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Herfried Madritsch Nagra (Geologist / Project Manager Field Investigation)
Geology of Northern Switzerland
Overview & some key questions regarding the region’s seismic exploration
Annual Convention 2015 Baden 20th June 2015
Background
DMT Petrologic: G. Rybarczyk, F. Rost
geosfer ag (St. Gallen): H. Naef, P. Hammer, T. Ibele
Geologisches Institut Universität Bern: H.R. Bläsi, A. Matter, A. Pfiffner
Départment des Geosciences Université de Fribourg: J. Mosar, D. Egli, M. Diem, M. Gruber
Geological Institute Universität Jena: J. Kley, A. Malz
Geoexplorers (Liestal): S. Schefer
Gruner Böhringer AG (Oberwil): P. Jordan, D. Arndt, J. Pietsch
Proseis AG (Zürich Oerlikon): B. Meier, P. Roth, P. Kuhn, S. Heuberger, S. Muff, B. Steiner
Nagra: W. Albert, J. Becker, P. Birkhäuser, P. Blaser, G. Deplazes, L. Kiefer, B. Kunz, M. Ruff, M. Schnellmann, T. Vietor
Ackknowlegments (contributing & supporting colleagues)
Geological Setting: The bigger picture
Nagra 2014
Geological Setting: Central Northern Switzerland
Tectonic map & synoptic stratigraphic profile (Nagra 2014)
Presentation concept:
Modified from Müller et al. 2002
«A journey through time»
1 Late Palezoic structures
2 Mesozoic stratigraphy
3 Late Cenozoic tectonics
Late Paleozoic structures
Late Paleozoic: Crystalline basement
Polyphase deformed gneisses & granitic intrusions
Crystalline Rocks are only exposed in the southern Schwarzwald Massif
Major Late Variscian fault zones
(Franzke in prep.)
Filename 9
Late Paleozoic: Permocarboniferous Trough
Carboniferous & Clastic sediments (coal bearing) Compilation of Permocarboniferous sediments (Leu 2008)
Late Paleozoic wrench faulting let to the formation of Permocarboniferous troughs
Late Paleozoic: Permocarboniferous Trough
Top Basement map of northern Switzerland with compilation of Permocarboniferous sediments (Leu 2008)
Tectonic model of the trough
Diebold et al. 1991
Late Paleozoic: Permocarboniferous Trough
Diebold et al. 1991 Marchant et al. 2000
Tectonic Model of the trough: wide range of possible interpretations
Late Paleozoic: Permocarboniferous Trough
Modified from Naef & Madritsch 2014
Aided by the high quality new seismic data the tectonic map of the trough was updated (> see follow-up presentation by B. Meier)
Mesozoic stratigraphy
Triassic: Evaporites
Anhydrite of the Lower Keuper
Early Triassic Mesozoic transgression Shallow marine to terrestrial environment Evaporites in the Lower & Middle Muschelkalk and the Keuper Formation Future detachment horizons during compressive Alpine foreland deformation
Ductile deformation of anhydrites in the Folded Jura
Triassic: Aquifers
Limestones & Dolomites of the Upper Muschelkalk Well cores of Upper Muschelkalk from the geo-thermal well Schlattingen-1 (see Frieg et al. 2015)
Early Triassic Mesozoic transgression Shallow marine to terrestrial environment Limestones & Dolomites of the Upper Muschelkalk Potenitally important aquifers!
Triassic: Marls
More details on tomorrow’s excursion!
Keuper sediments exposed in the clay pit of Frick
Liassic: Staffelegg-Formation
Homogeneous claystones of the Frick Member Frequent «hard beds» within the Gross Wolf Member
Revised stratigraphy by Reisdorf et al. (2011) Strongly condensed section (thickness of 20 – 50 m) Consituted of several different members containing clay-, lime and / or sandstones Characterized by lateral facies transistions
(e.g. Wetzel et al. 2003)
?
Liassic: Staffelegg-Formation
According to Nagra’s host rock definition the Staffelegg Formation consitutes to the «lower confining units» of the Opalinus Clay
Significant for site selection in SGT-E2
(e.g. Wetzel et al. 2003)
Facies distribution of the Staffelegg Fm. in northern
Switzerland (Kiefer et al. 2015)
?
Liassic: Staffelegg-Formation
Overview of the Frick clay quarry
More details on tomorrow’s excursion!
Dogger: Opalinus Clay
Clay stone deposited in a shallow epicontinental sea (70-130 m thick) Very high clay content (> 45 %) Regarded as the prioritory host rock for the disposal of radioactive waste in Switzerland
?
Paleogeographic situation at beginning of Opalinus Clay deposition (after Allia 1996)
Opalinus Clay in cores of the Benken well (Nagra 2002)
Dogger: Opalinus Clay
Main advantage over other host rock candidates: Very homogenous over several scales
Nagra 2002
Dogger: Opalinus Clay
Main advantage over other host rock candidates: Very homogenous over several scales
Further key properties very high sorption very low permeability self sealing properties
More details on Monday’s excursion to the Mont Terri rock laboratory
Upper Dogger: inkl. the «Brauner Dogger»
Comparatively complex stratigraphy between the Opalinus Clay & Base Malm Characterized by dramatic lateral facies changes due to increasingly differential subsidence On a regional scale, a western and an eastern facies area can be distinguished
Cross bedded limestone of the Hauptrogenstein Fm.
Western facies area Eastern Facies area
Sandstone intercalated clays of the Wedelsandstein Fm.
More details on tomorrow’s excursion!
Upper Dogger: inkl. the «Brauner Dogger»
The «Brauner Dogger» sequence in the east was proposed as potential host rock for LLW during SGT-E1 (Nagra 2008)
Intercalated hard beds suggest smaller scale facies changes within the sucession Key issue for seismic exploration (> see follow-up presentation by B. Meier)
Sandstone intercalated clays of the Wedelsandstein Fm. Seismofacies in the «Brauner Dogger» succession
Lower Malm: The Effingen Member
Part of the Wildegg Fm. deposited in an epicontinental basin Sandy marls intercalated by successions of limestone beds Strongly varying thickness across northern Switzerland (SW to NE: > 200m to < 50m) In the southwest the units was proposed as potential host rock for LLW
Deplazes et al. 2013
Upper Effingen Member with 3 distinct limestone beds successions & the
underlying very calcareous Gerstenhübel beds in the
Jakobsberg Quarry
Lower Malm: The Effingen Member
Limestone bed successions with strongly decreased clay content can be correlated over several 100 m using various geological & geophysical data sets
Nagra 2014
Well correlation of the Wildegg Fm. incl the
Effingen Member using quantitative clay content
curves derived from geophysical logs
Lower Malm: The Effingen Member
These continuous «hard beds» make the Effingern Member disadvantageous compared tow other nominated host rocks in particular Opalinus Clay
More details on tomorrow’s excursion!
Tectonic outcrop-scale fracture systems as observable in limestone beds within the Effingen Member (Madritsch, 2015)
Upper Malm: Villigen Formation
Dominated by micritic limestones of varying thickness
Facies distribution & paleogeography of Effingen Wildegg & Villigen Fm. (compiled by Nagra 2014 based on Gygi 2000, 1990)
Massif, micritic limestones of the Villigen Fm.
More details on tomorrow’s excursion!
Molasse sandstone (Early Miocene)
Siderolithic clay (Eocene) Carstified limestone (Upper Malm)
The Upper Malm represent the youngest Mesozoic sediments The Top Malm / Base Tertiary is marked by regional unconformity representing
~100 Ma of stratigraphic hiatus Very important seismic marker horizon (> see follow up presentation by B. Meier)
Late Mesozoic & Early Cenozoic: Uplift & erosion
Late Mesozoic & Early Cenozoic: Uplift & erosion Thermochronological data suggests approx.
800 m of uplift & erosion (Mazurek et al. 2006)
Most likely related to the developement of the Alpine forebuldge
Widely observed dilational mode-I type fractures most likely formed as a consequence.
More details on tomorrow’s excursion!
Late Cenozoic tectonics
Miocene: Molasse basin formation & normal faulting
OMM clastics dissected by a normal fault USM marls intercalated by sandstones
The area of Northern Switzerland becomes affected by flexural bending
Miocene: Molasse basin formation & normal faulting
Seismically expressed normal fault cutting through
the Mesozoic succession and rooting in a deep-seated
basement fault
(> see also follow-up presentation by B. Meier)
Reactivation of late Paleozoic basement structures (cf. Diebold & Noack 1997)
Miocene: Hegau tectonics & volcanism
Egli & Mosar 2014
Kinematics of faulting & relation to volcanic activity are still poorly understood
Ongoing collaborative research with the Université de Fribourg
Late Miocene: Jura Folding
Folded of Mesozoic strata
The Lägern Anticline
Ductile deformation of Triassic evaporites
caused by «Distant-push»
Buxtorf 1916, Laubscher 1961
(> see also follow-up presentation by B. Meier)
Late Miocene: Jura Folding
Indications for a secondary «thick-skinned» deformation phase underneath the Jura Mountains are increasing (e.g. Ustaszewski & Schmid 2007)
Possibly involving a reactivation of deep seated basement structures (Permocarboniferous Trough?)
Modified from Burkhard & Sommaruga 1999
Jura Folding: Defining today’s tectonic units
Nagra 2014
Late Miocene structures: Mandach-Thrust
Alternative interpretation approaches (Madritsch et al. 2013)
(> see also follow-up presentation by B. Meier)
Jura Folding: Defining today’s tectonic units
Nagra 2014
Late Miocene structures: Baden-Irchel-Herdern Lineament
Alternative interpretation approaches (Madritsch et al. 2013)
Triangle structures proves to be restorable and be geometrically valid (Malz et al. 2015a)
Late Miocene structures: Baden-Irchel-Herdern Lineament
Late Miocene structures: Implications
More details on tomorrow’s excursion!
Secondary detachments appear to have strong influence on the structural style
Malz et al. 2015b
The Paleozoic basement structures were reactivated multiple times
Late Miocene structures: Implications
Naef & Madritsch 2014 (> see also follow-up presentation by B. Meier)
Post-Pliocene: & what about Neotectonics?
Counterclockwise rotation of Central Italy with shortening in the southern Alps & Dinarides Instrumentally recorded recent shortening
across Swiss Alps: < 0.5 mm/a Time series are yet rather short (measurements close to error margin) &
may not be representative for the period of concern of a repository (1 Ma)
Post-Pliocene: & what about Neotectonics?
Quaternary deposits can be used as geomorphic markers to eventually detect or exclude subtle active deformation that might have occured over long time scales
Late glacial gravels in the Lower Aare Valley
Morphology of Early Pleistocene «Deckenschotter» Gravels
Post-Pliocene: & what about Neotectonics?
More details on tomorrow’s excursion!
Morphologic analysis of the Mandach Thrust east of the Beznau Isle (Nagra 2014)
The potential of these geomorphic approaches has
increased significantly due to the availabilty of high resolution digital
elevation models
(e.g. based on LiDAR data with vertical accuracy ~ < 50cm)
Geological overview: Resume
Northern Switzerland has a fascinating geological history
Highlights include:
− Complex facies transitions developed during Mesozoic sedimentation
− World class type examples of thin-skinned deformation structures
− Evidences for polyphase reactivation tectonics
Nagra’s exploration activities have continuously contributed to a better understanding of the region’s geology
The gained knowledge is of relevance for both, the geoscientific and the geoeconomic community.
besten dank für ihre aufmerksamkeit
Thank you for your attention!
«See you tomorrow in the Jura Mountains»
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