Hello! In response to your question, "terrigenous" "detrital", and "clastic" are all terms most commonly used in Sedimentary rock classification.

All rock types are classified by both texture and mineral composition. Detrital sedimentary rocks and Chemical/Biochemical/Organic Sedimentary rocks are the two general divisions discussed in Geology textbooks.

In short, "Detrital", or "Terrigenous clastic" rocks are composed of solid inorganic particles/sediments derived from rock weathering within the continental sedimentary rock environment. "Clastic" and "Bioclastic" are textures most commonly used to describe Chemical and Biochemical rocks composed of particles derived from formerly living organisms (i. e., shell shards, microfossils) within the marine sedimentary rock environment.

Hopefully, you'll find this helpful.

i am not a sediment geologit’s, so am not a total expert on sedimentary terms. The words yo are using are used people talking about rocks that are deposited the land into an ocean, stream or lake. The sedimentary rock will have grains which come from the land. Detritial means the rocks components are from the countryside. Terrigenous is used to say the rock contains things which were part of the land. Clastic means the particles are large enough to see what little fragments are from the land.

sediments which in time accumulate in the open ocean which are far enough from the land will not show obvious particles eroded from a nearby piece of land.m instead rocks that are only from the ocean that is far enough from the land, and therefore are not terrifenous usually are made from the microscopic plants and animals that rain down from the surface waters. the rock from such deposits will often be the little bodies of the little creatures that lived and died as part of the water column. If land is nearby, little grains from the land will form the rock. The land particles will overwhelm these little dead organisms, and therefore the rock that forms will represent the diet that washes out into the open water from the land. You need to be far enough from the land that the sediment that forms does not contain dirt from the land. To escape seeing little particles that are from the land, you have to be very far from the land. So the dirt from the land is So little that it Is not swamped by the dirt from th3e land.

- Terrigenous rocks emphasize the land-derived origin of sediments.

- Detrital deposits are loose, unconsolidated sedimentary particles.

- Clastic rocks are lithified sedimentary rocks made from clasts of pre-existing rocks.

The previous responses are helpful in two ways. First, they provided examples of common uses of the terms. Second, they show how the words can be used be interchangeably and may not be very specific because they are concepts and not actual physical features of the rocks. To understand these terms in whatever context you find them, I recommend going back to basics. First, take a look at the Wentworth scale of grain size (https://www.planetary.org/space-images/wentworth-1922-grain-size) to get a precise definition of mud, silt, sand and gravel. These definitions apply to all grains, regardless of their mineral composition. Then look into the concepts of "terrestrial" depositional environments (https://wiki.aapg.org/Depositional_environments#:~:text=Depositional%20environment%20is%20part%20of,marginal%20marine%2C%20and%20marine%20environments). Be sure to note that "detrital" and "clastic" rocks can also form in ocean environments and can be called limestone if their dominant mineralogy is carbonate.

Terrigenous rocks: Derived fom land or continents, mainly used to discriminate the source of sediment in (coastal) matrine environments

Detrital rocks: composed of fragments and particulate matter derived from pre-existing rocks by erosion, weathering and laid down after transport or left in situ. Classification is used when when present in rocks at a an amount of > 50 % detrial matter

Clastic rocks: composed of fragments of prexisting rocks.

The particles can be minerals or lithoclasts of different grain size from shale to conglomerate (pelite, arenite, rudite) or a regolith. Applicable to all three categories. Transport, compaction and diagenetic alteration are no modifier or reason for differentiation in this tripartite scheme

HGD

Terrigenous sedimentary rocks are specifically derived from terrestrial sources and encompass various rock types formed from these sediments. Detrital deposits refer more broadly to any accumulated debris from erosion, which may include terrigenous materials but is not limited to them. Clastic rocks focus on the fragmental nature of sediments that make up a significant category within terrigenous sedimentary rocks.