|Last modified December, 2013; email@example.com
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|Thybo H. and Artemieva I.M., 2013.
Moho and magmatic underplating in continental lithosphere.
Tectonophysics, 609, 605-619
|Artemieva I.M. and Meissner R., 2012.
Crustal thickness controlled by plate tectonics: a review of crust-mantle
interaction processes illustrated by European examples.
Tectonophysics, v. 530-531, 18–49
|Click on figures to enlarge images
|Location map for discussed seismic profiles
|Examples of underplating (dark blue) in different tectonic
settings. See paper for references.
Top: within the cratons (Wyoming, Baltic Shield, and
Left: in rift zones (Baikal, and 2 examples from Kenya)
Bottom: across the Kuril arc and along the Izu-Bonin arc.
|Sketch of the internal structure of the
terrestrial bodies and the relative volume of
the crust, mantle and core as percent of the
total volume of the bodies.
|Plate tectonics processes may have
a strong control on the crustal
|Sketch of major processes controlling crust-mantle material
exchange. Vertical and horizontal dimensions are not to scale
|Sketch illustrating geochemical relations between mantle, oceanic crust and
continental crust. Melting of the depleted convecting upper mantle generates
mid-ocean ridge basalts and produces oceanic crust. A significant amount of
the oceanic crust together with the associated residual depleted mantle is
recycled back in subduction zones refertilizing the mantle and producing
island-arc magmatism which plays an important role in formation of the
continental crust. The enriched upper mantle is the source of ocean-island
basalts. Large-scale mantle upwellings (plumes) as well as small-scale
convective instabilities (not shown) transport mantle material into the
continental lithosphere and lead to crustal growth, particularly notable in LIPs.
Vertical and horizontal dimensions are not to scale.
Gabbro/basalt – eclogite phase transitions in the crustal rocks.
Rainbow shading – eclogite stability field, colors refer to lithospheric
temperatures (purple for cold, red for hot). Pressure-depth conversion is made
assuming crustal density of 2.90 g/cm3.
(a) Bold black lines - phase diagram (after Spear, 1993). Shaded area and gray
boxes - extrapolated stability fields of eclogite, garnet granulite, and pyroxene
granulite-gabbro based on experimental data for the quartz tholeiite composition
(Ringwood and Green, 1966). Thin dashed lines – typical continental reference
(b) Depth to gabbro/basalt – eclogite phase transition (thick gray line) in different
continental settings plotted versus continental reference geotherms labeled in
heat flow values (after Artemieva, 2011). Tectonic provinces are marked on the top
in accordance with typical heat flow values. Gabbro/basalt – eclogite phase
transition limits crustal thickness to 40-45 km in cold stable platforms and to ~30
km in Phanerozoic basins.
Two cross-sections through the European crust constrained by allavailable
seismic data averaged within 600 km-wide corridors along the profiles.
Upper plots (a, c) show the subdivision of the lithosphere into compositional
layers as based on P-wave seismic velocities (Mengel et
al., 1991; Wedepohl, 1995): granites and gneisses (upper crust) Vp<6.4-6.5
km/s; felsic granulites (middle crust) Vp~6.4-6.8 km/s; mafic granulites (lower
crust) Vp~6.8-7.2 km/s; pyroxenites and eclogite (lowermost crust) 7.2-7.6
km/s; spinel lherzolites and harzburgites (lithospheric mantle) Vp>7.8 km/s. For
data sources see Pavlenkova (1996), Artemieva et al. (2006), Ziegler and
Desez (2006), Artemieva (2007), Kelly et al. (2007), Artemieva and Thybo (2011).
Lower plots (b, d) show variations in mean P wave velocity in the basement
of the European crust (i.e. the crust without the sediments) based on seismic
data. Dashed lines refer to in situ conditions (as sampled by seismic methods)
and reflect variations in both crustal composition and average crustal
temperatures. Solid lines - Vp variations corrected for lateral temperature
variations in the crust (based on Artemieva, 2003; 2006), which reflect
variations in the average crustal composition and anisotropy (in case it is
present). Zero corresponds to average in situ Vp=6.6 km/s in a region with a
platform geotherm (surface heat flow ~55 mW/m2). TESZ= Trans-European
Suture Zone; DDR= Dnieper-Donets paleorift; NGB= North German basin.
(e) P-wave seismic velocity structure of the European Variscides and
Caledonides (North German Basin) along the profile DEKORP/ BASIN9601.
Seismic velocities are derived from wide-angle seismic data and shown in
relation to the line drawing of the seismic reflection data (based on Bayer et al.,
(a) Seismic lamellae in the lower crust in various tectonic provinces where
normal incidence and wide-angle observations are available (based
oncompilation of Meissner et al., 2006).
Four boxes refer to different tectonic settings:
(b) Typical temperatures in the lithosphere of different continental tectonic
structures (based on Artemieva and Mooney, 2001). Colors match the
corresponding structures in plot (a). Cold lithospheric temperatures in the
Tibet and the Alps are associated with subducting lithospheric slabs.
Gray shading approximately marks the depths where seismic reflectivity is
observed. As the plot illustrates, seismic reflectivity is commonly restricted to a
depth with temperatures between 300 and 500 oC