Ignore for a second that Minecraft is probably supposed to mimic Earth, and imagine that it’s an exoplanet in some remote solar system you were dropped onto. You’re a planetary geologist sent to determine whether or not Minecraft exhibits plate tectonics.
For reference, Earth is the only planet we’re aware of that has plate tectonics; in particular, rigid plates with narrow deformation zones at plate boundaries. Other planets have different forms of tectonic activity, such as stagnant-lid tectonics (one single plate) on Mars or squishy-lid tectonics (magmatic intrusions create a thin lithosphere composed of small ephemeral plates) possibly on Venus or Archean Earth.
Earth is the only planet known to have granite. Granite formation depends on plate tectonics. At subduction zones, water wrung out of hydrated ocean crust causes partial melting of the ultramafic mantle above it (flux melting), creating mafic magma that rises into the crust through fractures. It undergoes fractional crystallization as well as assimilates crustal material, becoming felsic magma (enriched in silica and aluminum). When this magma cools, it forms granite.
Granite is the most abundant rock in the continental crust. Without water and plate tectonics driving subduction, granite could not form in quantities as found on Earth and in Minecraft.
A seminal 1983 paper describes the important connection between water and granites, entitled “No water, no granites – no oceans, no continents”. Without water to induce flux melting as described above, we wouldn’t have our granites.
More speculatively, water is thought by some to be a regulator for plate tectonics and to possibly have initiated it billions of years ago. Water lowers the melting point of rock, potentially resulting in a less viscous asthenosphere that enables subduction and convection, a plausible mechanism for plate tectonics. It may provide lubrication at faults, allowing plates to slide past each other more easily. Comparisons are commonly made to Venus, which, while similar in composition to Earth, lacks oceans in addition to plate tectonics.
Since granites and plate tectonics seem more likely to occur in the presence of water, the existence of water in Minecraft is a good sign. Or, at least, an absence of water could have been evidence that Minecraft did not have plate tectonics.
Planets without plate tectonics see large basaltic outpourings – their lava is exclusively mafic. Felsic lavas on Earth are mostly formed at subduction zones, where magma rises and incorporates silica-rich crustal material. We can infer that Minecraft’s lava is felsic because it creates obsidian on contact with water without exception, and obsidian only forms from felsic lava because its viscosity makes it harder to form mineral crystals.
In Minecraft, structures such as mountain ranges, mesas, and canyons mimic terrestrial formations largely shaped by tectonic processes. On Earth, mountains commonly result from subduction, mesas from uplift, and canyons from a combination of uplift and subsequent downcutting.
On other bodies without tectonics and accompanied weathering, features are dominated by other forces, such as impact craters and volcanism. Io, the largest moon of Jupiter and the most geologically active body in the solar system by some measures, has topographic swells and basins that are attributed to thermal changes in the basal lithosphere.
As other planets lack features associated with plate tectonics, Earth and Minecraft lack features on worlds with alterantive tectonic regimes. For instance, Mars harbors Olympus Mons, the tallest volcano in the solar system, towering 13.6 miles high. This volcano formed above a stationary hotspot, a feature unlikely to develop on a planet with mobile lithospheric plates. In Minecraft, the maximum elevation of mountains is 256 meters above sea level.
Many argue that plate tectonics is crucial to regulating the strength of a habitable planet’s atmospheric greenhouse effect. On Earth plate tectonics controls the long-term CO₂ cycle by driving degassing via volcanism and gassing via the continuous supply of rock it makes available to the silicate weathering process. Without such long-term cycling, planets like Earth would experience either runaway glaciation or greenhouse (as in Mars and Venus respectively). Climate stabilization as a result of tectonics on Earth has enabled the long-term evolution of life. Most think plate tectonics on Earth started after the emergence of simple life, but far before the development of complex life such as Minecraft’s sheeps and cows.
On Earth, tectonic processes govern the localities and form of Minecraft’s characteristic ores. Gold, for example, can be concentrated at convergent plate boundaries, where hot fluids pick them up and deposit them in fractures. Most copper comes from porphyry copper deposits, which occur at former or modern subduction zone systems. Meanwhile, Minecraft’s ores are arbitrarily distributed, and their occurrences do not correlate with tectonic features such as mountains and fault lines.
Plate tectonics is the means by which Earth radially drives heat to its surfaces. A flat world like Minecraft would not have retained heat in its core because it would not have a core. And forces like convection currents and gravity would not exist to drive the motion of plates. Plate tectonics simply could not have started.