Classification of Sandstone

Over 50 classification have been proposed

Most of them involve a ternary Q-R-L/R (quartz, feldspar, lithic/rock fragments) plot for framework grains and a major subdivision based on the relative amount of matrix

Major subdivision

Arenite (0-15% of matrix)

Wacke (15-75% of matrix)

Mudstone (75-100% of matrix)

Sedimentary rocks

Q end (mono-qz, poly-qz, chert)

Feldspars (K-feldspars, plagioclase)

Lithic/Rock fragments (

Basis of Classification

Volcanic rocks

Hypabyssal and plutonic igneous rocks

Modified portrayal of Gilbert's classification of silicate sandstones incorporating Folk's dual maturity concepts

After Williams, H., F.J. Turner, and C.M. Gilbert, 1982; modified after Dott, R.H., Jr., 1964; taken from Boggs, S., Jr., 1987)

For this course we will use a classification of sandstones that is partially based on Tracey (p. 257) and partially basedTurner, and Gilbert (p. 326).

Classification of sandstones (McBride, 1963)

Sandstone composition is typically determined microscopically by identifying mineral composition at 300, 400, etc equally spaced points across a thin-section00

After Terry & Chilingar, 1955)