Gabrielse et al. (1991, DNAG G-2) define a "terrane" as an area possessing unique tectonic assemblages (lithostratigraphic units representing a specific depositional or volcanic setting responding to a tectonic event), which differs from adjacent terranes and is bounded by faults. The term "terrane" does not have any genetic significance nor does it imply an origin far removed from adjacent terranes or its present position relative to the craton. Terranes are only defined by their internal assemblage composition. The “terrane” definition can be extended further. An "accreted terrane" refers to a terrane that has become attached to a continental margin in the later stage of its tectonic history. Several terranes can become amalgamated by overlap assemblages or "stitched together" by intrusions and form superterranes" before final accretion to a continent. "Subterranes" are divisions of terranes in which a certain affinity exists, but not necessarily a stratigraphic continuity. "Pericratonic terranes" are situated between accreted terranes and ancestral continental margin. They may have stratigraphic affinities to the continental margin or represent metamorphosed sediments that were deposited at or near the continent.
This definition has led some authors to criticize the terrane concept as being too vague and general, claiming it only confuses discussion and is neither an improvement over older terminology, which uses more descriptive terms like "sliver", "block" or "fragment", nor a new concept (Sengör & Dewey 1991 in Dewey et al. "Allochtonous terranes"). As well the term "terrane" (or "terrain") has already been used in geographic and stratigraphic connotation. A good example within the North American Cordillera is the debate around the Yukon-Tanana and the Nisling terrane definition (Mortensen, Tectonics 11, 1992). However, despite this criticism, the terrane concept is the accepted terminology used in modern discussion of the Canadian Cordillera.
Gabrielse, H., Monger, J. W. H., Wheeler, J. O. & Yorath, C. J. (1991): Part A. Morphogeological belts, tectonic assemblages and terranes. In: Geology of the Cordilleran Orogen in Canada (eds Gabrielse, H. & Yorath, C. J.) Geology of Canada, No. 4, pp. 15-28. Geological Survey of Canada.
Mortensen, J. K. (1992): Pre-mid-Mesozoic tectonic evolution of the Yukon-Tanana terrane, Yukon and Alaska. Tectonics, 11, 836-853.
Sengör, A. M. C. & Dewey, J. F. (1991): Terranology: vice or virtue? In: Allochtonous Terranes (eds Dewey, J. F., Gass, I. G., Curry, G. B., Harris, N. B. W. & Sengör, A. M. C.), pp. 1-21. Cambridge University Press.
Howell, D. G. (1989): Tectonics of Suspect Terranes: Mountain building and continental growth. Topics in the Earth Sciences 3, 232 p., Chapman & Hall, London.
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