Sandsteine

Sandsteine, or sandstone, are clastic sedimentary rocks formed by the consolidation of sand-sized mineral grains. The majority of sandstones are composed of quartz grains, but feldspar and lithic fragments can occur. The grains are typically cemented by minerals such as silica (quartz), calcite, or iron oxides, which bind the sediment together and influence color and strength.

Sandstone forms through lithification of sand deposits. This process includes compaction during burial and cementation during diagenesis. Depositional environments vary and include rivers, deltas, beaches, deserts, and submarine settings. Features such as cross-bedding and ripple marks can indicate ancient wind or water flow and help reconstruct past environments.

Classification depends on grain composition, sorting, and cement. Common varieties include quartz arenite (mostly quartz with well-sorted grains), arkose (significant feldspar content), lithic sandstone (abundant rock fragments), and wacke (more clay and matrix). Porosity and permeability are important properties for groundwater and hydrocarbon reservoirs; cement type and degree of compaction influence these characteristics. Color ranges from white to red and brown, often reflecting iron oxide cement or organic content.

Sandsteine have broad economic and scientific importance. They are widely used as building materials and decorative stone. Geologically, they host important aquifers and are common reservoir rocks for petroleum and natural gas. They also preserve fossils and provide records of ancient climates and environments through grain size, sorting, and sedimentary structures.

Globally, sandstones occur in many sedimentary basins and rock sequences. Notable examples include well-known desert and offshore formations, as well as significant regional successions such as quartz-rich sandstones in mature cratonic regions and arkosic sequences in transitional belts.