• journal_title：Journal of the Geological Society
• Contributor：Raik Bachmann ; Johannes Glodny ; Onno Oncken ; Wolfgang Seifert
• Publisher：Geological Society of London
• Date：2009-
• Format：text/html
• Language：en
• Identifier：10.1144/0016-76492008-024
• journal_abbrev：Journal of the Geological Society
• issn：0016-7649
• volume：166
• issue：2
• firstpage：217
• section：Research Article

We present new age data for the evolution of the suture zone between lower plate South Penninic and upper plate Austroalpine units in the Central European Alps. Rb/Sr deformation ages for mylonitized rocks of the South Penninic palaeosubduction mélange and for deformed Austroalpine basement (Eastern Switzerland) shed light on the pre-Alpine and Alpine deformation history along the suture, as well as on synsubduction interplate mass transfer. Rb/Sr age data define two age groups. The first group reflects pre-Alpine events within the upper plate basement, with varying degree of resetting by subsequent Alpine overprints. The second group marks the waning of subduction-related deformation along the South Penninic–Austroalpine suture zone, at around 50 Ma, and termination at c. 47 Ma. Identical Rb/Sr ages for pervasively deformed Austroalpine and South Penninic lithologies point to tectonic erosion of the upper plate during subduction. We propose that underplating of the Middle Penninic micro-continent at c. 50 Ma led to the cessation of deformation within the South Penninic mélange, and shifted the zone of active deformation into the footwall. This also caused a contemporaneous upper plate surface uplift and shutoff of sedimentation in Alpine Gosau-type forearc basins.