Origin and significance of olistostromes in the evolution of orogenic belts: A global synthesis |
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| Institution: | 1. Dipartimento di Scienze della Terra, Università di Torino, 10125 Torino, Italy;2. Dipartimento di Fisica e Scienze della Terra “Macedonio Melloni”, Università degli Studi di Parma, I-43124 Parma, Italy;3. Dipartimento di Matematica e Geoscienze, Università di Trieste, 34128 Trieste, Italy;4. Department of Geology and Environmental Earth Science, Miami University, Oxford, OH 45056, USA;5. Departamento de Geología, Universidad de Oviedo, 33005 Oviedo, Spain;1. Paleomagnetic Laboratory “Fort Hoofddijk”, Utrecht University, Budapestlaan 17, 3584CD Utrecht, The Netherlands;2. Departamento de Geología, University of Salamanca, 37008 Salamanca, Spain;3. Geology and Geography Department, Tomsk State University, Lenin Street 36, Tomsk 634050, Russian Federation;1. Sorbonne Université, CNRS-INSU, Institut des Sciences de la Terre de Paris, ISTeP UMR 7193, F-75005 Paris, France;2. Institut des Sciences de la Terre, Université Grenoble Alpes, CNRS, 1381 Rue de la piscine, 38041 Grenoble cedex, France;3. CRPG, UMR 7358 CNRS-Université de Lorraine, BP20, 15 rue Notre-Dame des Pauvres, 54500 Vandoeuvre-lès-Nancy, France;4. BRGM - French Geological Survey, 3 Avenue Claude Guillemin, 45100 Orléans, France;1. EOST, Institut de Physique du Globe, UMR 7516, Université de Strasbourg, 1 rue Blessig, 67084 Strasbourg, France;2. Centre for Lithospheric Research, Czech Geological Survey, 11821 Praha 1, Czech Republic;3. Institute of Petrology and Structural Geology, Charles University, 12843 Praha 2, Czech Republic;4. Géoazur, Université Sophia-Antipolis, 250 Rue A. Einstein, Sophia-Antipolis, 06560 Valbonne, France |
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| Abstract: | Olistostromes (sedimentary mélanges) represent the products of ancient submarine mass transport processes. We present a comparative analysis of the occurrences and internal structures of these sedimentary mélanges at a global scale with a focus on the Circum-Mediterranean, Appalachian and Circum-Pacific regions, and discuss their formation and time-progressive evolution in different tectonic settings. Lithological compositions, stratigraphy, and structural features of olistostromes reflect the operation of an entire spectrum of mass transport processes during their development through multi-stage deformation phases. The general physiography and tectonic setting of their depocenters, the nature, scale and rate of downslope transformation mechanisms, and global climatic events are the main factors controlling the internal structure and stratigraphy of olistostromes. Based on the tectonic settings of their formation olistostromes are classified as: (i) passive margin, (ii) convergent margin and subduction–accretion, and (iii) collisional and intra-collisional types. Systematic repetitions of these different olistostrome types in different orogenic belts provide excellent markers for the timing of various tectonic events during the Wilson cycle evolution of ocean basins. Olistostromes are best preserved in paleo active margins, covering vast areas of thousands of km2, where they underwent significant downslope translation, up to hundreds of kilometers. Incorporation of olistostromes into subduction–accretion complexes and orogenic belts takes place during discrete episodes of tectonic events, and their primary (sedimentary) fabric may be commonly reworked and overprinted by subsequent phases of tectonic and metamorphic events. We apply the basic nomenclature of structural geology, sedimentology and basin analysis in studying the internal structure, lithological makeup, and mechanisms of formation and extraordinary downslope mobility of olistostromes. |
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