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Tectonophysics 477 (2009) 119–134
Contents lists available at ScienceDirect
Tectonophysics
j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / t e c t o
Migmatites, granites and orogeny: Flow modes of partially-molten rocks and magmas
associated with melt/solid segregation in orogenic belts
Olivier Vanderhaeghe
G2R, Nancy-Université, CNRS, Boulevard des Aiguillettes B.P. 239 F-54506 Vandœuvre lès Nancy, France
a r t i c l e
i n f o
Article history:
Received 30 August 2008
Received in revised form 7 June 2009
Accepted 22 June 2009
Available online 28 June 2009
Keywords:
Migmatite
Granite
Orogeny
Crustal flow
Melt migration
Solid settling
a b s t r a c t
This paper presents a model for the genesis of migmatites and granites during orogenic evolution based on
the analysis of several Phanerozoic crustal segments and a review of the physical properties of partiallymolten rocks and magmas. This model inventories the modes of bulk flow of partially-molten rocks and
magmas and the mechanisms of melt/solid segregation for each mode.
Partial melting of rocks is associated with a strength decrease of two to three orders of magnitude leading to
strain partitioning expressed by channel flow driven either by forces related to plate tectonics (vertical
channel flow) or by the gravity force associated with lateral variations of crustal thicknesses (horizontal
channel flow). Although the structural characteristics of migmatites indicate that deformation plays a role in
melt migration, the emplacement of laccoliths of leucogranites above migmatites attests to the efficiency of
the buoyancy force.
Another decrease in apparent strength of about ten orders of magnitude is associated with the loss of
continuity of the solid framework marking the transition from partially-molten rocks to magmas. The
breakdown of the solid framework also allows for settling of the solid in suspension increasing the buoyancy
of the remaining magma. Accordingly, domes cored by diatexites (former heterogeneous magmas) and
mantled by metatexites (former partially-molten rocks) are interpreted as gravitational instabilities driven
by the relative buoyancy of the magma and permitted by the weakness of the partially-molten rocks.
This model provides a first order framework to elucidate the development of a crustal-scale horizontal
layering during the evolution of orogenic belts that are affected by partial melting. In this case, the middle
crust is dominated by migmatites with domes cored by diatexites and mantled by metatexites that
correspond to a partially-molten and magmatic zone, respectively. The granitic dikes and sills and the
associated laccoliths of leucogranites correspond to an intrusive zone overlying the partially-molten zone.
The refractory lower crust is potentially in part formed by accumulation of solids segregated from the
overlying heterogeneous magmas.
© 2009 Elsevier B.V. All rights reserved.
1. Introduction
The dynamic evolution of Phanerozoic orogenic belts at convergent plate boundaries is associated with extensive partial melting
of the continental crust as attested by the genesis and exhumation of
migmatitic and granitic terranes (Brown, 2001; Vanderhaeghe and
Teyssier, 2001b). The presence of silicate melts within zones of
thickened crust is also consistent with a low-velocity, high-reflectivity
and high-conductivity zone detected by geophysical tools beneath the
Altiplano (Schilling et al., 1997; Schmitz et al., 1997; Partzsch et al.,
2000), the Pyrenees (Pous et al., 1995) and the Tibetan plateau (Brown
et al., 1996; Nelson et al., 1996; Alsdorf and Nelson, 1999) although
alternative interpretations of these geophysical data are also proposed
(Makovsky and Klemperer, 1999; Hacker et al., 2000). Partial melting
changes rock rheology and density, and leads to the generation of a
two-phase medium allowing melt–solid segregation. The rheologic
E-mail address: olivier.vanderhaeghe@g2r.uhp-nancy.fr.
0040-1951/$ – see front matter © 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.tecto.2009.06.021
impact of partial melting affects the mechanics of rocks from the
outcrop to the crustal scale (Vanderhaeghe and Teyssier, 2001b;
Rosenberg and Handy, 2005), whereas melt segregation and magma
mobility are considered as the main processes leading to crustal
differentiation (Vielzeuf et al., 1990; Sawyer, 1994). Addressing these
issues requires distinguishing mechanisms of (i) the bulk flow of the
partially-molten rocks and magmas (ii) melt/solid segregation via
melt migration within partially-molten rocks and solid settling within
magmas and (iii) melt migration out of the partially-molten rocks.
Following the pioneering work of Mehnert (1968), structural
analysis of migmatites has evidenced the relationship between
deformation and melt migration (Weinberg, 1996; Brown and
Rushmer, 1997; Solar et al., 1998; Sawyer et al., 1999; Vanderhaeghe
et al., 1999b; Weinberg, 1999; Rosenberg, 2001; Vanderhaeghe, 2001).
It has also illustrated the mechanical relevance of distinguishing
metatexites from diatextites representing former partially-molten
rocks and magmas, respectively (Brown, 1973; Wickham, 1987; Burg
and Vanderhaeghe, 1993; Brown, 1994; Sawyer, 1994). At the crustal-
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
scale, the mechanical role of partial melting has been identified on the
basis of the structural and metamorphic characteristics of migmatites
and granites (Brown, 1993; Brown, 2001; Vanderhaeghe and Teyssier,
2001b). Several end-member situations for the dynamical link
between flow of partially-molten rocks and melt/solid segregation
have been identified encompassing migmatites and granites
deformed (i) by vertical extrusion in axial zones of relatively narrow
orogenic belts (Brown and Solar, 1998; Solar et al., 1998; Schulmann et
al., 2008); (ii) by lateral extrusion to the edges of continental plateaux
that correspond to large orogenic belts (Burchfiel et al., 1992; Hodges
et al., 1993; Weinberg and Searle, 1998; Beaumont et al., 2001;
Vanderhaeghe and Teyssier, 2001b; Grujic et al., 2002); and (iii) by
lateral and vertical flow in the axial zone of gravitationally collapsed
orogenic belts (Burg and Vanderhaeghe, 1993; Gardien et al., 1997;
Vanderhaeghe et al., 1999a; Ledru et al., 2001).
The goal of this paper is to inventory (1) the various modes of flow
of a partially-molten continental crust in a context of lithospheric plate
convergence and (2) discuss the characteristics of melt/solid segregation via granitic melt migration, magma mobility and solid settling for
each mode. The first part of the paper is a synthesis of theoretical and
experimental data on the rheology and density of partially-molten
rocks and magmas. These constraints are compared to the geological
characteristics of migmatitic terranes and associated granites and
granulites which lead to a generic model integrating partial melting,
flow of the partially-molten crust, granitic melt segregation, migration
and emplacement, and solid settling within magmas.
2. Physical characteristics of partially-molten rocks and magmas
2.1. Structural characteristics of partially-molten rocks and magmas
The structure of partially-molten rocks and magmas composed of a
mixture between a solid and a silicate melt fraction is characterized by
two geometric thresholds (Fig. 1) (Maaløe, 1982). One geometric
threshold is related to the melt connectivity and is referred to as the
percolation threshold. The other geometric threshold relates to the
continuity of the solid framework and marks the solid/liquid
mechanical transition.
Melt connectivity allows for melt/solid segregation and for
migration of the melt beyond the grain scale. In the case of partial
melting of a rock under static conditions, melt connectivity is
controlled by the wetting angle at the solid/melt interface and is
achieved by the genesis of a network of tubules at the grain
boundaries for only a few percent of melt in the partially-molten
rock (Bulau et al., 1979; Waff and Bulau, 1979; Jurewicz and Watson,
1984; Jurewicz and Watson, 1985; von Bargen and Waff, 1986; Laporte,
1994). Under dynamical conditions, melt connectivity is achieved for
even lower melt percentage and the melt topology is not consistent
with one controlled by interfacial energy (Zimmerman et al., 1999;
Kohlstedt, 2002; Holtzman et al., 2003). In deformed migmatitic
rocks, the former melt fraction is identified by its mineral composition
and its texture forming small veins and pockets along grain
boundaries (Brown et al., 1999; Rosenberg and Riller, 2000; Sawyer,
2000; Marchildon and Brown, 2003). This distribution is similar to the
one obtained in experimental deformation of partially-molten
material taken as an analog to rocks (Rosenberg and Handy, 2001).
At the macroscopic scale, the distribution of leucosomes, taken as a
proxy for the former melt fraction (Sawyer, 1999), is linked to the
structure of the rock and forms veins and pockets that are localized in
pressure shadows around competent crystals or in boudin necks,
along foliation planes, shear zones or fold's axial planes (Hand and
Dirks, 1992; Brown, 1994; Brown and Rushmer, 1997; Sawyer et al.,
1999; Vanderhaeghe, 1999; Vanderhaeghe, 2001). These observations
are further supported by the results of experimental deformation of
analog material showing similar features (Barraud et al., 2004).
During crystallization of a partially-molten or magmatic rock, the last
melt forms a network of veins and pockets localized along the
boundaries of euhedral crystals or filling microfractures (Bouchez
et al., 1992; Sawyer, 2000).
The continuity of the solid framework marks the transition
between partially-molten rocks, characterized by a continuous solid
framework, to magmas formed by solids and/or crystals in suspension
in a melt (Wickham, 1987; Sawyer, 1994; Vigneresse et al., 1996;
Vanderhaeghe, 2001). The continuity of a solid framework is a
function of the proportion, distribution, relative sizes and shapes of
the minerals and solids in suspension (Fernandez et al., 1983; Stauffer,
Fig. 1. Geometric evolution of partially-molten rocks and magmas during partial melting and crystallization. a) The three dimensional geometry of melt pockets is indicated for
dihedral angles of θ b 60°, θ = 60°, θ N 60°. b) The geometric evolution of partially-molten rocks during partial melting goes through two geometric thresholds, the liquid connectivity
and the solid connectivity. In turn, during crystallization, a magma goes across the same geometric thresholds (gray and black = solid crystals, yellow = melt). (For interpretation of
the references to colour in this figure legend, the reader is referred to the web version of this article.)
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Fig. 2. Rheology of partially-molten rocks and magmas as a function of melt fraction.
The strength of solid and partially-molten rocks is synthesized from the results of
experimental deformation (Arzi, 1978; Van der Molen and Paterson, 1979; Paquet et al.,
1981; Rushmer, 1991; Rutter and Neumann, 1995). The apparent strength of magmas is
synthesized based on both the theoretical evolution of suspensions (Roscoe, 1952;
Shaw, 1972; Lejeune and Richet, 1995) and on the results of experimental deformation
of magmas (Lange, 1994; Dingwell et al., 1996; Scaillet et al., 1997; Champallier et al.,
2008). In order to compare the strength of solid rocks with the viscosity of partiallymolten rocks and magmas, apparent strengths are calculated for a strain rate of 10− 5 s− 1.
The transition from a solid rock to a partially-molten rock is marked by two orders of
magnitude strength drop. The transition from a partially-molten rock to a magma is
marked by ten orders of magnitude strength drop. Metatexites represent formerly
partially-molten rocks. Diatexites and granites correspond to former magmas. The
metatexite/diatexite transition marks the former transition from partially-molten rocks to
magmas.
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the result of grain boundary diffusion and granular flow favored by the
presence of melt at grain boundaries (Dell'Angelo et al., 1987;
Dell'Angelo and Tullis, 1988; Paterson, 2001; Rosenberg and Handy,
2005). For about 20 to 40% of melt, a catastrophic loss in the rock's
strength is observed (Arzi, 1978; Van der Molen and Paterson, 1979;
Paquet et al., 1981; Rutter and Neumann, 1995; Rushmer, 1996). This is
interpreted as representing the mechanical transition from a solid to a
liquid marked by the loss of the continuity of the solid framework. The
viscosity of silicate melts mildly increases with the amount of solids in
suspension up to a crystal fraction of about 50 to 60% marked by a drastic
increase in viscosity caused by crystal interactions impeding viscous
flow of the magma (Lejeune and Richet, 1995; Caricchi et al., 2007;
Champallier et al., 2008).
The classical representation of the strength evolution of partiallymolten rocks and magmas in a logarithmic scale (Arzi, 1978) puts the
emphasis on the strength decrease marking the transition between
partially-molten rocks and magmas (Rosenberg and Handy, 2005).
When considering the strength of the continental crust as a whole, the
two to three orders of magnitude strength drop at the onset of melting
is probably the most significant one. Indeed, at the partially-molten
rock/magma transition, the strength of the partially-molten rocks is
already so small compared to the one of solid rocks that another drop
of ten orders of magnitudes does not make a difference when
considering the bulk strength at the scale of the continental crust.
However, the catastrophic loss of strength between partially-molten
rocks with a continuous solid framework and magmas with solids in
suspension is significant at the scale of the partially-molten layer.
2.3. Density of partially-molten rocks and silicate melts
The density of typical continental rocks ranges from 2650 kg/m3 to
3100 kg/m3 (Turcotte and Schubert, 1982; Herzberg et al., 1983;
Rudnick and Fountain, 1995). The density of silicate melt of felsic
composition is lower than the one of the solid rock it comes from and
ranges from 2400 kg/m3 to 2700 kg/m3 (Huppert and Sparks, 1988;
Lister, 1989; Cruden et al., 1995). The density of the two-phase melt/
1985; Arbaret et al., 1996; Gray et al., 2003). Following the partial
melting path, this second geometric threshold is reached only in the
case of relative inefficient melt migration compared to melt production (Sawyer, 1994). The solid/melt proportion for which the
continuity of the solid framework is lost is thus a function of the
efficiency of melt migration and on the characteristics of its
redistribution in the partially-molten rock. On the other hand,
crystallization experiments under static conditions indicate that a
skeleton of crystals is achieved for a relatively low crystal fraction of
~ 40% (Lejeune and Richet, 1995; Philpotts et al., 1996, 1999). When
subjected to deformation, melt flow induces redistribution of the
solids in suspension and a continuous solid framework is only
completed for a larger crystal fraction (Arbaret et al., 2000).
2.2. Rheology of partially-molten rocks and magmas
The rheologic evolution of partially-molten rocks and magmas is a
function of the proportion and distribution of the melt fraction and is
linked to the two geometric thresholds (Fig. 2). At one end of the
spectrum, solid rocks display plastic to viscous-plastic behaviors
characterized by a strength that is typically a function of the strain
rate (Kohlstedt, 1995). At the other end of the spectrum, silicate melts
have a viscous behavior close to Newtonian at geologically relevant
strain rates (Shaw,1972; Webb and Dingwell,1990; Dingwell et al.,1993;
Dingwell, 1995; Scaillet et al., 1997, 1998). Experimental deformation of
partially-molten rocks shows a two to three orders of magnitude
decrease in strength of the partially-molten rock compared to the
strength of the initial solid rock for only a few percents of melt in the rock
(Van der Molen and Paterson,1979; Paquet et al.,1981; Dell'Angelo et al.,
1987; Rutter and Neumann, 1995; Rushmer, 1996). This is interpreted as
Fig. 3. Density of partially-molten rocks and magmas as a function of melt fraction
taking into account melt migration and solid settling. The density of solid rocks (stars)
varies between typical rocks of the continental crust, namely gneiss 2700 kg/m3 and
amphibolite 3000 kg/m3 (Turcotte and Schubert, 1982; Herzberg et al., 1983; Rudnick
and Fountain, 1995). The density of silicate granitic melt (black line with double arrow)
spans a large range from 2400 kg/m3 to 2700 kg/m3 (Huppert and Sparks, 1988; Lister,
1989; Cruden et al., 1995). The dark gray shading indicates the range for the density of
melt/solid two-phase system in case of a closed system. The light gray shading indicates
the range of melt fraction that corresponds to melt connectivity and solid continuity.
Melt connectivity allows for melt migration whereas breakdown of the solid framework
allows for solid settling (stars in white circles). The thick black arrows depict the
evolution of the density of the melt/solid system (i) in case of melt migration leading to
a residual partially-molten rock with an increased density, and (ii) in case of solid
settling leaving a magma with an increased buoyancy relative to the one of the partiallymolten rock.
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
solid system is bounded by these two values, but is also a function of
the efficiency of melt/solid segregation during partial melting as well
as during crystallization (Fig. 3). If the melt remains in situ, one
expects a gradual evolution of the density of the melt/solid system
between the density of the solid rock and the one of the totally molten
rock. In this case, the density of the melt/solid system for a given
chemical composition is solely controlled by the compressibility and
the thermal expansion which are functions of the melt fraction and of
the pressure and temperature (Bottinga et al., 1983; Lange, 1994;
Knoche et al., 1995). In contrast, evaluating the density of the melt/
solid two-phase system in case it is not closed during partial melting
and crystallization requires addressing the effect of melt/solid
segregation associated with melt migration on one hand and to
solid settling, on the other hand (Fig. 3). During partial melting,
migration of a felsic melt with a lower density than the solid it comes
from leaves a solid residuum with a higher density compared to the
solid protolith and to the partially-molten layer. On the other end of
the spectrum, settling of solids (enclaves, residuum and crystals)
results in a lower density magma, and thus increasing the buoyancy of
the magma relative to the partially-molten rock.
2.4. Flow modes of partially-molten rocks and magmas
The structural features of migmatitic terranes provide constraints on
the flow modes of the partially-molten rocks and magmas (Fig. 4). Of
particular interest are, (i) the degree of homogeneity of the finite strain
fabric that serves as a basis to distinguish turbulent and laminar flows, (ii)
the degree of symmetry of the rock fabric that allows distinguishing
between coaxial and non-coaxial flow regimes, and (iii) the orientation of
the boundaries of the deformation zone. The presence of a roughly planar
synmigmatitic foliation calls for homogeneous deformation according to
dominant laminar flow whereas complex folds indicate heterogeneous
deformation and suggest turbulent flow. Metatexites typically display a
rather planar synmigmatitic foliation indicating that partially-molten
rocks are dominated by laminar flow (Burg and Vanderhaeghe, 1993;
Vanderhaeghe et al., 1999b; Ledru et al., 2001; Solar and Brown, 2001a;
Slagstad et al., 2005). The orientation of the channel and the degree of
symmetry of the rock fabric, measured by the kinematic vorticity (Means
et al., 1980), are indicative of the forces and of the relative motion applied
on the channel walls. The forces applied to the boundaries of the
deforming zone encompass tectonic forces (basal traction and horizontal
compression) and the gravity force associated with lateral variations of
gravitational potential energy. Alternatively, considering a kinematic
approach, this structural analysis leads to the identification of the relative
motion along the sides of the deforming zone. The flow in three
dimensions is fully described by a triclinic deformation matrix (Jiang,
1999). However, such complexity is not required to describe the flow of
partially-molten rocks and magmas and some simplifications are
possible. Indeed, the flow regimes relevant to partially-molten rocks
and magmas break down to (i) channel flow in two dimensions with
channel walls ranging from vertical to horizontal, (ii) channel flow in
three dimensions with horizontal channel walls, and (iii) domal flow.
Channel flow defines the displacement of material particles within a
channel with parallel walls and includes turbulent and laminar flows.
Channel flow in two dimensions (plane strain) is bracketed between
two kinematic end-members, namely (i) pure shear (Poiseuille flow)
and (ii) simple shear (Couette flow) (Fig. 4) (Turcotte and Schubert,
1982). These two end-members are distinguished on the basis of the
degree of symmetry of the finite strain fabric. In the pure shear case, a
square at the initial state is deformed into a rectangle and the fabric
shows one axis and two planes of symmetry. In the simple shear case, a
square at the initial state is deformed into a rhombohedron and the
fabric displays only one axis of symmetry. The case of transpression
(Sanderson and Marchini, 1984) combining pure shear and simple shear
in a channel with vertical walls with a free upper surface and a fixed
bottom surface, has been particularly well studied (Tikoff and Teyssier,
Fig. 4. Mechanisms of melt segregation, melt migration, magma mobility and solid
segregation. Schematic representation of fracturing, percolation and diapirism
(gray = solid crystals, white = melt).
1994; Tikoff and Fossen, 1999). In the case of transpression, deformation
of the orogenic belt is assumed to be caused by horizontal compression.
Alternatively, one could consider that deformation of the orogenic belt
in a convergent setting is dominated by the basal traction force
associated with subduction. In this case, flow in the migmatites within
the channel would record simple shear and the channel walls would be
oriented parallel to the subduction plane (Fig. 4). Several end-members
are distinguished for nonplane strain flow in three dimensions. 3D flow
in a channel with horizontal walls is driven by the gravity force
associated with lateral variations of gravitational potential energy (Bird,
1991; Royden, 1996; Rey et al., 2001; Vanderhaeghe and Teyssier,
2001b). In the case of continental plateaux, gravity-driven flow
corresponds to redistribution of the accreted crust and does not imply
net thinning. This redistribution occurs potentially in three dimensions
(Royden et al., 1997; Vanderhaeghe and Teyssier, 2001b). The rheologic
properties of the crustal blocks surrounding the continental plateau
might influence the flow characteristics (Clark et al., 2005a). Zones of
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
convergent flow might be associated with crustal thickening, whereas
zones of divergent flow might be related to crustal thinning. Domal flow
characterized by a vertical axis of symmetry corresponds to another
end-member for nonplane strain 3D flow. In the case of laminar flow,
flow lines are parallel to the boundaries of the dome with a maximum
displacement in the center. Turbulent flow results in mushroom-shape
patterns of flow (Dixon, 1975; Jackson and Talbot, 1989).
2.5. Melt segregation and migration, magma mobility, and solid
segregation
The main driving forces for differential melt/solid motion in a
partially-molten rock or a magma are (i) the buoyancy of the melt;
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(ii) the pressure gradient arising from heterogeneous deformation of
the rock's solid framework and (iii) strain partitioning owing to the
rheologic contrast between the melt, the magma and the solid (Brown
et al., 1995; Weinberg, 1996; Vanderhaeghe, 2001). At the grain scale,
surface tension might also play a role in the force balance (Laporte,
1994; Parsons et al., 2008). Melt segregation describes the motion of
the melt relative to the solid at the grain scale, melt migration implies
motion of the melt beyond the grain scale and magma mobility refers
to the motion of the melt with solid particles in suspension relative to
the host solid or partially-molten rock (Sawyer, 1994; Vanderhaeghe,
2001). In turn, solid segregation describes the motion of solid particles
relative to the melt in a magma. The mechanisms allowing for melt
segregation and migration, and for magma mobility are percolation,
Fig. 5. Flow modes of partially-molten rocks and magmas. (a) The flow modes of a weak crustal layer caused by forces related to lithospheric plate convergence, namely the basal
traction force, Ft, the horizontal compression force, Fc, and the gravity force stemming out lateral variations of the gravitational potential energy. 1. Flow modes in an orogenic wedge
encompass 1a Couette flow (simple shear) and 1b Poiseuille flow (pure shear). 2. Flow mode associated with development of a continental plateau is caused by gravity-driven flow
responsible for lateral channel flow without net crustal thinning. 3. Flow mode associated with gravitational collapse corresponds to lateral flow with net crustal thinning.
(b) Channel flow encompassing Couette and Poiseuille flow modes. (c) Diapiric domal flow.
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
fracturing and diapirism (Brown et al., 1995; Weinberg, 1996;
Vanderhaeghe, 1999, 2001) (Fig. 5).
Percolation corresponds to the migration of an interconnected
melt fraction through a continuous solid framework (Stauffer, 1985).
In the most simple models, migration of the melt is associated with
homogeneous deformation of the solid matrix by compaction (Sleep,
1974; McKenzie, 1984; Scott and Stevenson, 1986; Stevenson, 1989;
Rabinowicz and Vigneresse, 2004). Experimental deformation of rock
containing a small percentage of melt shows that deformation of the
solid framework activates migration of the melt fraction from
contractional to dilatational sites (Holtzman et al., 2003; Zimmerman
and Kohlstedt, 2004). In this case, heterogeneous deformation of the
solid matrix creates pressure gradients providing an additional driving
force for melt segregation and migration (Robin, 1979; Van Der Molen,
1985a,b; Brown et al., 1995).
Fracturing implies an increase in the melt or magma pressure
beyond the yield strength of the rock causing rupture (Petford et al.,
1993; Rubin, 1993a). Indeed, in experimental deformation of partiallymolten rocks, melt migration is associated with fracturing caused by
melt pressure build-up in the closed-system conditions of the piston
(Van der Molen and Paterson, 1979; Paquet et al., 1981; Brown and
Rushmer, 1997). Such features are also reproduced in experimental
deformation using analog materials (Rosenberg and Handy, 2001;
Barraud et al., 2004).
Diapirism corresponds to the development of gravitational
instabilities in a multi-layer system with an inverted density gradient
owing to the buoyancy of the melt or magma (Biot and Odé, 1965;
Ramberg, 1981; Weinberg and Schmeling, 1992; Cruden et al., 1995). A
difference in density between the dome core and the mantling rocks
of 0.1 g/cm3 is sufficient to drive the instability (Fletcher, 1972). The
geometric characteristics of the diapirs are a function of the viscosity
contrast and relative thicknesses of the layers (Biot and Odé, 1965;
Fletcher, 1972; Dixon, 1975; Ramberg, 1981; Jackson and Talbot, 1989;
Cruden, 1990; Weinberg and Schmeling, 1992; Weinberg and
Podladchikov, 1994).
The segregation of solid particles in a magma occurs by settling
owing to their higher density (Shaw, 1965; Kerr and Lister, 1991;
Cruden et al., 1995) or by mutual interactions during flow of the
magma (Bagnold, 1954; Manley and Mason, 1954; Bagnold, 1956;
Mason and Bartok, 1957; Barriere, 1976; Jeffrey and Acrivos, 1976). The
efficiency of solid segregation by settling or interaction depends on
the melt and solid rheologies and on the shape aspect ratio of the solid
particles (Cruden et al., 1995; Arbaret et al., 1996, 2000). It is also a
function of the flow characteristics of the magma (Bagnold, 1956;
Fig. 6. Model for the evolution of the melt/solid two-phase system during partial melting addressing melt migration and solid settling. 1. Partial melting of a solid rock leads to a melt
phase trapped along rock-forming minerals. 2. Melt segregation at the grain-scale is permitted by melt connectivity between melt pockets and leads to the formation of granitic veins.
3a. Melt migration, allowed by melt connectivity beyond the grain-scale, leads to the formation of laccolithic leucogranites. 3b. In case of inefficient drainage of the partially-molten
rock, partial melting proceeds beyond the partially-molten rock/magma transition. 4. Solid settling in the magma is associated with the accumulation of refractory solids leaving a
more differentiated magma.
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Fernandez et al., 1983; Cruden et al., 1995; Arbaret et al., 2001;
Mancktelow et al., 2002). Active convection is more favorable for
maintaining solids in suspension than a static situation (Shaw, 1965;
Kerr and Lister, 1992; Cruden et al., 1995).
The relative efficiency of the various mechanisms of melt
segregation and magma mobility is a function of the rock rheology
and of the regional strain rate (Rubin, 1993b; Weinberg and
Podladchikov, 1994; Weinberg, 1996, 1999). The rheology of the
continental crust and the strain rate at which it is deformed is in turn
essentially controlled by its thermal evolution. Percolation as opposed
to fracturing is favored in case of low strain rate. Fracturing, quite the
opposite of diaprisim, occurs preferentially in case of large viscosity
contrasts between the melt or magma and its matrix (Rubin, 1993a;
Weinberg, 1996). A melt or magma with a low-viscosity is able to
migrate rapidly before cooling at the contact to its host rock (Clemens
and Mawer, 1992; Petford et al., 1993; Rubin, 1993a).
3. Flow of a partially-molten crust and melt/solid segregation
during orogenic evolution
3.1. Force balance and thermal evolution of orogenic belts in convergent
settings
Deformation of the continental crust in zones of lithospheric
convergence results from the interplay between (i) tectonic forces
applied to the boundaries of the system (horizontal compression and
basal traction), (ii) gravity forces derived from lateral variations of
crustal thicknesses (Artyushkov, 1973; England and McKenzie, 1982;
Molnar, 1988; Royden, 1996; Rey et al., 2001), and (iii) the buoyancy
forces related to burial of low-density rocks or to the genesis of
partially-molten rocks and magmas (Ramberg, 1981).
The thermal evolution of the orogenic belt in such a context is
controlled by the relative effects of (i) heat production related to
radioactive decay and deformation, (ii) heat advection associated with
plate motion and associated rock displacements, and (iii) heat
conduction (England and Thompson, 1984, 1986; Molnar and England,
1990; Henry et al., 1997; Huerta et al., 1998; Burg and Gerya, 2005).
Subduction results in downward advection of the relatively cold
lithospheric plate and causes the development of low geothermal
gradients at the contact between the converging plates (Toksöz et al.,
1971). If convergence is also accommodated by the development of an
orogenic belt concentrated in radioactive elements, the cooling effect
of subduction is counteracted by the production of heat by radioactive
decay (Goffé et al., 2003; Vanderhaeghe et al., 2003). The characteristic time delay between crustal accretion and the required temperature increase putting a significant amount of the accretionary belt
under partial melting conditions is on the order of tens of My (England
and Thompson, 1984; Henry et al., 1997; Huerta et al., 1998;
Vanderhaeghe et al., 2003). This delay might be shortened if the
mantle heat flux is increased in case of mantle delamination
(Houseman et al., 1981; Kay and Mahlburg Kay, 1993; Schott et al.,
2000; Morency and Doin, 2004; Lustrino, 2005), or if deformation of
the crustal belt releases significant heat (Molnar and England, 1990;
Burg and Gerya, 2005).
The geological record of migmatitic and granitic terranes suggests
that partial melting and magmatism are intimately linked to the
thermal–mechanical evolution of orogenic belts in a variety of tectonic
situations comprising crustal-scale orogenic wedges, continental
plateaux and collapsed orogens. Each of these situations can be
viewed as a specific mode for the behavior of the crust at convergent
boundaries. For each mode, (i) the flow characteristic of the partiallymolten layer and eventually of a magmatic layer, (ii) the mechanisms
of melt migration out of the partially-molten layer, and (iii) the
mechanisms of solid settling within the magmatic layer leading to an
accumulation layer are discussed. Development of an orogenic wedge,
a continental plateau and collapse could also correspond to distinct
125
stages depicting the thermal–mechanical evolution of the crust at
convergent plate boundaries. The parameters controlling the transitions between these stages are discussed considering the role of
partial melting and magmatism on one hand and the consequences in
terms of the genesis of migmatites, granites and granulites.
3.2. Migmatites, granites and granulites
A model for the genetic link between migmatites and granites is
proposed in Fig. 6. Partial melting of fertile lithologies at the grain
scale leads to the generation of small leucosome pockets at grain
boundaries. Partial melting beyond the first percolation threshold
corresponds to melt connectivity and allows melt migration beyond
the grain scale to form leucosomes. The connectivity of leucosomes to
form a network of granitic dikes and sills leads to melt migration out
of the partially-molten zone to form intrusive laccoliths of leucogranites. These granites are characterized by a homogeneous texture
and have composition likely close to the eutectic or peritectic ones. If
partial melting proceeds and melt migration is not efficient to drain
the partially-molten zone, then the accumulation of melt leads to the
transition from partially-molten rocks to magmas marked by the loss
of the continuity of the solid framework allowing solid settling.
Four crustal zones are defined with reference to the efficiency of
the processes of melt/solid segregation via melt migration, magma
mobility and solid settling, namely from top to bottom, (i) the
intrusive zone characterized by the emplacement of laccoliths of
homogeneous leucogranite, (ii) the partially-molten zone responsible
for the formation of metatexites, (iii) the magmatic zone corresponding to the genesis of diatexites and heterogeneous granites, and (iv)
the accumulation zone characterized by a more refractory composition and granulite-facies metamorphism.
3.3. Orogenic wedge formation
In the case of sufficient increase in temperature, the orogenic belt
is affected by partial melting (Fig. 7a). Migmatites and granites
extruded in the axial zone of relatively narrow orogenic belts are
exemplified by the northern Appalachians (Brown and Solar, 1998;
Solar and Brown, 2001b), the Variscan South Armorican (Berthé et al.,
1979; Vigneresse and Brun, 1983; D'Lemos et al., 1992) and Bohemian
massifs (Racek et al., 2006; Tajcmanova et al., 2006; Schulmann et al.,
2008). These terranes are characterized regionally by a steep foliation
developed under greenschist to amphibolite facies metamorphism
(Schulmann et al., 1994; Solar and Brown, 2001a). These migmatites
are characterized by a steeply-dipping synmigmatitic foliation in
metatexites and by elongated domes cored by diatexites (Solar et al.,
1998; Solar and Brown, 2001a). Melt migration at depth within the
partially-molten layer, is likely to occur by melt percolation aided by
heterogeneous rock deformation, whereas at higher structural level, in
the intrusion zone, fracturing is the most probable mechanism.
Crustal-scale vertical shear zones control the development of a
network of granitic dikes feeding laccoliths of leucogranites emplaced
within mylonitic zones at the amphibolite/greenschist facies transition that could represent a fossil brittle/ductile transition (Vigneresse,
1995; Brown and Solar, 1998; Solar et al., 1998; Zak et al., 2005). The
predominance of metatexites corroborates the efficiency of melt
segregation and migration in such context. Indeed, in this mode, both
convergence-related forces and buoyancy of the melt act in concert to
favor melt segregation within the steeply-dipping synmigmatitic
foliation planes and upward melt migration along these structural
pathways.
In the northern Appalachians, U–Pb geochronology on zircon
suggests that the emplacement of leucogranites did not span more
than 5 My (Solar et al., 1998) and thus implies that the orogenic crust
did not remain partially molten for a long time period. Geochemical
signatures of the granites, of the metapelites and of the migmatites
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Fig. 7. Model for the impact of melt segregation and migration, magma mobility, and solid segregation on crustal differentiation during the tectonic evolution of orogenic belts. The
inset provides a legend and illustrates the four different zones associated with partial melting and magmatism in the orogenic crust. The three block diagrams depict each a particular
scenario for the behavior of the continental crust and associated partial melting and magmatism. Under favorable circumstances, these modes correspond to successive stages of the
thermal–mechanical evolution of a model orogenic belt, encompassing the formation of (a) an orogenic wedge (t1), (b) the development of a continental plateau (t2), and
(c) gravitational collapse of the orogenic belt (t3). Major structural features, thrusts (black lines) and foliations (dashed black lines) and the 400 °C and 750 °C isotherms are shown
for each stage.
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
suggest that partial melting of fertile metapelites is the main source
for the genesis of the migmatites and the granitic magmas (Brown and
Pressley, 1999; Solar and Brown, 2001b). In addition of being fertile
these metapelites are typically enriched in radioactive elements
providing a significant heat source for metamorphism and partial
melting (Vigneresse et al., 1987; Chamberlain and Sonder, 1990;
Vigneresse, 1990; Solar and Brown, 2001b).
In these examples, the genesis of migmatites is synchronous to
horizontal shortening and transpression in response to plate convergence (Schulmann et al., 1994; Solar and Brown, 2001a). The
formation of these crustal segments results from the tectonic
accretion of terranes dominated by clastic sedimentary rocks between
older continental blocks (Thompson et al., 1997, 2001; Schulmann
et al., 2003). Partitioning of convergence-related strain in the weak
sedimentary sequence leads to localized thickening and to the
formation of a orogenic belt dominated by metapelites both, fertile
(Vielzeuf and Holloway, 1988) and highly radiogenic (Chamberlain
and Sonder, 1990). The temperature increase in such context is
potentially associated with the combined effects of heat produced by
deformation and by radioactive decay leading to partial melting which
further weakens the accretionary belt (Brown and Solar, 1998; Solar
and Brown, 2001a; Thompson et al., 2001; Schulmann et al., 2003). In
such contexts, exhumation is likely controlled by erosion but lateral
sliding of upper crustal-scale slices might also contribute as is
proposed for the Montagne Noire (Aerden and Malavieille, 1999). A
steady-state situation is reached if exhumation by erosion or tectonic
denudation balances the influx of material related to convergence in
which case exhumation of migmatites and granites is expected at a
constant rate.
3.4. Continental plateau development
Migmatites and granites exhumed at the front of continental
plateaux (Fig. 7b) are exemplified by the southern edge of the Tibetan
plateau (Le Fort et al., 1987; Burchfiel et al., 1992; Hodges et al., 1992;
Grujic et al., 1996; Weinberg and Searle, 1998). Past analog of this
situation might be illustrated by the Grenvillian Province (Sawyer,
1991; Timmermann et al., 2002; Slagstad et al., 2004), and the
Western Superior Province (Culshaw et al., 2006).
Key features of this end-member case are illustrated by the
Himalaya–Tibet example. The High Himalayan Crystalline (HHC) is
dominantly composed by metatexites with a shallow-dipping synmigmatitic foliation (Burg et al., 1983, 1984b; Brunel, 1986; Pêcher,
1989; Barbey et al., 1995, 1996; Weinberg and Searle, 1998). The HHC is
delimited by the Main Central Thrust (MCT) at its base (Brun et al.,
1985; Brunel, 1986) and the South Tibetan Detachment (STD) at its
top (Burchfiel et al., 1992; Hodges et al., 1992). Kinematical and
metamorphic studies of the HHC are consistent with its ductile
extrusion between these two major tectonic contacts (Hodges et al.,
1993; Grujic et al., 1996, 2002; Robyr et al., 2006). Granites form
laccolithic plutons emplaced within the STD at the contact between
the HHC and the overlying deformed Tethyan sedimentary sequences
(Burg et al., 1984a; Le Fort et al., 1987; Harris and Massey, 1994; Guillot
et al., 1995; Scaillet et al., 1995; Searle et al., 1997; Searle, 1999). The
HHC is pervasively intruded by a network of granitic dikes that are
oblique to the synmigmatitic foliation and feed the leucogranitic
plutons (Weinberg and Searle, 1998). The petrological and geochemical characteristics of the granites and the migmatites of the HHC also
suggest that these rocks are genetically linked (Le Fort et al., 1987;
France-Lanord and Le Fort, 1988; Harris and Massey, 1994; Barbey
et al., 1995; Guillot and Le Fort, 1995; Harrison et al., 1999). The
melting reactions are consistent for melt generation by isobaric
heating (Visonà and Lombardo, 2002). To the North of the STD,
migmatites and granites are also exhumed in domal structures aligned
along the North Himalayan antiform (Burg et al., 1984b; Chen et al.,
1990; Guillot et al., 1998; Rolland et al., 2001; Mahéo et al., 2002; Lee
127
et al., 2004). The predominance of metatexites suggests that the
partially-molten rock/magma transition was not reached either
because of insufficient melting or owing to efficient melt migration
to feed the large Himalayan leucogranites. In contrast, domes cored by
diatexites are present at the rear of the plateau margin within an
antiformal structure trending parallel to the himalayan belt (Chen
et al., 1990; Guillot et al., 1998; Lee et al., 2000; Rolland et al., 2001;
Mahéo et al., 2002). The antiformal structure might respond to
localized exhumation and isostatic rebound of the lower strength
underlying rocks as proposed by some authors (Burg et al., 1997;
Beaumont et al., 2001). In contrast, the fact that domes are cored by
diatexites favors an origin by the development of gravitational
instabilities driven by the buoyancy of the magmas. The contrasting
characteristics of migmatites exhumed along the edge of and within
the Tibetan plateau might indicate that partial melting beyond the
partially-molten rock/magma transition requires relatively rapid
decompression triggered either by focused erosion or by crustal
extension (Teyssier and Whitney, 2002). Geochronology indicates late
Oligocene–early Miocene ages for the granites emplaced to the South
of the STD whereas granites exhumed in the North Himalayan
antiform are dated in the late Miocene (Scharer et al., 1986; Maluski
et al., 1988; Coleman, 1998; Schneider et al., 1999; Walker et al., 1999).
Bright spots, high electric conductivity and low-velocity below 10 to
15 km underneath Tibet are consistent with the presence of silicate
melts (Nelson et al., 1996; Gaillard et al., 2004). These data suggest
that a partially-molten layer is progressively extruded by large-scale
horizontal lateral flow and exhumed to the edges of the Tibetan
plateau since at least the last 20 My (Beaumont et al., 2001;
Vanderhaeghe and Teyssier, 2001b).
The transition from vertical to lateral extrusion corresponds to the
transition from the development and growth of a wedge-shaped
orogenic belt to the development and growth of a continental plateau.
This transition occurs when the weak partially-molten zone generated
by thermal maturation of the orogenic belt reaches a critical volume
(Vanderhaeghe et al., 2003). Flow of partially-molten rocks corresponds
to lateral channel flow. This flow eventually leads to exhumation of
migmatites and granites by extrusion along the edges of large
continental plateaux such as is currently the case along the southern
edge of the Tibet plateau. In this case, lateral channel flow is driven by
the gravity force that arises from lateral variations in crustal thickness
(Artyushkov, 1973; Molnar, 1988; Royden, 1996; Rey et al., 2001). The
partially-molten crust partitions this gravity-driven horizontal flow
owing to its low-viscosity in contrast with the upper part of the crust
which transmits convergence-related forces (Vanderhaeghe and
Teyssier, 2001b; Vanderhaeghe et al., 2003). Localized exhumation at
the edges of the plateau might be caused by local uplift and erosion
(Beaumont et al., 2001) in response to dynamic pressure developed at
the boundary of the flowing partially-molten layer as suggested by
numerical models (Clark et al., 2004, 2005b). The distribution and
textural characteristics of granitic veins indicate that at deep structural
level, melt migration proceeds by percolation aided by heterogeneous
deformation of the partially-molten rocks. At higher structural levels,
granitic dike and sill networks feeding laccoliths of leucogranites attest
to the efficiency of melt buoyancy to drive melt migration. Indeed, in
the case of lateral flow of a partially-molten crust and development of
continental plateau, upward melt migration and magma mobility
probably indicate that buoyancy alone is sufficient as a driving force.
Indeed, if melt migration was solely controlled by pressure gradients
owing to heterogeneous deformation, in the continental plateau mode,
lateral flow should predominantly lead to lateral melt migration.
3.5. Orogenic gravitational collapse
Migmatites and granites are exhumed in the axial zone of
gravitationally collapsed orogenic belts (Fig. 7c) as proposed for the
Paleozoic Caledonian belt in Norway (Chauvet et al., 1992; Andersen et
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al., 1994), Variscan belt of western Europe (Doblas, 1991; Rey et al.,
1991–1992; Van Den Driessche and Brun, 1992; Vissers, 1992; Burg
and Vanderhaeghe, 1993; Burg et al., 1994; Gardien et al., 1997;
Lardeaux et al., 2001; Ledru et al., 2001), the Mesozoic North
American Cordillera (Coney and Harms, 1984; Amato et al., 1994;
Foster and Fanning, 1997; Vanderhaeghe and Teyssier, 1997; Vanderhaeghe et al., 1999b; Liu, 2001), and part of the Cenozoic alpine belt
(Dinter and Royden, 1993; Sokoutis et al., 1993; Gautier and Brun,
1994; Vanderhaeghe, 2004; Duchêne et al., 2006).
In these examples, migmatites and granites are exhumed and
juxtaposed with upper crustal units along low-angle detachment
zones (Vanderhaeghe et al., 1999a). The synmigmatitic foliation of
metatexites is dominantly shallow-dipping but also describes kilometer-scale domal structures cored by diatexites (Burg and Vanderhaeghe, 1993; Lagarde et al., 1994; Vanderhaeghe et al., 1999b; Ledru
et al., 2001; Vanderhaeghe, 2004; Whitney et al., 2004). Granites form
laccolithic plutons emplaced below the low-angle detachment zones
(Lister and Baldwin, 1993; Foster and Fanning, 1997; Vanderhaeghe et
al., 1999b; Teyssier et al., 2005). The diatexites and the granitic
laccoliths are structurally connected by a network of granitic dikes and
sills that intrude the metatexites (Vanderhaeghe, 1999; Vanderhaeghe
et al., 1999a). The petrologic and geochemical signatures of the
leucogranites are consistent with an origin, at least in part, by partial
melting of the dominantly metapelitic protolith of the metatexites
(Downes and Leyreloup, 1986; Downes et al., 1990; Williamson et al.,
1992; Gardien et al., 1997; Enkelmann et al., 2006). The ages of
intrusive leucogranites span more than 10 My in the Canadian
Cordillera (Parrish et al., 1988; Carr, 1991, 1992; Parrish, 1995;
Vanderhaeghe et al., 1999b; Gordon et al., 2008; Kruckenberg et al.,
2008) and more than 30 My in the French Massif Central (Duthou et
al., 1984; Mougeot et al., 1997), part of the Variscan belt of western
Europe. In both cases, the ages obtained from migmatites are similar
to the younger ages obtained from leucogranites. These data suggest
that in these examples, the orogenic crust remained partially molten
for at least 10 My, feeding granites emplaced at higher structural level
and that this partially-molten layer flowed horizontally and vertically
before eventually crystallizing during gravitational collapse of the
orogenic crust.
The exhumation of migmatites and granites in the axial zone of
large orogenic belt is attributed to gravitational collapse caused by a
modification of the lithospheric-scale force balance related to (i) a
change in lithospheric plate kinematics or (ii) a change in lithospheric-scale mass distribution (Houseman et al., 1981; Molnar et al.,
1993; Rey et al., 2001). The style of deformation accommodating
gravitational collapse of orogenic belts is strongly controlled by the
rheological layering of the crust at the onset of collapse (Buck, 1991;
Rey et al., 2001). In particular, the presence of a partially-molten layer
and the emplacement of granitic laccoliths at the brittle/ductile
transition favor strain partitioning owing to the induced rheologic
contrasts between solid rocks, partially-molten rocks and magmas
(Vanderhaeghe and Teyssier, 2001a).
Shallow-dipping synmigmatitic foliation of exhumed metatexites
indicates that flow of the partially-molten layer corresponds to
horizontal channel flow. In this context, flow of the partially-molten
layer responds dominantly to the gravity force associated with lateral
variations of crustal thickness applied along its horizontal boundaries.
In contrast to the gravity-driven flow associated with the growth of a
continental plateau, during gravitational orogenic collapse, horizontal
flow results in crustal net thinning. Migmatitic terrains exposed in the
axial zone of collapsed orogenic belts typically consist in both
metatexites and diatexites. This attests for the accumulation of the
melt fraction beyond the partially-molten rock/magma transition and
thus for relatively inefficient melt segregation within the partiallymolten rock and melt migration out of the source region. The gravity
force that arises from lateral variations of crustal thickness favors melt
segregation in shallow-dipping synmigmatitic foliation planes that
might in turn constitute mechanical barriers impeding upward
buoyancy-driven flow of the melt and magma (Van Der Molen,
1985a,b). However, the development of diapirs from centimeter-scale
cauliflower structures to kilometer-scale domes cored by diatexites
and the formation of leucogranitic laccolithic plutons indicate that
upward melt migration and magma mobility are possible in such
context despite the relatively unfavorable mechanical conditions
(Burg and Vanderhaeghe, 1993). In the case of gravitational collapse,
upward melt migration and magma mobility could be driven by both,
buoyancy forces and pressure gradients induced by localized
horizontal extension. The efficiency of upward melt migration is
further evidenced by the presence of laccolithic leucogranites
emplaced along mylonitic zones interpreted as corresponding to the
brittle–ductile transition (Vigneresse, 1995; Vanderhaeghe, 1999;
Vanderhaeghe et al., 1999b).
3.6. Migmatite domes
Domal structures typical of Precambrian granite-greenstone belts
and also of migmatitic gneissic terranes (see review in Whitney et al.,
2004) have been interpreted either as resulting from (i) fold
interferences (Myers and Watkins, 1985; Brown et al., 1992; Yin,
2004), (ii) 3D deformation in transpressional to transtensional
kinematic regimes (Yin, 2004), or (iii) diapirs reflecting the development of gravitational instabilities (Ramberg, 1980, 1981). In this paper,
I discuss only domes cored by diatexites and mantled by metatexites
and displaying structural characteristics indicative of flow under
magmatic or partially-molten state. Migmatite domes are cored by
diatexites surrounded by metatexites (Burg and Vanderhaeghe, 1993;
Amato et al., 1994; Vanderhaeghe and Teyssier, 1997; Vanderhaeghe et
al., 1999b; Ledru et al., 2001). Synmigmatitic foliations of migmatites
underlined by leucosome/melanosome/mesososome alternations and
by the preferred orientation of enclaves attest to flow of the partiallymolten rocks and magmas. Domes are defined by the concentric
pattern of foliation trajectories and down-dip mineral lineations
(Brun et al., 1981; Ramsay, 1989). The concentric pattern is
particularly well expressed by the attitude of the synmigmatitic
foliation of metatexites in contrast with the internal structure of
diatexites that tends to be more heterogeneous (Hippertt, 1994;
Vanderhaeghe et al., 1999b; Vanderhaeghe, 2004). In contrast, the
down-dip attitude of mineral lineation is better expressed in
diatexites compared to metatexites (Vanderhaeghe et al., 1999b;
Ledru et al., 2001; Vanderhaeghe, 2004). Additional structural
characteristics of migmatite domes encompass cascading folds and
shear zones, most pronounced in the metatexites consistent with the
upward motion of the dome's core (Vanderhaeghe et al., 1999b;
Kruckenberg et al., 2008). Domes are typically not isolated but are part
of a multiple domes and basins structure as exemplified in the
Shuswap Metamorphic Core Complex within the Canadian Cordillera
(Vanderhaeghe et al., 1999b). In turn, within the migmatite core,
foliation trajectories typically outline second-order domes such as the
Thor–Odin dome in the Canadian Cordillera (Vanderhaeghe et al.,
1999b), the Naxos dome in the Aegean domain (Vanderhaeghe, 2004),
and the Velay dome in the French Massif Central (Lagarde et al., 1994;
Ledru et al., 2001). Triple points in between domes and subdomes are
marked by plunging stretching and mineral lineations and by prolate
finite strain ellipsoids. These structural characteristics are interpreted
as resulting from the development of diapirs (Schwerdtner et al.,
1978; Ramberg, 1980; Brun et al., 1981; Burg and Vanderhaeghe, 1993;
Vanderhaeghe, 2004) as they are similar to the ones obtained in
analog experiments of diapiric gravitational instabilities (Dixon, 1975;
Ramberg, 1981; Jackson and Talbot, 1989; Cruden, 1990).
According to the physical characteristics discussed in the density
and rheology sections, gravitational instabilities are most prone to
develop at the transition between the partially-molten and magmatic
zones. Indeed, it corresponds to the maximum potential density
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O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
difference owing to the combined effects of melt migration out of the
partially-molten zone and to solid settling within the magmatic zone.
The low strength of partially-molten rocks and the viscous behavior of
magmatic rocks are also favorable for the development of diapirs.
These gravitational instabilities are likely to be confined to the
partially-molten layer as the overlying solid rocks are potentially
stronger and less dense than the residual partially-molten rocks.
Natural migmatite domes differ from the model by their typical
elliptical instead of rounded shapes and in the distribution of lineation
and finite strain ellipsoids (Whitney et al., 2004). Accordingly, the
structural complexity of natural migmatite domes suggests they are
not solely the result of the development of gravitational instabilities.
Second-order domes have been interpreted as representing multiple
intrusions (Bouchez and Diot, 1990) or as recording convection within
the magmatic bodies (Talbot, 1979; Weinberg, 1997). The latter
proposition is also supported by the rather heterogeneous structural
record of diatexites (Ledru et al., 2001; Vanderhaeghe, 2004; Whitney
et al., 2004) consistent with turbulent flow. At the regional scale,
partial melting of the crust is likely to occur in active geodynamic
settings under the control of plate-tectonic derived forces that are
probably dominating large-scale flow of partially-molten rocks.
Furthermore, the structural relationships between domes and folds
on one hand, and between domes and detachment shear zones on the
other hand, suggest that diapir nucleation is associated with the
development of mechanical instabilities such as folds, boudins or
shear zones (Vanderhaeghe et al., 1999b; Yin, 2004). Note that in cross
section, domes and antiforms might be confused, but it is nevertheless
important to distinguish structures which formation is driven by
volume forces (domes) from structures which formation is induced by
surface forces (channel flows). In particular, the antiforms that form as
a result of isostatic rebound of the footwall of an extensional
detachment are often confused with domes. The driving force for
antiform formation in this case is the lower strength of the lower
structural level whereas in the case of domal structures, the driving
force for upward motion of the magmas coring the domes is, at least in
part, their buoyancy.
3.7. Residual lower crust
The lower crust associated with migmatitic middle crust is only
exposed in a few examples (Fountain and Salisbury, 1981; Dewey,
1986; Rudnick and Fountain, 1995). One of the best examples is the
Variscan lower crust exposed in the western Alps (Fountain, 1976;
Schenk, 1981; Pin and Sills, 1986; Brodie et al., 1989; Zingg et al., 1990;
Henk et al., 1997; Hermann et al., 1997; Barboza et al., 1999; Handy et
al., 1999) and in Calabria (Schenk, 1984; Caggianelli et al., 1991) owing
to overthrusting during the Alpine orogeny. Samples of the Variscan
lower crust are also brought back to the surface as xenoliths in
Cenozoic lavas in the French Massif Central (Leyreloup et al., 1977;
Downes et al., 1990; Costa and Rey, 1995). In these examples, the lower
crust is composed by alternating mafic and felsic gneisses affected by
granulite-facies metamorphism (T ~1000 °C; P ~10 kbar) coeval with
the development of a composite foliation. U/Pb dating of zircon from
these rocks indicates that granulite-facies metamorphism is roughly
synchronous to slightly younger than the amphibolite facies metamorphism associated with pervasive partial melting of the middle
crust (Hunziker and Zingg, 1980; Schnetger, 1994; Costa and Rey,
1995; Vavra et al., 1996; Boriani and Villa, 1997; Lu et al., 1997;
Müntener et al., 2000; Rossi et al., 2006). These data suggest that part
of the Variscan lower crust of western Europe corresponds to
magmatic rocks with a mantle origin and another part corresponds
to the residue left after melt extraction (Sills and Tarney, 1984; Pin and
Sills, 1986; Pin and Duthou, 1990; Vielzeuf et al., 1990; Vigneresse,
1990; Zingg et al., 1990; Henk et al., 1997; Barboza et al., 1999; Handy
et al., 1999). Two scenarios are possible to explain the residual nature
of the lower crust, namely (i) that it corresponds to the solid left after
129
melt extraction from a partially-molten layer, or (ii) that it formed by
accumulation of residuum solids by settling within a dominantly
magmatic layer. According to the arguments developed above, I favor
the second option. Despite the fact that natural examples represent
dominantly lower crust formed during orogenic gravitational collapse,
the reasoning provided in this context should also hold for the other
two modes and the development of a residuum accumulation layer is
expected during the evolution of partially-molten orogenic wedge and
the development of a continental plateau.
4. Conclusion
The structural and metamorphic record of migmatitic and granitic
terranes indicate that the thermal–mechanical evolution of the
related orogenic belts is associated with pervasive partial melting
and magmatism. Orogenic crust affected by partial melting is typically
characterized by a crustal-scale layering with from bottom to top:
- granulite-facies refractory lower crust,
- amphibolite-facies migmatites with foliations ranging from vertical to horizontal and delineating domes cored by diatexites and
mantled by metatexites,
- laccoliths of leucogranites structurally connected to migmatites by
a network of granitic dikes and sills.
Accordingly, two types of granites are distinguished, namely, (i)
laccoliths of leucogranites formed by melt migration out of the
partially-molten zone and emplaced in a higher structural level, and
(ii) diatexites that correspond to heterogeneous granites and formed
as a consequence of melt accumulation within the partially-molten
zone and of solid settling within the magma.
This crustal-scale compositional layering results from the combined effects of partial melting, melt migration and solid settling
during the evolution of the orogenic belt. Indeed, density and viscosity
contrasts between the silicate melt and the solid rock favour both
strain partitioning and melt/solid segregation. The onset of partial
melting, associated with a strength drop of two to three orders of
magnitude, leads to strain partitioning between solid and partiallymolten rocks. This is expressed by channel flow driven by forces
related to plate tectonics (vertical channel flow) or related to the
gravity force associated with lateral variations in crustal thicknesses
(horizontal channel flow).
Another decrease in apparent strength of about ten orders of
magnitudes is associated with the transition between partiallymolten rocks and magmas. The breakdown of the solid framework
allows settling of denser residuum solids in suspension in the magma
which causes a decrease in the density of the remaining magma. The
relative buoyancy of the magma compared to the partially-molten
rocks is further increased by melt migration out of partially-molten
rocks leaving a denser residue. Solid settling within the magmatic
layer leads to the formation of a refractory lower crust by accumulation of residuum solids. Domes cored by diatexites are thus caused, at
least in part, by the development of gravitational instabilities owing to
the relative buoyancy of the viscous magmatic and allowed by the
limited strength of viscous-plastic partially-molten rocks.
Bulk flow of partially-molten rocks and magmas is associated with
melt/solid segregation owing to melt migration and solid settling
controlled in part by deformation but which leads, irrespectively of
the geodynamic context, to the emplacement of laccoliths of
leucogranites at the brittle/ductile transition and to the development
of a refractory lower crust suggesting that buoyancy contrast
dominates these processes.
Acknowledgments
This paper stems out animated discussions with colleagues
including Patrick Ledru, Jean-Pierre Burg, Patrice Rey, Christian
Author's personal copy
130
O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Teyssier, Jean-François Moyen, Véronique Gardien, Fabien Solgadi,
Edward Sawyer, Seth Kruckenberg, Pierre Barbey and Stéphanie
Duchêne to quote only a few. I hope that they will share some of the
concepts that are presented here. This research has been supported by
funds from the CNRS, the BRGM (France) and NSF (USA). The first
version of the manuscript has benefited from acute reviews by Claudio
Rosenberg and Gary Solar.
References
Aerden, D.G.A.M., Malavieille, J., 1999. Origin of a large-scale fold nappe in the Montagne
Noire, Variscan belt, France. Journal of Structural Geology 21 (10), 1321–1333.
Alsdorf, D., Nelson, K.D., 1999. Tibetan satellite magnetic low: evidence for widespread
melt in the Tibetan crust? Geology 27, 943–946.
Amato, J.M., Wright, J.E., Gans, P.B., Miller, E.L., 1994. Magmatically induced
metamorphism and deformation in the Kigluaik gneiss dome, Seward peninsula,
Alaska. Tectonics 13, 515–527.
Andersen, T.B., Osmundsen, P.T., Jolivet, L., 1994. Deep crustal fabrics and a model for the
extensional collapse of the southwest Norwegian Caledonides. Journal of Structural
Geology 16 (9), 1191–1203.
Arbaret, L., Diot, H., Bouchez, J.-L., 1996. Shape fabrics of particles in low concentration
suspensions: 2D analogue experiments and application to tiling in magma. Journal
of Structural Geology 18 (7), 941–950.
Arbaret, L., et al., 2000. Analogue and numerical modelling of shape fabrics: application
to strain and flow determination in magmas. Transactions of the Royal Society of
Edinburgh. Earth Sciences 91 (1–2), 97–109.
Arbaret, L., Mancktelow, N.S., Burg, J.P., 2001. Shape-preferred orientation and matrix
interaction of threedimensional particles in analogue simple shear flow. Journal of
Structural Geology 23, 113–125.
Artyushkov, E.V., 1973. Stresses in the lithosphere caused by crustal thickness
inhomogeneities. Journal of Geophysical Research 78, 7675–7708.
Arzi, A.A., 1978. Critical phenomena in the rheology of partially melted rocks.
Tectonophysics 44, 173–184.
Bagnold, R.A., 1954. Experiments on a gravity-free dispersion of large solid spheres in a
newtonian fluid under shear. Proceedings of the Royal Society of London. Series A
255, 49–63.
Bagnold, R.A., 1956. The flow of cohesionless grains in fluids. Philosophical Transactions.
Royal Society of London 249, 235–297.
Barbey, P., Allé, P., Brouand, M., Albarede, F., 1995. Rare-earth patterns in zircons from
the Manaslu Granite and Tibetan slab migmatites (Himalaya); insights in the origin
and evolution of a crustally-derived granite magma. Chemical Geology 125 (1–2),
1–17.
Barbey, P., Brouand, M., Le Fort, P., Pêcher, A., 1996. Granite–migmatite genetic link: the
example of the Manaslu granite and Tibetan Slab migmatites in central Nepal.
Lithos 38, 63–79.
Barboza, S.A., Bergantz, G.W., Brown, M., 1999. Regional granulite facies metamorphism
in the Ivrea zone: is the Mafic Complex the smoking gun or a red herring? Geology
27 (5), 447–450.
Barraud, J., Gardien, V., Allemand, P., Grandjean, P., 2004. Analogue models of melt-flow
networks in folding migmatites. Journal of Structural Geology 26, 307–324.
Barriere, M., 1976. Flowage differentiation: limitation of the “Bagnold effect” to the
narrow intrusions. Contributions to Mineralogy and Petrology 55, 139–145.
Beaumont, C., Jamieson, R.A., Nguyen, M.H., Lee, B., 2001. Himalayan tectonics explained
by extrusion of a low-viscosity crustal channel coupled to focused surface
denudation. Nature 414 (6865), 738–742.
Berthé, D., Choukroune, P., Jégouzo, P., 1979. Orthogneiss, mylonite and non coaxial
deformation of granites: the example of the South Armorican Shear Zone. Journal of
Structural Geology 1 (1), 31–42.
Biot, M.A., Odé, H., 1965. Theory of gravity instability with variable overburden and
compaction. Geophysics 30, 213–227.
Bird, P., 1991. Lateral extrusion of lower crust from under high topography, in the
isostatic limit. Journal of Geophysical Research 96 (B6), 10,275–10,286.
Boriani, A.C., Villa, I.M., 1997. Geochronology of regional metamorphism in the Ivrea–
Verbano Zone and Serie dei Laghi, Italian Alps. Schweizerische Mineralogische und
Petrographische Mitteilungen 77 (3), 381–401.
Bottinga, Y., Richet, P., Weill, D.F., 1983. Calculation of the density and thermal expansion
coefficient of silicate liquids. Bulletin de Minéralogie 106, 129–138.
Bouchez, J.L., Diot, H., 1990. Nested granites in question: contrasted emplacement
kinematics of independent magmas in the Zaër pluton, Morocco. Geology 18,
966–969.
Bouchez, J.-L., Delas, C., Gleizes, G., Nédélec, A., Cuney, M., 1992. Submagmatic
microfractures in granites. Geology 20, 35–38.
Brodie, K.H., Rex, D., Rutter, E.H. (Eds.), 1989. On the age of deep crutal extension
faulting in the Ivrea zone, Northern Italy: Alpine Tectonics, vol. 45. 203–210 pp.
Brown, M., 1973. The definition of metatexis, diatexis and migmatite. Proceedings of the
Geological Association 84, 371–382.
Brown, M., 1993. P–T–t evolution of orogenic belts and the causes of regional
metamorphism. Journal of the Geological Society of London 150, 227–241.
Brown, M., 1994. The generation, segregation, ascent and emplacement of granite
magma: the migmatite-to-crustally-derived granite connection in thickened
orogens. Earth Science Reviews 36, 83–130.
Brown, M., 2001. Orogeny, migmatites and leucogranites: a review. Proceedings of the
Indian Academy of Sciences. A Earth and Planetary Sciences 110 (4), 313–336.
Brown, M., Pressley, R.A., 1999. Crustal melting in nature: prosecuting source processes.
Physics and Chemistry of the Earth. Part A: Solid Earth and Geodesy 24 (3),
305–316.
Brown, M., Rushmer, T., 1997. The role of deformation in the movement of granitic melt:
views from the laboratory and the field. In: Holness, M.B. (Ed.), Deformationenhanced fluid transport in the Earth's crust and mantle. The Mineralogical Series.
Chapman & Hall, pp. 111–144.
Brown, M., Solar, G.S., 1998. Granite ascent and emplacement during contractional
deformation in convergent orogens. Journal of Structural Geology 20 (9–10),1365–1393.
Brown, R.L., et al., 1992. The Monashee décollement of the southern Canadian
Cordillera: a crustal scale shear zone linking the Rocky Mountain Foreland belt to
lower crust beneath accreted terranes. In: McClay, K.R. (Ed.), Thrust Tectonics.
Chapman and Hall, London, pp. 353–364.
Brown, M., Averkin, Y.A., McLellan, E.L., Sawyer, E.W., 1995. Melt segregation in
migmatites. Journal of Geophysical Research 100 (B8), 15,655–15,679.
Brown, L.D., et al., 1996. Bright spots, structure, and magmatism in southern Tibet from
INDEPTH seismic reflection profiling. Science 274, 1688–1690.
Brown, M.A., Brown, M., Carlson, W.D., Denison, C., 1999. Topology of syntectonic meltflow networks in the deep crust: inferences from three-dimensional, images of
leucosome geometry in migmatites. American Mineralogist 84, 1793–1818.
Brun, J.-P., Gapais, D., Le Theoff, B., 1981. The mantled gneiss domes of Kuopuo
(Finland): interfering diapirs. Tectonophysics 74, 283–304.
Brun, J.-P., Burg, J.-P., Chen, G.M., 1985. Strain trajectories above the Main Central Thrust
(Himalaya) in southern Tibet. Nature 313 (6001), 388–390.
Brunel, M., 1986. Ductile thrusting in the Himalayas: shear sense criteria and stretching
lineations. Tectonics 5 (2), 247–265.
Buck, W.R., 1991. Modes of continental lithospheric extension. Journal of Geophysical
Research 96 (B12), 20,161–20,178.
Bulau, J.R., Waff, H.S., Tyburczy, J.A., 1979. Mechanical and thermodynamic constraints
of fluid distribution in partial melts. Journal of Geophysical Research 84, 6102–6108.
Burchfiel, B.C., et al., 1992. The South Tibetan Detachment System, Himalayan Orogen:
extension contemporaneous with and parallel to shortening in a collisional
mountain belt. Geological Society of America Special Paper 269, 1–41.
Burg, J.-P., Gerya, T.V., 2005. The role of viscous heating in Barrovian metamorphism of
collisional orogens: thermomechanical models and application to the Lepontine
Dome in the Central Alps. Journal of Metamorphic Geology 23 (2), 75–95.
Burg, J.-P., Vanderhaeghe, O., 1993. Structures and way-up criteria in migmatites, with
application to the Velay Dome (French Massif Central). Journal of Structural
Geology 15 (11), 1293–1301.
Burg, J.-P., Proust, F., Tapponnier, P., Chen, G.M., 1983. Deformation phases and tectonic
evolution of the Lhasa block (southern Tibet, China). Eclogae Geologicae Helvetiae
76 (3), 643–665.
Burg, J.P., Brunel, M., Gapais, D., Chen, G.M., Liu, G.H., 1984a. Deformation of
leucogranites of the crystalline Main Central sheet in southern Tibet (China).
Journal of Structural Geology 6 (5), 535–542.
Burg, J.P., Guiraud, M., Chen, G.M., Li, G.C., 1984b. Himalayan metamorphism and
deformations in the North Himalayan Belt (southern Tibet, China). Earth and
Planetary Science Letters 69 (2), 391–400.
Burg, J.-P., Van Den Driessche, J., Brun, J.-P., 1994. Syn- to post-thickening extension in
the Variscan Belt of Western Europe: modes and structural consequences. Geologie
de la France 3, 33–51.
Burg, J.-P., et al., 1997. Exhumation during crustal folding in the Namche–Barwa
syntaxis. Terra Nova 9 (2), 53–56.
Caggianelli, A., et al., 1991. Lower crustal granite genesis connected with chemical
fractionation in the continental crust of Calabria (southern Italy). European Journal
of Mineralogy 3 (1), 159–180.
Caricchi, L., et al., 2007. Non-Newtonian rheology of crystal-bearing magmas and
implications for magma ascent dynamics. Earth and Planetary Science Letters 264
(3–4), 402–419.
Carr, S.D., 1991. U–Pb zircon and titanite ages of three Mesozoic igneous rocks south of
the Thor–Odin–Pinnacles area, southern Omineca Belt, British Columbia. Canadian
Journal of Earth Sciences 28, 1877–1882.
Carr, S.D., 1992. Tectonic setting and U–Pb geochronology of the early Tertiary Ladybird
leucogranite suite, Thor–Odin–Pinnacles area, southern Omineca belt, British
Colombia. Tectonics 11 (2), 258–278.
Chamberlain, C.P., Sonder, L.J., 1990. Heat-producing elements and the thermal and
baric patterns of metamorphic belts. Science 250, 763–769.
Champallier, R., Bystricky, M., Arbaret, L., 2008. Experimental investigation of magma
rheology at 300Â MPa: from pure hydrous melt to 76Â vol.% of crystals. Earth and
Planetary Science Letters 267 (3–4), 571–583.
Chauvet, A., Kienast, J.-R., Pinardon, J.-L., Brunel, M., 1992. Petrological constraints and
PT path of Devonian collapse tectonics within the Scandian mountain belt (Western
Gneiss Region, Norway). Journal of the Geological Society of London 149, 383–400.
Chen, Z., et al., 1990. The Kangmar dome: a metamorphic core complex in southern
Xizang (Tibet). Science 250 (4987), 1552–1556.
Clark, M.K., et al., 2004. Surface uplift, tectonics, and erosion of eastern Tibet from largescale drainage patterns. Tectonics 23 (1), 1–20 TC1006.
Clark, M.K., Bush, J.W.M., Royden, L.H., 2005a. Dynamic topography produced by lower
crustal flow against rheological strength heterogeneities bordering the Tibetan
Plateau. Geophysical Journal International 162 (2), 575–590.
Clark, M.K., et al., 2005b. Late Cenozoic uplift of southeastern Tibet. Geology 33 (6), 525–528.
Clemens, J.D., Mawer, C.K., 1992. Granitic magma transport by fracture propagation.
Tectonophysics 204, 339–360.
Coleman, M.E., 1998. U–Pb constraints on Oligocene–Miocene deformation and anatexis
within the Central Himalaya, Marsyandi Valley, Nepal. American Journal of Science
298 (7), 553–571.
Author's personal copy
O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Coney, P.J., Harms, T.A., 1984. Cordilleran metamorphic core complexes: Cenozoic
extensional relics of Mesozoic compression. Geology 12, 550–554.
Costa, S., Rey, P., 1995. Lower crustal rejuvenation and growth during post-thickening
collapse: insights from a crustal cross section through a Variscan metamorphic core
complex. Geology 23 (10), 905–908.
Cruden, A., 1990. Flow and fabric development during the diapiric rise of magma.
Journal of Geology 98, 681–698.
Cruden, A., Koyi, H., Schmeling, H., 1995. Diapiric basal entrainment of mafic into felsic
magma. Earth and Planetary Science Letters 131, 321–340.
Culshaw, N.G., Beaumont, C., Jamieson, R.A., 2006. The orogenic superstructure–
infrastructure concept: revisited, quantified, and revived. Geology 34 (9), 733–736.
Dell'Angelo, L.N., Tullis, J., 1988. Experimental deformation of partially melted granitic
aggregates. Journal of Metamorphic Geology 6, 495–515.
Dell'Angelo, L.N., Tullis, J., Yund, R.A., 1987. Transition from dislocation creep to meltenhanced diffusion creep in fine-grained granitic aggregates. Tectonophysics 139,
325–332.
Dewey, J.F., 1986. Diversity in the lower continental crust. In: Dawson, J.B., Carswell,
D.A., Hall, J., Wedepohl, K.H. (Eds.), The nature of the lower continental crust,
pp. 71–78.
Dingwell, D.B., 1995. Viscosity and anelasticity of melts and glasses. In: Ahrens, T.
(Ed.), Mineral physics and crystallography. A handbook of physical constants.
AGU, pp. 209–217.
Dingwell, D.B., Bagdassarov, N.S., Bussod, J., Webb, S.L., 1993. Magma rheology. In: Luth,
R.W. (Ed.), Short Handbook on Experiments at high Pressure and Applications to
the Earth's Mantle. Mineralogical Association of Canada, Ontario, pp. 131–196.
Dingwell, D.B., Romano, C., Hess, K.U., 1996. The effect of water in the viscosity of a
haplogranitic melt under P–T–X conditions relevant to silicic volcanism. Contributions to Mineralogy and Petrology 124, 19–28.
Dinter, D.A., Royden, L., 1993. Late Cenozoic extension in northeastern Greece: Strymon
Valley detachment system and Rhodope metamorphic core complex. Geology 21
(1), 45–48.
Dixon, J.M., 1975. Finite strain and progressive deformation in models of diapiric
structures. Tectonophysics 28, 89–124.
D'Lemos, R.S., Brown, M., Strachan, R.A., 1992. Granite magma generation, ascent and
emplacement within a transpressional orogen. Journal of the Geological Society of
London 149, 487–490.
Doblas, M., 1991. Late Hercynian extensional and transcurrent tectonics in Central
Iberia. Tectonophysics 191, 325–344.
Downes, H., Leyreloup, A., 1986. Granulitic xenoliths from the French Massic Central:
petrology, Sr and Nd isotope systematics and model ages estimates. In: Dawson, J.B.
E.A. (Ed.), The nature of the lower continental crust. Geological Society of London,
pp. 319–330.
Downes, H., Dupuy, C., Leyreloup, A.F., 1990. Crustal evolution of the Hercynian belt of
western Europe: evidence from lower crustal xenoliths (French Massif Central).
Chemical Geology 83, 209–231.
Duchêne, S., Aïssa, R., Vanderhaeghe, O., 2006. Pressure–temperature–time evolution of
metamorphic rocks from Naxos (Cyclades, Greece): constraints from thermobarometry and Rb/Sr dating. Geodinamica Acta 19 (5), 301–321.
Duthou, J.-L., Cantagrel, J.-M., Didier, J., Vialette, Y., 1984. Palaeozoic granitoids from the
French Massif Central: age and origin studied by 87Rb–87Sr system. Physics of the
Earth and Planetary Interiors 35, 131–144.
England, P.C., McKenzie, D.P., 1982. A thin viscous sheet model for continental
deformation. Geophysical Journal of the Royal Astronomical Society 70, 292–321.
England, P.C., Thompson, A.B., 1984. Pressure–Temperature–time paths of regional
metamorphism I. heat transfer during the evolution of regions of thickened
continental crust. Journal of Petrology 25 (4), 894–928.
England, P.C., Thompson, A., 1986. Some thermal and tectonic models for crustal
melting in continental collision zones. Geological Society Special Publication 19,
83–94.
Enkelmann, E., et al., 2006. Cenozoic exhumation and deformation of northeastern Tibet
and the Qinling: is Tibetan lower crustal flow diverging around the Sichuan basin?
Bulletin of the Geological Society of America 118 (5–6), 651–671.
Fernandez, A., Feybesse, J.L., Mezure, J.F., 1983. Theoretical and experimental study of
fabric developed by different shaped markers in two-dimensional simple shear.
Bulletin de la SocieÂte GeÂologique de France 25, 319–326.
Fletcher, R.C., 1972. Application of a mathematical model to the emplacement of
mantled gneiss domes. American Journal of Science 272, 197–216.
Foster, D.A., Fanning, C.M., 1997. Geochronology of the northern Idaho batholith and the
Bitteroot metamorphic core complex: magmatism preceding and contemporaneous with extension. Geological Society of America Bulletin 109 (4), 379–394.
Fountain, D.M., 1976. The Ivrea–Verbano and Strona–Ceneri Zones, Northern Italy: a
cross-section of the continental crust—new evidence from seismic velocities of rock
samples. Tectonophysics 33 (1–2), 145–165.
Fountain, D.M., Salisbury, M.H., 1981. Exposed cross-sections through the continental
crust: implication for crustal structure, petrology and evolution. Earth and
Planetary Science Letters 56, 263–277.
France-Lanord, C., Le Fort, P., 1988. Crustal melting and granite genesis during the
Himalayan collision orogenesis. Transactions of the Royal Geological Society of
Edimburgh 79, 183–195.
Gaillard, F., Scaillet, B., Pichavant, M., 2004. Evidence for present-day leucogranite
pluton growth in Tibet. Geology 32 (9), 801–804.
Gardien, V., Lardeaux, J.-M., Ledru, P., Allemand, P., Guillot, S., 1997. Metamorphism
during late orogenic extension: insights from the French Variscan belt. Bulletin de
la Societe Geologique de France 168 (3), 271–286.
Gautier, P., Brun, J.-P., 1994. Ductile crust exhumation and extensional detachments in
the central Aegean (Cyclades and Evvia Islands). Geodinamica Acta 7 (2), 57–85.
131
Goffé, B., Bousquet, R., Henry, P., Le Pichon, X., 2003. Effect of the chemical composition
of the crust on the metamorphic evolution of orogenic wedges. Journal of
Metamorphic Geology 21 (2), 123–141.
Gordon, S.M., Whitney, D.L., Teyssier, C., Grove, M., Dunlap, W.J., 2008. Timescales of
migmatization, melt crystallization, and cooling in a Cordilleran gneiss dome, the
Valhalla Complex, southeastern British Columbia. Tectonics 18, 1154–1177.
Gray, N.H., Philpotts, A.R., Dickson, L.D., 2003. Quantitative measures of textural
anisotropy resulting from magmatic compaction illustrated by a sample from the
Palisades sill, New Jersey. Journal of Volcanology and Geothermal Research 121,
293–312.
Grujic, D., et al., 1996. Ductile extrusion of the Higher Himalayan Crystalline in Bhutan:
evidence from quartz microfabrics. Tectonophysics 260 (1–3 SPEC. ISS), 21–43.
Grujic, D., Hollister, L.S., Parrish, R.R., 2002. Himalayan metamorphic sequence as an
orogenic channel: insight from Bhutan. Earth and Planetary Science Letters 198
(1–2), 177–191.
Guillot, S., Le Fort, P., 1995. Geochemical constraints on the bimodal origin of high
Himalayan leucogranites. Lithos 221–234.
Guillot, S., Le Fort, P., Pecher, A., Barman, M.R., Aprahamian, J., 1995. Contact
metamorphism and depth of emplacement of the Manaslu granite (central
Nepal) implications for Himalayan orogenesis. Tectonophysics 241 (1–2), 99–119.
Guillot, S., Pochat, S., Zakarian, N., Hodges, K.V., 1998. Metamorphic evolution of the
Kangmar dome (SE-Xizang, Tibet): implications for the internal Himalayan zones.
Comptes Rendus de l'Academie de Sciences — Serie IIa: Sciences de la Terre et des
Planetes 327 (9), 577–582.
Hacker, B.R., et al., 2000. Hot and dry deep crustal xenoliths from Tibet. Science 287,
2463–2466.
Hand, M., Dirks, P.H.G.M., 1992. The influence of deformation on the formation of
axial-planar leucosomes and the segregation of small melt bodies within the
migmatitic Napperby Gneiss, central Australia. Journal of Structural Geology 14,
591–604.
Handy, M., Franz, L., Heller, F., Janott, B., Zurbriggen, R., 1999. Multistage accretion,
orogenic stacking, and exhumation of continental crust (Ivrea crustal section, Italy
and Switzerland). Tectonics 18, 1154–1177.
Harris, N., Massey, J., 1994. Decompression and anatexis of Himalayan metapelites.
Tectonics 1537–1546.
Harrison, T.M., et al., 1999. Origin and episodic emplacement of the Manaslu intrusive
complex, Central Himalaya. Journal of Petrology 40, 3–19.
Henk, A., Franz, L., Teufel, S., Oncken, O., 1997. Magmatic underplating, extension, and
crustal reequilibration: insights from a cross-section through the Ivrea Zone and
Strona–Ceneri Zone, northern Italy. Journal of Geology 105 (3), 367–377.
Henry, P., Le Pichon, X., Goffé, B., 1997. Kinematic, thermal and petrological model of the
Himalayas: constraints related to metamorphism within the underthrust Indian
crust and topographic elevation. Tectonophysics 273, 31–56.
Hermann, J., Müntener, O., Trommsdorff, V., Hansmann, W., 1997. Fossil crust-to-mantle
transition, Val Malenco (Italian Alps). Journal of Geophysical Research 102,
20123–20132.
Herzberg, C.T., Fyfe, W.S., Carr, M.J., 1983. Density constraints on the formation of the
continental moho and crust. Contributions to Mineralogy and Petrology 84, 1–5.
Hippertt, J.F., 1994. Structures indicative of helicoidal flow in a migmatitic diapir (Bacao
Complex, southeastern Brazil). Tectonophysics 234, 169–196.
Hodges, K.V., et al., 1992. Simultaneous Miocene extension and shortening in the
Himalayan orogen. Nature 258, 1466–1470.
Hodges, K.V., Burchfiel, B.C., Royden, L.H., Chen, Z., Liu, Y., 1993. The metamorphic
signature of contemporaneous extension and shortening in the central Himalayan
orogen: data from the Nyalam transect, southern Tibet. Journal of Metamorphic
Geology 11 (5), 721–737.
Holtzman, B.K., Groebner, N.J., Zimmerman, M.E., Ginsberg, S.B., Kohlstedt, D.L., 2003.
Deformation-driven melt segregation in partially molten rocks. Geochemistry,
Geophysics, Geosystems 4, 8607.
Houseman, G.A., McKenzie, D.P., Molnar, P., 1981. Convective instability of a thickened
boundary layer and its relevance for the thermal evolution of continental
convergent belts. Journal of Geophysical Research 86 (B7), 6115–6132.
Huerta, A.D., Royden, L.H., Hodges, K.V., 1998. The thermal structure of collisional
orogens as a response to accretion, erosion, and radiogenic heating. Journal of
Geophysical Research B: Solid Earth 103 (7), 15287–15302.
Hunziker, J.C., Zingg, A., 1980. Lower paleozoic ampibolite to granulite facies
metamorphism in the Ivrea Zone (southern Alps, Northern Italy). Schweizerische
Mineralogische und Petrographische Mitteilungen 60, 181–213.
Huppert, H.E., Sparks, R.S.J., 1988. The generation of granitic magmas by intrusion of
basalt into continental crust. Journal of Petrology 29 (3), 599–624.
Jackson, M.P.A., Talbot, C.J., 1989. Anatomy of mushroom-shaped diapirs. Journal of
Structural Geology 11 (1/2), 211–230.
Jeffrey, D.J., Acrivos, A., 1976. The rheological properties of suspensions of rigid particles.
AIChE Journal 22, 417–432.
Jiang, D., 1999. Vorticity decomposition and its application to sectional flow
characterization. Tectonophysics 301, 243–259.
Jurewicz, S.R., Watson, E.B., 1984. Distribution of partial melt in a felsic system: the
importance of surface energy. Contributions to Mineralogy and Petrology 85,
125–129.
Jurewicz, S.R., Watson, E.B., 1985. The distribution of partial melt in a granitic system:
the application of liquid phase sintering theory. Geochimica et Cosmochimica Acta
49, 1109–1121.
Kay, R.W., Mahlburg Kay, S., 1993. Delamination and delamination magmatism.
Tectonophysics 219 (1–3), 177–189.
Kerr, R.C., Lister, J.R., 1991. The effects of shape on crystal settling and on the rheology of
magmas. Journal of Geology 99, 457–467.
Author's personal copy
132
O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Kerr, R.C., Lister, J.R., 1992. Further results for convection driven by the differential
sedimentation of particles. Journal of Fluid Mechanics 243, 227–245.
Knoche, R., Dingwell, D.B., Webb, S.L., 1995. Melt densities for leucogranites and granitic
pegmatites: partial molar volumes for SiO2, Al2O3, Na2O, K2O, Li2O, Rb2O, Cs2O,
MgO, SrO, BaO, B2O3, P2O5, F2O−1, TiO2, Nb2O5, Ta2O5, and WO3. Geochimica et
Cosmochimica Acta 59 (22), 4645–4652.
Kohlstedt, D.L., 1995. Strength of the lithosphere: constraints imposed by laboratory
experiments. Journal of Geophysical Research 100 (B9), 17,587–17,602.
Kohlstedt, D.L., 2002. Partial melting and deformation. Reviews in Mineralogy and
Geochemistry 51 (1), 121–135.
Kruckenberg, S., Whithney, D.L., Teyssier, C., Fanning, C.M., Dunlap, W.J., 2008.
Paleocene–Eocene migmatite crystallization, extension, and exhumation in the
hinterland of the northern Cordillera: Okanogan dome, Washington, USA.
Geological Society of America Bulletin 120, 912–929.
Lagarde, J.-L., Dallain, C., Ledru, P., Courrioux, G., 1994. Strain pattern within the Variscan
granite dome of Velay, French Massif Central. Journal of Structural Geology 16,
839–852.
Lange, R.A., 1994. The effect of H2O, CO2 and F on the density and viscosity of silicate
melts. In: Carroll, M., Holloway, J.R. (Eds.), Volatiles in Magmas, Reviews in
Mineralogy. Mineralogical Society of America, Washington D.C., pp. 331–369.
Laporte, D., 1994. Wetting behavior of partial melts during crustal anatexis: the
distribution of hydrous silicic melts in polycrystalline aggregates of quartz.
Contributions to Mineralogy and Petrology 116, 486–499.
Lardeaux, J.M., Ledru, P., Daniel, I., Duchene, S., 2001. The Variscan French Massif
Central—a new addition to the ultra-high pressure metamorphic ‘club’: exhumation
processes and geodynamic consequences. Tectonophysics 332, 143–167.
Le Fort, P., et al., 1987. Crustal generation of Himalayan leucogranites. Tectonophysics
134, 39–57.
Ledru, P., et al., 2001. The Velay dome (French Massif Central): melt generation and granite
emplacement during orogenic evolution. Tectonophysics 342 (3–4), 207–237.
Lee, J., et al., 2000. Evolution of the Kangmar Dome, Southern Tibet: structural,
petrologic, and thermochronologic constraints. Tectonics 19 (5), 872–895.
Lee, J., Hacker, B., Wang, Y., 2004. Evolution of North Himalayan gneiss domes:
structural and metamorphic studies in Mabja Dome, southern Tibet. Journal of
Structural Geology 26 (12), 2297–2316.
Lejeune, A.-M., Richet, P., 1995. Rheology of crystal-bearing silicate melts: an
experimental study at high viscosities. Journal of Geophysical Research 100 (B3),
4215–4229.
Leyreloup, A., Dupuy, C., Andriambolona, R., 1977. Catazonal xenoliths in French
Neogene volcanic rocks, constitution of the lower crust. Contributions to
Mineralogy and Petrology 62, 283–300.
Lister, J.R., 1989. Selective withdrawal from a viscous two-layer system. Journal of Fluid
Mechanics 198, 231–254.
Lister, G.S., Baldwin, S.L., 1993. Plutonism and the origin of metamorphic core
complexes. Geology 21, 607–610.
Liu, M., 2001. Cenozoic extension and magmatism in the North American Cordillera: the
role of gravitational collapse. Tectonophysics 342, 407–433.
Lu, M., Hofmann, A.W., Mazzucchelli, M., Rivalenti, G., 1997. The mafic–ultramafic
complex near finero (Ivrea–Verbano Zone), II. geochronology and isotope
geochemistry. Chemical Geology 140 (3–4), 223–235.
Lustrino, M., 2005. How the delamination and detachment of lower crust can influence
basaltic magmatism. Earth Science Reviews 72 (1–2), 21–38.
Maaløe, S., 1982. Geochemical aspects of permeability controlled partial melting and
fractional crystallization. Cosmochimica Acta 46, 43–57.
Mahéo, G., Guillot, S., Blichert-Toft, J., Rolland, Y., Pécher, A., 2002. A slab breakoff model
for the Neogene thermal evolution of South Karakorum and South Tibet. Earth and
Planetary Science Letters 195 (1–2), 45–58.
Makovsky, Y., Klemperer, S.L., 1999. Measuring the seismic properties of Tibetan bright
spots: evidence for free aqueous fluids in the Tibetan middle crust. Journal of
Geophysical Research B: Solid Earth 10795–10825.
Maluski, H., Matte, P., Brunel, M., Xiao, X., 1988. The 39Ar–40Ar dating of metamorphic
and plutonic events in the North and High Himalaya Belts (southern Tibet–China).
Tectonics 7 (2), 299–326.
Mancktelow, N.S., Arbaret, L., Pennacchioni, G., 2002. Experimental observations on the
effect of interface slip on rotation and stabilisation of rigid particles in simple shear
and a comparisons with natural mylonites. Journal of Structural Geology 24 (3),
567–585.
Manley, R.S., Mason, S.G., 1954. Viscosity of suspension of spheres note on the particle
interaction coefficient. Canadian Journal of Chemistry 32, 763–767.
Marchildon, N., Brown, M., 2003. Spatial distribution of melt-bearing structures in
anatectic rocks from Southern Brittany, France: implications for melt transfer at
grain- to orogen-scale. Tectonophysics 364 (3–4), 215–235.
Mason, S.G. and Bartok, W., 1957. The behavior of suspended particles in laminar shear,
Rheol. Disperse System, Univ. Coll. Swansea (1959), pp. 16–48.
McKenzie, D.P., 1984. The generation and compaction of partially molten rocks. Journal
of Petrology 25, 713–765.
Means, W.D., Hobbs, B.E., Lister, G.S., Williams, P.F., 1980. Vorticity and non-coaxiality in
progressive deformations. Journal of Structural Geology 2 (3), 371–378.
Mehnert, K.R., 1968. Migmatites and the origin of granitic rocks. Elsevier, Amsterdam,
London. 405 pp.
Molnar, P., 1988. Continental tectonics in the aftermath of plate tectonics. Nature 335,
131–137.
Molnar, P., England, P., 1990. Temperatures, heat flux and frictional stress near major
thrust faults. Journal of Geophysical Research 95, 4833–4856 B.
Molnar, P., England, P., Martinod, J., 1993. Mantle dynamics, uplift of the Tibetan Plateau,
and the Indian monsoon. Reviews of Geophysics 31 (4), 357–396.
Morency, C., Doin, M.-P., 2004. Numerical simulations of the mantle lithosphere
delamination. Journal of Geophysical Research B: Solid Earth 109 (3), 1–17 B03410.
Mougeot, R., Respaut, J.-P., Ledru, P., Marignac, C., 1997. U–Pb chronology on accessory
minerals of the Velay anatectic dome (French Massif Central. European Journal of
Mineralogy 9, 141–156.
Müntener, O., Hermann, J., Trommsdorff, V., 2000. Cooling history and exhumation of
lower crustal granulite and upper mantle (Malenco, Eastern Central Alps). Journal
of Petrology 41, 175–200.
Myers, J.D., Watkins, K.P., 1985. Origin of granite-greenstone patterns, Yilgarn Block,
Western Australia. Geology 13, 778–780.
Nelson, K.D., et al., 1996. Partially molten middle crust beneath southern Tibet:
synthesis of project INDEPTH results. Science 274, 1684–1688.
Paquet, J., François, P., Nédélec, A., 1981. Effect of partial melting on rock deformation:
experimental and natural evidences on rocks of granitic composition. Tectonophysics 78, 545–565.
Parrish, R.R., 1995. Thermal evolution of the southeastern Canadian Cordillera. Canadian
Journal of Earth Sciences 32, 1618–1642.
Parrish, R.R., Carr, S.D., Parkinson, D.L., 1988. Eocene extensional tectonics and
geochronology of the Southern Omineca belt, British Colombia and Washington.
Tectonics 7 (2), 181–212.
Parsons, R.A., Nimmo, F., Hustoft, J.W., Holtzman, B.K., Kohlstedt, D.L., 2008. An
experimental and numerical study of surface tension-driven melt flow. Earth and
Planetary Science Letters 267 (3–4), 548–557.
Partzsch, G.M., Schilling, F.R., Arndt, J., 2000. The influence of partial melting on the
electrical behavior of crustal rocks: laboratory examinations, model calculations
and geological interpretations. Tectonophysics 317, 189–203.
Paterson, M.S., 2001. A granular flow theory for the deformation of partially molten
rock. Tectonophysics 335 (1–2), 51–61.
Pêcher, A., 1989. The metamorphism in the Central Himalaya. Journal of Metamorphic
Geology 7, 31–41.
Petford, N., Kerr, R.C., Lister, J.R., 1993. Dike transport of granitoid magmas. Geology 21,
845–848.
Philpotts, A.R., Carroll, M., Hill, J.M., 1996. Crystal-mush compaction and the origin of
pegmatitic segregation sheets in a thick flood-basalt flow in the Mesozoic Hartford
basin, Connecticut. Journal of Petrology 37, 811–836.
Philpotts, A.R., Brustman, C.M., Shi, J., Carlson, W.D., Denison, C., 1999. Plagioclase-chain
networks in slowly cooled basaltic magma. American Mineralogist 84, 1819–1829.
Pin, C., Duthou, J.L., 1990. Sources of Hercynian granitoids from the french Massif
Central: inferences from Nd isotopes and consequences for crustal evolution.
Chemical Geology 83, 281–296.
Pin, C., Sills, J.D., 1986. Petrogenesis of layered gabbros and ultramafic rocks from Val
Sesia, the Ivrea Zone, NW Italy: trace element and isotope geochemistry. The Nature
of the Lower Continental Crust, pp. 231–249.
Pous, J., Munoz, J.A., Ledo, J.J., Liesa, M., 1995. Partial melting of subducted continental
lower crust in the Pyrenees. Journal of the Geological Society of London 152 (2),
217–220.
Rabinowicz, M., Vigneresse, J.-L., 2004. Melt segregation under compaction and shear
channeling: application to ganitic magma segregation in a continental crust.
Journal of Geophysical Research B: Solid Earth B04407, 1–20.
Racek, M., Stipska, P., Pitra, P., Schulmann, K., Lexa, O., 2006. Metamorphic record of
burial and exhumation of orogenic lower and middle crust: a new tectonothermal
model for the Drosendorf window (Bohemian Massif, Austria). Mineralogy and
Petrology 86 (3–4), 221–251.
Ramberg, H., 1980. Diapirism and gravity-collapse in the Scandinavian Caledonides.
Journal of the Gelogical Society of London 137, 262–270.
Ramberg, H., 1981. The role of gravity in orogenic belts. In: McKlay, K.R., Price, N.J. (Eds.),
Geol. Soac. Spec. Publ., vol. 9, pp. 125–140.
Ramsay, J.G., 1989. Emplacement kinematics of a granite diapir: the Chindamora
batholit, Zimbabwe. Journal of Structural Geology 11, 191–209.
Rey, P., Burg, J.-P., Caron, J.-M., 1991-1992. Middle and Late Carboniferous extension in
the Variscan Belt: structural and petrological evidences from the Vosges massif
(Eastern France. Geodinamica Acta 5 (1–2), 17–36.
Rey, P., Vanderhaeghe, O., Teyssier, C., 2001. Gravitational collapse of the continental
crust: definition, regimes and modes. Tectonophysics 342 (3–4), 435–449.
Robin, P.-Y.F., 1979. Theory of metamorphic segregation and related processes.
Geochmica Cosmochimica Acta 43, 1587–1600.
Robyr, M., Hacker, B.R., Mattinson, J.M., 2006. Doming in compressional orogenic
settings: new geochronological constraints from the NW Himalaya. Tectonics
25 (2).
Rolland, Y., Mahéo, G., Guillot, S., Pécher, A., 2001. Tectono-metamorphic evolution of the
Karakorum Metamorphic complex (Dassu–Askole area, NE Pakistan): exhumation of
mid-crustal HT-MP gneisses in a convergent context. Journal of Metamorphic Geology
19, 717–737.
Roscoe, R., 1952. The viscosity of suspensions of rigid spheres. British Journal of Applied
Physics 3, 267–269.
Rosenberg, C.L., 2001. Deformation of partially molten granite: a review and comparison
of experimental and natural case studies. International Journal of Earth Sciences 90
(1), 60–76.
Rosenberg, C.L., Handy, M.R., 2001. Mechanisms and orientation of melt segregation
paths during pure shearing of a partially molten rock analog (norcamphorbenzamide). Journal of Structural Geology 23 (12), 1917–1932.
Rosenberg, C.L., Handy, M.R., 2005. Experimental deformation of partially melted
granite revisited: implications for the continental crust. Journal of Metamorphic
Geology 23 (1), 19–28.
Rosenberg, C.L., Riller, U., 2000. Partial-melt topology in statically and dynamically
recrystallized granite. Geology 28, 7–10.
Author's personal copy
O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Rossi, P., Cocherie, A., Fanning, C.M., Deloule, E., 2006. Variscan to eo-Alpine events
recorded in European lower-crust zircons sampled from the French Massif Central
and Corsica, France. Lithos Geochronolgy of Orogenic Processes — Crystal–Chemical
to Continental Scale Interpretations, vol. 87(3–4), pp. 235–260.
Royden, L., 1996. Coupling and decoupling of crust and mantle in convergent orogens:
implications for strain partitioning in the crust. Journal of Geophysical Research 101
(B8), 17,679–17,705.
Royden, L.H., et al., 1997. Surface deformation and lower crustal flow in eastern Tibet.
Science 276, 788–790.
Rubin, A.M., 1993a. Dikes vs. diapirs in viscoelastic rock. Earth and Planetary Science
Letters 119, 641–659.
Rubin, A.M., 1993b. On the thermal viability of dikes leaving magma chambers.
Geophysical Research Letters 20 (4), 257–260.
Rudnick, R., Fountain, D., 1995. Nature and composition of the continental crust: a lower
crustal perspective. Reviews of Geophysics 33 (3), 267–309.
Rushmer, T., 1991. Partial melting of two amphibolites: contrasting experimental results
under fluid-absent conditions. Contributions to Mineralogy and Petrology 107,
41–59.
Rushmer, T., 1996. Melt segregation in the lower crust: how have experiments helped
us? Transactions of the Royal Society of Edinburgh. Earth Sciences 87, 73–83.
Rutter, E.H., Neumann, D.H., 1995. Experimental deformation of partially molten
Westerly granite under fluid-absent conditions, with implications for the extraction
of granitic magmas. Journal of Geophysical Research 100, 15,697–15,715.
Sanderson, D.J., Marchini, W.R.D., 1984. Transpression. Journal of Structural Geology 6,
449–458.
Sawyer, E.W., 1991. Disequilibrium melting and the rate of melt-residuum separation
during migmatization of mafic rocks from the Grenville front, Quebec. Journal of
Petrology 32, 701–738.
Sawyer, E.W., 1994. Melt segregation in the continental crust. Geology 22, 1019–1022.
Sawyer, E.W., 1999. Criteria for the recognition of partial melt. Physics and Chemistry of
the Earth 24, 269–279.
Sawyer, E., 2000. Grain-scale and outcrop-scale distrbution and movement of melt in a
crystallising granite. Transactions of the Royal Society of Edinburgh. Earth Sciences
91, 73–85.
Sawyer, E.W., Dombroski, C., Collins, W.J., 1999. Movement of melt during synchronous
regional deformation and granulite-facies anatexis, an example from the Wuluma
Hills, central Austraila. In: Castro, A., Fernandez, C., Vigneresse, J.L. (Eds.),
Understanding granites: integrating new and classical techniques: The Geological
Society of London, Special Publications, London, pp. 221–237.
Scaillet, B., Pecher, A., Rochette, P., Champenois, M., 1995. The Gangotri granite (Garhwal
Himalaya): laccolithic emplacement in an extending collisional belt. Journal of
Geophysical Research 100 (B1), 585–607.
Scaillet, B., Holtz, F., Pichavant, M., 1997. Rheological properties of granitic magmas in
their crystallization range. In: Bouchez, J.-L., Hutton, D., Stephens, W.E. (Eds.),
Granite: from segregation of melt to emplacement fabrics. Kluwer, Dordrecht, pp.
11–29.
Scaillet, B., Holtz, F., Pichavant, M., 1998. Phase equilibrium constraints on the viscosity
of silicic magmas. Journal of Geophysical Research 103, 27257–27266.
Scharer, U., Xu, R.H., Allegre, C.J., 1986. U–(Th)–Pb systematics and ages of Himalayan
leucogranites, South Tibet. Earth and Planetary Science Letters 77 (1), 35–48.
Schenk, V., 1981. Synchronous uplift of the lower crust of the Ivrea Zone and of southern
Calabria and its possible consequences for the hercynian orogeny in southern
Europe. Earth and Planetary Science Letters 56, 305–320.
Schenk, V., 1984. Petrology of felsic granulites, metapelites, metabasics, ultramafics, and
metacarbontates from southern Calabria (Italy): prograde metamorphism, uplift
and cooling of a former lower crust. Journal of Petrology 25, 255–298.
Schilling, F.R., Partzsch, G.M., Brasse, H., Schwarz, G., 1997. Partial melting below the
magmatic arc in the central Andes deduced from geoelectromagnetic field experiments and laboratory data. Physics of the Earth and Planetary Interiors 103, 17–31.
Schmitz, M., Heinsohn, W.-D., Schilling, F.R., 1997. Seismic, gravity and petrological
evidence for partial melt beneath the thickened Central Andean crust (21–23 S).
Tectonophysics 270, 313–326.
Schneider, D.A., Edwards, M.A., Kidd, W.S.F., Zeitler, P.K., Coath, C.D., 1999. Early Miocene
anatexis identified in the western syntaxis, Pakistan Himalaya. Earth and Planetary
Science Letters 167 (3–4), 121–129.
Schnetger, B., 1994. Partial melting during the evolution of the amphibolite- to
granulite-facies gneisses of the Ivrea Zone, northern Italy. Chemical Geology 113
(1–2), 71–101.
Schott, B., Yuen, D.A., Schmeling, H., 2000. The significance of shear heating in continental
delamination. Physics of the Earth and Planetary Interiors 118 (3–4), 273–290.
Schulmann, K., et al., 1994. Large-scale strain partitioning and migration of deformation
during nappe stacking: a case study in the S.E. Bohemian Massif (Thaya dome).
Journal of Structural Geology 16 (3), 355–370.
Schulmann, K., Thompson, A.B., Lexa, O., Ježek, J., 2003. Strain distribution and fabric
development modeled in active and ancient transpressive zones. Journal of
Geophysical Research 108, 1–14.
Schulmann, K., et al., 2008. Vertical extrusion and horizontal channel flow of orogenic
lower crust: key exhumation mechanisms in large hot orogens? Journal of
Metamorphic Geology 26 (2), 273–297.
Schwerdtner, W.M., Sutcliffe, R.H., Troeng, B., 1978. Patterns of total strain in the crestal
region of immature diapirs. Canadian Journal of Earth Sciences 15, 1437–1447.
Scott, D.R., Stevenson, D.J., 1986. Magma ascent by porous flow. Journal of Geophysical
Research 91 (B9), 9283–9296.
Searle, M.P., 1999. Emplacement of Himalayan leucogranites by magma injection along
giant sill complexes: examples from the Cho Oyu, Gyachung Kang and Everest
leucogranites (Nepal Himalaya). Tectonophysics 17, 773–783.
133
Searle, M.P., et al., 1997. Shisha Pangma leucogranite, South Tibetan Himalaya: field
relations, geochemistry, age, origin, and emplacement. Journal of Geology 105,
295–318.
Shaw, H.R., 1965. Comments on viscosity, crystal settling, and convection in granitic
magmas. American Journal of Science 263, 120–152.
Shaw, H.R., 1972. Viscosities of magmatic silicate liquid: an empirical method of
prediction. American Journal of Science 272, 870–893.
Sills, J.D., Tarney, J., 1984. Petrogenesis and tectonic significance of amphibolites
interlayered with metasedimentary gneisses in the Ivrea Zone, Southern Alps,
Northwest Italy. Tectonophysics 107, 187–206.
Slagstad, T., Hamilton, M.A., Jamieson, R.A., Culshaw, N.G., 2004. Timing and duration of
melting in the mid orogenic crust: constraints from U–Pb (SHRIMP) data, Muskoka
and Shawanaga domains, Grenville Province, Ontario. Canadian Journal of Earth
Sciences 41 (11), 1339–1365.
Slagstad, T., Jamieson, R.A., Culshaw, N.G., 2005. Formation, crystallization, and
migration of melt in the mid-orogenic crust: Muskoka domain migmatites,
Grenville Province, Ontario. Journal of Petrology 893–919.
Sleep, N.H., 1974. Segregation of magma from a mostly crystalline mush. Geological
Society of America Bulletin 85, 1225–1232.
Sokoutis, D., Brun, J.-P., Van Den Driessche, J., Pavlides, S., 1993. A major Oligo-Miocene
detachment in southern Rhodope controlling north Aegean extension. Journal of
the Geological Society of London 150, 243–246.
Solar, G.S., Brown, M., 2001a. Deformation partitioning during transpression in
response to Early Devonian oblique convergence, Northern Appalachian orogen,
USA. Journal of Structural Geology 1043–1065.
Solar, G.S., Brown, M., 2001b. Petrogenesis of migmatites in Maine, USA: possible source
of peraluminous leucogranite in Plutons? Journal of Petrology 42 (4), 789–823.
Solar, G.S., Pressley, R.A., Brown, M., Tucker, R.D., 1998. Granite ascent in convergent
orogenic belts: testing a model. Geology 711–714.
Stauffer, D., 1985. Introduction to Percolation Theory, London. 124 pp.
Stevenson, D.J., 1989. Spontaneous small-scale melt segregation in partial melts
undergoing deformation. Geophysical Research Letters 16 (9), 1067–1070.
Tajcmanova, L., Konopasek, J., Schulmann, K., 2006. Thermal evolution of the orogenic
lower crust during exhumation within a thickened Moldanubian root of the
Variscan belt of Central Europe. Journal of Metamorphic Geology 119–134.
Talbot, C.J., 1979. Infracstructural migmatitic upwelling in East Greenland interpreted as
thermal convective structures. Precambrian Research 8, 77–93.
Teyssier, C., Whitney, D.L., 2002. Gneiss domes and orogeny. Geology 30, 1139–1142.
Teyssier, C., et al., 2005. Flow of partially molten crust and origin of detachments during
collapse of the Cordilleran Orogen: Geological Society Special Publication, vol. (245,
pp. 39–64.
Thompson, A.B., Schulmann, K., Jezek, J., 1997. Extrusion tectonics and elevation of
lower crustal metamorphic rocks in convergent orogens. Geology 25 (6), 491–494.
Thompson, A.B., Schulmann, K., Jezek, J., Tolar, V., 2001. Thermally softened continental
extensional zones (arcs and rifts) as precursors to thickened orogenic belts.
Tectonophysics 332 (1–2), 115–141.
Tikoff, B., Fossen, H., 1999. Three-dimensional reference deformations and strain facies.
Journal of Structural Geology 21 (11), 1497–1512.
Tikoff, B., Teyssier, C., 1994. Strain modeling of displacement-field partitioning in
transpressional orogens. Journal of Structural Geology 16 (11), 1575–1588.
Timmermann, H., Jamieson, R.A., Parrish, R.R., Culshaw, N.G., 2002. Coeval migmatites
and granulites, Muskoka domain, southwestern Grenville Province, Ontario.
Canadian Journal of Earth Sciences 239–258.
Toksöz, M.N., Minear, J.W., Julian, B., 1971. Temperature field and geophysical effects of a
downgoing slab. Journal of Geophysical Research 76, 113–1138.
Turcotte, D.L., Schubert, G., 1982. Geodynamics: applications of continuum physics to
geological problems. John Wiley & Sons, New York. 450 pp.
Van Den Driessche, J., Brun, J.-P., 1992. Structure and evolution of late Variscan extensional
gneiss dome (Montagne Noire, southern Massif central, France). Geodinamica Acta 5
(1–2), 85–99.
Van Der Molen, I., 1985a. Interlayer material transport during layer-normal shortening.
Part I: the model. Tectonophysics 115, 275–295.
Van Der Molen, I., 1985b. Interlayer material transport during layer-normal shortening.
Part II: boudinage, pinch-and-swell and migmatite at Sondre Stromfjord airport,
West Greenland. Tectonophysics 115, 297–313.
Van der Molen, I., Paterson, M.S., 1979. Experimental deformation of partially-melted
granite. Contribution to Mineralogy and Petrology 70, 299–318.
Vanderhaeghe, O., 1999. Pervasive melt migration from migmatites to leucogranite in
the Shuswap metamorphic core complex, Canada: control of regional deformation.
Tectonophysics 312 (1), 35–55.
Vanderhaeghe, O., 2001. Melt segregation, pervasive melt migration and magma mobility
in the continental crust: the structural record from pores to orogens. Physics and
Chemistry of the Earth, Part A: Solid Earth and Geodesy 26 (4–5), 213–223.
Vanderhaeghe, O., 2004. Structural development of the Naxos migmatite dome. In:
Teyssier, W.D.L.C., Siddoway, C. (Eds.), Gneiss Domes in Orogeny: Geological Society
of America Special Paper, Boulder, pp. 211–227.
Vanderhaeghe, O., Teyssier, C., 1997. Formation of the Shuswap metamorphic core complex
during late-orogenic collapse of the Canadian Cordillera: role of ductile thinning and
partial melting of the mid- to lower crust. Geodinamica Acta 10 (2), 41–58.
Vanderhaeghe, O., Teyssier, C., 2001a. Crustal-scale rheological transitions during lateorogenic collapse. Tectonophysics 335 (1–2), 211–228.
Vanderhaeghe, O., Teyssier, C., 2001b. Partial melting and flow of orogens. Tectonophysics 342, 451–472.
Vanderhaeghe, O., Burg, J.-P., Teyssier, C., 1999a. Exhumation of migmatites in two
collapsed orogens: Canadian Cordillera and French Variscides: Geological Society
Special Publication, vol. 154, pp. 181–204.
Author's personal copy
134
O. Vanderhaeghe / Tectonophysics 477 (2009) 119–134
Vanderhaeghe, O., Teyssier, C., Wysoczanski, R., 1999b. Structural and geochronologic
constraints on the role of partial melting during the formation of the Shuswap
metamorphic core complex at the latitude of the Thor–Odin dome, British
Columbia. Canadian Journal of Earth Sciences 36, 917–943.
Vanderhaeghe, O., Medvedev, S., Fullsack, P., Beaumont, C., Jamieson, R.A., 2003.
Evolution of orogenic wedges and continental plateaux: insights from crustal
thermal–mechanical models overlying subducting mantle lithosphere. Geophysical
Journal International 153 (1), 27–51.
Vavra, G., Gebauer, D., Schmid, R., Compston, W., 1996. Multiple zircon growth and
recrystallization during polyphase Late Carboniferous to Triassic metamorphism in
granulites of the Ivrea Zone (Southern Alps); an ion microprobe (SHRIMP) study.
Contributions to Mineralogy and Petrology 122 (4), 337–358.
Vielzeuf, D., Holloway, J.R., 1988. Experimental determination of the fluid absent
melting reaction in the pelitic system. Consequences for crustal differentiation.
Contribution to Mineralogy and Petrology 98, 257–276.
Vielzeuf, D., Clemens, J.D., Pin, C., Moinet, E., 1990. Granites, granulites and crustal
differentiation. In: Vielzeuf, D., Vidal, P. (Eds.), Granulites and Crustal Evolution.
Kluwer, Dordrecht, pp. 59–85.
Vigneresse, J.L., 1990. Thermal data and crustal structure, role of granites and the
depleted lower crust, granulites and crustal evolution, pp. 551–568.
Vigneresse, J.L., 1995. Control of granite emplacement by regional deformation.
Tectonophysics 173–186.
Vigneresse, J.-L., Brun, J.-P., 1983. Les leucogranites armoricains marqueurs de la
déformation régionale: apport de la gravimétrie. Bulletin de la Société géologique
de France 25, 357–366.
Vigneresse, J.L., Jolivet, J., Cuney, M., Bienfait, G., 1987. Heat flow, heat production and
granite depth in western France. Geophysical Research Letters 275–278.
Vigneresse, J.-L., Barbey, P., Cuney, M., 1996. Rheological transitions during partial
melting and crystallization with application to felsic magma segregation and
transfer. Journal of Petrology 70 (6), 1579–1600.
Visonà, D., Lombardo, B., 2002. Two-mica and tourmaline leucogranites from the
Everest–Makalu region (Nepal–Tibet). Himalayan leucogranite genesis by isobaric
heating? Lithos 62 (3–4), 125–150.
Vissers, R.M., 1992. Variscan extension in the Pyrenees. Tectonics 11 (6), 1369–1384.
von Bargen, N., Waff, H.S., 1986. Permeabilities, interfacial areas and curvatures of
partially molten systems: results of numerical computations of equilibrium
microstructures. Journal of Geophysical Research 91 (89), 9,261–9,275.
Waff, S.H., Bulau, J.R., 1979. Equilibrium fluid distribution in an ultramafic partial melt
under hydrostatic stress conditions. Journal of Geophysical Research 84, 6,109–6,114.
Walker, J.D., et al., 1999. Metamorphism, melting, and extension: age constraints from
the High Himalayan Slab of southeast Zanskar and northwest Lahaul. Journal of
Geology 107 (4), 473–495.
Webb, S.L., Dingwell, D.B., 1990. Non-Newtonian rheology of igneous melts at high
stresses and strain rates: experimental results for rhyolite, andesite, basalt, and
nephelinite. Journal of Geophysical Research 95 (B10), 15,695–15,701.
Weinberg, R.F., 1996. Ascent mechanism of felsic magmas: news and views.
Transactions of the Royal Society of Edinburgh 87, 95–103.
Weinberg, R.F., 1997. Diapir-driven crustal convection: decompression melting, renewal
of the magma source and the origin of nested plutons. Tectonophysics 271 (3–4),
217–229.
Weinberg, R.F., 1999. Mesoscale pervasive felsic magma migration: alternatives to
dyking. Lithos 46 (3), 393–410.
Weinberg, R.F., Podladchikov, Y., 1994. Diapiric ascent of magmas through power law
crust and mantle. Journal of Geophysical Research 99 (B5), 9543–9559.
Weinberg, R.F., Schmeling, H., 1992. Polydiapirs: multiwavelength gravity structures.
Journal of Structural Geology 14 (4), 425–436.
Weinberg, R.F., Searle, M.P., 1998. The Pangong Injection Complex, Indian Karakoram: a
case of pervasive granite flow through hot viscous crust. Journal of the Geological
Society (London) 155, 883–891.
Whitney, D.L., Teyssier, C., Vanderhaeghe, O., 2004. Gneiss Domes and Crustal Flow. In:
Whitney, D.L., Teyssier, C., Siddoway, C. (Eds.), Gneiss domes in orogeny: Geological
Society of America Special Paper, Boulder, pp. 15–34.
Wickham, S.M., 1987. The segregation and emplacement of granitic magmas. Journal of
the Geological Society of London 144, 281–297.
Williamson, B.J., Downes, H., Thirwall, M.F., 1992. The relationship between crustal
magmatic underplating and granite genesis: an example from the Velay granite
complex, Massif Central, France. Trans. Royal Soc. Edinburgh, Earth Sciences 83,
235–245.
Yin, A., 2004. Gneiss Domes and Gneiss Dome Systems, pp. 1–14.
Zak, J., Schulmann, K., Hrouda, F., 2005. Multiple magmatic fabrics in the Sazava pluton
(Bohemian Massif, Czech Republic): a result of superposition of wrench-dominated
regional transpression on final emplacement. Journal of Structural Geology
805–822.
Zimmerman, M.E., Kohlstedt, D.L., 2004. Rheological properties of partially molten
lherzolite. Journal of Petrology 45, 275–298.
Zimmerman, M.E., Zhang, S., Kohlstedt, D.L., Karato, S.-I., 1999. Melt distribution in
mantle rocks deformed in shear. Geophysical Research Letters 26 (10), 1505–1508.
Zingg, A., Handy, M.R., Hunziker, J.C., Schmid, S.M., 1990. Tectonometamorphic history
of the Ivrea Zone and its relationship to the crustal evolution of the Southern Alps.
Tectonophysics 182 (1–2), 169–192.