3.3.5 Complex (Kompleks)
3.3.5.1 A complex is a lithodemic unit consisting of a mixture or assemblage of rocks belonging to two, or all, of the classes of rocks, i.e. igneous, sedimentary and metamorphic rocks.
3.3.5.2 Complex has no rank in the lithodemic classification system.
3.3.5.3 No limitation is placed on the dimensions of a complex, but it generally has a regional extent.
3.3.5.4 A complex is mappable at the surface and traceable in the subsurface using geological and geophysical methods.
3.3.5.5 The individual, associated bodies of different rock units making up a complex may be formally named lithodemes, lithostratigraphical units, and/or informal and unnamed lithological units. They have often been deformed together to form a complicated structural pattern, but this is not a prerequisite. A complex of large regional extent may contain other complexes of smaller areal distribution.
3.3.5.6 A complex is given a formal or an informal name in accordance with the "general rules for naming and defining geological units" (Chap. 2). Names made up of a geographical name between the words "the ... Complex" should preferably only be used for formally defined complexes (see Section 2.3.2).
3.3.5.7.a A complex is a practical mapping entity in areas where it is difficult or impractical to distinguish individual lithodemic or stratigraphical units on the map scale in question.
3.3.5.7.b A complex is often comparable in size to a suite or supersuite.
3.3.5.7.c A volcanic complex is an assemblage of different kinds of volcanic rocks and associated intrusive and weathering products (Fig. 1). Volcanic complexes or intrusive-volcanic complexes that are included in a thick sequence of sedimentary rocks can be defined together with these as a supergroup (see Section 3.2.4.1).
3.3.5.7.d A structural complex is an assemblage of different kinds of rocks intermixed by tectonic processes (Fig. 1).
3.3.5.7.e Except for c and d, geological units consisting of assemblages of different rocks of a single class should not be designated as a complex, but as an intrusive suite or a metamorphic suite, for example.
3.3.5.7.f The term "complex" is also used in connection with joint complex (Section 3.9.3), fault complex (Section 3.9.7) and nappe complex (Section 3.11.5) (see Section 1.2).
3.3.5.7.g The term "series" has often been used for lithodemic and lithostratigraphical units corresponding to suite, supersuite, complex, group and supergroup. "Series" is not to be used in formal names, i.e. names containing a geographical name (or an alternative name in the case of the continental shelf), for any geological units of this sort, nor for tectonostratigraphical units (see Section 2.3.2).
3.3.5.8 Examples: The term "complex" has been used for many lithodemic units in Norway, mostly informally. Not all of these are complexes according to the above definition. "Gabbro complexes" are, for example, either a gabbro lithodeme or a gabbro suite. The assemblage of strongly metamorphosed gneissic and plutonic rocks in West Finnmark (Krauskopf 1954, Roberts 1974) may be defined as a complex. Ring structures (as in the Oslo Region) consisting of several bodies of plutonic and minor intrusive rocks will be ring suites. If they also contain volcanic and perhaps sedimentary rocks they will be ring complexes or cauldrons.
3.3.5.9 Key reference: NACSN (1983).
