At https://phys.org/news/2019-08-massive-methane-reservoir.html … link forwarded by Robert (but see also https://tallbloke.wordpress.com/2019/08/21/origin-of-massive-methane-res… ) … which comes with some useful comments. New findings published in PNAS provide evidence of the formation and abundance of abiotic methane – methane formed by chemical reactions that do not involve organic matter. It shows that methane found on other planets and moons could well have a similar origin. It is no longer a mystery we are told. Abiotic methane exists.
Methane, it is known, is being released from deep sea vents – from under the sea bed. It is an abundant substance on the sea floor. It exists in the crust and the Mantle. Scientists analysed rocks using Raman spectroscopy, a laser based microscope that allows them to identify fluids and minerals in a thin slice of rock. Just two ingredients are necessary – water and olivine.
At https://phys.org/news/2019-08-closer-methane-mystery-mars.html … a step closer to solving the methane mystery on Mars. A similar subject matter to the above. We are told that methane puffing out of a crater (a surface vent perhaps rather than an ocean vent) could be a sign of life – or not. It could be non biological activity under the planets's surface. The study redefines the concentration of methane in the atmosphere and how it varies over time – but where does it come from.