Jacques Malavieille | CNRS- Universite de Montpellier (original) (raw)

Papers by Jacques Malavieille

Geosciences, 2021

Based on the review of the available stratigraphic, tectonic, morphological, geodetic, and seismo... more Based on the review of the available stratigraphic, tectonic, morphological, geodetic, and seismological data, along with new structural observations, we present a reappraisal of the potential seismogenic faults and fault systems in the inner northwest Apennines, Italy, which was the site, one century ago, of the devastating Mw ~6.5, 1920 Fivizzano earthquake. Our updated fault catalog provides the fault locations, as well as the description of their architecture, large-scale segmentation, cumulative displacements, evidence for recent to present activity, and long-term slip rates. Our work documents that a dense network of active faults, and thus potential earthquake fault sources, exists in the region. We discuss the seismogenic potential of these faults, and propose a general tectonic scenario that might account for their development.

Eos, Transactions American Geophysical Union, 1997

A joint French‐Taiwanese cruise in May and June 1996 on the French research vessel L'Atalante... more A joint French‐Taiwanese cruise in May and June 1996 on the French research vessel L'Atalante has provided detailed structural images of the sea floor east and southwest of Taiwan. High quality swath bathymetry (see Figure 1) and seismic reflection profiles collected in southeastern and southwestern offshore areas near Taiwan will increase our understanding of how the Luzon Arc is deformed by its collision with the Chinese passive margin and how the Manila Trench connects with the deformation front on Taiwan. The data collected off the eastern coast of Taiwan will elucidate the nature of the plate boundary between the Ryukyu subduction zone and the Taiwan mountain belt and reveal the mode of back arc opening in the Southern Okinawa Trough. The investigations will contribute to understanding the processes of accretion of an arc to a continent prior to the ultimate collision between continents.

Tectonics, 1992

Sandbox modeling is used to study the deformation of accretionary wedges caused by the subduction... more Sandbox modeling is used to study the deformation of accretionary wedges caused by the subduction of oceanic ridges. The first experiment incorporates a massive ridge within a sand wedge. The wedge thickens and shortens when the forward propagation of the basal decollement ceases. The wedge thickening results in taper change, reactivation of preexisting thrusts, and retreat of the frontal part of the sand wedge. Similar mechanisms may have affected some margins that have undergone ridge subduction such as the Tonga margin after the subduction of the oblique Louisville oceanic ridge. The second experiment shows the effects of an active basement thrust slice as it enters a subduction zone. This process may have happened in the eastern Nankai accretionary wedge. Initially, the wedge in this experiment behaved similarly to that of the first experiment. Rapidly the topographic slope changed, the wedge thickened above the basement slice generating a slope break in the topography; a deeper...

Geologische Rundschau, 1994

International Journal of Earth Sciences, 2010

Frontiers in Earth Sciences, 2009

Tectonophysics, 1993

Although numerous transfer zones of deformation have been observed in thrust wedges, their mechan... more Although numerous transfer zones of deformation have been observed in thrust wedges, their mechanisms and conditions of development are poorly understood. In this paper three basic questions are addressed: (1) what are the parameters controlling the genesis of transfer zones? (2) what are the kinematics of thrust propagation during transfer zone development? and (3) which kinds of geological structure link the two compartments on either side of the transfer zone? We attempted to solve these problems using a 3-D experimental approach. Sand models were used to simulate the foreland, a rigid, but mobile, backstop was used to produced a thrust Coulomb wedge which was studied during the various stages of its formation. Shortening led to the development of transfer zones in the wedge, separating two domains of homogenous behaviour and connecting thrust planes in different domains. The experimental results show that the development of transfer zones is controlled by mechanical and/or geometrical parameters such as: (1) variations in the sedimentary thickness in the foreland; (2) the steepness of the backstop; (3) domains with different basal friction in the foreland; (4) kinked backstop geometry. During deformation of the models, two types of thrust sequence were identified: alternative thrust propagations on both sides of the transfer zone and synchronous thrust propagations which are anastomosed within the transfer zone. 3-D reconstructions revealed that the thrust deformations observed in the transfer zone are oblique ramps. The frontal thrust bending of the Barbados accretionary complez, as well as the imbrication of thrust in the "Castellane" arc and the oblique ramp in the Zanskar Range, are discussed in relation to the mechanisms and structures revealed by the models. The results of analogue modelling suggest that the development of transfer zones is directly linked to variations in the boundary conditions (mechanical and/or geometrical) between two adjacent parts of a thrust wedge.

Tectonophysics, 1998

In many active margins, severe deformation is observed at the front of the overriding plate where... more In many active margins, severe deformation is observed at the front of the overriding plate where seamounts or aseismic ridges subduct. Such deformation appears to be a main tectonic feature of these areas which influences the morphology and the seismicity of the margin. To better understand the different stages of seamount subduction, we have performed sandbox experiments to study in detail the evolution of deformation both in space and time and thus complement seismic images and bathymetry interpretation. We focus, in this paper, on the surface deformation directly comparable with seafloor morphology. Two types of subducting seamounts were modelled: relatively small conical seamounts, and larger flat-topped seamounts. The indentation of the margin by the seamount inhibits frontal accretion and produces a re-entrant. The margin uplift includes displacement along backthrusts which propagate from the base of the seamount, and out-of-sequence forethrusts which define a shadow zone located on the landward flank of the seamount. When the seamount is totally buried beneath the margin, this landward shielded zone disappears and a larger one is created in the wake of the asperity due to the elevated position of the décollement. As a consequence, a section of the margin front follows behind the seamount to greater depth. A 'slip-line' network develops concurrently above the subducting seamount flanks from the transtension along the boundaries of the shadow zone. In a final stage, normal faults, controlled by the shape of the seamount, develop in the subsiding wake of the asperity. Swath-bathymetric data from the Costa Rica margin reveal detailed surface deformation of the margin above three subducting seamounts. Shaded perspective views highlight the detailed structure of the seafloor and compare well with surface deformation in the sandbox experiments. The good correlation between the marine data and experimental results strengthen a structural interpretation of the Costa Rican seamount subduction.

Tectonophysics, 2001

Fission-track analysis on zircons and apatites yields new information about the timing of deforma... more Fission-track analysis on zircons and apatites yields new information about the timing of deformation of the northern Tibetan plateau. Ages on zircons, ranging from 221 ± 22 to 96 ± 4 Ma are indicative of a general late Triassic-early Jurassic cooling probably driven by the collision between the Qiantang and Kunlun blocks. Mid-Jurassic slow cooling is recorded also in the apatites in regions not affected by later Cenozoic deformation. This Jurassic denudation was followed by a period of sedimentation during the Cretaceous, except along the Altyn Tagh fault (ATF) zone, and in some restricted areas of the western and eastern Qilian Shan. This long and relatively quiet period ended at about 40 ± 10 Ma along the major Altyn Tagh and Kunlun strike-slip fault zones, which were activated by the India-Asia collision. This first movement along lithospheric faults resulted in the eastward extrusion of the Tibet plateau, which was followed, in late Oligocene-Miocene times, by a major compression event, initiating the formation of the high relief of north Tibet. A final compressional event took place at 9-5 Ma and is well correlated with high sedimentation rates in the basins of this region. This compression induced continental subduction in the Kunlun ranges, the Altun Shan belt, and possibly the Qilian Shan belt.

Tectonophysics, 2012

The volume comprises some of the contributions presented during the 10th edition of the Alpine Me... more The volume comprises some of the contributions presented during the 10th edition of the Alpine Meeting "CorseAlp 2011". It has been held in Saint Florent (Corsica) between 10th and 16th of April 2011 under the auspices of Societe Geologique de France, Societa Geologica Italiana and the INGV (Istituto Nazionale di Geofisica e Vulcanologia) and with the collaboration of colleagues of Universite de Corse (M.-M. Spella, M. and J. Ferrandini and L. Ciancaleoni) and the support of the city council of S. Florent. The meeting was framed in the series of "Alpine Workshops" e.g., Siegesmund et al. (2008), Handy and Rosenberg (2011), which are held every two years to develop interdisciplinary research on Alpine-type orogens. It hosted a variety of topical sessions from regional geology to process-oriented field and laboratory studies and gave the opportunity to collect multidisciplinary and multiscale approaches to geodynamic studies including continental rifting and ocean opening, oceanic and continental subduction, late- to post orogenic extension, exhumation of deep seated rocks, back-arc opening and microcontinent rotation, interfering orogenic-scale tectonics and surface processes, tectonics and seismic hazard within the Alpine chain and Mediterranean realms.

Tectonics, 2000

Sandbox experiments, using a two-dimensional and a three-dimensional approach, are used to study ... more Sandbox experiments, using a two-dimensional and a three-dimensional approach, are used to study the deformation of margins in response to seamount subduction. Successive mechanisms of deformation are activated during the subduction of conical seamounts. First, reactivation of the frontal thrusts and compaction of the accretionary wedge is observed. Then, back thrusting and, conjugate strike-slip faulting develops above the leading slope of the subducted seamount. The basal décollement is deflected upward in the wake of the subducting high, and a large shadow zone develops behind the seamount trailing slope. Consequently, frontal accretion is inhibited and part of the frontal margin is dragged into the subduction zone. When the main décollement returns to its basal level in the wake of the seamount, the margin records a rapid subsidence and a new accretionary wedge develops, closing the margin reentrant. The sediments underthrusted in the wake of the seamount into the shadow zone, are underplated beneath the rear part of the accretionary wedge. Substantial shortening and thickening of the deformable seaward termination of the upper plate basement, associated with basal erosion is observed. Seamount subduction induces significant material transfer within the accretionary wedge, favors large tectonic erosion of the frontal margin and thickening of the rear part of the margin. The subduction and underplating of relatively undeformed, water-ladden sediments, associated with fluid expulsion along the fractures affecting the margin could modify the fluid pressure along the basal décollement. Consequently, significant variations of the effective basal friction and local mechanical coupling between the two plates could be expected around the subducting seamount.

Journal of Structural Geology, 1990

Abstract A theoretical model is presented to explain the relation between the different strain re... more Abstract A theoretical model is presented to explain the relation between the different strain regimes in a ductile décollement level and the ramp geometry. This model accounts for a simple shear regime in the basal flat level and a less rotational and more flattening strain regime along the ramp. The model is applied to a field example where the ramp dip and the shear value on the basal flat are estimated from pressure shadow data.

Journal of Structural Geology, 1998

The structural evolution of accretionary wedges was modeled in a series of analog experiments wit... more The structural evolution of accretionary wedges was modeled in a series of analog experiments with systematically varying initial boundary conditions. The two principle parameters investigated were basal friction and thickness of sediment Input (relative to subducted sediment Output). Material transfer (in terms of degree and location of accretion and erosion) is quantified as a function of these two parameters. Low basal friction produces long, thin wedges, by continuous frontal accretion of imbricate thrusts. Simultaneously, substantial basal erosion may occur, with little influence on the frontal dynamics. The formation of an outer arc high with an accompanying forearc basin depends upon the relative amount of basal erosion, the opening of the subduction window. Spacing of thrust faults is proportional to the layer thickness confirming the principle of self-similar wedge growth from critical wedge theory. High basal friction typically generates steep wedges, marked by an erosional, mass wasting frontal slope in the cases 150. This is due to underthrusting and/or subduction of the entire sedimentary section. The case I < 0 also features the late development of normal faulting and an extensional forearc basin. For both low and high basal friction the material balance affects the wedge slope; erosive conditions (I < 0) lead to steeper wedges than accretionary conditions (I>O). For low basal friction the primary modes of material transfer are frontal accretion and basal erosion. For high basal friction the primary modes of material transfer are underthrusting/underplating and frontal erosion. Applying the experimental results to active convergent margins, parallels may be drawn. Thus, the Barbados Ridge Complex is interpreted to be a good example of a low basal friction wedge with an accretionary material balance, while the Japan and Mariana margins provide examples of an erosive material balance. $

Journal of Metamorphic Geology, 2011

In Alpine Corsica (France), deeply subducted metabasalts are well preserved as lawsonite-bearing ... more In Alpine Corsica (France), deeply subducted metabasalts are well preserved as lawsonite-bearing eclogite (Law-Ecl), occurrence of which is restricted to 10 localities worldwide. The Corsican Law-Ecl, consisting of omphacite + lawsonite + garnet + phengite + titanite, occurs as both single undeformed metabasaltic pillows surrounded by lawsonite blueschist (Law-Bs), and carbonate-bearing eclogitic veins. Law-Bs are found as variably deformed metabasaltic pillows locally cross-cut by eclogitic veins and consist of glaucophane + actinolite + lawsonite + garnet + phengite + titanite. Field evidence and microstructures reveal that both Law-Ecl and Law-Bs are stable at the metamorphic peak in the lawsonite-eclogite stability field. Isochemical phase diagrams (pseudosections) calculated for representative Law-Ecl and Law-Bs samples indicate that both lithologies equilibrated at the same conditions of 520 ± 20°C and 2.3 ± 0.1 GPa. Therefore, the coexistence at the same peak metamorphic conditions of Law-Ecl and Law-Bs implies that different portions of deeply subducted oceanic crust may store significantly different H 2 O contents, depending on bulk-rock chemical composition. In addition, thermodynamic modelling of phase equilibria indicates that the occurring progressive dehydration reactions, which are significantly depending on bulk-rock chemical composition, strongly influence rock densification and eclogite formation in subducting slabs.

Journal of Geophysical Research: Solid Earth, 1994

Based on observations from both modem convergent margins and sandbox modeling, we examine the pos... more Based on observations from both modem convergent margins and sandbox modeling, we examine the possible conditions favoring frontal accretion and/or frontal and basal tectonic erosion. Mean characteristic parameters (μ, μ*b and λ) are used to discuss the mechanical stability of 28 transects across the frontal part of convergent margins where the Coulomb theory is applicable. Natural observations reveal that “typical accretionary wedges” are characterized by low tapers with smooth surface slope and subducting plate, low convergence rates and thick trench sediment, while “nonaccretionary wedges” display large tapers with irregular surface slopes and rough subducting plate, high convergence rates and almost no trench fill. Sandbox experiments were performed to illustrate the effects of seamounts/ridges in the subduction zone on the deformation of an accretionary wedge. These experiments show that a wedge of sand is first trapped and pushed in front of the seamount which acts as a moving...