TY - JOUR A1 - Förster, Hans-Jürgen A1 - Romer, Rolf L. A1 - Gottesmann, Bärbel A1 - Tischendorf, Gerhard A1 - Rhede, Dieter T1 - Are the granites of the Aue-Schwarzenberg Zone (Erzgebirge, Germany) a major source for metalliferous ore deposits? : a geochemical, Sr-Nd-Pb isotopic, and geochronological study N2 - The Aue-Schwarzenberg Granite Zone (ASGZ), in the western Erzgebirge of Germany, is composed of small, late- Variscan F-poor biotite and two-mica granites. The biotite granites (Aue granite suite, Beierfeld, Bernsbach) are weakly to mildly peraluminous (A/CNK = 1.07-1.14; 70-76 wt% SiO2), display similar Sr-87/Sr-86 initial ratios (0.7065-0.7077; t = 325 Ma), and exhibit a narrow range in epsilon Nd-325 (-2.6 to -3.5). They are closely affiliated compositionally with the biotite granites in the distant, more voluminous Nejdek massif (Czech Republic). The two-mica granites (Schwarzenberg granite suite, Lauter) are Si-rich (74-77 wt% SiO2) and mildly to strongly peraluminous (A/CNK = 1.17- 1.26). The granites from Schwarzenberg Lire distinctly higher in their Sr(i)ratios (0.709-0.713; t = 325 Ma) and possess lower values of epsilon Nd-325 (-4.9 to -5.2) relative to the biotite granites. The Lauter granites have a Nd-isotopic composition between -3.6 and -4.0 (t = 325 Ma). Mean Th-U-total Pb uraninite ages (Ma +/- 2 sigma) obtained for the granites from the Aue Suite (324.3 +/- 3. 1), Beierfeld (323.7 +/- 3.1), Bernsbach (320.7 +/- 2.9), Schwarzenberg (323.3 +/- 2.4), and the Kirchberg granite al Burkersdorf (322.7 +/- 3.5) indicate that magmatism in the ASGZ commenced in the Namurian and took place early within the major episode of granite formation in the Erzgebirge-Vogtland zone (327-318 Ma). Geochemical and mineralogical patterns of variably altered samples imply that the ASGZ granites are unlikely to have significantly contributed to the formation of spatially associated metalliferous ore deposits (Sn, W, Mo, Ph, Zn, Bi, Co, Ni), except for uranium. In particular the Aue granite suite should have served as major Source for U accumulated in the economically important post-granitic deposits of Schneeberg and Schlema-Alberoda. Y1 - 2009 UR - http://www.schweizerbart.de/j/n-jb-min/ U6 - https://doi.org/10.1127/0077-7757/2009/0138 SN - 0077-7757 ER - TY - JOUR A1 - Förster, Hans-Jürgen A1 - Tischendorf, Gerhard A1 - Rhede, Dieter A1 - Naumann, R. A1 - Gottesmann, Bärbel A1 - Lange, W T1 - Cs-rich lithium micas and Mn-rich lithian siderophyllite in miarolitic NYF pegmatites of the Konigshain granite, Lausitz, Germany N2 - Annite and Fe-rich siderophyllite constitute the rock-forming micas in the late-Variscan composite granite pluton of Konigshain, Lausitz, Germany. This multiphase pluton is composed of three fractionated, but not chemically specialized monzogranite types, which contain lithophile elements such as Li, Rb, Cs, Sn, and F in average quantities. Abundant miarolitic pegmatites of the NYF family with a broad diversity of rare minerals occur in the apical part of the pluton. These pegmatitic cavities locally contain di- and trioctabedral micas as well as cation-deficient micas. Trioctahedral micas comprise F-rich manganoan lithian siderophyllite to manganoan zinnwaldite, zinnwaldite, and minor lepidolite. The formula [calculated on the basis of 22 anion valencies and 2 (F + OH + Cl)] of the most Mn-rich siderophyllite is (K0.85Rb0.08Na0.04)(0.97)(Al0.99Li0.91Fe0.51Mn0.42Ti0.01Zn0.01)(2.85) (Si3.21Al0.79)(4)O- 10(F1.80OH0.19Cl0.01)(2). This mica constitutes one of the most Mn-rich siderophyllite compositions reported to date. The lithium micas poorer in Mn are distinguished by elevated concentrations of Rb (up to 2.5 wt % Rb2O), CS (UP to 1.2 wt % Cs2O), and F (up to 9.6 wt %). This fluorine content is probably consistent with the maximum possible F occupation of 2 of the (F,OH,Cl)-site. The structural formula of the most Li-rich lepidolite is (K0.83Rb0.07Cs0.03)(0.93) (Li1.62Al1.00Fe0.38)(3.00)(Si3.62Al0.38)(4) O-10(F1.91OH0.09)(2). During hydrothermal alteration, lepidolite and zinnwaldite became partially depleted in K, Li, Rb, Cs, and F and gradually transformed into cation-deficient micas (lithian phengite to illite of phengitic affinity) Y1 - 2005 ER - TY - JOUR A1 - Gottesmann, Bärbel A1 - Förster, Hans-Jürgen T1 - Sekaninaite from the Satzung granite (Erzgebirge, Germany) : magmatic or xenolithic? N2 - In the earliest emplaced granite subintrusion of the multiphase peraluminous Satzung pluton, Erzgebirge, Germany, a mineral aggregate was observed consisting of sekaninaite (X-Fe = 0.74-0.94), Zn-rich hercynite (X-Zn = 0.03- 0.11), tri- and dioctahedral layer silicates of different composition and color, and minor quartz. Geological, textural, and compositional criteria argue that the sekaninaite, hercynite, quartz, and the brown biotite are not primary or secondary granite minerals, but are of metamorphic origin representing a xenolith uptaken from the granite melt near its level of emplacement. The metamorphic origin is supported by the occurrence of this mineral assemblage in metamorphic rocks exposed locally in the Erzgebirge basement. Reaction of the polymineralic metamorphic aggregate with the surrounding melt and subsequent interaction with alkali-, F- and LILE-rich residual fluids account for the widespread decomposition of the sekaninaite and formation of several layer silicates including green biotite, muscovite, berthierine/Fe chlorite, and sericite. The observed enrichment of the relic sekaninaite and its replacement products in elements such as Na, Li, Be, Rb, Cs, and F is result of interaction of the metamorphic fragment with the surrounding melt/fluid, in accordance with the evolved nature of the Satzung magmatic-hydrothermal system Y1 - 2004 SN - 0935-1221 ER -