Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

Kinematic evolution and structural styles of fold-and-thrust belts

J. POBLET1* & R. J. LISLE2 1Departamento de Geologı´a, Universidad de Oviedo, C/Jesu´s Arias de Velasco s/n, 33005 Oviedo, Spain 2School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff CF10 3YE, UK *Corresponding author (e-mail: [email protected])

Abstract: Fold-and-thrust (FAT) belts occur worldwide and have long been the focus of research of structural geologists who have devised a variety of techniques to image, characterize and model their main structural features. This introductory chapter reviews the principal geological features of FAT belts formed in different settings, emphasizing aspects related to their kinematic evolution and structural styles. Despite great advances, challenges remain, particularly in the understanding of the spatial and temporal evolution (4D) of FAT belts and their controlling factors. These research efforts are being assisted by the growing availability to researchers of relatively new tools to collect field data, high quality 3D seismic data, and computer and laboratory modelling tools. This volume includes technical papers presented in the conference ‘International Meeting of Young Researchers in Structural Geology and Tectonics (YORSGET-08)’ held in Oviedo (Spain), together with other papers on the same theme. These papers deal with FAT belts in different parts of the world and cover a broad range of different aspects, from detailed structural analysis of single structures to regional issues, and from studies based on classical field structural geology to modelling.

Fold-and-thrust belts, or FAT belts for short, have a The application of classical methods of studying worldwide distribution (see surveys in Nemcok deformation mechanisms in rocks and of quantify- et al. 2005; Cooper 2007), have formed in all eras ing geological strain (e.g. Ramsay 1967; Durney of geological time, and are widely recognized as & Ramsay 1973; Fry 1979a, b) to FAT belts has the most common mode in which the crust accom- led to greater understanding of deformation on a modates shortening. Generations of geologists have small scale and has given insights into the mechan- struggled to understand their origin, geometry, evol- isms responsible for the development of individual ution and the control exerted on them by different structures such as folds and faults. A number of structural, tectonic, stratigraphic and petrological techniques were initially devised to analyze the parameters (see for instance monographic books structure of FAT belts, for example: (a) balanced such as McClay & Price 1981; MacQueen & and restored cross-sections (e.g. Dahlstrom 1969; Leckie 1992; McClay 1992a, 1994; Mitra & Fisher Mitra & Namson 1989); (b) construction of geologi- 1992; Nemcok et al. 2005; Lacombe et al. 2007). cal cross-sections using techniques such as depth to A number of factors have contributed to our detachment estimations (e.g. Chamberlin 1910; greater understanding of the structure of FAT Mitra & Namson 1989) and the Busk and dip belts; some of them derive from detailed analyses domain methods (Busk 1929; Suppe 1985, respect- of prevalent patterns of faulting and folding and ively); and (c) advances in the understanding of their related structural features, whereas others quantitative relationships between thrusts and their come from other earth science disciplines. Many related folds and the rules to help to constrain the important concepts were developed and applied structural geometries (Suppe 1983; Jamison 1987; to FAT belts as early as the 1970s, or even before, Mitra 1990; Suppe & Medwedeff 1990). These tech- and have been subsequently modified. Since a com- niques have enabled construction and validation of prehensive historical review of research progress admissible and retro-deformable geological sections is almost impossible here, only a few important across single structures, structural units and entire landmarks are briefly described, starting with struc- FAT belts. They have also provided guidelines for tural methods from small- to large-scale and seismic interpretation, and proved to be essential following with techniques applied to these regions tools in structural interpretation widely applied else- furnished by related disciplines such as petroleum where, particularly in areas of scarce and/or poor geology, geophysics, geomorphology, petrology quality data. The study of accretionary wedges and sedimentology. played a key role in the development of the

From:Poblet,J.&Lisle, R. J. (eds) Kinematic Evolution and Structural Styles of Fold-and-Thrust Belts. Geological Society, London, Special Publications, 349, 1–24. DOI: 10.1144/SP349.1 0305-8719/11/$15.00 # The Geological Society of London 2011. Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

2 J. POBLET & R. J. LISLE

Coulomb wedge theory (e.g. Davis et al. 1983; isotopes, magnetostratigraphy, fission tracks, cos- Dahlen et al. 1984). This theory, which incorporates mogenic nuclides, and so on (e.g. Vance & Mu¨ller the best of the gravity-driven v. surface force-driven 2003; Alle`gre 2008; Lisker et al. 2009; Dunai motion hypotheses, was a major step forward in the 2010) have enabled estimates to be derived for understanding of the kinematics and dynamics of both the timing and the short- and long-term rates FAT belts because it allowed the inclusion of the of motion of single structures and larger-scale tec- effects of gravity and topography and provided tonic processes. These have demonstrated, for answers to the problems of structure sequencing in instance, that synchronous movement of different these regions. thrusts is a significant feature in the kinematic evol- The contribution of geophysics has been hugely ution of FAT belts, which, in turn, has important beneficial to FAT belt research. In particular, since implications for thrust sequences and the balancing/ many belts contain major oil and gas accumulations restoration of cross-sections and forward modelling in structural traps, the geophysical explorations of thrust terrains. A great deal of recent research has carried out by the hydrocarbon industry have sup- been focused on the dynamic interaction between plied an enormous amount of subsurface data. FAT belt evolution and surficial processes such as From the early seismic experiments in the late syn-kinematic sedimentation, erosion, uplift and 1920s in the Zagros FAT belt and in Oklahoma subsidence from lithosphere-scale (e.g. Beaumont until the present day, seismic imaging has furnished et al. 1992; Kooi & Beaumont 1996) to individual additional constraints on the geological interpret- structure-scale (e.g. Riba 1976; Suppe et al. 1992; ation of the deep geometry of structures, which Hardy & Poblet 1994). Thus, whereas the geometry had previously relied on geological data collected of the syn-tectonic sediments and basins within the at the surface. Seismic has, in some cases, also FAT belts is influenced by development of struc- allowed mapping of subsurface structures that are tures, the latter in turn are themselves strongly decoupled from their surface structural expression. affected by sedimentation and erosion. In short, Without forgetting the important contribution studies based on tectonic geomorphology and made by some other branches of geophysics, such palaeoseismology, P–T–t paths, geochronology as gravimetry for constraining of the deep structural and surficial processes in FAT belts sparked an configuration, or palaeomagnetism in the under- increasing interest in quantitative modelling of the standing of rotations around vertical axes, one of evolution of these belts at various scales. the most important boons to mapping of FAT belts has been the development of 3D seismic survey methods. 3D seismic data volumes provide a con- Types of FAT belts tinuous and more accurate image of the subsurface than can be obtained with 2D seismic methods Summarizing the main features of FAT belts is not (Hart 1999). Aided by the development of structural an easy task because they are remarkably diverse. tools, for example, Geosec 3D, 3D Move, Lithotect Although they exhibit a number of common charac- and Gocad software packages to visualize, charac- teristics, no single map or cross-section can provide terize and model the 3D structure of folds and a universal portrayal of a FAT belt because many thrusts, 3D seismic is starting to supply answers, parameters exert an important influence on them particularly with respect to the questions of the (see, for instance, Fitz-Diaz et al. 2011). These geometry of structures along strike and whether factors include the plate tectonics setting in which structures evolve in a self-similar fashion, that is, they developed, whether only the cover or both the whether observed spatial variations in fold geome- cover and basement rocks are involved in the struc- try reflect temporal geometric evolution (Elliott tures, the role of mechanical stratigraphy, the pres- 1976; Means 1976), or whether they evolve through ence, distribution and thickness of a salt/shale different structural forms. detachment, the occurrence of syn-orogenic ero- The contributions of tectonic geomorphology sion and deposition leading to burial, the depth to and palaeo-seismology of mountain fronts (Bull detachment and the effective elastic thickness of 2007 and references therein) have helped to deter- the lithosphere (e.g. Royden 1993), the occurrence mine the development of structures through the of pre-existing basement structures, the timing and study of the landscape evolution and offset/position deformation rates, and so on. All of these factors of landforms. Furthermore, P–T–t data (e.g. Spear are important, though a discussion of their effect is & Selverstone 1983; England & Thompson 1984; beyond the scope of this paper. Thompson & England 1984) collected from the FAT belts are typical regions in most orogenic interiors of FAT belts have been employed to inter- belts controlled by compressional tectonics and pret the burial, thermal and subsequent uplift have been documented in environments resulting histories operating during emplacement of thrust from plate convergence such as those formed sheets. In addition, geochronology studies using at plate collision boundaries (e.g. Himalayas, Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 3

Apennines), at plate subduction boundaries (e.g. of the belt, which is usually filled in with debris Andes, Zagros) and at intraplate locations influ- eroded from the mountain belt and in some cases enced by neighbour plate convergence (e.g. affected by the prograding thrust system which Yinshan belt and Western Ordos belt in China). carries forward the older foreland basin. This Accretionary prisms are a special type of FAT belt uplifted, shortened and transported basin is known developed in subduction zones such as the Barbados as a piggy-back basin. prism. FAT belts known as toe thrust belts develop Some FAT belts include a slate belt (Hobbs et al. in deep water at the leading edge of large-scale grav- 1976; Twiss & Moores 1992) such as that of Wales itationally driven sedimentary prisms on continental (e.g. Smith & George 1961), which mainly consists margins such as those in the Gulf of Mexico and off- of a monotonous series of relatively unfossiliferous shore Brazil, or in thick delta complexes such as the deep-water sediments, such as shales and slates. Niger delta or in deltas in northwest Borneo. FAT These sediments were deposited in relatively belts may also form due to transpression at oblique internal positions of the belt, such as the edge of plate boundaries, where the overall plate conver- passive continental margins or offshore volcanic gence involves strike-slip components of motion, environments. Slate belts are narrow, elongate fea- such as part of the southern Carpathians and the tures parallel to the orogenic belt. The stratigraphy Central-South Trinidad thrust belt, or along large- and structure of slate belts is usually difficult to scale transform or transcurrent faults at restraining reconstruct due to poor exposure conditions, the bends or oversteps and at fault splays, such as the lack of fossils and stratigraphic markers as well as Transverse Ranges of the San Andreas transform the metamorphic conditions up to low grade. The fault and perhaps the Palmyride belt in Syria in low competence contrasts within these sedimentary relationship to the Dead Sea transform fault. piles results in tight to isoclinal flattened folds with thickened hinges which can possess near-similar Foreland FAT belts and crystalline thrusts geometry. They exhibit variably inclined axial surfaces, from upright to recumbent. They include One of the most well-known types of FAT belts are parasitic folds and can form fold nappes, with the foreland FAT belts that are 10 to 1000 kilo- more than one fold generation present in some metres wide and constitute the external zones of cases. Pervasive continuous foliation such as a orogens (Figs 1 & 2). The Canadian Rocky Moun- slaty cleavage and phyllitic foliations, overprinted tains zone (Price 1981) is one of the best examples by later spaced foliations in some cases accom- of a foreland FAT belt. These FAT belts typically panied by folding, and by kink bands, become domi- involve an unmetamorphosed or low-grade meta- nant. Although thrusts are present, the lack of morphic sedimentary cover, whose thickness marker beds makes them difficult to map. decreases towards the foreland (interior of a conti- On the thickened side of the orogenic belts in nent), deposited over a metamorphic/igneous base- the transition to the crystalline core of a mountain ment, whose top usually dips towards the hinterland chain, metamorphic rocks, either as basement slices (ancient sea), that constitute the passive continental or as progressively metamorphosed sedimentary margin. They usually exhibit a wedge geometry in rocks, appear. The thrusts involving metamorphic cross-sectional view and this shape is maintained and/or igneous rocks are usually known as crys- throughout the deformational history of the belt. talline thrusts (Hatcher 1995) and have been Deformation is confined to the uppermost part of known for many decades in the Alps, Appalachians, the crust bounded by a sole thrust (basal detach- Scandinavian and British Caledonides. Whereas the ment) that dips gently towards the hinterland and thrusts closer to the undeformed regions form under rises stratigraphically upwards towards the foreland; brittle conditions, those close to the metamorphic the sole thrust may be blind or may reach the topo- core develop under ductile to brittle conditions. graphic surface in some cases (Figs 1–3). There Thus, the thrust surface may be initiated due to a may be various detachments above the sole thrust local ductile behaviour, whereas the thrust sheet that tend to rise up towards the foreland, but all of may be transported by brittle translation. In con- them ultimately branch off from the main sole trast to those FAT belts developed in regions occu- fault. Many thrusts surfaces are asymptotic at pied by sedimentary rocks where bedding is the depth, forming imbricate thrust systems in which main structural discontinuity, appropriately oriented thrust surfaces may maintain an approximately pre-existing faults, well-developed foliations and regular spacing. However, other types of thrust ductile-brittle transitions are the main mechanical systems such as duplex, antiformal stacks, triangle weaknesses that allow the propagation of crystalline zones and intercutaneous wedges (Butler 1982; thrusts. Crystalline thrust sheets are among the McClay 1992b) are common as well (Figs 1–4). largest structures in orogenic belts and may form The loading effect of a FAT belt creates accommo- as large slabs or on the overturned limbs between dation space in the foreland basin developed in front recumbent folds because of continued transport 4 Downloaded from http://sp.lyellcollection.org/

MOUNTAIN ROCKY MOUNTAINS FOOTHILLS TRENCH .PBE .J LISLE J. R. & POBLET J. SW Pu Bo Sm Ru In La Mc NE BT OB Bz

0 Km

-5 16 15 14 13

-10 byguestonSeptember27,2021 BASEMENT 0 10 20 km

H = V

Fig. 1. Balanced geological section across the Rocky Mountains Foothills, Cordilleran FAT belt. Note the sub-vertical to overturned thrusts in the southwestern part of the cross-section, probably due to underlying folding and thrusting (modified from Price 1981). Downloaded from IEAISADSYE FFL-N-HUTBELTS FOLD-AND-THRUST OF STYLES AND KINEMATICS http://sp.lyellcollection.org/ byguestonSeptember27,2021

Fig. 2. (a) Simplified structural map of the foreland FAT belt of the Variscan Orogen in northwest Iberian Peninsula (Cantabrian Zone), which exhibits an orocline geometry

(Ibero-Armorican or Asturian arc). Dominant thrusting style in the SW portion of the belt changes to a dominant folding style in the NW part of the belt. (b) Balanced geological 5 section across the Cantabrian Zone. The cross-section line is located in Figure 2a. Note the sub-vertical to overturned thrusts in the east part of the cross-section probably due to thrust sheet stacking. Both figures are modified from Pe´rez-Estau´n et al. (1988). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

6 J. POBLET & R. J. LISLE

Fig. 3. Geological section across the south end of one of the largest structures within the leading edge of the southern Canadian Cordillera, called the Highwood structure, SW Alberta, which is relayed by the Turner Valley structure to the north (modified from MacKay 1996). The Highwood structure is interpreted as a sort of intracutaneous wedge including imbricate thrust systems, an antiformal stack, duplexes and backthrusts.

(fold nappes). Usually, multiple generations of fault focal mechanisms. The Nankai accretionary folds, accompanied by foliations, produce a variety prism (Morgan & Karig 1995) is a classical of fold interference structures. Thus, apart from example of this type of belt. Because they are com- thrusts, a frequent sequence of deformations posed of heterogeneous material, the internal struc- observed in these regions includes recumbent iso- ture of the prism is highly variable. Accretionary clinal folds refolded by upright, more open folds, prisms have a wedge shape in cross-sectional view and finally deformed by smaller-scale kink bands. and their fronts are usually scalloped in map view. The bulk geometry of the prism and its detailed structure are strongly controlled by the thickness Accretionary prisms of the sedimentary pile of the subducting oceanic Accretionary prisms (e.g. Casey Moore & Silver plate. The wedge is underlain by a detachment 1987; von Huene & Scholl 1991) are the main that ramps up to progressively shallower levels locus of deformation in subduction zones, where towards the trench, and propagates seaward decou- the rock assemblages are mechanically scraped off pling mass from the downgoing slab that accretes the downgoing oceanic slab and accreted to the to the overriding slab usually in the form of duplex seaward edge of the upper advancing plate (tectonic underplating). While this happens, the forming thrust sheets (Fig. 5). Many earthquakes upper part of the trench fill or offscrapped sequence that take place in subduction zones display thrust is incorporated in the accretionary prism at the toe of the wedge (frontal accretion). Seaward of the emer- gent frontal thrust, blind thrusts emanate upwards from the detachment level while the detachment propagates leading to an imbricate thrust system with related folds. Sediments deposited in the syncl- inal troughs form piggy-back basins that usually evolve into asymmetrical tilted basins due to the general wedge tilting and may become incorporated into the prism as a result of thrust activity. In addition, deformation may reach the inner boundary of the accretionary prism leading to folding and backthrusting (rear accretion). Large-scale long- Fig. 4. Folded repetitions of Devonian limestones term margin subsidence observed in many wedges caused by thrust sheet stacking in the Somiedo nappe requires thinning of the upper plate, and since sedi- (Juan Luis Alonso, pers. com.), foreland FAT belt, mentation continued during subsidence, erosion Variscan orogen, NW Iberian Peninsula (Cantabrian along the upper plate’s base must have been Zone). occurred (subduction erosion). The processes that Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 7

(a) WE

7.00 deformation front accretionary prism 8.00 TWT (sec)

detachment 9.00

10.00

0 5 km

(b) S N

7.00

8.00 TWT (sec)

9.00

10.00

11.00

0 2 4 km

Fig. 5. (a) Line drawing of a seismic profile through the Barbados accretionary prism in which the detachment truncates some underlying horizons (modified from Westbrook et al. 1988). (b) Seismic profile showing the toe of the seaward frontal portion of the accretionary wedge in the North Iberian Atlantic margin, Bay of Biscay, developed as the western prolongation of the Pyrenees during Tertiary times (data courtesy of F. J. A. Pulgar and Marconi team, from Ferna´ndez-Viejo et al. in press). The section displays growth ramp anticlines and synclines including Mesozoic and Tertiary sediments deposited before, during (growth strata) and after fold development. caused the erosion are still being discussed (see von accretionary prisms is that in the latter there is a Huene et al. 2004 for a summary): hydrofracturing lack of rheological contrast among the different of the upper plate due to elevated pore-fluid pressure sedimentary beds and the generally weak, water- or physical abrasion caused by horst and graben rich sediments of the accretionary prism become entering the trench axis. Accretionary prisms pervasively disrupted. Such chaotic deposits are exhibit abundant small-scale folds, cleavages, called melanges. boudins and veins. They usually include mud or ser- pentinite diapirs in sediment-dominated or igneous- Toe thrust belts basement prisms respectively. Thrust systems are often strongly affected by the collision of seamounts Toe thrust belts (e.g. Worrall & Snelson 1989; or fracture zones. Lateral faults commonly cut Cobbold et al. 1995) exhibit distinctive features. across the prisms and faulting of the lower litho- Unlike other FAT belts, they do not require litho- spheric plate sometimes reflects pre-existing struc- spheric shortening, their deformation and transport ture and may have some effect on the structure are achieved entirely by gravity. They are generally of the upper plate. Blueschists may form at the detached on salt or overpressured shales and are, base of large accretionary prisms if pressures are therefore, unrelated to the basement. In some high due to substantial lithostatic overburden and cases, the down-slope advance of the glide com- temperatures are low due to the relatively cold plex is balanced by shortening in the frontal, lower downgoing slab. However, if the subducting slab portion located on the flat basin floor and by exten- is not cool, then blueschists do not form and the sion in the rear, upper part located on the inclined wet sediment may melt creating small granitic intru- basin margin (Fig. 6). However in other cases the sions. One of the main differences between the ductile substrate migrates forwards under the differ- conventional FAT belts and those developed in ential load to give extension on the delta top and Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

8 J. POBLET & R. J. LISLE

W ESW NE 0 0 TWT (sec) 2 2 4 4

TWT (sec) TWT 6 6 8 8 20 km

H = V

Fig. 6. Line drawing of a seismic profile through the offshore Eastern Venezuela basin deformed during Neogene times due to gravity collapse superimposed on a Mesozoic passive margin. Normal faulting and associated rollover anticlines in the rear part of the complex are balanced by thrusting and related folding in the frontal portion (modified from Di Croce 1995). contraction at the delta toe (Fig. 7). The contrac- considerable distances (60–160 km in the case of tional structures developed include folds and the Campos Basin; Nemcok et al. 2005). These thrusts as well as structures involving salt or shale FAT belts are controlled by the interaction of such as tongues, wedges and canopies, and may several parameters such as the width and dip of accommodate significant amounts of shortening the basin margin, the distribution, thickness and (100 km in the case of the Campos Basin, Brazil; rheology of the detachment horizon, the temporal Demercian et al. 1993) and may have travelled and spatial variation of the sedimentary loading,

(a) delta progradation

delta delta top slope

delta-toe fold- delta-top graben and-thrust belt

10 cm

(b) delta-top graben delta sediments delta slope delta-toe fold-and-thrust belt

mobile substrate 10 cm

Fig. 7. (a) Top view and (b) cross-sectional view of an experimental sandbox model designed to simulate differential sedimentary loading in a progradational delta system developed on top of a ductile substrate. The structures developed during delta progradation are delta-top extensional faults giving rise to a graben and a FAT belt at the foot of the delta slope (modified from McClay et al. 2000). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 9 and the occurrence of barriers to the gliding move- (a) In different portions of the belt following ment such as seamounts or tilted fault blocks. The a transversal pattern, such as the Rocky main cause of the instability is the strongly Mountains-USA Cordillera that exhibits thin- reduced basal traction caused by an extremely skinned styles in the interior and thick-skinned weak layer at the base of the wedge. styles in the outer part (Hamilton 1988); in some cases the different structural styles are developed in adjacent regions, so that the steep Structural styles and evolution of faults that penetrate the basement rocks become FAT belts sub-horizontal when they reach the cover and are responsible for its detachment such as in Relationships between FAT belts the Alps (e.g. Hayward & Graham 1989). and basement-involved belts (b) Along strike of the belt, such as the Andes (Fig. 8a) in which the structural style varies The style of deformation of FAT belts (see for from thin-skinned styles in regions over instance the Canadian Rocky Mountains in Bally inclined slab segments and thick sedimentary et al. 1966; Price 1981), in which thrusting involves basins filled with cover rocks (Fig. 8b1) to tran- only the sedimentary cover whereas the basement sitional thin/thick-skinned styles (Fig. 8b2) to remains unaffected by the thrusting, is known as thick-skinned over flat segments of the sub- thin-skinned deformation (Figs 1–3 & 8b1). As ducted plate and little sedimentary cover on we trace the thrusts back into the hinterland, base- top of the crystalline basement (Fig. 8b3) ment rocks become involved in the thrust sheets (e.g. Mingramm et al. 1979; Allmendinger (crystalline thrusts). These basement rocks may et al. 1983). have been transported in a ‘thin-skinned’ manner (c) Superimposed in the same region but devel- on sub-horizontal thrusts over other basement or oped during different times, such as the Bohe- cover rocks. Eventually, the thrusts root down into mian Massif where an initial thin-skinned crystalline basement rocks and lose their thin- event is followed by a thick-skinned phase in skinned character. The thin-skinned structural style which thrusts involve crystalline rocks and contrasts with the thick-skinned style of basement- cross-cut older structures (Rez et al. 2011). involved belts (Coward 1983), in which both the Some shortening-dominated regions formed by basement and the cover are deformed due to con- reactivation of inherited structures include elements traction (Fig. 8b3), such as the Laramide uplifts from both FAT belts (thin-skinned) and basement- (e.g. Schmidt et al. 1993). Usually, in contrast to involved belts (thick-skinned). Thus, folds are FAT belts, rocks have not been transported over related to steep faults that do not emanate from a long distances in basement-involved belts. In these detachment and cause relatively small displace- belts the basement is incorporated into the thrust ments of the rocks. However, these belts are not sheets due to: (a) steep faults that penetrate the proper thick-skinned belts because the basement basement and create basement uplifts; and/or (b) rocks are not involved in the deformation similarly reactivated inherited basement fabrics that control to thin-skinned belts (Fig. 9). the subsequent thrust architectures such as inverted Amongst other factors, the presence of evapor- half-grabens. The basement uplifts of the thick- ites or shales at depth has a crucial impact on the skinned belts may consist of fault blocks whose structural style of the orogenic belt as a result of uplift and rotation caused forced folding of the the efficiency of the detachment. The occurrence cover sequences that drape relatively unfolded of basement fabrics exerts an essential control on basement rocks (e.g. USA Rocky Mountain fore- the structural style as well; thus, passive margin land, Prucha et al. 1965; Stearns 1971) or blocks basins filled by post-rift sedimentary prisms formed by folded basement and cover rocks (Berg tapering onto the cratons favour the FAT belts 1962; Blackstone 1983). The thick-skinned belts (thin-skinned style), whereas intra-cratonic rift caused by reactivation of pre-existing faults systems tend to give rise to basement-involved exhibit different features depending mainly on belts (thick-skinned structural style). whether all the faults were reactivated or only a few of them, the degree of reactivation, the angle between the direction of compression and the Along-strike geometry strike of the old faults, the main features of the inherited faults and the rheology of the involved On a large-scale in map view, FAT belts may be: (a) sequences. linear; (b) sinuous, when they show geometrical FAT and basement-involved belts coexist and variations along-strike in the form of salients or vir- are somehow related in many orogenic belts. gations where the belt bulges into the undeformed These different structural styles may be distributed: region, and recesses, reentrants or syntaxis where 10 Downloaded from http://sp.lyellcollection.org/ .PBE .J LISLE J. R. & POBLET J. byguestonSeptember27,2021

Fig. 8. (a) Simplified structural map of the frontal portion of the Andes, NW Argentina, showing the transition between the Subandean Ranges and the Santa Barbara System (modified from Uliana et al. 1995). (b) Three regional-scale geological cross-sections (modified from Mingramm et al. 1979) whose cross-section lines are located in Figure 1a. Section 1 across the Subandean Ranges exhibits a classical thin-skinned structural style, section 3 across the Santa Barbara System illustrates the typical thick-skinned style, and section 2 across the transition between both ranges interfered by the oblique Lomas de Olmedo Trough shows an intermediate structural style. Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 11

WNW ESE Busang Sehigan Sebulu Separi Badak Tunu anticline anticline anticline anticline

Pliocene-Pleistocene Miocene

20 km H = V

Fig. 9. Geological section across the Mahakam delta, Kalimantan, Indonesia, showing tight, anticlines whose steeper limb is bounded by a fault and broad synclines developed in sand, shale and coal-rich sequences of Miocene age. The folds developed due to regional-scale contractional reactivation of delta-top extensional growth faults produced during delta progradation. The faults root into the overpressured shale delta sequence (modified from McClay et al. 2000). the belt has not propagated far into the undeformed Structural evolution region (salients and recesses may have experienced different kinematic evolutions); and (c) curved or Most FAT belts exhibit an orogenic polarity which arcuate, usually known as oroclines (Fig. 2a). The may vary along the belt, like the Himalayas (e.g. term ‘orocline’ was originally applied to curved Antolı´n et al. 2011). Thus, folds verge usually mountain belts which were initially straight, or at towards the foreland in the case of foreland FAT least straighter than they are today. However, in belts (Figs 1–3 & 8b1), towards the trench in the the last few years, the definition has been broadened case of accretionary wedges (Fig. 5b) and towards to include any curved mountain belt, regardless the basin in the case of toe thrust belts (Figs 6 & of its original shape. The Appalachians of eastern 7b), and thrusts show a sense of movement of North America are a classical example of a top-to-the-foreland, and deformation becomes sinuous mountain belt (e.g. Mitra 1997), whereas younger towards the foreland with thrusts develop- the Ibero-Armorican Variscan belt and its pro- ing in a break-forward or piggy-back sequence longation in the Variscan Pyrenees (Garcı´a- (Figs 10 & 11) defining a regional foreland-directed Sansegundo et al. 2011) is a well-known example tectonic transport direction. Although a dominant of an orocline. Many parameters influence the orientation of the tectonic transport vector prevails, occurrence of curved geometries in map-view, for in detail the sense of motion of each thrust sheet example, interaction of the propagating belt with may vary in its orientation spatially and/or basement highs, along-strike pinch-outs of favour- through time (e.g. Simo´n & Liesa 2011). In addition able detachment horizons, lateral variations in stra- to folds and thrusts vergent and directed respect- tigraphic thicknesses and/or lithologies, interaction ively towards undeformed regions following a of the belt with strike-slip faults, superposition of break-forward propagation sequence, other types second deformation events with tectonic transport of structures (backthrusts and back-vergent folds, directions oblique or perpendicular to that respon- out-of-sequence thrusts and/or reactivated thrusts) sible for the belt formation, and so on. occur in many belts behind the deformation front The non-straight geometry in map-view of some (Figs 3 & 11). As new thrusts and related folds belts may be also caused by the fact that individual develop, unless the thrust ramp spacing is relatively thrust sheets are not necessarily continuous along large compared to the displacement along each strike. Thrust surfaces may merge or be truncated thrust, early thrusts steepen due to rotation of the by another thrust, but they can also transfer slip to thrust imbricates (Figs 1, 2 & 10) accompanied by another thrust fault through a transfer or relay a certain amount of slip on the thrusts. Tilting and zone, splay up and distribute movement among folding of the earliest thrusts makes continued slip several smaller-scale thrusts, strike into the axial on them increasingly difficult, and eventually they zones of folds that accommodate shortening or become inactive and too difficult to reactivate. become segmented by sub-vertical faults, called New thrusts with their associated folds may propa- tear or transfer faults, that separate different parts gate breaching, cutting through and/or folding the of the thrust sheet with distinct displacement, differ- older thrust surfaces and related folds. ential types of structures responsible for shortening The kinematic evolution briefly described above accommodation (e.g. folding dominated in one tear is satisfactorily explained by the critical-taper fault block v. thrusting dominated in the other tear theory. This requires the thrust wedges (Fig. 11) to fault block) or connect non coplanar parts of a maintain a critical taper angle (equal to the detach- thrust surface. ment surface dip plus surface-slope angle) to Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

12 J. POBLET & R. J. LISLE

Fig. 10. Schematic development of an imbricate thrust system and related fault-propagation folds following a break-forward sequence and steepening of the earliest (hinterlandward) thrusts (modified from Mitra 1990).

(a)

5 cm H = V (b) Undeformed Foreland-vergent imbricate thrust system Maximum uplift

2 1 4 3 5 3 6 4 7 6 8 8 Slumped material

Basal detachment 5 cm H = V

Fig. 11. (a) Cross-sectional view of an experimental sandbox model designed to simulate an orogenic wedge. The experiment was performed at the Fault Dynamics Laboratories conducted by K. R. McClay and is displayed at the Geological Museum–University of Oviedo (photograph courtesy of L. M. Rodrı´guez-Terente). (b) Schematic cross-section of an experimental thrust wedge derived from analysis of a series of scaled sandbox models showing three different regions and the general sequence of development of thrust faults. The backthrusts at the rear portion of the wedge were active during various growth stages. The scale is approximate (modified from Huiqi et al. 1992). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 13 produce a dynamic equilibrium among different flats, usually within the incompetent horizons such stresses: traction at the wedge base, compressive as shales and evaporites, and bedding-oblique push at the back of the wedge, and the slope stress parts, called thrust ramps, so that they step up and at the topographic surface. The wedge is thickened cut across competent beds such as sandstones and and shortened internally as thrusts override each limestones (Fig. 13a). After thrust movement, all other, folds develop, penetrative strain occurs and/ sorts of situations are possible: hanging wall flats or duplexes bounding rock packages are accreted over footwall flats, hanging wall flats over footwall from beneath the wedge. When the wedge reaches ramps, hanging wall ramps over footwall flats and a critical taper angle, it slides stably along the hanging wall ramps over footwall ramps. Since the detachment towards undeformed areas. During flats, that usually exceed the ramps in length, and translation, the thrust wedge is lengthened as the ramps are linked, overall the thrusts acquire thrusts propagate towards undeformed regions and stairstep geometries. The occurrence of thrust new material is added to its toe causing the taper ramps with strikes perpendicular to the tectonic angle to decrease because it distributes topographic transport vector (frontal ramps), forming an acute elevation over a longer distance. When a subcritical angle to the transport direction (oblique ramps) or taper angle is reached, stable sliding stops and with strikes parallel to the transport direction internal deformation occurs again within the (lateral ramps) (Fig. 13b), leads to development of wedge. If the wedge reaches a temporary supercriti- fault-bend folds (Rich 1934; Suppe 1983) due to cal taper angle, the surface slope is decreased by the necessity of beds to conform to the thrust wedge thinning due to erosion, collapses in a surface geometry (Fig. 14) and fault-propagation series of extensional faults, similar to large land- folds (Mitra 1990; Suppe & Medwedeff 1990) in slides, and/or slumps that remove material from those cases in which shortening is accommodated the surface (Fig. 12). The subcritical, critical and by both thrust ramp propagation and synchronous supracritical stages may occur more than once folding (Fig. 15). Although different types of ramp during the evolution of a thrust wedge (e.g. Torres- folds are the most typical modes of fold-thrust inter- Carbonell et al. 2011). action in FAT belts, for example, the Iberian Varis- can Massif (Mantero et al. 2011) or the Carpathians Fold-thrust interaction (Poul et al. 2011), not all folds in FAT belts are underlain by thrust ramps. Thus, simultaneously The alternation of competent and incompetent with propagation of a bedding-parallel thrust lithologies exerts an important control on the geo- surface (detachment or de´collement) or when a dis- metry of thrust surfaces. Thus, thrust surfaces placement gradient occurs along a detachment, exhibit bedding-parallel segments, known as thrust detachment folds (Jamison 1987) form above or

Fig. 12. Geological section across the Ainsa Basin, southern Pyrenees, showing thrusts and related folds (fault-bend, fault-propagation and detachment folds) partly truncated by extensional faults, which in turn, are cut and offset by part of the displacement along some thrusts. Since the relationships between thrusts and extensional faults indicate that they developed synchronously, the extensional surfaces are interpreted to reflect the episodic extensional collapse of the Pyrenean thrust wedge that advanced progressively into a marine foreland basin (modified from Mun˜oz et al. 1994). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

14 J. POBLET & R. J. LISLE

(a) Hanging wall ramp over footwall flat NW SE Hanging wall flat Hanging wall ramp over footwall ramp over footwall ramp Hanging wall flat M Upper Silurian 0 m idd Ord over footwall flat le nd ovi a cian

Cambrian and Ordovician dolostones 3000 m H = V Basal Cambrian sediments

(b)

Frontal ramp

Lateral ramp Oblique ramp

Tectonic transport vector

Fig. 13. (a) Geological section across the Nittany anticlinorium, Central Appalachians (section originally from Perry 1978 simplified by Geiser 1988) showing a staircase geometry of the thrust surfaces and all sorts of hanging wall and footwall ramp and flat situations. (b) 3D sketch showing the geometry of a thrust surface including frontal, oblique and lateral ramps. below the detachment surface as in the case of the fault-propagation and detachment folds) or to break- Pico del A´ guila detachment anticline in the southern thrust folds such as the Maiella Mountain anticline Pyrenees (Vidal-Royo et al. 2011) (Fig. 16). Apart in the Apennines (Masini et al. 2011) if folding from ramp folds and detachment folds, other types developed before faulting. The dominant fold style of thrust-related folds develop for example, drag is class 1B to 1C (Ramsay 1967) and most folds folds, and so on. All these folds can develop in the are asymmetric with a vergence towards unde- frontal part of thrust sheets (leading edge folds), in formed regions. Usually in the hinge zones of the rear portion of the thrust sheets (trailing edge folds cored by incompetent units such as argilla- folds), or within the thrust sheets (intraplate folds). ceous sediments, slaty cleavage may develop. As deformation increases, folds become tighter The folds described so far form under non- and overturned limbs may develop, and when they metamorphic or low-grade metamorphic conditions. are too tight to accommodate more shortening In regions where the basement is involved in the they become locked-up and can be cut across by thrust sheets and deformation takes place under reverse faults (Fig. 17) giving rise to hybrid medium to high-grade metamorphic conditions, thrust-related folds (breakthrough and transported large recumbent folds form with vergence towards Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 15

Fig. 14. Geological section across the Pine Mountain thrust system, southern Appalachians, in which the Powell Valley anticline is interpreted as a fault-bend fold cored by a duplex structure (modified from Suppe 1985). the undeformed regions. These are accompanied by transitions from dominant folding to dominant a pervasive cleavage. Various fold generations thrusting have been reported in the Appalachians occur, for example, in the Iberian Variscan Massif (Gwinn 1964), in the Canadian Rocky Mountains (see Ferna´ndez et al. 2011). (Wheeler et al. 1972) and in the Cantabrian Moun- Folding is a subordinate phenomenon related to tains (Julivert & Arboleya 1984) amongst other thrusting in many belts in which imbricate thrust FAT belts. faults dominate, for example, in the Valley and Ridge province of the Appalachian Chain (Mitra 1988) or in the Southeastern Pyrenees (Mun˜oz Contributions in this book 1992). However in other belts, folds dominate the tectonic architecture, for example, in Papua Much current research on the structure of FAT New Guinea (Smith 1965) or in the Western Irish belts is focused on structural studies of regions or Namurian Basin (Tanner et al. 2011). Along-strike individual structures, and on the geometry and

W E

Pleistocene Miocene Pliocene Mesozoic Bedding dip

2 km H = V

Fig. 15. Geological section across the Meilin anticline, western Taiwan, interpreted as a simple-step fault-propagation fold (modified from Suppe 1985). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

16 J. POBLET & R. J. LISLE

evolution of these regions employing kinematic, mechanical and experimental modelling. In keeping with the main trends of current research, this special publication is devoted to the kinematic evolution and structural styles of FAT belts. The topics of the papers included in this volume range from detailed structural analysis of individual structures to large-scale regional studies of FAT belts and from classical structural geology studies based on data collected in the field to numerical modelling. The papers included in this Special Publication are a selection of the works on FAT belts presented in various sessions at the ‘International Meeting of Fig. 16. Satellite image of the External Sierras in the frontal part of the south Pyrenean foreland FAT belt Young Researchers in Structural Geology and Tec- showing a detachment fold train formed by narrow, tonics (YORSGET-08)’ held at Oviedo (Asturias, rounded-hinge anticlines separated by wide, flat-bottom Spain) in June–July 2008 together with others on synclines affecting Triassic, Cretaceous, Paleocene, the same topic matured over a similar period. This Eocene and Oligocene sedimentary rocks. meeting was organized by M. Gutie´rrez-Medina, C. Lo´pez-Ferna´ndez, D. Pedreira and J. Poblet to jointly celebrate the 400 years anniversary of the foundation of the University of Oviedo and the

S PURI 1, 1A, 1B N

Sea level Orubadi Formation

Puri Formation

Eocene limestone

1000 m P6 Ieru Formation P7

P8 P9 P10

P5/6 2000 m P7 P10 P8 1A P9 1B P5/6

P5/6

3000 m H = V 1

Fig. 17. Geological section across the Puri anticline, a long structure located in the leading edge of the Papua New Guinea FAT belt, showing out-of-sequence thrusting cutting across the steep forelimb of the fold and involving Eocene to Miocene rocks (modified from Medd 1996). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 17

50 years anniversary of the Geology Faculty at discrete-element modelling to explore the evolution Oviedo. The meeting attracted 53 oral presentations of the Pico del A´ guila anticline, a detachment fold and 90 posters, and an audience of 201 participants formed during Eocene–Oligocene in the Spanish from 25 countries, and included a field excursion to side of the Pyrenean FAT belt. This numerical tech- the Variscan FAT belt of NW Iberian Peninsula. nique treats the different units as an assemblage of This conference included a special session in circular elements that mutually interact with elastic memory of the structural geologist Martin Casey forces influenced by gravity and obey Newton’s from the University of Leeds (UK) who died in equations of motion. Regarding the role of the 2008 and was a recognized authority on the model- mechanical stratigraphy, the competent beds expe- ling of natural deformation features and the author rience rigid-body translation/rotation, localized of papers fundamental to the understanding of the faulting and minor shearing, whereas incompetent deformation responses of rock. In addition, this beds suffer high strain and are deformed by complex Special Publication includes the last article written structures. The occurrence of extensional faults, by the structural geologist Florentino Dı´az-Garcı´a stretching and gravitational instabilities in the crest from the University of Oviedo (Spain) who of the anticline becomes substantially reduced when devoted his research efforts to the study of the the model incorporates growth strata, and defor- Variscan belt in northwestern Iberian Peninsula mation is confined to the core of the structure and who, unfortunately, died in 2009. This volume leading to a tighter, narrower fold than in those situ- does not attempt to provide a comprehensive cover- ations in which growth strata is lacking. age of FAT belts, but puts together some contri- butions on specific topics of interest within this 3D data applications research theme, some of them presenting new con- cepts and techniques and others applying well- This section contains two articles focussed on the known concepts and techniques to new regions. determination of the kinematic evolution of folds and thrusts employing 3D data. Tanner et al. col- Internal deformation lected structural and stratigraphic data along the western Irish coast using high resolution GPS, con- The first two articles of this special publication structed 3D geological surfaces and plotted the data describe the application of two different methods onto a north–south vertical plane in order to obtain a to analyze the internal deformation undergone by balanced section parallel to the tectonic transport thrust-related anticlines. Masini et al. carried out direction across the western Irish Namurian Basin. field mapping and collected structural data in This basin is interpreted as a FAT belt developed order to construct two sections across the Maiella in front of the northward propagating Variscan Mountain anticline, a structure located in the Central orogenic front in which folding predominates over Apennines, Italy, that resulted from Messinian– thrusting. Subsequently, passive markers were Early Pliocene extension and subsequent Late Plio- included in the cross-section that was sequentially cene shortening. They employed a strain simulation restored and decompacted to various Carboniferous technique based on the inclusion of circular strain syn-tectonic horizons. This allowed them to visual- markers in the cross-sections, subsequent sequential ize variations in the folds’ wavelength along restoration of the cross-section and the strain the cross-section and to deduce how fold uplift markers, and application of a mathematical model evolved through time. Since accurate ages of the to obtain strain ellipses for each strain marker. horizons are available, they were able to estimate According to their structural model, the Maiella folding- and thrusting-induced shortening rates structure is a break-thrust fold that underwent small and concluded that although the basin was subjected amounts of extension associated with two main to comparatively very little shortening with respect normal faults and subsequent shortening due to a to similar tectonic settings, the rates of orogenic major thrust and folding. The simulation of the shortening are within the typical ranges for FAT strain distribution shows high strain intensity in belts. They also found that the Western Irish Namur- both limbs and low deformation in the anticline ian Basin underwent an anomalous strong subsi- crest and in part of the thrust footwall. In the dence during its evolution. Simo´n & Liesa anticline forelimb, where the strain is greater, illustrate how construction of various geological high deformation is concentrated in two symmetric sections through the Utrillas thrust sheet in the triangular zones separated by the thrust ramp. Iberian Chain, Spain, perpendicular and oblique to The distribution of strain intensity predicted in the frontal thrust trace, allows a 3D reconstruction different structural positions of the Maiella structure of the geometry of the main thrust surface formed is in broad agreement with the distribution of by ramps oriented in different directions. Detailed fracture density obtained from field data by pre- structural analysis and tectono-sedimentary rela- vious authors. Vidal-Royo et al. employ 2D tionships with the deposits of the adjacent foreland Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

18 J. POBLET & R. J. LISLE and piggy-back Tertiary basins furnished data on the During the subsequent period, corresponding to a Eocene-Oligocene incremental motion history subcritical Coulomb wedge stage, backthrusting involving different tectonic transport directions. A accommodated significant shortening. The last schematic, plan-view retro-deformation of the dis- period consisted of a new critical stage caused by tinctly oriented thrust ramps enabled estimation of renewed foreland-directed thrusting at the wedge the finite horizontal displacement along the thrust. front. Fitz-Diaz et al. compare the structural style The successive transport directions towards the of one traverse across the southern Canadian Rocky ENE, NNE and north obtained are consistent with Mountains with another one across the Mexican the development of two superposed main sets of FAT belt. Although the age of deformation, the folds and with the evolution of the intraplate stress overall structural pattern and the total amount of fields through Tertiary times. shortening are similar, the dominant tectonic style consists of imbricate thrust sheets with relatively Tectonic and magnetic fabrics little internal deformation in the former and indi- vidual thrust sheets with much more internal defor- This section deals with the information supplied by mation, such as buckle folds, in the latter. One of the magnetic fabrics to decipher the tectonic evol- the reasons for the differences in tectonic style is ution of structures. Antolı´n et al. combined the ani- the facies distribution; massive platform limestone sotropy of magnetic susceptibility and structural separated by thinly-bedded basinal limestone in analysis of a Triassic flysch to decipher the tectonic the Mexico section, so that strain is concentrated evolution of the Tethyan Himalaya FAT belt, Tibet. toward the margins between platforms and basins, These authors defined a southern domain charac- and thick platform carbonates forming continuous terized by a magnetic foliation parallel to the first resistant units in Canada. Other possible reasons tectonic foliation in accordance with the south for the differences in tectonic style between the vergence of the belt, and a northern domain in two sections include the taper angle of the tectonic which the magnetic foliation and the second tectonic wedges and the amount of friction along the foliation show a vergence opposite to that of the basal detachment. Himalayan system. Both domains are separated by a zone where both tectonic foliations coexist and Structural evolution-case studies where an intermediate magnetic fabric is developed. The magnetic lineation supplied information on the The last section of this publication contains five north–south transport direction of the thrust sheets. articles that unravel the sequence of deformations The different orientation of the magnetic foliations in various belts located in Spain and in the Czech suggest a Middle Miocene clockwise rotation Republic. Based on field mapping and struc- around a vertical axis which could be explained as tural analysis of the Palaeozoic basement of the a result of large-scale dextral shearing caused by Central Pyrenees, France-Andorra-Spain, Garcı´a- eastward extrusion of the Tibetan Plateau or block Sansegundo et al. propose a new division of this rotations due to intrusion and exhumation of the portion of the Variscan FAT belt into two different North Himalayan domes. zones: non-metamorphic and metamorphic units, and a new sequence of Variscan deformations. Thrust wedges The non-metamorphic units include thrust systems and related folds with a poorly developed cleavage, The two articles in this section discuss the structural whereas in the metamorphic units two fold sets with style and evolution of thrust wedges in various axial plane cleavage and thrusts approximately American FAT belts. The geological map and sec- coeval with the second fold generation occur. The tions across the eastern Fuegian Andes FAT belt, structure of the Pyrenean non-metamorphic units Argentina, constructed by Torres-Carbonell et al. has Variscan foreland affinities and is comparable reveal that the structure of this region consists of to that of the Cantabrian Zone (foreland FAT belt various thrusts and backthrusts rooted at the base of the Iberian Massif ), whereas the deformation of the Cretaceous and within the Paleocene rocks. observed in the Pyrenean metamorphic units is The occurrence of syn-tectonic sequences bounded characteristic of the Variscan hinterland and is con- by unconformities allowed them to perform a sistent with the features of the West Asturian- sequential cross-section restoration, decipher the Leonese Zone or Central-Iberian Zone. The relative kinematic evolution and timing of structural devel- position of the foreland and hinterland, with the opment and unravel the behaviour of the Coulomb non-metamorphic units located southwards of the wedge from Eocene to Oligocene times. The metamorphic ones, and the south-directed motion oldest stage was characterized by propagation of of the Variscan thrusts, suggest that the Variscan the basal detachment and formation of foreland- Pyrenees may be equivalent to northern branch of directed thrusts leading to a taper angle decrease. the Ibero-Armorican or Asturian arc. Structural Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 19 analysis in the Palaeozoic rocks that constitute the normal and strike-slip faults of probable Alpine Forcarei synform, located in the northwest part of age were responsible for the compartmentalization the Iberian Variscan Massif, Spain, allowed of the region into numerous small-scale blocks. Ferna´ndez et al. to conclude that two main Varis- Poul et al. present a new model for the controversial can deformation events occurred. The first event in isolated ridges made up of Upper Jurassic lime- this region caused a pervasive cleavage, a stretching stones that constitute the Pavlov Hills located in lineation, the Forcarei Thrust and other related the Outer Western Carpathians, Czech Republic. structures such as minor folds. The second event These uplands have been interpreted in the past produced the large-scale Forcarei Synform and a as relicts of island ridges, exotic bodies derived sub-vertical crenulation cleavage parallel to its from the basement, klippes, olistoliths and blocks axial plane, an intersection lineation and minor bounded by faults. However, according to their folds which caused fold interference patterns with new model based on geological mapping and geo- previous ones. The dominantly sinistral shear logical interpretation of seismic lines, the present- deduced from the analysis of quartz fabrics and day geometry and position of these ridges resulted kinematic indicators related to the first deformation from fault-bend folds related to antiformal stacks is interpreted as a result of top-to-the-south displa- detached at the base of the Upper Jurassic lime- cement along the Forcarei Thrust combined with stones, subsequently offset by strike-slip faults clockwise rotation along a sub-vertical axis evol- sub-perpendicular to the thrusts trace. Unlike ving to dominant clockwise rotation in the last previous models for this region, this new inter- stages of thrust motion, subsequently folded into a pretation including northwest-directed thrusts with synform during the second deformation event. flats and ramps is consistent with the structural Mantero et al. document two deformation phases style described for the Outer Western Carpathians. in the Devonian and Carboniferous rocks of the Puebla de Guzma´n antiform located in the Iberian Pyrite Belt in the south part of the Iberian Variscan Concluding remarks Massif, Spain, which could be the result of a pro- gressive deformation related to the growth of the If progress is to be made in the understanding of the South Portuguese Zone orogenic wedge. The first evolution and styles of FAT belts, from small-scale deformation phase gave rise to a widespread pen- to lithosphere-scale sections, and from both the pure etrative cleavage linked to thrusts at deep crustal scientific and applied points of view, detailed multi- levels and folds above them. The second defor- disciplinary studies are required. These studies will mation phase consists of thrusts, which constitute need to integrate information from structural geo- the most pronounced cartographic-scale structures, logy, stratigraphy–sedimentology, petrology, geo- and two fold sets with axial plane crenulation clea- chronology, geomorphology and geophysics, and vages. Despite the widespread presence of folds, the take maximum advantage of all the new data that enveloping surfaces of bedding are sub-horizontal, are being acquired by recently developed technol- and steep or overturned dips are restricted to the ogies. Accurate analyses of many aspects of individ- vicinity of frontal or lateral thrust ramps due to ual fold-and-thrust structures located in different fault-propagation folds. The thrust displacement is FAT belts, such as their 2D and 3D geometry, distributed into a large number of thrusts and the strain and fracture patterns, formation mechanisms important thickening produced in this region is and history (timing, uplift and shortening magni- due to thrust sheet stacking. Geological mapping, tudes and rates), have been carried out in recent cross-section construction, structural analysis, and times employing field and/or subsurface data, sedimentological and biostratigraphical data of experimental and/or numerical models. If inte- Upper Devonian and Lower Carboniferous rocks grated into large-scale models of each FAT belt, allowed Rez et al. to establish a new Variscan these separate data collected in different parts of sequence of deformations for the southern part of the belt would have an extraordinary impact on the Moravian Karst (Bohemian Massif, Czech the understanding of the mechanisms responsible Republic). Both deformation events involved for the origin and evolution of these regions. northeast-directed thrusting suggesting progressive Due perhaps to interest from the economical deformation during a constant stress orientation. point of view and the abundance of data derived, it The first event consisted of ‘thin-skinned’ thrusting seems that whilst the FAT belts located in external and related folding and caused tectonic juxtaposi- zones of cordilleras are relatively well studied, the tion of two distinct facies of coeval sequences. FAT belts in interior parts of orogens have received The second deformational event led to ‘thick- less attention and require more detailed research on skinned’ thrusting, which involved the crystalline the more complex structures found therein, on the rocks of the Brno Massif and cross-cut first phase degree of basement involvement in the structures, thrusts, and folding of previous structures. Later on the control exerted by pre-existing structures, Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

20 J. POBLET & R. J. LISLE and on the structural and temporal relationships between the tectonic processes responsible for between the inner and outer portions of FAT belts. mountain building and climate-dependant surface A great deal of research is being done in offshore processes on various time and space scales to main- FAT belts because, although they are inaccessible, tain the dynamic equilibrium of orogenic wedges. seismic imaging is excellent especially with 3D seismic data and precise analyses of folds and modern technology. However seismic data may thrusts show that even simple structures are often far provide an incomplete picture. For instance, the more complex than expected. For instance, many initial attempts to contrast measurements of exten- FAT belts exhibit faulted folds not well described sion and contraction in a particular submarine toe by current theories; while some sections across indi- thrust belt yielded different figures. This suggests vidual structures may conform to proposed theories, that deformation is accommodated by other mech- the structures can exhibit rapid changes in 3D anisms apart from structures displayed in the leading to a variety of complex fold-thrust architec- seismic data. Existing kinematic algorithms for tures along strike. The capabilities of end-member fold-thrust systems are not able to consider this, fold-thrust interaction models, especially those and therefore, they are likely to yield poor predic- embedded within many structural analysis software tions of subseismic deformation and fault zone packages, are relatively restricted because they architecture. This means that current models need assume that deformation mainly causes displace- to incorporate the strain undergone by rocks ment along faults and fold amplification. The amongst other parameters. Much less research is models do not entertain other type of behaviours. carried out in many onshore FAT belts because However, discrete element modelling is beginning they are developed in severe terrains, the structures to allow us to build geologically realistic models. are complex and the subsurface data are poor in Geomechanics has to be the next step in structural quality and/or quantity. This is the reason why geology research, to provide the additional con- understanding them has been strongly guided by straints that geometry and kinematics do not, and geometrical models, fed by surface geological needs to be applied at all scales, from small-scale maps and sparse subsurface data, and which, in deformational features to entire FAT belts. The some cases, involve an important level of uncer- last decades have seen a proliferation of quantitative tainty rarely addressed in modern studies. Nowa- approaches to studying FAT belts by means of geo- days, since many geometrical models have been metrical, kinematical and some mechanical numeri- developed to predict the subsurface and 3D features cal modelling and physical experiments proving to of the structures, it would be essential to test them on be powerful tools for simulating the structural evol- well-known natural and experimental structures in ution of these belts. Although the present-day which the complete geometry of the structure are models of FAT belts have reached high levels of available; this would permit magnitudes of errors sophistication and are the subject of many present- in the structural interpretations to be quantified day publications, detailed field and subsurface and would guide future improvements of these observations on FAT belts are still essential models. In addition, onshore FAT belts have to be because natural examples based research is the ulti- revisited and detailed work carried out in order to mate test of the theoretical and physical models. We revise the old interpretations in the light of the hope that this Special Publication will serve as a new concepts which, in turn, will provide additional reference on future research and understanding of conceptual and numerical models for this type both the spatial and temporal evolution (4D) of of regions. FAT belts. Contrasting the insights gained from analyzing active FAT belts, in which the structures are rela- Comments by J. Turner substantially improved the initial tively well preserved and processes can be observed version of this manuscript. We are indebted to the and quantified with a certain degree of confidence, reviewers of the articles included in this Special Publi- with those gained from examining exhumed belts cation and of those manuscripts that, unfortunately, could would contribute substantially to better constraint not be part of this book. It was a pleasure to work with the 4D evolution of these regions. For instance, in the efficient staff of the Geological Society of London, in recent years, the role of surficial processes has particular A. Hills, T. Anderson and H. Floyd-Walker. been emphasized in several studies on the evolution Thanks to Carlos Olivares for reviewing the format of of FAT belts. The impact of erosion and sedimen- the manuscripts included in this publication and figure tation in controlling geomorphology, fold-thrust drafting, and Mayte Bulnes for critical reading of this manuscript and figure drafting. We acknowledge growth, exhumation processes and deformation financial support by research grant CGL2008-03786/ history has been explored through numerical and BTE (Mechanical analysis of deformation in folds) experimental methods. More data, such as uplift funded by the Spanish Ministry for Science and Inno- estimates, and so on, collected in different FAT vation. J. Poblet is grateful to the Consolider programme belts are needed to further elucidate the interactions project CSD2006-0041 (Topo-Iberia). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 21

Referenes Dahlen, F. A., Suppe,J.&Davis, D. 1984. Mechanics of fold-and-thrust belts and accretionary wedges – cohe- Alle`gre, C. J. 2008. Isotope Geology. Cambridge Univer- sive Coulomb theory. Journal of Geophysical sity Press, Cambridge. Research, 89, 87–101. Allmendinger, R. W., Ramos, V. A., Jordan, T. E., Dahlstrom, C. D. A. 1969. Balanced cross sections. Palma,M.&Isacks, B. L. 1983. Paleogeography Canadian Journal of Earth Sciences, 6, 743–757. and Andean structural geometry, northwest Argentina. Davis, D., Suppe,J.&Dahlen, F. A. 1983. Mechanics of Tectonics, 2, 1–16. fold/thrust belts and accretionary wedges. Journal of Antolı´n, B., Erwin, A., Chiara, M., Dunkl, I., Ding, Geophysical Research, 88, 1153–1172. L., Gloaguen,R.&El Bay, R. 2011. Kinematic Demercian, S., Szatmari,P.&Cobbold, P. R. 1993. evolution of the eastern Tethyan Himalaya: con- Style and pattern of salt diapirs due to thin-skinned straints from magnetic fabric and structural proper- gravitational gliding, Campos and Santos basins, off- ties of the Triassic flysch in SE Tibet. In: Poblet, shore Brazil. Tectonophysics, 228, 393–433. J. & Lisle, R. J. (eds) Kinematic Evolution and Di Croce, J. 1995. Eastern Venezuela Basin: sequence Structural Styles of Fold-and-Thrust Belts. Geologi- stratigraphy and structural evolution. PhD thesis, cal Society, London, Special Publications, 349, Rice University, Houston. 99–121. Dunai, T. 2010. Cosmogenic Nuclides. Cambridge Uni- Bally, A. W., Gordy,P.L.&Stewart, G. A. 1966. versity Press, Cambridge. Structure, seismic data, and orogenic evolution of Durney,D.W.&Ramsay, J. G. 1973. Incremental strains southern Canadian Rocky Mountains. Bulletin of measured by syntectonic crystal growth. In: Dejong, Canadian Petroleum Geology, 14, 337–381. K. A. & Scholten, R. (eds) Gravity and Tectonics. Beaumont, C., Fullsack,P.&Hamilton, J. 1992. Ero- Wiley, New York, 67–96. sional control of active compressional orogens. In: Elliott, D. 1976. The energy balance and deformation McClay, K. R. (ed.) Thrust Tectonics. Chapman & mechanisms of thrust sheets. Philosophical Trans- Hall, London, 377–390. actions of the Royal Society of London A, 283, Berg, R. R. 1962. Mountain flank thrusting in Rocky 289–312. Mountain foreland, Wyoming and Colorado. American England,P.C.&Thompson, A. B. 1984. Pressure temp- Association of Petroleum Geologists Bulletin, 46, erature time paths of regional metamorphism. 1. Heat- 2019–2032. transfer during the evolution of regions of thickened Blackstone, D. L. 1983. Laramide compressional tec- continental-crust. Journal of Petrology, 25, 894–928. tonics, southern Wyoming. University of Wyoming Ferna´ndez, F. J., Dı´az-Garcı´a,F.&Marquinez,J. Contributions to Geology, 19, 105–122. 2011. Kinematics of the Forcarei Synform (NW Bull, W. B. 2007. Tectonic Geomorphology of Moun- Iberian Variscan belt). In: Poblet,J.&Lisle,R.J. tains. A New Approach to Paleoseismology. Blackwell (eds) Kinematic Evolution and Structural Styles of Publishing, Oxford. Fold-and-Thrust Belts. Geological Society, London, Busk, H. G. 1929. Earth Flexures. Cambridge University Special Publications, 349, 183–198. Press, London. Ferna´ndez-Viejo, G., Gallastegui, J., Pulgar, J. A., Butler, R. W. H. 1982. The terminology of structures Gallart, J. & MARCONI TEAM. in press. The in thrust belts. Journal of Structural Geology, 4, MARCONI project: a seismic view into the eastern part 239–245. of the Bay of Biscay. Tectonophysics, doi: 10.1016/ Casey Moore,J.&Silver, E. A. 1987. Continental j.tecto.2010.06.020. margin tectonics: submarine accretionary prisms. Fitz-Diaz, E., Hudleston,P.&Tolson, G. 2011. Com- Reviews of Geophysics, 25, 1305–1312. parison of tectonic styles in the Mexican and Canadian Cobbold, P. R., Szatmari, P., Demercian, L. S., Rocky Mountain Fold–Thrust Belt. In: Poblet,J.& Coelho,D.&Rossello, E. A. 1995. Seismic and Lisle, R. J. (eds) Kinematic Evolution and Structural experimental evidence for thin-skinned horizontal Styles of Fold-and-Thrust Belts. Geological Society, shortening by convergent radial gliding on evaporites, London Special Publications, 349, 149–166. deep-water Santos Basin, Brazil. In: Jackson, Fry, N. 1979a. Random point distribution and strain M. P. A., Roberts,D.G.&Snelson, S. (eds) measurement in rocks. Tectonophysics, 60, 89–105. Salt Tectonics: A Global Perspective. American Fry, N. 1979b. Density distribution techniques and Association of Petroleum Geologists Memoir, 65, strained line length method for determination of finite 305–321. strain. Journal of Structural Geology, 1, 221–229. Cooper, M. 2007. Structural style and hydrocarbon Garcı´a-Sansegundo, J., Poblet, J., Alonso,J.L.& prospectivity in fold and thrust belts: a global review. Clariana, P. 2011. Hinterland-foreland zonation In: Ries, A. C., Butler,R.W.H.&Graham,R.H. of the Variscan orogen in the Central Pyrenees: (eds) Deformation of the Continental Crust: the comparison with the northern part of the Iberian Varis- Legacy of Mike Coward. Geological Society, London, can Massif. In: Poblet,J.&Lisle, R. J. (eds) Special Publications, 272, 447–472. Kinematic Evolution and Structural Styles of Fold- Coward, M. P. 1983. Thrust tectonics, thin-skinned and-Thrust Belts. Geological Society, London, Spe- or thick-skinned and the continuation of thrusts to cial Publications, 349, 167–182. deep in the crust. Journal of Structural Geology, 5, Geiser, P. A. 1988. The role of kinematics in the recon- 113–125. struction and analysis of geological cross sections in Chamberlin, R. T. 1910. The appalachian folds of central deformed terranes. In: Mitra,G.&Wojtal,S.F. Pennsylvania. Journal of Geology, 18, 228–251. (eds) Geometries and Mechanisms of Thrusting, With Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

22 J. POBLET & R. J. LISLE

Special Reference To the Appalachians. Geological Fold-and-Thrust Belts. Geological Society, London, Society of America, Special Paper, 222, 47–76. Special Publications, 349, 199–218. Gwinn, V. E. 1964. Thin-skinned tectonics in the plateau Masini, M., Bigi, S., Poblet, J., Bulnes, M., Di Cuia,R. and northwestern Valley and Ridge provinces of the & Casabianca, D. 2011. Kinematic evolution and Central Appalachians. Bulletin of the Geological strain simulation, based on cross-section restoration, Society of America, 75, 863–900. of the Maiella Mountain: an analogue for oil fields in Hamilton, W. B. 1988. Laramide crustal shortening. In: the Apennines (Italy). In: Poblet,J.&Lisle,R.J. Schmidt,C.J.&Perry,W.J.Jr. (eds) Interaction (eds) Kinematic Evolution and Structural Styles of of the Rocky Mountain Foreland and the Cordilleran Fold-and-Thrust Belts. Geological Society, London, Thrust Belt. Geological Society of America Memoir, Special Publications, 349, 25–44. 171, 27–39. Means, W. D. 1976. Stress and Strain. Springer-Verlag, Hardy,S.&Poblet, J. 1994. Geometric and numerical New York. model of progressive limb rotation in detachment Medd, D. M. 1996. Recent triangle zone deformation in folds. Geology, 22, 371–374. Papua New Guinea. Bulletin of Canadian Petroleum Hart, B. S. 1999. Definition of subsurface stratigraphy, Geology, 44, 400–409. structure and rock properties from 3-D seismic data. McClay, K. R. 1992a. Thrust Tectonics. Chapman & Hall, Earth Science Reviews, 47, 189–218. London. Hatcher,R.D.Jr. 1995. Structural Geology. Principles, McClay, K. R. 1992b. Glossary of thrust tectonics terms. Concepts and Problems. Prentice Hall Inc., Englewood In: McClay, K. R. (ed.) Thrust Tectonics. Chapman & Cliffs, NJ. Hall, London, 419–433. Hayward,A.B.&Graham, R. H. 1989. Some geo- McClay, K. R. 1994. Thrust Tectonics and Hydrocarbon metrical characteristics of inversion. In: Cooper, Systems. American Association of Petroleum Geo- M. A. & Williams, G. D. (eds) Inversion Tectonics. logists Memoir, 82, Tulsa. Geological Society, London, Special Publications, McClay,K.R.&Price, N. J. 1981. Thrust and Nappe 44, 17–39. Tectonics. Geological Society, London, Special Pub- Hobbs, B. E., Means,W.D.&Williams, P. F. 1976. An lications, 9. Outline of Structural Geology. John Wiley & Sons, McClay, K., Dooley, T., Ferguson,A.&Poblet,J. Inc., New York. 2000. Tectonic evolution of the Sanga Sanga Block, Huiqi, L., McClay,K.R.&Powell, D. 1992. Physical Mahakam delta, Kalimantan, Indonesia. American models of thrust wedges. In: McClay, K. R. (ed.) Association of Petroleum Geologists Bulletin, 84, Thrust Tectonics. Chapman & Hall, London, 71–81. 765–786. Jamison, W. R. 1987. Geometric analysis of fold develop- Mingramm, A., Russo, A., Pozzo,A.&Cazau, L. 1979. ment in overthrust terranes. Journal of Structural Sierras Subandinas. II Simposio de Geologı´a Regional Geology, 9, 207–219. Argentina, Co´rdoba (Argentina), 1, 95–138. Julivert,M.&Arboleya, M. L. 1984. A geometrical Mitra, G. 1997. Evolution of salients in a fold-and-thrust and kinematical approach to the nappe structure in an belt: the effects of sedimentary basin geometry, strain arcuate fold belt: the Cantabrian nappes (Hercynian distribution and critical taper. In:aSengupt , S. (ed.) chain, NW Spain). Journal of Structural Geology, 6, Evolution of Geological Structures in Micro- to 499–519. Macro-Scales. Chapman & Hall, London, 59–90. Kooi,H.&Beaumont, C. 1996. Large-scale geomorphol- Mitra, S. 1988. Effects of deformation mechanisms on ogy: classical concepts reconciled and integrated with reservoir potential in Central Appalachian overthrust contemporary ideas via a surface processes model. belt. American Association of Petroleum Geologists Journal of Geophysical Research-Solid Earth, 101, Bulletin, 72, 536–554. 3361–3386. Mitra, S. 1990. Fault-propagation folds: geometry, kin- Lacombe, O., Lave´, J., Roure,F.&Verge´s, J. 2007. ematics and hydrocarbon traps. American Association Thrust Belts and Foreland Basins. Springer, Berlin. of Petroleum Geologists Bulletin, 74, 921–945. Lisker, F., Ventura,B.&Glasmacher, U. A. 2009. Mitra,S.&Fisher, G. W. 1992. Structural Geology of Thermochronological Methods: From Palaeotempera- Folds and Thrust Belts. John Hopkins University ture Constraints to Landscape Evolution Models. Press, Baltimore. Geological Society, London, Special Publications, Mitra,S.&Namson, J. 1989. Equal area balancing. 324. American Journal of Science, 289, 563–599. MacKay, P. A. 1996. The Highwood Structure: a tectonic Morgan,J.K.&Karig, D. E. 1995. Kinematics and a wedge at the foreland edge of the southern Canadian balanced and restored cross-section across the toe of Cordillera. Bulletin of Canadian Petroleum Geology, the eastern Nankai accretionary prism. Journal of 44, 215–232. Structural Geology, 17, 31–45. MacQueen,R.W.&Leckie, D. A. 1992. Foreland Mun˜oz, J. A. 1992. Evolution of a continental collision Basins and Fold Belts. American Association of Pet- belt: ECORS-Pyrenees crustal balanced cross-section. roleum Geologists Memoir, 55. In: McClay, K. R. (ed.) Thrust Tectonics. Chapman Mantero, E. M., Alonso-Chaves, F. M., Garcı´a- & Hall, London, 235–246. Navarro,E.&Azor, A. 2011. Tectonic style Mun˜oz, J. A., McClay,K.&Poblet, J. 1994. Synchro- and structural analysis of the Puebla de Guzma´n nous extension and contraction in frontal thrust sheets Antiform (Iberian Pyrite Belt, South Portuguese of the Spanish Pyrenees. Geology, 22, 921–924. Zone, SW Spain). In: Poblet,J.&Lisle,R.J. Nemcok, M., Schamel,S.&Gayer, R. 2005. Thrust- (eds) Kinematic Evolution and Structural Styles of belts. Structural Architecture, Thermal Regimes and Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

KINEMATICS AND STYLES OF FOLD-AND-THRUST BELTS 23

Petroleum Systems. Cambridge University Press, Spear,F.S.&Selverstone, J. 1983. Quantitative p–t Cambridge. paths from zoned minerals – theory and tectonic appli- Pe´rez-Estau´ n, A., Bastida,F.et al. 1988. A thin- cations. Contributions to Mineralogy and Petrology, skinned tectonics model for an arcuate fold and thrust 83, 348–357. belt: the Cantabrian Zone (Variscan Ibero-Armorican Stearns, D. W. 1971. Mechanisms of drape folding in Arc). Tectonics, 7, 517–537. the Wyoming province. Wyoming Geological Associ- Perry,W.J.Jr. 1978. Sequential deformation in the ation 23rd Annual Field Conference Guidebook, Central Appalachians. American Journal of Science, 125–144. 278, 518–542. Suppe, J. 1983. Geometry and kinematics of fault- Price, R. A. 1981. The Cordilleran foreland thrust and bend folding. American Journal of Science, 283, fold belt in the southern Canadian Rocky Mountains. 684–721. In: McClay,K.R.&Price, N. J. (eds) Thrust Suppe, J. 1985. Principles of Structural Geology. Prentice- and Nappe Tectonics. Geological Society, London, Hall, Englewood Cliffs, NJ. Special Publications, 9, 427–448. Suppe,J.&Medwedeff, D. A. 1990. Geometry and kin- Poul, I., Melichar,R.&Janecka, J. 2011. Thrust ematics of fault propagation folding. Eclogae Geologi- tectonics of the Upper Jurassic limestones in the cae Helvetiae, 83, 409–454. Pavlov Hills (Outer Western Carpathians, Czech Suppe, J., Chou,G.T.&Hook, S. C. 1992. Rates of Republic). In: Poblet,J.&Lisle, R. J. (eds) Kin- folding and faulting determined from growth strata. ematic Evolution and Structural Styles of Fold-and- In: McClay, K. R. (ed.) Thrust Tectonics. Chapman Thrust Belts. Geological Society, London, Special & Hall, London, 105–121. Publications, 349, 233–244. Tanner, D. C., Bense,F.A.&Ertl, G. 2011. Kinematic Prucha, J. J., Graham,J.A.&Nickelsen, R. P. 1965. retro-modelling of a cross-section through a thrust- Basement-controlled deformation in Wyoming and-fold belt: the Western Irish Namurian Basin. In: Province of Rocky Mountains Foreland. American Poblet,J.&Lisle, R. J. (eds) Kinematic Evolution Association of Petroleum Geologists Bulletin, 49, and Structural Styles of Fold-and-Thrust Belts. Geo- 966–992. logical Society, London, Special Publications, 349, Ramsay, J. G. 1967. Folding and Fracturing of Rocks. 61–76. McGraw-Hill, New York. Thompson,A.B.&England, P. C. 1984. Pressure temp- Rez, J., Melichar,R.&Kalvoda, J. 2011. Polyphase erature time paths of regional metamorphism. 2. Their deformation of the Variscan accretionary wedge: an inference and interpretation using mineral assemblages example from the southern part of the Moravian in metamorphic rocks. Journal of Petrology, 25, Karst (Bohemian Massif, Czech Republic). In: 929–955. Poblet,J.&Lisle, R. J. (eds) Kinematic Evolution Torres-Carbonell, P. J., Dimieri,L.V.&Olivero,E.B. and Structural Styles of Fold-and-Thrust Belts. 2011. Progressive deformation of a Coulomb thrust- Geological Society, London, Special Publications, wedge: the eastern Fuegian Andes Thrust-Fold Belt. 349, 219–231. In: Poblet,J.&Lisle, R. J. (eds) Kinematic Evolution Riba, O. 1976. Syntectonic unconformities of the Alto and Structural Styles of Fold-and-Thrust Belts. Cardener, Spanish Pyrenees: a genetic interpretation. Geological Society, London, Special Publications, Sedimentary Geology, 15, 213–233. 349, 123–147. Rich, J. L. 1934. Mechanics of low-angle overthrust Twiss,R.J.&Moores, E. M. 1992. Structural Geology. faulting as illustrated by Cumberland thrust block, W. H. Freeman & Company, NewYork. Virginia, Kentucky, and Tennessee. American Uliana, M. A., Arteaga, M. E., Legarreta, L., Association of Petroleum Geologists Bulletin, 18, Cerda´n,J.J.&Peroni, G. O. 1995. Inversion struc- 1584–1596. tures and hydrocarbon occurrence in Argentina. In: Royden, L. H. 1993. The tectonic expression slab pull at Buchanan,J.G.&Buchanan, P. G. (eds) Basin continental convergent boundaries. Tectonics, 12, Inversion. Geological Society, London, Special Publi- 303–325. cations, 88, 211–233. Schmidt, C. J., Chase,R.B.&Erslev, E. A. 1993. Vance,D.&Mu¨ ller, W. 2003. Geochronology: Linking Laramide Basement Deformation in the Rocky the Isotopic Record With Petrology and Textures. Mountain Foreland of the Western United States. Geological Society, London, Special Publications, Special Paper Geological Society of America, 280, 220. Boulder. Vidal-Royo, O., Hardy,S.&Mun˜oz, J. A. 2011. The Simo´n,J.L.&Liesa, C. L. 2011. Incremental slip history roles of complex mechanical stratigraphy and syn- of a thrust: diverse transport directions and internal kinematic sedimentation in fold development: insights folding of the Utrillas thrust sheet (NE Iberian from discrete-element modelling and application to the Chain, Spain). In: Poblet,J.&Lisle, R. J. (eds) Pico del A´ guila anticline (External Sierras, Southern Kinematic Evolution and Structural Styles of Fold- Pyrenees). In: Poblet,J.&Lisle, R. J. (eds) Kin- and-Thrust Belts. Geological Society, London, ematic Evolution and Structural Styles of Fold-and- Special Publications, 349, 77–97. Thrust Belts. Geological Society, London, Special Smith,B.&George, T. N. 1961. British Regional Geo- Publications, 349, 45–59. logy, North Wales. Institute of Geological Science, Von Huene,R.&Scholl, D. W. 1991. Observations at London. convergent margins concerning sediment subduction, Smith, J. G. 1965. Orogenesis in western Papua and New subduction erosion, and the growth of continental Guinea. Tectonophysics, 2, 1–27. crust. Reviews of Geophysics, 29, 279–316. Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021

24 J. POBLET & R. J. LISLE

Von Huene, R., Ranero,C.R.&Vannucchi, P. 2004. Douglas, R. J. W. (eds) Variations in Tectonic Generic model of subduction erosion. Geology, 32, Styles in Canada. Geological Association of Canada, 913–916. Special Paper, 11, 1–82. Westbrook, G. K., Ladd, J. W., Buhl, P., Bangs,N.& Worrall,D.M.&Snelson, S. 1989. Evolution of the Tilley, G. J. 1988. Cross section of an accretionary northern Gulf of Mexico, with emphasis on Cenozoic wedge: Barbados Ridge complex. Geology, 16, growth faulting and the role of salt. In: Bally,A.W. 631–635. & Palmer, A. R. (eds) The Geology of North Wheeler, J. O., Aitken,J.D.et al. 1972. The Cordil- America: an Overview. Geological Society of leran structural province. In: Price,R.A.& America, Boulder, 97–138.