Structural inheritance during multilayer buckle folding How preexisting

Structural inheritance during multilayer buckle folding: How pre-existing asymmetries result in parasitic folds with wrong vergence Marcel Frehner & Timothy Schmid Geological Institute, ETH Zurich, Switzerland Overview Introduction & Motivation Numerical model setup Discussion & Conclusions Results 1: Pick your favorite 1: Geometry 2: Theory 2: Rheology 3: Wrong vergence 3: Boundary conds 3: s=variable 2: Structural inheritance 4: Research question 4: FE-method 1: Reference 1: Mechanism of de-amplification 2: s=0 4: Spacing 3: Conclusions References & Further reading Links are in such Remarks: gray-framed boxes Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid Key messages appear in pink balloons. See the 2 minute -ness marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 1

Structural inheritance during multilayer buckle folding: How pre-existing asymmetries result in parasitic folds with wrong vergence Marcel Frehner & Timothy Schmid Geological Institute, ETH Zurich, Switzerland § Parasitic folds: in hed gy s i l b pu lo Just ural Geo ruct J. St § Same fold axis and axial plane orientation as major fold § Characteristic asymmetry (vergence) S, Z-, and M-folds Is it possible to inherit a pre-existing geometrical asymmetry during buckle folding? Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 2

Structural inheritance during multilayer buckle folding: How pre-existing asymmetries result in parasitic folds with wrong vergence § Minor fold first grows both in amplitude and in asymmetry Parasitic fold with wrong vergence § However, it soon de-amplifies and decreases its Check out our fully asymmetry very interactive PICO efficiently. presentation Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 3

Home Introduction 1: Pick your favorite Introduction 1: Pick your favorite parasitic fold 2: Theory 3: Wrong vergence 4: Research question Gneiss from the Caledonides Loch Cluanie, Scottland by David Chew Cycladic Blueschist Unit Syros, Greece by Marcel Frehner Mount Rubin Western Antarctica by Chris Wilson From the structural geology online teaching resources by the University of Leeds Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 4

Home Introduction 1: Pick your favorite Introduction 1: Pick your favorite parasitic fold 2: Theory 3: Wrong vergence 4: Research question Gneiss from the Caledonides Loch Cluanie, Scottland by David Chew Cycladic Blueschist Unit Syros, Greece Note how by Marcel Frehner Excellent choice! This is also one of our favorite fold images. Thanks to David Chew of the University of Dublin. Choose another fold Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid the parasitic folds of the thin layers exhibit a very Mount Rubin characteristic asymmetric shape Western Antarctica relative to the larger-scale fold. by Chris Wilson Learn more about this characteristic asymmetry From the structural geology online teaching resources by the University of Leeds marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 5

Home Introduction 1: Pick your favorite Introduction 1: Pick your favorite parasitic fold Yeah, this is a really nice one. Good choice. Thanks to Chris Wilson of the Monash University. Choose another fold 2: Theory 3: Wrong vergence 4: Research question Gneiss from the Caledonides Note how the parasitic Loch Cluanie, Scottland the thin layers exhibit by David Chew folds of a very characteristic asymmetric shape relative to the larger-scale fold. Cycladic Blueschist Unit more about this Learn Syros, characteristic Greece asymmetry by Marcel Frehner Mount Rubin Western Antarctica by Chris Wilson From the structural geology online teaching resources by the University of Leeds Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 6

Home Introduction 1: Pick your favorite Introduction 1: Pick your favorite parasitic fold Gneiss from the Caledonides Loch Cluanie, Scottland by David Chew 2: Theory 3: Wrong vergence 4: Research question Cycladic Blueschist Unit Syros, Greece by Marcel Frehner Mount Rubin Note how the parasitic folds of Antarctica the thin layers exhibit a very. Western by Chris Wilson characteristic asymmetric shape relative to the larger-scale fold. Learn more about this characteristic asymmetry Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid From the structural geology online teaching resources by the University of Leeds Thanks for voting for our example. Did you choose it because you really like it or just to be nice? Well, we certainly like it. Choose another fold marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 7

Home Introduction 1: Pick your favorite 2: Theory Introduction 1: Pick your favorite parasitic fold Gneiss from the Caledonides Loch Cluanie, Scottland by David Chew Note how the parasitic folds of the thin layers exhibit a very characteristic asymmetric shape relative to the larger-scale fold. Learn more about this characteristic asymmetry Cycladic Blueschist Unit Syros, Greece by Marcel Frehner Mount Rubin Western Antarctica by Chris Wilson 3: Wrong vergence 4: Research question This is indeed a beautiful parasitic fold example. Unfortunately, the teachers of Leed’s structural geology course don’t specify where this nice fold can be found. Choose another fold From the structural geology online teaching resources by the University of Leeds Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 8

Home Introduction 1: Pick your favorite Introduction 2: Parasitic fold theory 2: Theory 3: Wrong vergence 4: Research question 2. 1: Pumpelly’s rule What are parasitic folds? § Parasitic folds develop simultaneously with the larger fold. § Hence, they share the same (or similar) fold axis orientation and axial plane orientation as the larger fold. From Fossen § Pumpelly et al. (1894) emphasized the (2016) “general parallelism which exists between the minute and general structure”. § As a result, parasitic folds exhibit a characteristic asymmetry (fold vergence): § S- and Z-shape on either limb of the larger fold § symmetric M-shape close to the hinge of the larger fold But, does this always have to be the case? Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid How does this work mechanically? marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 9

Home Introduction 1: Pick your favorite 2: Theory Introduction 2: Parasitic fold theory 3: Wrong vergence 4: Research question 2. 2: Mechanical models § For layer-parallel pure-shear, both analog and numerical models have shown: § The thin layer folds amplify first resulting in upright symmetric folds. § The larger-scale fold amplifies later. § On the limbs of the larger-scale fold, the small-scale folds are sheared into an asymmetric geometry, Go back to leading to S- and Z-folds Pumpelly’s rule following Pumpelly’s rule. § Close to the hinge of the larger-scale fold, the small-scale folds remain symmetric (Mfolds). But, does this always have to be the case? Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid Analog model: Ramberg (1963) Numerical model: Frehner & Schmalholz (2006) marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 10

Home Introduction 1: Pick your favorite Introduction 3: Parasitic folds with wrong vergence 2: Theory 3: Wrong vergence 4: Research question 3. 1: Question Pumpelly’s rule seems to be axiomatic. van der Pluijm & Marshak (2004) wrote: “In any case, remember that a pattern of fold vergence opposite to that in Figure 10. 16 (a “Christmas-tree” geometry) cannot be produced in a single fold generation (Figure 10. 17). In fact, this geometry is diagnostic of the presence of at least two fold generations. ” Exceptions to Pumpelly’s rule: Folds under gravitational collapse Type 3 fold interference pattern Folds in simple shear FIGURE 10. 17 (van der Pluijm & Marshak, 2004): Right and wrong in fold vergence. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid This led us to Research the following question marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 11

Home Introduction 1: Pick your favorite Introduction 3: Parasitic folds with wrong vergence 2: Theory 3: Wrong vergence 4: Research question 3. 2: Folds under gravitational collapse § Harrison & Falcon (1934) described large-scale collapse structures on the flanks of large antiform-controlled topographic ridges. § These collapse structures resemble parasitic folds with a wrong vergence relative to the larger-scale antiform. From lecture notes of Jean-Pierre Burg after Harrison & Falcon (1934) Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid Go back marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 12

Home Introduction 1: Pick your favorite Introduction 3: Parasitic folds with wrong vergence 2: Theory 3: Wrong vergence 4: Research question 3. 3: Type 3 fold interference pattern § Fold interference patterns occur when two consecutive fold generations are visible at the same time. Development of type 3 § Type 3 interference patterns occur fold interference when the two folding events share patterns (van der their fold axis orientation, but have Pluijm & Marshak, an axial plane orientation roughly 2004) perpendicular to each other. § Type 3 interference patterns can resemble parasitic folds with wrong vergence if the second folding event occurs on a much larger scale than the first. Type 3 interference pattern resembling parasitic folds with wrong vergence (Fossen, 2016) Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid Go back marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 13

Home Introduction 1: Pick your favorite Introduction 3: Parasitic folds with wrong vergence 2: Theory 3: Wrong vergence 4: Research question 3. 4: Folds in simple shear § Llorens et al. (2013) demonstrated that layers oriented obliquely in a ductile shear zone can develop different vergences during a single simple-shear deformation event or even unfold completely while other layers remain folded. § This unpredictable vergence may lead to fold patterns resembling parasitic folds with wrong vergence. Multilayer folds in simple shear with increasing shear strain (Llorens et al. , 2013) Go back Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 14

Home Introduction 1: Pick your favorite Introduction 4: Research question 2: Theory 3: Wrong vergence 4: Research question Our research question Is it possible to inherit a pre-existing geometrical asymmetry during buckle folding in layer-parallel pure-shear? If so, how and under which circumstances. Go back to the overview page Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 15

Home Numerical model setup 1: Geometry Numerical model setup 1: Geometrical setup 2: Rheology 3: Boundary conds Go to 2 nd part 4: FE-method 1. 1: Two-layer system § Three high-viscosity layers (viscosity h. L) intercalated with a low-viscosity matrix (h. M). § The two outer layers have equal thickness H 0 and a distance to each other of H 0. § The two-layer system develops a dominant wavelength of (Schmid & Podladchikov, 2010) § Sandwiched between them, the third, thin layer is 10 x thinner (h 0=0. 1 H 0). § All layers exhibit an initial sinusoidal perturbation with the dominant wavelength: § We model only a quarter of the two-layer dominant wavelength, ld. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 16

Home Numerical model setup 1: Geometry Numerical model setup 1: Geometrical setup 2: Rheology 3: Boundary conds Go to 1 st part 4: FE-method 1. 2: Thin central layer § In addition, the thin central layer exhibits an asymmetric initial perturbation: § This asymmetry leads to a wrong vergence of the developing small-scale fold. § The initial skew angle is: § The thin layer also exhibits a small-amplitude random red noise (Ar=0. 02 A 0) to allow other small-scale folds to develop independently of the prescribed asymmetry. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 17

Home Numerical model setup 1: Geometry Numerical model setup 2: Continuum Mechanics & Rheology 2: Rheology 3: Boundary conds 4: FE-method We assume incompressible linear viscous rheology (Newtonian). § Rheology: § Incompressibility: Deformation is assumed to be slow (i. e. inertia terms are ignored) and independent of gravity. § Force balance: Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 18

Home Numerical model setup 1: Geometry Numerical model setup 3: Boundary conditions 2: Rheology 3: Boundary conds 4: FE-method Bottom boundary: Non-moving free slip § Zero traction § Zero boundary-perpendicular velocity Top boundary: Free surface § Zero traction § Zero boundary-perpendicular normal stress Left and right boundary: Moving free slip § Zero traction § Boundary-perpendicular velocity is adapted every time step to maintain a constant horizontal strain rate. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 19

Home Numerical model setup 1: Geometry Numerical model setup 4: Finite-element method 2: Rheology 3: Boundary conds 4: FE-method We employ the 2 D finite-element method: § Lagrangian body-fitting numerical mesh § Isoparametric triangular T 7/3 elements with the following shape functions: § 7 bi-quadratic continuous for velocity degrees of freedom § 3 linear discontinuous for pressure degrees of freedom § Mixed velocity-pressure-penalty formulation using Galerkin method § Numerical integration on 7 Gauss-Legendre quadrature points § Uzawa-type iteration to enforce incompressibility § Coordinates of the numerical mesh are moved every time step to deform the model § More details on the method: Frehner & Schmalholz (2006), Frehner (2011) Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 20

Home Results 1: Reference 3: s=variable Results 1: Reference simulation 1. 1: Simulation snapshots 2: s=0 4: Spacing This simulation as a movie See more… Skew angles Evolution of central thin layer Shifts Reference simulation with § aini = 60° § h. M /h. L = 100 § asymmetry centered on the larger-scale fold limb § Colors: Second invariant of strain rate § Dashed line: Larger-scale median line The initial asymmetry survives the early stages of buckling resulting in an alleged parasitic fold with wrong vergence, alongside true parasitic folds with correct vergence. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 21

Home Results 1: Reference 3: s=variable Results 1: Reference simulation 1. 2: Movie 2: s=0 4: Spacing This movie in static view See more… Skew angles Evolution of central thin layer Shifts Reference simulation with § aini = 60° § h. M /h. L = 100 § asymmetry centered on the larger-scale fold limb § Colors: Second invariant of strain rate § Dashed line: Larger-scale median line The initial asymmetry survives the early stages of buckling resulting in an alleged parasitic fold with wrong vergence, alongside true parasitic folds with correct vergence. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 22

Home Results 1: Reference 3: s=variable Results 1: Reference simulation 1. 3: Evolution of thin central layer 2: s=0 4: Spacing Back to static simulation view See more… Skew angles Back to movie Shifts § We calculate the distance of the thin central layer to the larger-scale median line to explore the dynamics of the thin layer evolution. Note that… § the initial asymmetry first amplifies and later deamplifies while § small-scale folds away from the initial asymmetry amplify continuously. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 23

Home Results 1: Reference 3: s=variable 2: s=0 Results 2: Asymmetries centered on fold limb 2. 1: Simulation snapshots 4: Spacing Evolution of central thin layer Simulations with § aini = [15°, 30°, 90°, 120°] § h. M /h. L = 100 § asymmetry centered on the larger-scale fold limb § Colors: Second invariant of strain rate § Dashed line: Larger-scale median line The initial asymmetry almost disappears with increasing shortening Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 24

Home Results 1: Reference 3: s=variable 2: s=0 Results 2: Asymmetries centered on fold limb 2. 2: Evolution of thin central layer 4: Spacing Back to simulation snapshots § Distance of thin central layer to the larger-scale median line § From this data, we calculate thin-layer amplitude and fold vergence. Check it out Note that, for all initial skew angles… § the initial asymmetry first amplifies and later deamplifies while § small-scale folds away from the initial asymmetry amplify continuously. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 25

Home Results 1: Reference 3: s=variable 2: s=0 Results 2: Asymmetries centered on fold limb 2. 3: Fold amplitude and vergence evolution 4: Spacing Back to simulation snapshots § From the geometry of the Go back to thin layer relative to the this data larger-scale median line, we calculate the amplitude evolution of the thin-layer asymmetry (solid lines) as well as the amplitude evolution of the thin layer at the larger-scale fold hinge (dashed lines). For all initial skew angles the initial asymmetry first amplifies and later deamplifies. § From the same data, we also calculate the evolution of the skew angle of the asymmetry. The skew angle evolves very similar to the amplitude of the asymmetry. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 26

Home Results 1: Reference 3: s=variable Results 3: Asymmetries shifted on fold limb 3. 1: Different shifts 2: s=0 4: Spacing See different skew angles for the most extreme shift Three simulations with § aini = 60° § h. M /h. L = 100 § asymmetry variably shifted on the larger-scale fold limb (towards synformal hinge) § Colors: Second invariant of strain rate § Dashed line: Larger-scale median line Asymmetry de-amplifies less the closer it is to the larger-scale fold hinge. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 27

Home Results 1: Reference 3: s=variable Results 3: Asymmetries shifted on fold limb 3. 2: Different skew angles 2: s=0 4: Spacing Go back to the different shifts Simulations with § aini = [15°, 30°, 60°, 90°, 120°] § h. M /h. L = 100 § Most extreme shift of asymmetry on the larger-scale fold limb (towards synformal hinge) If the asymmetry is close to the larger-scale fold hinge, the asymmetry does not d-amplify, independent of the initial skew angle. The skew angle stabilizes with increasing shortening. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 28

Home Results 1: Reference 3: s=variable Results 4: Varying layer spacing 2: s=0 4: Spacing We also tested different layer spacings. We tested for § the two outer thick layers having a spacing of [1, 1. 5, 2, 3] H 0, whereas the first is the reference case. § aini=[30°, 60°, 90°] § h. M /h. L=100 The tested layer spacing does hardly affect the thin layer dynamics. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 29

Home Discussion & Conclusions 1: Mechanism Discussion & Conclusions 1: Mechanism of de-amplification 2: Structural inheritance 3: Conclusions § During amplification of the larger-scale fold, two effects take place between the two thick layers (also Frehner & Schmalholz, 2006): § Layer-perpendicular flattening § Flexural flow § The resulting deformation field is a complex combination of pure and simple shear. § Pure shear (layer-perpendicular flattening) squeezes the folds of the thin layer. § Simple shear (i. e. , flexural flow) has a rotational component opposite to the vergence of the asymmetry. § Hence, both effects work against the asymmetry resulting in an efficient de-amplification and unfolding of the asymmetry as soon as the largerscale fold amplifies. § Closer to the larger-scale fold hinge, both effects diminish. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid Showcase simulation illustrating the deformation between the thick layers. marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 30

Home Discussion & Conclusions 1: Mechanism 2: Structural inheritance Discussion & Conclusions 3: Conclusions 2: Potential for structural inheritance of asymmetry § On larger-scale fold limbs, deamplification and unfolding is very efficient. Potential for structural inheritance is small. Asymmetry may survive only if shortening is small. Otherwise, parasitic folds with correct vergence will overprint the asymmetry. § Closer to larger-scale fold hinge, deamplification and unfolding is less efficient. Potential for structural inheritance is larger. If inherited, the asymmetric fold will develop a type 3 interference pattern. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid Comparison between vergence evolution on the larger-scale fold limb (solid) and hinge (dashed) marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 31

Home Discussion & Conclusions 1: Mechanism Discussion & Conclusions 3: Conclusions 2: Structural inheritance 3: Conclusions § During buckling of the two thick layers on the larger-scale, two processes work against the asymmetry with wrong vergence: § Layer-perpendicular flattening § The rotational component of flexural flow § Therefore, the potential of structural inheritance on the larger-scale fold limb is small. § Pre-existing asymmetries that are open and/or exhibit low amplitude are prone to de-amplification and may disappear during buckling of the multilayer system. § Large-amplitude and/or tight to isoclinal folds may be inherited and develop type 3 fold interference patterns. § Close to the larger-scale fold hinge, the potential for structural inheritance is significantly larger. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 32

Home References & Further reading This work: § Frehner M. , Schmid T. , 2016 Parasitic folds with wrong vergence: How pre-existing geometrical asymmetries can be inherited during multilayer buckle folding. J. Struct. Geol. 87, 19– 29, doi: 10. 1016/j. jsg. 2016. 04. 004. Numerical method used in this study: § Frehner M. , 2011: The neutral lines in buckle folds. J. Struct. Geol. 33, 1501– 1508. About parasitic folds& Buckle folding theory: § Frehner M. , Schmalholz S. M. , 2006: Numerical simulations of parasitic folding in multilayers. J. Struct. Geol. 28, 1647– 1657. § Pumpelly R. , Wolff J. E. , Dale T. N. , 1894: Geology of the Green Mountains in Massachusetts. U. S. Geological Survey Monograph 23. § Ramberg H. , 1963: Evolution of drag folds. Geological Magazine 100, 97– 106. § Schmid D. W. , Podladchikov, Y. Y. , 2010: Fold amplification rates and dominant wavelength selection in multilayer stacks. Philosophical Magazine 86, 3409– 3423. Field examples of parasitic folds with alledged wrong vergence: § Duncan I. J. , 1984: Structural evolution of the Thor-Odin gneiss dome. Tectonophysics 101, 87– 130 § Froitzheim N. , Schmid S. M. , Conti P. , 1994: Repeated change from crustal shortening to orogen-parallel extension in the Austroalpine units of Graubünden. Eclogae Geologicae Helvetiae 87, 559– 612. § Pleuger J. , Nagel T. J. , Walter J. M. , Jansen E. , Froitzheim, N. , 2008: On the role and importance of orogen-parallel and -perpendicular extension, transcurrent shearing, and backthrusting in the Monte Rosa nappe and the Southern Steep Belt of the Alps (Penninic zone, Switzerland Italy). Geological Society, London, Special Publications 298, 251– 280. Numerical models of unfolding: § Frehner M. , Reif D. , Grasemann B. , 2012: Mechanical versus kinematical shortening reconstructions of the Zagros High Folded Zone (Kurdistan region of Iraq). Tectonics 31, TC 3002. § Lechmann S. M. , Schmalholz S. M. , Burg J. -P. , Marques F. O. , 2010: Dynamic unfolding of multilayers: 2 D numerical approach and application to turbidites in SW Portugal. Tectonophysics 494, 64– 74. § Llorens M. -G. , Bons P. D. , Griera A. , Gomez-Rivas E. , 2013: When do folds unfold during progressive shear? . Geology 41, 563– 56. § Schmalholz S. M. , 2008: 3 D numerical modeling of forward folding and reverse unfolding of a viscous single-layer: Implications for the formation of folds and fold patterns. Tectonophysics 446, 31– 4. Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 33

Yes, you got it. This was a link. Go back to the overview page Structural inheritance during multilayer buckle folding Marcel Frehner & Timothy Schmid marcel. frehner@erdw. ethz. ch | 21. 04. 2016 | 34