Diagenetic modeling of siliciclastic systems: Status report

Abstract

Basin analysis (the reconstruction of the dynamics and history of sedimentary basins) has entered a quantitative stage that requires analytical lithologic data. These data must include geologic parameters that describe the characteristics of sediments and the diagenetic changes that they undergo through time. Diagenesis is controlled by eight geologic parameters: sediment composition, temperature history, rate of accommodation (subsidence + sea-level changes + sediment compaction), rate of sediment accumulation, age (time that sediments have been exposed to other variables), internal sediment-body architecture (sedimentary texture and structure), sediment-body external geometry, and fluid chemistry and flow history. Tectonic and paleogeographic settings determine the primary compositions of both chemical and siliciclastic sediments. Siliciclastic provenances are reflected by the mineralogy of sandstones. The source or sources of sediment in sandstone units within genetic sequences and the contribution of each source need to be evaluated in terms of quantitative effects on the various diagenetic styles observed. With the use of modern settings as partial analogues, stratigraphic, sedimentologic, and petrographic data can be used to reconstruct sandstone architecture and to draw inferences about original pore fluid chemistry. Subsidence histories, isotopic signatures, trace element compositions, and fluid inclusion studies combined with petrographic observations can be used to set constraints on the geologic parameters for sandstone bodies within a time-temperature-basin setting framework. As more insight is gained into the reaction kinetics within specific paleotectonic and depositional settings, diagenetic modeling will become increasingly more quantitative and precise.