caa a22 4500 465791786 CHVBK 20180323112026.0 cr unu---uuuuu 170327e19900301xx s 000 0 eng 10.1007/BF00678985 doi (NATIONALLICENCE)springer-10.1007/BF00678985 Simon K. Geochemisches Institut der Universität, D-3400, Göttingen, Federal Republic of Germany aut Hydrothermal alteration of Variscan granites, southern Schwarzwald, Federal Republic of Germany [Elektronische Daten] [K. Simon] Hercynian S-type granites from the southeastern Schwarzwald granite series represent cogenetic biotite-and two-mica granites. Oxygen- and hydrogen-isotope data show that hydrothermal alteration invoking isotopically light surface waters resulted in a drastic reduction in δ18O and δD and pronounced disequilibrium between the minerals. Effective water-rock ratios are calculated to be high, about 0.8 vol units. A shift in the18O/16O and the chemical composition of the fluid due to water-rock interaction is continuously traced from pure H2O with meteoric isotopic character in the deep-seated biotite granites to slightly saline water with rock-equilibrated isotopic composition in the two-mica granites at a shallower level. Substantial retrograde hydrometamorphism in the temperature range 500° to 200° C resulted mineralogically in high-temperature chloritization of biotite, and low-temperature muscovitization as well as feldspar alteration, respectively. Another result of the re-equilibration of cations is strong disturbance of the Rb−Sr system which affects measured ages and initial87Sr/86Sr values. Hydrothermal differentiation and alteration probably overlap to a very large extent magmatic differentiation processes. Springer-Verlag, 1990 Contributions to Mineralogy and Petrology Springer-Verlag 105/2(1990-03-01), 177-196 0010-7999 105:2<177 1990 105 410 https://doi.org/10.1007/BF00678985 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00678985 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Simon K. Geochemisches Institut der Universität, D-3400, Göttingen, Federal Republic of Germany aut NATIONALLICENCE 773 0- Contributions to Mineralogy and Petrology Springer-Verlag 105/2(1990-03-01), 177-196 0010-7999 105:2<177 1990 105 410 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer