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 Cryogenian period (720--635~million years ago) in the Neoproterozoic era featured two phases of global or near-global ice cover, termed `Snowball Earth'. Here we present a comprehensive sensitivity study considering different scenarios for the Cryogenian continental configuration, orbital geometry, and short-term volcanic cooling effects in a consistent model framework, using the climate model of intermediate complexity CLIMBER-3α.
The continental configurations comprise palaeogeography reconstructions for both Snowball-Earth periods from two different sources, as well as two idealised configurations with either uniformly dispersed continents or a single polar supercontinent. Orbital geometries are sampled as multiple different combinations of the
parameters obliquity, eccentricity, and argument of perihelion. For volcanic eruptions, we differentiate between single globally homogeneous perturbations, single zonally resolved perturbations, and random sequences of globally homogeneous perturbations with realistic statistics.
The CO2 threshold lies between 10 and 250 ppm for all simulations.