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Journal of the Geological Society, London, Vol. 160, 2003, pp. 429-434. Printed in Great Britain.
Abstract:
Orogenic cycles may be viewed as comprising two extensional stages that are separated by a stage of contraction. This sequence has characterized the evolution of most mountain belts resulting from continental collision, and the structural signature of individual stages is recognized on a wide variety of scales, i.e. from microscopic to regional. Whereas the history of mountain belts is generally inferred from observations carried out at different sites, the entire sequence of deformation is very rarely recorded in single exposures. The double switch in tectonic regime that led to the development of the Lucanian Apennines in southern Italy, from pre-orogenic drifting through synorogenic thrusting to post-orogenic extension, is preserved in a superb metre-scale outcrop at Serra Manarella, in the vicinity of San Fele. A Late Jurassic, synsedimentary normal fault is sealed by strata affected by a Mid-Pliocene thrust-related fold. This composite structure, in turn, is truncated by a Mid-Pleistocene normal fault. Observation of these relationships represents a unique opportunity to unequivocally establish the relative chronology of deformations in the Lucanian Apennines, and may provide useful constraints for regional cross-section restoration.
Keywords: Southern Italy, Lucanian Apennines, orogeny, inversion tectonics, structural analysis.
The repeated opening and closure of oceans along the same trends, and the consequent fragmentation and reassembly of continents have long supported the concept, known as the Wilson cycle, of periodical recurrence in erogenic events. Although several aspects implied in the original definition of orogenic cycle, as formulated by Wilson (1966), have been questioned and modified by the affirmation of plate tectonics in the late 1970s (Dewey & Bird 1970; see also discussion by Moores & Twiss 1995, pp. 297-299), a certain cyclicity in orogenic events is recognized in the geological record worldwide (Ryan & Dewey 1997, and references therein). Orogenic cycles, in their broader definition, may be viewed as resulting from the combination of two extensional deformation stages, namely, pre-orogenic and post-orogenic extension, separated by an intervening stage of synorogenic contraction. This sequence of alternating deformations, indicated as positive (from extension to contraction) and negative (from contraction to extension) tectonic inversion, respectively (terminology after Williams et al. 1989), has characterized the history of most mountain belts...