Structural and petrologic aspects of the emplacement of granitoid plutons : case studies from the western margin of the Joshua Flat-Beer Creek-Pluton (White-Inyo Mountains, California) and the Flasergranitoid zone (Odenwald, Germany)

The Joshua Flat-Beer Creek Pluton (JBP) in the White-Inyo-Mountains, California, is part of the Inyo batholith and was emplaced 180-160 Ma ago. The intrusion consists of three phases. Field relations, remote sensing data and major element geochemistry suggest an intrusion sequence Marble Canyon Diorite --> Joshua Flat Monzonite --> Beer Creek Granodiorite as nested diapirs. Thermobarometry shows that the JBP intruded at temperatures between 664 and 900 °C into a depth of c. 8 km. In the contact aureole three metamorphic zones were distinguished with decreasing distance from the pluton: the andalusite-cordierite, sillimanite, and cordierite-K-feldspar zones, respectively. The Na-in-cordierite thermometer gave c. 730 °C as the peak metamorphic temperature in the innermost aureole. Relative low contents of volatiles in cordierite from pelites (measured by infra-red spectroscopy) indicate that the intrusion and related contact metamorphism took place under water undersaturated conditions. Fabrics in the contact aureole document several emplacement mechanisms such as stoping and dyking, ductile downward flow, partial melting and magma chamber expansion. Ductile downward flow and stoping made most of the space for the pluton. AMS (anisotropy of the magnetic susceptibility), quartz-c-axes and strain measurements support the field observations. The plutons of the Flasergranitoid Zone in the Crystalline Odenwald Zone intruded around 325 Ma ago. Intrusion conditions of five dioritic to granitic plutons were determined with hornblende geothermobarometry. The plutons intruded into a depth of 13 to 20 km at temperatures between 600 and 800°C. Most of the igneous rocks from the Flasergranitoid Zone (Germany) show a pronounced planar fabric. Structural investigations of the Ludwigshöhe granite (AMS, quartz-c-axes and shape orientation measurements) prove that these planar fabrics can be the product of pure magmatic processes.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2000

Authors dc:creator

• Dietl, Carlo
• Stein, Eckardt
• Kontny, Agnes

Contributors dc:contributor

• Greiling, Reinhard O.()

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/1409

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:1409