Subduction polarity reversal at the junction between the Western Alps and the Northern Apennines, Italy

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• 作者：Gianluca Vignaroli ; Claudio Faccenna ; Laurent Jolivet ; Claudia Piromallo ; Federico Rossetti
• 关键词：Western Alps ; Northern Apennines ; Voltri Massif ; Tomography ; Kinematic reconstruction ; Extensional detachment ; Toroidal flow
• 刊名：Tectonophysics
• 出版年：2008
• 出版时间：1 April 2008
• 年：2008
• 卷：450
• 期：1-4
• 页码：34-50
• 全文大小：4454 K

文摘

The controversial relationship between the orogenic segments of the Western Alps and the Northern Apennines is here explored integrating recently published 3D tomographic models of subduction with new and re-interpreted geological observations from the eclogitic domain of the Voltri Massif (Ligurian Alps, Italy), where the two belts joint each other. The Voltri Massif is here described as an extensional domain accommodating the opposing outward migration of the Alpine and Apennine thrust fronts, since about 30–35 Ma. Using tomographic images of the upper mantle and paleotectonic reconstructions, we propose that this extensional setting represents the surface manifestation of an along strike change in polarity of the subducted oceanic slab whose polarity changed laterally in space and in time. Our tectonic model suggests that the westward shift of the Alpine thrust front from the Oligocene onward was the consequence of the toroidal asthenospheric flow induced by the retreat of the Apenninic slab.