detritic

Detritic, often used as a variant of detrital in geological literature, refers to sediments and sedimentary rocks formed from mechanical weathering debris produced by the breakdown of preexisting rocks. These detrital materials are transported by wind, water, or ice and eventually deposited, later compacted and cemented to form clastic rocks.

Detritic materials are characterized by discrete mineral grains and rock fragments rather than chemical precipitates. The composition typically includes quartz, feldspar, and lithic fragments, with additional clay minerals in finer beds. Textures range from well-sorted, well-rounded sands to poorly sorted, angular fragments. Detritic rocks are named primarily by grain size: sandstone (sand-sized grains), siltstone (silt-sized), and mudstone or shale (clay-sized). Coarser equivalents include conglomerates and breccias.

A key distinction is between detritic (detrital) sediments and chemical or biogenic sediments, which form from precipitation of minerals from solution or from biological activity. Detritic rocks record physical weathering and transport processes rather than chemical or organic precipitation.

Depositional environments for detritic sediments are diverse and include rivers and floodplains, deltas, beaches, deserts with aeolian dunes, deep-sea turbidites, and glacial outwash plains. The internal geometry and grain characteristics of detritic rocks preserve information about transport distance, energy conditions, and sediment provenance.

Diagenesis processes such as compaction and cementation (often by quartz overgrowths, calcite, or iron-oxide cements) lithify detrital sediments into solid rocks. The term detritic emphasizes the mechanical origin of the material, contrasting with chemically or biogenically derived sediments.