Impact of magmatic intrusion on diagenesis of shallow marine sandstones: An example from Qasim Formation, Northwest Saudi Arabia

Igneous intrusions are common in sedimentary basins, and their occurrence can significantly affect the diagenesis reservoir quality evolution of sandstones, thereby strongly impacting hydrocarbons-, geothermal-, CO 2 -storage potentials. The Qasim sandstones Tabuk region (NW Saudi Arabia) experienced shallow burial (<2 km) when Tertiary magma intruded to form basaltic sills (0.4–4 m thick). sedimentology, tectono-stratigraphic framework, provenance, chemostratigraphy Formation have been extensively covered literature. However, impact magmatic intrusion on remains enigmatic. This study employed thin-section petrography, QEMSCAN, XRD, SEM, energy-dispersive spectrometer analyses investigate role sandstones. results indicate that porosity is principally influenced by primary depositional characteristics (grain size sorting), diagenetic alterations, intrusions. Sandstones with coarser grain better sorting best intergranular vice versa . “normal” processes affected occurred during both (eodiagenesis) uplift (telodiagenesis). eogenetic alterations include mechanical compaction, early cementation calcite, pyrite, kaolinite, whereas telogenetic formation goethite, hematite. Overall, compaction main driver for loss intrusion-related dissolution quartz grains, rounded overgrowths, calcite cement, transformation kaolinite into dickite chlorite. Detrital overgrowths undergone due acidic pore fluids from high temperature. a dissolution-recrystallization fashion, amounts increase fine-grained sediments away sill contact hydrodynamic deposited muscovite (which kaolinite) low energy environments. chloritization was localized, magma-induced goethite likely supplied requisite Fe content. Additionally, has resulted towards contact. values compactional relatively remained similar at contact, as too thin exert significant vertical loading. relevance understanding hydrocarbon exploration exploitation sediment-lava sequences, development systems.