3.7.14 Basin (Basseng)
3.7.14.1 A basin is a present-day or former landform and/or structural form element. Basins can have any shape whatsoever in horizontal section. A basin is often bounded by faults. It often contains sedimentary and/or volcanic strata (Figs. 9, 10).
3.7.14.2 Any basin can also be classified as a depression.
3.7.14.3 No limitations are placed on the dimensions of a basin.
3.7.14.4 A basin is mappable with the help of geomorphological, geological and/or geophysical methods.
3.7.14.5 A basin will often be divisible into smaller geomorphological and/or structural elements.
3.7.14.6 A basin can be given a formal or an informal name in accordance with the "general rules for naming and defining geological units" (Chap. 2) and the rules for naming geological form units (Section 3.7.1). The proper name (Section 2.2.2) is placed between the words "the ... Basin" (formal) in the compound name.
3.7.14.7.a A structural basin need not be, or have been, a landform. Sub-basins (underbassenger) are small basins which, in structural terms, form part of a larger, main basin. Palaeobasins (paleobassenger) are former basins that are no longer geologically active, either tectonically or sedimentologically.
3.7.14.7.b Rooted palaeobasins (rotfaste paleobassenger) are former basins situated where they originally formed, and are recognized by the preservation of their primary shape, structural framework and a basinal stratigraphical sequence. Rooted palaeobasins are given formal or informal names. A specific sedimentary basin related to a certain unit within a stratigraphical succession (a member, formation or group) can be named, preferably informally, after the relevant lithostratigraphical unit. Structural basins on the continental shelf are rooted palaeobasins.
3.7.14.7.c1 Rootless palaeobasins (rotløse paleobassenger) are former basins which can only be recognized because a basinal stratigraphical succession is preserved. The original sedimentary surfaces of the basin may be entirely or partially destroyed by tectonic deformation. Rootless palaeobasins exist as transported sequences in thrust nappes.
Rootless palaeobasins are to be named after the lithostratigraphical unit defining the basin. The proper name used for that unit will be the only relevant geographical name that can be naturally associated with the former basin.
3.7.14.7.c2 Rootless palaeobasins which have previously had a very large regional distribution, such as an enclosed ocean or ocean arm, should be given names that are not derived from any present-day land or sea area, or from any existing, named structural element. Such names may have a mythological origin (e.g. Tethys Ocean, Iapetus Ocean).
3.7.14.8 Examples: The Tromsø Basin (Rønnevik et al. 1975b) is a rooted structural basin on the continental shelf. The Valdres Basin, the Hedmark Basin and the Engerdal Basin are rootless, Late Precambrian basins (Kumpulainen & Nystuen 1985). From Finnmark, Siedlecka (1985) has defined the Late Precambrian Barents Sea Basin, which is also a rootless palaeobasin. The Kråkenes Basin is an example of a small Quaternary basin of sedimentation (Larsen & Mangerud 1981).
The Zechstein Basin is named after the lithostratigraphical unit, Zechstein, which defines the distribution and history of the basin (Taylor 1984).
3.7.14.9 Key reference: Bates & Jackson (1980).
