Is bacteria responsible for earthquakes?

Plate tectonics visualised

I recently came across this interesting study by Shengxing Zhang, from the Laboratory of Seismology and Physics of Earth's Interior at the University of Science and Technology of China. The study, titled "Photoferrotrophic Bacteria Initiated Plate Tectonics in the Neoarchean," delves into the intriguing connection between ancient photoferrotrophic bacteria and the initiation of plate tectonics during the Neoarchean period.

The abstract states: 

Plate tectonics distinguishes Earth from the other terrestrial planets but its initiation mechanism and onset time are debated. We propose plate tectonics was initiated by the deposition of magnetite-rich banded iron formations (BIFs) through biogeochemical iron cycling in Neoarchean oceans. In the photic zone of proto-continental margins, photoferrotrophic bacteria efficiently oxidized the dissolved Fe(II) and induced massive precipitation of ferric oxyhydroxide, which would rapidly react with Fe(II)-rich hydrothermal fluids from coeval vigorous volcanism in Neoarchean oceans to produce magnetite-rich BIFs. Mechanical models demonstrate that the localization of high-density BIF deposition near proto-continents induces collapse of the lithosphere and can initiate the earliest subduction. The peak deposition of BIFs in 2.75–2.40 Ga provides a time constraint on the inception of plate tectonics.

This text discusses various mechanisms proposed for the onset of plate tectonics, exploring geophysical processes such as subduction initiation. It introduces the idea that banded iron formations (BIFs), early Precambrian iron-rich sediments, could play a role in subduction initiation due to their high density and sequence thicknesses. The text also details the formation of BIFs through the activities of photoferrotrophic bacteria in Archean oceans, emphasising the potential influence of a young biosphere on Earth's solid processes.

Proposed onset of early plate movement 

From what I can understand, the study makes an interesting point by highlighting significant observations related to the peak deposition of BIFs (2.75–2.40 Ga) and the large-scale development of BIF-hosted basins during this period. It suggests a depositional rate and iron depositional rate for these iron-rich BIFs, emphasising their potential role in initiating subduction along proto-continental margins. The proposal is that the loading from these heavy magnetite-rich BIFs could have induced lithospheric rupture and subduction, potentially marking the origin of plate tectonics. This provides a new and novel perspective on the interaction between Earth's early biosphere, sedimentation processes, and the geological evolution of tectonic plates. 

It’s a unique perspective that ties together geology, biology, and the Earth’s dynamic history. Thoroughly interesting stuff!