Comprehensive geochemical investigations of metabasites yielded constraints for a correlation of, or discrimination between the different tectonic units within the northeast Bavarian crystalline basement.
Major-, trace- and rare-earth element chemistry studies of metabasite intercalations within different tectonic units of the East Bavarian crystalline basement leads to the following geochemical classification: The flaser amphibolites of the Erbendorf-Vohenstrauss Zone (ZEV) exhibit an enriched, E-MORB- or intraplate-like tholeiitic character, whereas the schistose and striped amphibolites of the ZEV and of the Tirschenreuth-Mahring Zone show N-MORB compositions. The metagabbros of the ZEV are transitional between these two types. The metabasites of the Erbendorf Greenschist Zone are similar to modern island-arc basalts (tholeiitic to calc-alkaline). The Fichtelgebirge crystalline complex contains amphibolites of enriched tholeiitic to alkaline i.e., intraplate character.
On the Island of Andros, Cycladic Blueschist Belt, metamorphosed ferromanganoan sediments occur in widespread lateral distribution. They form concordant layers and lenses within a uniform sequence of quartz-rich metapelitic schists which can be derived from pelagic siliceous mudstones. Three main types of ferromanganoan metasediments were geochemically investigated: (1) piemontite—spessartine and piemontite quartzites (PSQ), containing braunite-rich lenses; (2) spessartine quartzites (SQ); and (3) Napyroxene quartzites (NpxQ). Textural and geochemical evidence leads to the conclusion that PSQ is derived from a Mn-nodule-bearing sediment consisting of a mixture of terrigenous illitic clay with biogenic radiolarian ooze. Compared to recent nodule-bearing sediments, PSQ is markedly enriched in Cu, Pb, Sr and As. We assume that these elements were mobilized, during diagenesis and/or early metamorphism, from the sedimentary column, and were subsequently concentrated in minerals like piemontite, ardennite and braunite under highly oxidizing conditions. In contrast to PSQ, SQ and NpxQ are derived from parent sediments rich in smectite. SQ shows a higher Al/Fe ratio in rock composition than NpxQ and may change into NpxQ by a decreasing content of spessartine. While SQ is chemically equivalent to a montmorillonitic clay + Mn2+ + Na+, almost spessartine-free NpxQ can be derived from Fe-rich nontronitic clay + Na+. Mn2+ required for the formation of SQ was probably mobilized from adjacent Mn-nodule-bearing sediments (PSQ).
The granodiorites and quartz diorites of the Fürstenstein igneous complex (Bayerischer Wald), the diorites of the Spessart crystalline area (including schollen of amphibolite, and schlieren rich in K-feldspar) as well as the diorites and hornblende gabbros of the central Odenwald igneous complex have been compared. 65 rock specimens have been analyzed for the major and minor elements Si, Ti, Al, Fe3+, Fe2+, Mn, Mg, Ca, Na, K, P, as well as for the trace elements Zn, Cu, Ni, Rb, Sr, Zr, Ba, and (semiquantitative) V, and Cr using X-ray spectrometric, flame photometric, titrimetric, and UV-spectrometric methods. 33 additional analyses (major and minor elements only) have been taken from literature.
Die Granodiorite und QuarzGlimmer-Diorite aus dem Intrusivgebiet von Fürstenstein (Bayerischer Wald), der Diorit des südlichen Vorspessarts mit eingeschalteten Amphibolitschollen und kalifeldspatreichen Schlieren, sowie die Diorite und Hornblendegabbros des mittleren Bergsträßer Odenwaldes wurden geochemisch verglichen. Zur Bestimmung der Haupt-, Neben- und Spurenelemente in 65 Gesteinsproben wurden röntgenspektrometrische, titrimetrische, flammenphotometrische und emissionsspektralanalytische Methoden herangezogen. Zusätzlich fanden 33 chemische Analysen aus der Literatur Verwendung.
