Classification of sedimentsLecture 2

Jyoti KhatiwadaRoll no 10

Classification of sediments

classification and nomenclature of sediments

Siliciclastic sedimentary particles• The composition of siliciclastic sedimentary rocks includes

the chemical and mineralogical components of the framework as well as the cementing material that make up these rocks. Boggs divides them into four categories; major minerals, accessory minerals, rock fragments, and chemical sediments.

Gravel sand clay mixture

Classification of clastic sediments

classificationName of Particle

Size Range Loose Sediment

Consolidated Rock

Boulder >256 mm Gravel

Conglomerate or Breccia (depends on rounding)

Cobble 64 - 256 mm Gravel

Pebble 2 - 64 mm Gravel

Sand 1/16 - 2mm Sand Sandstone

Silt 1/256 - 1/16 mm

Silt Siltstone

Clay <1/256 mm Clay Claystone, mudstone, and shale

Carbonate sediments

Carbonate sediments• Modern carbonate sediments are comprised of three

principal minerals: aragonite, calcite (CaCO3) and dolomite (CaMg (CO3)2). The mineral type is determined by the organism from which the grains are derived. Once lithified, these will generally form limestone, although chemical diagenesis or lithification in specialized conditions that concentrate magnesium (i.e, evaporation) can form dolomite.

• Classified as biogenic grains and non skeletal grains

Sand silt clay classification

Gravel Sand clay classification