3.11.6 Nappe System (Dekkesystem)
3.11.6.1 A nappe system is defined as two or more nappes that are geometrically closely related to one another. The movements along the floor thrusts of the individual nappes took place during the same deformational event (see Section 4.8).
3.11.6.2 Nappe system is a tectonostratigraphical unit ranking next above nappe and equivalent in rank to nappe complex.
3.11.6.3 A nappe system has a regional extent, but all the individual nappes in the system need not be present wherever it is found. In areas where the nappe system thins, only one or a few of its component nappes may be present.
3.11.6.4 A nappe system is mappable on the surface and traceable in the subsurface with the help of geological and/or geophysical methods.
3.11.6.5 A nappe system usually contains several individual nappes and thrust sheets that can be distinguished from one another by their content of lithostratigraphical, lithodemic and biostratigraphical units.
3.11.6.6 Nappe systems can be given formal or informal names in accordance with the "general rules for naming and defining geological units" (Chap. 2) and the provisions of Section 3.11.1.2. They are not to be given the same geographical name as any of the nappes in the system, or as any of the lithological units. In areas where the nappe system thins, its name is retained even if it only survives as a single nappe. In informal contexts the geographical name of the nappe system can be used together with the term "the nappes". Informal names of this kind which are in use can, if desired, and following appropriate documentation, have their rank changed to nappe system. The proper name (Section 2.2.2) is combined with the words "the ... Nappe System" in formal names.
3.11.6.7.a The term nappe system must only be used when it is established that the movements along all the thrust faults are of the same age or belong to the same deformational event. If this is not documented, the term nappe complex is to be used (Fig. 27).
3.11.6.7.b The term nappe system (dekkesystem) must not be confused with the term thrust system which refers to thrusts that are geometrically and genetically related (Boyer & Elliott 1982).
3.11.6.8 Examples: Many related nappes and thrust sheets in the lower allochthon (Gee & Sturt 1985) of the Caledonian mountain chain of Scandinavia are assumed to have been displaced during the same deformational phase. Such nappe piles may comprise nappe systems.
3.11.6.9 Key reference: this Code.
