound waves, produced a seismic profile and this was used in conjunction with bathymetry data from a few years ago, on an earlier expedition, to look for the genesis of thee tsunami wave. It involved reconstructing seafloor morphology. At Thera, sediments formed as a result of pyroclastic flows that entered the ocean. However, there was substantial destabilisation of sediments and rocks from the flanks of the volcano. The displacement of water by the landslide generated the tsunami wave, we are told. That seems to have substantiated what had previously been only a theory. They add, the volcano displaced ten times the amount of sea water than a recent volcano in Indonesia, 2018. One question that remains unanswered, in the press release at least, is did a tsunami wave travel as far as Egypt, washing up tufa in the Nile delta?

At https://phys.org/news/2023-06-earthquakes-frequently-britain-ireland.html … why do earthquakes occur more often in Britain than in nearby Ireland? It depends on the thickness of the lithosphere we are told. What caused the thinning of the lithosphere in western Britain? Delamination perhaps – or a stretching of the crust as Ireland broke away from Britain.

At https://phys.org/news/2023-06-earthquake-tsunami.html … we are in the territory of megathrust earthquakes and tsunami waves that travel for miles. We are also deep in Plate Tectonics theory and how it si thought to work.

At https://phys.org/news/2023-06-unusual-deformation-earth-largest-continental.html …. we have compute modelling of the East African Rift system, in relation to an African superplume and unusual deformation. It involves stretching and breking that reaches deep inside the earth – stretching the lithosphere, or crust. That sounds a lot like what has happened in western Britian, and possibly in the North Sea. The lithosphere is the outermost rigid layer of the earth, the crusty bit. As it stretches the shallower bits experience brittle deformation, via earthquakes and breaking rocks. See the full paper at https://doi.org/10.1029/2022.JBO25800

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