What does detrital mean in geology ?

Detrital : definition

A detrital rock is a sedimentary rock formed by 50% or more of rock or mineral debris torn from older continental rocks.

The most important are the terrigenous detrital rocks (80 to 90% of the detrital rocks). These are divided into three particle size classes according to the size of the dominant debris : rudites (more than 2 mm), arenites (2 mm to 62.5 µm) and lutites (less than 62.5 µm). Gravels, sands and clays are respectively modern, not yet lithified, equivalents of these three categories.

A detrital deposit is a deposit of sedimentary origin formed :
- by accumulation in rivers or on the shore of certain minerals (gold, diamond, rutile, magnetite, etc...) transported by water after destruction of the source rocks by erosion : these are the placers.
- by on-site concentration of certain insoluble minerals or metals after elimination by dissolution of other mineral compounds (zirconium, titanium, rare earth deposits, as well as bauxite deposits) : these are the residual deposits.