Diagenesis is the change of
sediments or existing
sedimentary rocks into a different sedimentary rock during and after rock formation (
lithification), at temperatures and pressures less than that required for the formation of
metamorphic rocks. It does not include changes from
weathering. It is any chemical, physical, or biological change undergone by a
sediment after its initial deposition, after its
lithification. This process excludes surface alteration (
weathering) and
metamorphism. These changes happen at relatively low temperatures and pressures and result in changes to the rock's original
mineralogy and texture. There is no sharp boundary between diagenesis and
metamorphism, but the latter occurs at higher
temperatures and
pressures than the former. Hydrothermal solutions, meteoric groundwater, porosity, permeability, solubility, and time are all influential factors.
