Jean-Luc Epard

• PhD
• Professor (Associate) at University of Lausanne

The region surrounding Zermatt (SW Switzerland and NW Italy) displays some classic examples of imbrications between continental and oceanic units. In particular, the studied units, called Cimes Blanches and Frilihorn or Faisceau Vermiculaire , consist of a set of thin bands of continent-derived metasediments intercalated at different levels within...

Here, we revise and update the biostratigraphy of larger foraminiferal assemblages in three sections of the Priabonian Sanetsch Formation in the Helvetic Nappes of theWestern Swiss Alps: The Sex Rouge (SE) and the Sanetsch Buvette (SA) sections in the Wildhorn Nappe Complex, and the Col des Essets (ETS) section in the most external Morcles Nappe. I...

The Schistes Lustrés form a large and complex unit at the top of the Penninic nappe stack of the Alpine belt. Calcschists, partly of Late Cretaceous age, constitute the dominant lithology. They are closely associated both with blueschist facies Piemont-Ligurian ophiolites and continent-derived Mesozoic metasediments. The question of whether the Sch...

The Gemmi-Lämmerenalp area gives easy access to excellent outcrops of a mildly deformed Upper Jurassic-Lower Cretaceous and Paleogene sedimentary sequence of the North-Helvetic Doldenhorn nappe. Traditionally, field camps are organized by the ETH and the University of Lausanne to train students in geological mapping, stratigraphical and structural...

Energy tunnels allow the harvesting of untapped heat at shallow depths in the underground to meet the thermal energy requirements of buildings and infrastructures over large areas. Such heat can derive from two sources: the ground surrounding energy tunnels and the air circulating in the environment internal to these tunnels. To date, various inves...

EPARD J.-L., GEX P. & VUST M., 2020. Les blocs erratiques propriété de la Société Vaudoise des Sciences Naturelles. Bulletin de la Société Vaudoise des Sciences naturelles 99: 29-66. Résumé Seize blocs erratiques, propriété de la Société Vaudoise des Sciences Naturelles, ont été étudiés des points de vue historique, pétrographique et lichénologique...

The Mont Fort nappe, former uppermost subunit of the Grand St-Bernard nappe system, is an independent tectonic unit with specific structural and stratigraphic characteristics (Middle Penninic, NW Italy and SW Switzerland). It consists in a Paleozoic basement, overlain by a thin, discontinuous cover of Triassic-Jurassic metasediments, mainly breccia...

We apply three-dimensional (3-D) thermo-mechanical numerical simulations of the shortening of the upper crustal region of a passive margin in order to investigate the control of 3-D laterally variable inherited structures on fold-and-thrust belt evolution and associated nappe formation. We consider tectonic inheritance by employing an initial model...

Abstract. Fold-and-thrust belts and associated tectonic nappes are common in orogenic regions. They exhibit a wide variety of geometries and often a considerable along-strike variation. However, the mechanics of fold-and-thrust belt formation and the control of the initial geological configuration on this formation are still incompletely understood...

The Lepontine gneiss dome represents a unique region of the Central Alps where Oligocene–Miocene amphibolite facies grade rocks and fold nappes of the deepest tectonic level of the Alpine orogenic belt are exposed in a tectonic window. The Cenozoic structures of the Maggia nappe reveals a giant tens of kilometre-scale tubular fold structure that cr...

The contacts between different tectonic units are commonly highlighted by the presence of distinctive markers such as well-developed mylonitic fabric or intercalation of cornieule level or tectonized slices. In some cases, an abrupt change in the mineralogical assemblages, indicating contrasting tectono-metamorphic histories, may also help to ident...

The Tso Morari nappe is well known for having suffered ultrahigh-pressure metamorphism in the northwest Himalaya. Its pressure-temperature evolution has been widely studied and debated since the end of the 1990s. However, the lithostratigraphy, structures and metamorphism of the tectonic units around the Tso Morari nappe are poorly known, especiall...

The deformation pattern in active orogens is in general diffuse and distributed, and is expressed by spatially scattered seismicity and fault network. We select two relating datasets in the region encompassing Switzerland and analyse how they compare with each other. The datasets are not complete but are the best datasets currently available which...

The Mont Fort nappe is the upper tectonic subdivision of the former Grand St-Bernard (GSB) nappe (Escher 1988, Escher et al. 1997). Subsequent research has confirmed its tectonic and stratigraphic independence from the rest of the GSB nappe (e.g. Gouffon 1993). It consists of a Paleozoic basement overlain by a thin Mesozoic sedimentary cover, compr...

The detection and characterisation of geological layers, as well as the precise quantification of their geometrical properties, is of primary interest in several domains of geology. Nevertheless, geological data gathering is commonly limited by access issues during fieldwork investigations. Here we present complementary and alternative tools aimed...

The eclogitic Adula nappe of the Central Alps (cantons Graubünden and Ticino, Switzerland) displays an exceptionally complex internal structure with the particularity of enclosing numerous slices of Mesozoic cover rocks (Internal Mesozoic) within the Palaeozoic gneiss basement. This study is principally based on detailed lithological and structural...

The geologic structures and metamorphic zonation of the northwestern Indian Himalaya contrast significantly with those in the central and eastern parts of the range, where the high-grade metamorphic rocks of the High Himalayan Crystalline (HHC) thrust southward over the weakly metamorphosed sediments of the Lesser Himalaya along the Main Central Th...

The Adula nappe belongs to the Lower Penninic domain of the Central Swiss Alps. It consists mostly of pre-Triassic basement lithologies occurring as strongly folded and sheared gneisses of various types with mafic boudins. We propose a new lithostratigraphy for the northern Adula nappe basement that is supported by detailed field investigations, U–...

This contribution investigates the distribution of rock slope deformations (RSD) and their relationships with tectonic structures, lithological and topographic contexts. This is performed in a moderate relief context (1,100–2,500 masl.) affected by thin-skin tectonic. The proposed inventory, along the Livingstone range anticlinorium (LRA), contains...

In the central parts of the Himalayas, the High Himalayan Crystalline (HHC) high-grade rocks are exhumed in the frontal part of the range, as a consequence of a tectonic extrusion controlled by combined thrusting along the Main Central Thrust (MCT) and extension along the South Tibetan Detachment System (STDS). In the NW Himalaya, however, the hang...

Structural and rock mass quality characterization of rock slopes using remote methods has greatly improved over the last years. In particular, the use of GB-LiDAR and High Resolution Digital Elevation Models allows identifying geometry and characteristics of ductile and brittle structures with the possibility to extend the investigations to other i...

Many factors influence and affect the development of rock slope deformations, either by predisposing slopes to failure or by triggering the failure leading to the final collapse. These factors include the inherent slope's parameters (structural settings, lithology, groundwater, slope morphology, …) and the external parameters that independently inf...

We present a one-dimensional shear zone model with a power-law flow law and a temperature dependent viscosity. The analytical solution for the velocity profile across the shear zone depends only on the single dimensionless parameter β. β depends on the activation energy of the applied flow law, the temperature at the base of the shear zone and the...

New stratigraphic data along a profile from the Helvetic Gotthard massif to the remnants of the North Penninic basin in eastern Ticino and Graubünden are presented. The stratigraphic record together with existing geochemical and structural data, motivate a new interpretation of the fossil European distal margin. We introduce a new group of Triassic...

A simple thermo-mechanical crustal-scale shear zone model applied to the Morcles nappe (Switzerland)

Turtle Mountain area (Alberta, Canada) became well known in 1903 when a 40 Mm 3 rock avalanche, the Frank Slide, affected its eastern side. Portions of the mountain still display potential instabilities and are monitored using most recent techniques. Structural settings of Turtle Mountain are investigated to understand the present day scar morpholo...

The Teggiolo zone is the sedimentary cover of the Antigorio nappe, one of the lowest tectonic units of the Penninic Central Alps. Detailed mapping, stratigraphic and structural analyses, and comparisons with less metamorphic series in several well-studied domains of the Alps, provide a new stratigraphic interpretation. The Teggiolo zone is comprise...

New fission track and Ar/Ar geochronological data provide time constraints on the exhumation history of the Himalayan nappes in the Mandi (Beas valley) – Tso Morari transect of the NW Indian Himalaya. Results from this and previous studies suggest that the SW-directed North Himalayan nappes were emplaced by detachment from the underthrusted upper I...

Résumé.–GALSTER F., EPARD J.-L. & MASSON H., 2010. Les nappes de Soja et de Luzzone-Terri: découverte d'un élément Briançonnais sous le front de la nappe de l'Adula (Tessin NE, Alpes centrales). Bulletin de la Société vaudoise des Sciences naturelles 92.2: 61-75. La nappe classique de Soja, située sous le front de l'Adula dans le NE du Tessin, est...

Discovery of fossils in the Adula nappe, new stratigraphic data and tectonic consequences (Central Alps). Bulletin de la Société vaudoise des Sciences naturelles 92.2: 77-84. Crinoid plates have been found in the Mesozoic sediments of the highly metamorphic (eclogite facies) Adula nappe. They occur in a dolomitic breccia formation that had previous...

Turtle Mountain is located in the Foothills in southwest Alberta and is formed by highly fractured Paleozoic carbonates rocks and Mesozoic clastic rocks. This area is mainly affected by two major geological structures that are the Turtle Mountain anticline and the Turtle Mountain thrust. This site has become famous after a 30 M m3 rock avalanche of...

DOI = 10.3126/hjs.v5i7.1336 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.157-8

DOI = 10.3126/hjs.v5i7.1337 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.159-160

DOI = 10.3126/hjs.v5i7.1254 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.52

Detailed field work and zircon analysis have improved the knowledge of the lithostratigraphy at the base of the Siviez-Mischabel nappe in the Mattertal (St-Niklaus-Törbel area). They confirm the existence of an overturned limb and clarify the structure of the St-Niklaus syncline. The following formations can be observed: • Polymetamorphic gneisse...

Migmatitic rocks developed in metagraywackes during the Variscan orogeny in the Aiguilles-Rouges Massif (western Alps). Partial melting took place 320 Ma ago in a 500 m-wide vertical shear zone. Three leucosome types have been recognised on the basis of size and morphology: (1) large leucosomes > 2 cm wide and > 40 cm long lacking mafic selvage, bu...

A continental subduction-related and multistage exhumation process for the Tso Morari ultra-high pressure nappe is proposed. The model is constrained by published thermo-barometry and age data, combined with new geological and tectonic maps. Additionally, observations on the structural and metamorphic evolution of the Tso Morari area and the North...

The application of the Fry method to measure strain in deformed porphyritic granites is discussed. This method requires that the distribution of markers has to satisfy at least two conditions. It has to be homogeneous and isotropic. Statistics on point distribution with the help of a Morishita diagram can easily test homogeneity. Isotropy can be ch...

The hypabyssal root zone of an ocean island volcano can be directly observed in the uplifted Basal Complex of Fuerteventura (Canary Islands). This complex records a long-lasting magmatic activity characterised by the intrusion of numerous magma batches as small plutons, dykes, dyke swarms and ring-dyke complexes of alkali-gabbros, pyroxenites, syen...

This paper aims to describe the possible SE extension of the Zanskar Shear Zone and its relation with other extensional and compressional structures. New structural and metamorphic data were collected in the Baralacha La, Yunam, Lingti region and a new geologic map of the studied area is proposed. The new data reveal that an E-verging syncline (the...

In the NW Himalaya of India, high-grade metamorphic rocks of the High Himalayan Crystalline Zone (HHCZ) are exposed as a 50km large dome along the Miyar and Gianbul valleys. This Gianbul dome is cored by migmatitic paragneiss formed at peak conditions around 750°C and 8kbar, and symmetrically surrounded by sillimanite, kyanite±staurolite, garnet, b...

The Zanskar shear zone is a syn-orogenic extensional structure located in the Western Himalaya. This one-km thick shear zone forms the transition between the High Himalayan Crystalline metamorphic series and the lower grade metamorphic sediments of the Tethyan Himalaya (Dèzes et al., 1999; Herren, 1987). The area at the SE end of the shear zone (Ka...

The structure of the Himalaya is dominated by two belts of SW-verging folds and thrusts. The North Himalayan nappes occur in the Tethys Himalaya to the north and the intracontinental Main Central and Main Boundary Thrust are located in the Higher Himalaya to the south. These SW-directed thrusts have been formed by underthrusting of the North Indian...

A new geological transect through the Tso Morari gneiss dome and the Upper Precambrian to Cretaceous sediments of the Spiti region has been used to determine the nappe structures of the Tethys Himalaya. The newly defined SW-directed Tso Morari, Tetraogal and Mata nappes have been formed by shearing off the upper crust of the north Indian continenta...

The southern border of the Rocroi Massif has been the subject of recent investigations. This area affected by Caledonian and Variscan orogenies show complex structures difficult to interpret. The use of the software POLYPLI version 2.0 together with field observations was a successful way to test several interpretations and to model the studied zon...

We describe how to make the necessary measurements and manipulations to balance and restore cross sections using the widely available programs Canvas™, Photoshop™, and Excel™. Data or cross sections are input to Canvas from a flatbed scanner or a video camera, or sections are constructed using program drafting tools. Scanned photos and captured vid...

A new simple geometric model is proposed that explains the possible relationships between superficial thrust sheets and deeper fold nappes. It demonstrates that the simultaneous formation of these two types of structures at different levels of the crust is kinematically and geometrically possible. The model is based on the difference of rheological...

Detachment anticlines formed above a stratigraphically fixed detachment horizon and without thinning in the syncline will, in general, require layer-parallel shortening. A kinematic model for detachment folds is presented that has planar limbs and is area-balanced but requires bed-length changes that can be expressed as layer-parallel strain. The f...

The Crystalline Nappe of the High Himalayan Crystalline has been examined along the Kulu Valley and its vicinity. This nappe was believed to have undergone deformation related only to its transport towards the SW essentially during the "Main Central Thrust event'. New data has led to the conclusion that during the Himalayan orogeny, two distinctive...

The classical constant-area relationship for balancing cross-sections is reformulated to accommodate layer-parallel strain leading to a general equation for the layer-parallel strain in a fold formed above a stratigraphically fixed detachment horizon. The strain required for area balance can be calculated from a knowledge of the fold shape and the...

Since 1986, several near-vertical seismic reflection profiles have been recorded in Switzerland in order to map the deep geologic structure of the Alps. One objective of this endeavour has been to determine the geometries of the autochthonous basement and of the external crystalline massifs, important elements for understanding the geodynamics of t...

A plot of the excess area in cross section vs. the depth to a reference level for several stratigraphic horizons in a compressional fold produces a curve that gives the depth to detachment. The curve is a straight line for detachment folds. The slope of the line is the displacement on the lower detachment and the depth intercept (where excess area...

Contractional detachment folds form above a stratigraphically fixed detachment horizon. The classical depth-to-detachment calculation is based on the assumptions of constant bed length and constant area, and may produce geometrically and kinematically unrealistic results. Detachment horizons that are stratigraphically fixed, synclines that are not...

Text in French; summary in English and French. At head of title: Université de Lausanne. Faculté des sciences. Institut de géologie et de paléontologie. Thesis (Ph. D.)--Université de Lausanne. Includes bibliographical references (p. 159-165).

Formation names are proposed to describe Triassic and Liassic rocks of the Dauphinoise zone in the area between the Belledonne, Aiguelles-Rouges and Mont-Blanc external crystalline Massifs (French Alps, Savoie). We give a description of their lithostratigraphic content, an inventory of their faunas, and synthetic schemes of longitudinal and transve...

Detailed profiles in the Triassic and Liassic series SW of Chamonix (Col de Tricot and Arandellys) prove that the Mesozoic sediments of the internal part of the Chamonix zone are in stratigraphic contact with the crystalline basement of the Mont-Blanc massif. The 'Mont-Blanc thrust' does not exist.-from English summary

The 'Gres de Taveyanne' basic greywacke formation, occurring between Les Diablerets and the Aar massif, was sampled from four tectonic nappe units of the Helvetic realm. Four mineral zones are distinguished: 1) the laumontite zone, characterized by this mineral and corresponding with the zeolite facies; 2) the prehnite-pumpellyite zone, between the...