Geology in Japan

8 Sep 2020

At https://phys.org/news/2020-09-japan-geologic-history-discovery-metamorph... ... Japan's geological history is now in question after the discovery of metamorphic rock with microdiamonds in it. Researchers in Japan have discovered microdiamonds in metamorphic rock strata, an unusual phenomenon that is also known from the Italian Alps. They are said to form in collision  zones - one plate crashing into another. Although it is possible collisions of the cosmic kind might be inferred, but left unsaid. This is said to show the crust has penetrated deeper than 125km below the surface - as in subduction, one plate travelling beneath another. In the Alps the collision of the plates is said to have uplifted the mountains, crumpling the crust at the surface. In Japan we are told it is the subduction of ocean plates that are responsible. Interesting idea as Japan was formerly part of a continental shelf system once joined to China, and possibly even some of the Melanesian islands.

... the rocks themselves are said to date back 100,000 years ago, all part of the Cretaceous story. Was something else at work here as we have in the image above a Cretaceous/Paleogene sedimentary basin. This is of course the K/T boundary. Is it possible that the asteroid strike caused the Deccan Traps and microdiamonds embedded in metamorphic rock?