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    Program

• Timetable
• Field program (Neves area): August 22^nd to 24^th
• Lecture program (Varna, Brixen): August 25^th to 28^th

    Timetable    22-28 August 2012

• 22^nd afternoon (16.00): arrival at Bruneck (Brunico) train station and transfer to the Chemnitzerhütte (Rifugio Porro) for dinner and overnight
• 23-24^th : field work on the glaciated outcrops in front of the southern Grosser Möseler (Mesule) glacier (photo)
• 25^th morning: move to Varna (Brixen)
• 25-28^th: classroom teaching in Varna (Brixen)
• 29^th morning: depart

Field Program

The field course will be held in the Nevessee (Lago di Neves) area (South Tyrol, northeast Italy) and will address the structural analysis of deformation structures within the Tauern meta-granitoids. The structures are present on polished outcrops at the base of the south-eastern Grosser Möseler (Mesule) glacier (Fig. 1, Fig. 2) that provide spectacular exposures for structural analysis of 2D deformation geometries. The area is located at about 2600 m and is reachable by a well-marked track from the Chemnitzerhütte (Rifugio Porro), at 2419 m. We will stay at this hut, which one reaches along a broad path from the Nevessee in about 1 hr 45 mins walking time (about a 500 m climb).
>From the geological point of view, the area is located just north of a thick belt of Alpine amphibolite facies mylonites (well visible on the aerial photograph of Fig. 3), which can be investigated along the path from the hut to the glacier. The study area represents a low strain domain, which largely escaped the Alpine structural overprint. It is therefore possible to analyse in detail the progressive development of discrete ductile shear zones that exploit a network of brittle precursors (joints) and pre-existing magmatic or fluid–induced compositional heterogeneities.
During the field analysis, students will gain familiarity with the following structures:

• magmatic structures (including different acid and basic intrusives, magma mingling, etc.): Fig. 4a, Fig. 4b, Fig. 4c, Fig. 4d, Fig. 4e);

• joints;

• epidote veins and alteration haloes along joints and fractures (Fig. 5a, Fig. 5b, Fig. 5c);

• single and paired discrete shear zones nucleating on planar compositional and structural heterogeneities (Fig. 6a, Fig. 6b, Fig. 6c, Fig. 6d, Fig.6e , Fig.6f, Fig.6g);

• quartz-biotite-plagioclase-biotite-calcite veins (Fig. 7a, Fig. 7b, Fig. 7c);

• intersecting ductile shear zones (Fig. 8a, Fig. 8b, Fig. 8c).

• late stage quartz-chlorite-epidote vein systems (Fig. 9a, Fig. 9b, Fig. 9c).

See all the pictures !!!

Suggested reading:

• Mancktelow, N.S. and Pennacchioni, G., 2005. The control of precursor brittle fracture and fluid–rock interaction on the development of single and paired ductile shear zones. Journal of Structural Geology 27, 645–661. PDF
• Mancktelow, N.S. and Pennacchioni, G., 2010. Why calcite can be stronger than quartz. Journal of Geophysical Research 115, B01402, doi:10.1029/2009JB006526. PDF
• Pennacchioni, G. and Mancktelow, N.S., 2007. Nucleation and initial growth of a shear zone network within compositionally and structurally heterogeneous granitoids under amphibolite facies conditions. Journal of Structural Geology 29, 1757-1780. PDF

Students will be taught to analyse:

• the time relationships between the different intrusions of the pre-Alpine protolith;

• the control of structural and compositional heterogeneities on nucleation of shear zones;

• the role of fluids during ductile deformation;

• the kinematic relationships between the different structural element of the deformation network (shear zones and veins);

• the interference between intersecting shear zones.

Lecture Program

The second part of the school will include a series of lectures The classes will cover the following topics:

1) Solid-state ductile deformations within cooling of plutons.
Teacher: Giorgio Pennacchioni (Padua University, Italy)

The lecture will describe the solid-state deformation structures developed in different plutons (e.g.: Adamello, Southern Alps, Italy; Mono Pass Intrusive Suite, Sierra Nevada, California) during their cooling. The main focus will be on deformation structures developed at  high temperatures (T ≥ 500°C) and the role of structural (joints) and compositional (e.g. dykes) heterogeneities on nucleation of shear zones. The deformation structures in  cooling plutons will be compared with those seen during the field excursion in the Tauern metagranitoids in the Neves area. These observations provide the basis of a new model for the nucleation of ductile shear zones in granitoid plutons.

2) Fluid rock interaction along shear zone networks.
Teacher: Stephen Cox (ANU, Australia)

(a) Fluid involvement in the mechanics of faults and shear zones:
     -  failure modes
     -  Mohr circle treatments of brittle fracture mechanics
     - evidence for overpressures during rock deformation
     -  failure mode diagrams - a new way to explore the effects of fluid pressures on rock stress
(b) Coupling between deformation and permeablity enhancement in faults and shear zones.
(c) Reaction-enhanced permeability.
(d) Chemical fluid-rock interaction in faults and shear zones: reaction weakening and reaction strengthening.
(e) Isotopic signatures of reactive transport in networks of faults and shear zones.

Practical exercises - application of failure mode diagrams to explore the strength and mechanical behaviour of rocks.

3) Microstructural studies on fluid-rock interaction and deformation mechanisms in mylonitic shear zones.
Teacher: Luca Menegon (Tromsø University, Norway)

      The lecture will show examples of deformation microstructures of quartz and K-feldspar in natural shear zones formed at mid- to lower-crustal conditions. The observations will be discussed in terms of (i) the effect of fluid rock interaction on the activation of different deformation mechanisms, and (ii) the implications for the strength evolution of the mid- to lower crust. The following topics will be addressed:
(a) Introduction to methods for quantitative microstructural and texture analysis (e.g., SEM-based techniques, image analysis, texture goniometry)
(b) Effect of hydrous fluids on the creep strength and deformation microstructures of quartz: when can we extrapolate lab-derived flow laws to natural conditions?
(c) Fluids, replacement reactions and deformation in granitoids
(d) Transition from fracturing to viscous flow in K-feldspar

4) Rock analogue and numerical modelling of shear zone structures.
Teachers: Neil Mancktelow (ETH-Zurich, Switzerland) and Dani Schmid (Oslo University, Norway)

(a) Strain localization and the development of heterogeneous shear zones
(b) Shear zone ends and transfer zones
(c) Stress refraction in layered and anisotropic rocks
(d) Tectonic variation in pressure in deforming rocks and its importance for controlling fluid-rock interaction
(e) Flanking structures developed around planar heterogeneities in shear zones
(f) Deformation and rotation and/or stabilization of clasts in shear zones

5) Deformation of Quartz in Nature and Experiments.
Teachers: Michael Stipp (GEOMAR Kiel, Germany)

(a) Crystal plastic deformation microstructures in nature and experiments
(b) The brittle to plastic transition in nature and experiments.
(c) Experimental piezometers and flow laws: Correlating deformation conditions between laboratory and            Earth.
(d) Rheology of the Earth's crust.

Practical exercises -Measuring stress in nature and experiment

6) Experimental and microstructural investigations of rocks deforming at varying stresses.
Teacher: Claudia Trepmann (Ludwig-Maimilians University Munich, Germany)

      The lecture will show examples, how microstructures can be used to give information on the stress history during deformation. For this, TEM, SEM and EBSD analyses of naturally and experimentally produced microstructures will be discussed in the view of the following topics:
(a) Deformation at the lower tip of a seismic active fault zone
     - Deformation at transiently high and then rapidly decreasing stresses
     - Recrystallization after deformation at low stress
(b) Deformation of HP-LT metamorphic rocks in subduction zones
     - Low stress deformation by dissolution-precipitation creep
     - Local stress concentrations due to viscosity contrasts

Further Information

• The field area is easy of access and no climbing or special Alpine experience is required. However, the field course is in a high mountain environment and adequate equipment is essential. What do you need? Download the checklist!
  The work area is at 2600m a.s.l. We will be outside the whole day (with a packed lunch provided by the hut). The weather can be warm and sunny but can also be very cold, windy and, in the worst case, snowy.

• Course language: English.

• Course participants: priority is given to PhD students, post-Docs and young researchers specializing in structural geology. Finishing masters students in the process of starting PhD will be considered if there are places left.

• Course max number of participants: 35 (on a first come first served basis).