diageneesi

Diagenesis refers to all physical, chemical, and biological changes that happen to sediment after it is deposited, but before it undergoes metamorphism. These processes occur at relatively low temperatures and pressures, typically at or near the Earth's surface. Diagenesis is a crucial stage in the formation of sedimentary rocks.

The changes can include compaction, where the weight of overlying sediment squeezes out water and reduces pore space. Cementation is another key process, where minerals precipitate from pore fluids and bind sediment grains together, hardening the sediment into rock. Dissolution can also occur, where some minerals are dissolved by pore fluids, creating or enlarging pore spaces. Recrystallization involves the change in crystal size or shape of minerals. Biological activity, such as the burrowing of organisms or the activity of microorganisms, can also significantly alter sediment during diagenesis.

These diagenetic processes are highly dependent on factors like the original sediment composition, the chemistry of the pore fluids, temperature, pressure, and the time elapsed since deposition. Diagenesis plays a vital role in determining the porosity and permeability of sedimentary rocks, which are critical for the storage of groundwater and hydrocarbons. It also influences the mineralogy and texture of the final rock.