The data presented are whole-rock geochemical analyses (major and minor elements, REE) of highliy deformed and metamorphosed rocks of the Middle and Eastern Erzgebirge nappe stacks. Geochemical discrimination was used to identify the protolith nature of a sample series representing metasedimentary, metagranitoidic, metarhyolitic, and metabasaltic rock types. Discrimination between para- and orthogneisses was also supported by mathematical factor analysis. According to new geochronological data, ages of the sample series range between Neoproterozoic to Ordovician.
Analyses with different methods (ICP, AAS, XRF, OES, WET) were made between 1979 and 1991 in different laboratories of the German Democratic Republic (GDR) and the early GFZ German Research Centre for Geosciences. Economical constraints limited the capacity of and access to labs, and also available techniques in the GDR - limiting the spectrum of elements to be analysed, especially that of REE, as well. Switching from lab to lab (see table) became a neccessary tool. Despite these problems, all data proved to be comparable. This also applies in comparison to data from later used techniques (ICP, from 1991 on) on some additional sample material, regardless of its higher resolution. In few cases, detection limits have not been communicated (see template). The data are reported with the EarthChem Templates (https://doi.org/10.26022/IEDA/112263).
German title: Gesamtgesteins-Geochemie (Haupt-, Spurenelemente, REE) an hoch-deformierten und metamorphosierten Gesteinen der Mittel- und Osterzgebirgirgischen Deckenstapel
The Shackleton Range in Antarctica is an example for alpine-type ultramafic rocks occurring as lenses in high-grade gneisses. The lenses consist of garnet- and/or spinel-bearing peridotite and pyroxenite taken during the GEISHA expedition in 1987/1988 by W. Schubert in the Haskard Highlands. In olivine-bearing rocks, garnet testifies to high-pressure conditions - that were unrecognised in this area until recently. Generally, ultramafic rocks are valuable tracers of suture zones, such as palaeo-subduction and collision zones. If the high-pressure imprint in the Shackleton Range resulted from the Pan-African collisional event, the ultramafic rocks are very important to better understand the amalgamation of the Gondwana supercontinent, provided their pressure-temperature-time (PTt) evolution is known. The general intention of this project is to unravel the PTt evolution of the Haskard Highland ultramafic, and closely associated mafic, rocks. The reconstruction of detailed PT paths was the prime task of the first year. Ongoing research is directed at geochronological and geochemical investigations of the ultramafic rocks and closely associated metabasites. Preliminary results imply that the Shackleton Range is one of the few examples of Pan-African eclogite-facies rocks in general; other examples are known from Mali (e. g. Jahn et al. 2001) and Zambia (e. g. John and Schenk 2003). Moreover, the study area is possibly the first example of eclogite-facies ultramafic rocks related to Pan-African collision (Schmädicke and Will 2006). The continuation of the newly discovered suture zone within Antarctica and beyond remains unknown. Future research is needed to unravel (i) the nature of the protoliths and (ii) the time of protolith formation in order to put the Shackleton Range into the proper geodynamic framework.