The Jovian moon Io is geologically active like Earth, yet it experiences heat pipe tectonics instead of plate tectonics.
Heat-pipe tectonics is a cooling mode of terrestrial planets in which the main heat transport mechanism on the planet is volcanism through the outer hard shell, also called the lithosphere. Heat-pipe tectonics initiates when volcanism becomes the dominant surface heat transfer process. Melted rocks and other more volatile planetary materials are transferred from the mantle to the surface via localized vents. Melts cool down and solidify forming layers of cool volcanic materials. Newly erupted materials deposit on top of and bury older layers. The accumulation of volcanic layers on the shell and the corresponding evacuation of materials at depth causes the downward transfer of superficial materials such that the shell materials continuously descend toward the planet's interior. - From Wikipedia
Imagine an earthlike planet with a mass of about 1.5 earth-masses, that experiences similar heating and tectonics to Io. What would the crust be made of? Basalt, Andesite or a mixture?
Going by Io as an example, one would expect basalt. Basalt is what Earth's oceanic crust is made of and flood vulcanism, which will most likely create a lot of the surface of this world, creates basalt as well.
On the other hand andesites are created if volatile-rich material sinks into the mantle and returns through vulcanism. On earth andesite is created near subduction zones and accumulates there over the eons. However on this world, subduction would happen everywhere and so andesite might form everywhere.
Some might wonder why this is relevant to my worldbuilding, however this will determine how the world will look at large.
Silicate-rich magmas are typically formed at destructive plate boundaries, by partial melting and/or assimilation of crustal rocks (which are richer in silica than the rock of the mantle). Such magmas erupt as andesites and rhyolites or are intruded as granite masses. The more extensive silicate chain molecules render these magmas highly viscous, so when eruption occurs it is usually explosive (e.g. Mt St Helens).
Low-silica magmas are typically formed by partial melting of mantle rocks beneath mid-ccean ridges or at “hot spots” like Hawaii. These magmas erupt as basalts or intrude as gabbro, and are far less viscous. Eruptions are generally effusive. - From the Geological Society
So basaltic magma would mean that the world would have a shallow profile and would look a lot like Io and andesitic would mean that the world's profile would be sharper, as the more viscous lava can build larger mountains. If a mixture of say, regular andesitic vulcanism and periodic basaltic flood vulcanism is the most plausabile answer, that would be interesting as well.
So how will the geology of this world look like? Andesite or basalt? Or can I do whatever I deem plausable since noone can prove me wrong?