diageneshistorik

Diageneshistorik is the study of the diagenetic history of sedimentary rocks, i.e., the sequence of physical, chemical, and biological changes that occur after deposition and before metamorphism. It records when and where processes such as compaction, cementation, dissolution, replacement, and recrystallization happened, and how they altered mineralogy, porosity, and permeability.

Key diagenetic processes include mechanical compaction, which reduces primary porosity; cementation by minerals such as calcite, quartz, or dolomite; authigenic clay formation (illite, kaolinite); and dissolution that creates secondary porosity. Replacement and recrystallization can modify grain boundaries, while stylolites reflect pressure solution during burial. Pore-water chemistry, temperature, and pressure, along with depositional environment, govern the sequence and extent of diagenesis. In carbonate rocks, dolomitization, micritization, and cementation are common; in siliciclastic rocks, quartz overgrowth and clay diagenesis are dominant.

Significance: The diageneshistorik controls rock properties important for hydrocarbon systems and groundwater, including porosity, permeability, and fluid flow pathways. It helps reconstruct burial history, basin evolution, and past fluid-rock interactions.

Methods: Researchers study diagenetic history using petrography (thin section), cathodoluminescence, scanning electron microscopy, X-ray diffraction, stable isotopes and fluid inclusions, and burial-history modeling. Integrating core data, well logs, and regional geology yields a coherent diagenetic sequence.

Examples: Early diagenesis may cement grains in shallow burial; quartz overgrowth reduces porosity in sandstones; carbonate rocks may experience dolomitization or calcite cementation, altering porosity and permeability.