Deciphering orogenic evolution

Abstract

Deciphering orogenic evolution requires the integration of a growing number of geological and geophysical techniques on various spatial and temporal scales. Contrasting visions of mountain building and lithospheric deformation have been proposed in recent years. These models depend on the respective roles assigned to the mantle, the crust or the sediments. This article summarizes the contents of the Special Issue dedicated to "Geodynamics and Orogenesis" following the "Réunion des Sciences de la Terre" 2010 conference held in Bordeaux, France. Further, based on the example of the Western Alps-Mediterranean domain we emphasize the possibility to integrate long and short term, plate-to sample-scale, datasets in order to constrain orogenic evolution.

Review of metamorphic and kinematic data from Internal Crystalline Massifs (Western Alps): PTt paths and exhumation history

“…As emphasized by several authors (e.g. Beltrando et al, 2010a,b), the Early Oligocene is characterized in the Alps by a rapid change in tectonic setting, which can be interpret as a transition towards post-collisional rotation of Apulia driven by subduction in the Mediterranean domain (Rolland et al, 2012). This transition occurring at 35-30 Ma is also documented from the study of external Alpine sedimentary basins (Dumont et al, 2012).…”

Geological setting of the southern termination of Western Alps

“…This age-span could correspond, in the Maritime Alps and Western Ligurian Alps, to the switch from sinistral tectonics to a compressional one (Maino et al 2013 (Piana et al 1997(Piana et al , 2006Dela Pierre et al 2003). This event induced the dextral reactivation of the main NW-SE striking shear zones at regional scale (Sanchez et al 2011a;Rolland et al 2012;Bauve et al 2014), although in the study area sinistral movements are still locally recorded along the D2 event (see Fig. 5) with shear reactivation of the S2 foliation (Fig.…”

“…Consequently, the presence of a major kinematic "transfer zone" (Ligurian sinistral transfer, LST in Fig. 19) at the southern termination of the Western Alps arc could be envisaged as a major crustal feature that may have provided the left-lateral "southern disengaging lineament" (Giglia et al 1996) necessary for the Oligocene westward indentation (Dumont et al 2011(Dumont et al , 2012 and counterclockwise rotation (Collombet et al 2002;Rolland et al 2012) of Adria promontory, as invoked in literature during the last decades (see "Structural setting at the southern termination of the Western Alps" section for details), and roughly described as "Stura couloir" or Stura Fault.…”

Collision kinematics in the western external Alps

“…These values added to the shortening estimates from the cross sections (Table ) provide the following convergence values since 35 Ma for the external zone: around 270 km of convergence for the northern part of the studied area (Mont Bland and Aar massifs) and around 140 km for the southern part (Oisans massif). This variation in convergence along strike the Alpine arc witnesses the rotation of Adria relatively to Europe [ Ustaszewski et al , ; Handy et al , , and references therein], which is recorded in many ECMs [e.g., Rolland et al , , , ]. This rotation may be due to the push of the African plate coupled to the slab rollbacks (especially in western Mediterranean [e.g., Dewey et al , ; Jolivet and Faccenna , ; Faccenna et al , ]).…”