Baltica- and Gondwana-derived sediments in the Mid-German Crystalline Rise (Central Europe): Implications for the closure of the Rheic ocean

Combined U-Pb and LU-Hf isotope analysis of detrital zircons reveals that the Mid-German Crystalline Rise (MGCR) contains Palaeozoic sediments of distinct provenance in close proximity Zircons from a metapelite of the Brotterode group were derived from a Gondwanan Source. whereas zircons from the Rogis quartzite of the Ruhla group point to provenance from Baltica Brotterode zircons mostly yield ages of 500-720 Ma and 2 0-2 1 Ga, and show an age gap between 1.0 and 1 7 Ga, which is characteristic of Gondwana/peri-Gondwanan detrital zircon populations Combined U-Pb and Hf isotope data suggest intense crustal recycling at 2 6-2.9 Ga, 1 8-2 1 Ga, and 570-720 Ma as well as formation of juvenile crust during the latter two periods In contrast, zircons of the Rogis quartzite mostly yield ages between 0 9 and 1 8 Ga. which are typical of southwestern Baltica Minor age populations at 435-466 and 550-660 Ma indicate that the quartzite is younger than Late Ordovician/Early Silurian, and that the Baltica-derived sediment is contaminated by minor pen-Gondwanan, perhaps Avalonia-derived detritus. Minor age populations at 2 0, 2.56, 2 67, and 2 86 Ga additionally point to a Svecofenman and/or Karelian source U-Pb and Hf isotope data imply that the Baltica-derived zircons were produced mainly through melting Of Juvenile Palaeo- to Mesoproterozoic crust. The data presented here indicate that the MGCR hosts the Rheic suture between Gondwana and Balonia, and that this suture zone was closed in a complex sequence of stages from the Late Silurian onwards (C) 2009 International Association for Gondwana Research Published by Elsevier B V All rights reserved