caa a22 4500 445839244 CHVBK 20180317145338.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s00015-010-0050-0 doi (NATIONALLICENCE)springer-10.1007/s00015-010-0050-0 Late Alpine brittle faulting in the Rotondo granite (Switzerland): deformation mechanisms and fault evolution [Elektronische Daten] [Volker Lützenkirchen, Simon Loew] The unlined Bedretto tunnel in the Central Swiss Alps has been used to investigate in detail the fault architecture and late Alpine brittle faulting processes in the Rotondo granite on macroscopic and microscopic scales. Brittle faults in the late Variscan Rotondo granite preferentially are situated within the extent of preexisting ductile shear zones. Only in relatively few cases the damage zone extends into or develops in the previously undeformed granite. Slickensides suggest a predominant (dextral) strike-slip movement along these steeply dipping and NE-SW-striking faults. Microstructures of these fault rocks illustrate a multi-stage retrograde deformation history from ductile to brittle conditions up to the cessation of fault activity. In addition these fabrics allow identifying cataclastic flow, fluid-assisted brecciation and chemical corrosive wear as important deformation mechanisms during this retrogressive deformation path. Based on the analysis of zeolite microfabrics (laumontite and stilbite; hydrated Ca-Al- and Na-Ca-Al-silicate, respectively) in fault breccias, cataclasites and open fractures we conclude, that the main phase of active brittle faulting started below 280°C and ceased ca. 14Ma ago at temperatures slightly above 200°C. This corresponds to a depth of approx. 7km. Swiss Geological Society, 2011 Fault nationallicence Gotthard massif nationallicence Rotondo nationallicence Granite nationallicence Zeolite nationallicence P-T -evolution nationallicence Lützenkirchen Volker Matousek, Baumann & Niggli AG, Mäderstrasse 8, 5400, Baden, Switzerland aut Loew Simon Swiss Federal Institute of Technology (ETH Zurich), Sonneggstrasse 5, 8092, Zurich, Switzerland aut Swiss Journal of Geosciences SP Birkhäuser Verlag Basel 104/1(2011-05-01), 31-54 1661-8726 104:1<31 2011 104 15 https://doi.org/10.1007/s00015-010-0050-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00015-010-0050-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lützenkirchen Volker Matousek, Baumann & Niggli AG, Mäderstrasse 8, 5400, Baden, Switzerland aut NATIONALLICENCE 700 1- Loew Simon Swiss Federal Institute of Technology (ETH Zurich), Sonneggstrasse 5, 8092, Zurich, Switzerland aut NATIONALLICENCE 773 0- Swiss Journal of Geosciences SP Birkhäuser Verlag Basel 104/1(2011-05-01), 31-54 1661-8726 104:1<31 2011 104 15 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer