6.1C - Geological Processes Releasing Carbon
Geological processes release carbon into the atmosphere through volcanic out-gassing at ocean ridges/subduction zones, and the chemical weathering of rocks.
Geological carbon can also be released into the atmosphere through geological processes:
- carbon dioxide in the atmosphere reacts with moisture to form weak carbonic acid. When this falls as rain, it reacts with some of the surface minerals and slowly dissolves them. This is chemical weathering: the decomposition of rock minerals in their original position by agents such as water, oxygen, carbon dioxide and organic acids.
- pockets of carbon dioxide exist in the Earth's crust. Volcanic eruptions and earthquakes can release these gas pockets. Outgassing is the release of gas, previously dissolved, trapped, frozen or absorbed in some material (e.g. rock). It occurs mainly along mid-ocean ridges, subduction zones and at magma hotspots.