TY - JOUR A1 - Bousquet, Romain A1 - Goffe, B. A1 - Le Pichon, X. A1 - de Capitani, Christian A1 - Chopin, C. A1 - Henry, P. T1 - Subduction factory : 1. Theoretical mineralogy, densities, seismic wave speeds, and H2O contents Y1 - 2005 ER - TY - GEN A1 - Bousquet, Romain A1 - De Capitani, Christian A1 - Arcay, Diane T1 - Feedback of the metamorphic changes on the subducting processes T2 - Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society Y1 - 2006 U6 - https://doi.org/10.1016/j.gca.2006.06.228 SN - 0016-7037 VL - 70 IS - 18 SP - A62 EP - A62 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Arcay, Diane A1 - Doin, Marie Pierre A1 - Tric, Emmanuel A1 - Bousquet, Romain A1 - de Capitani, Christian T1 - Overriding plate thinning in subduction zones : localized convection induced by slab dehydration N2 - In subduction zones, many observations indicate that the backarc thermal state is particularly hot and that the upper lithosphere is thin, even if no recent extension episode has occurred. This might result from free thermal convection favored by low viscosities in the hydrated mantle wedge. We perform 2-D numerical experiments of the convective mantle wedge interaction with both the downgoing slab and the overriding plate to test this hypothesis, explore its physical mechanism, and assess its dependencies on some relevant rock properties. Water transfers across the subducting plate and the mantle wedge are explicitly modeled by including in the calculation realistic hydration/ dehydration reaction boundaries for a water-saturated mantle and oceanic crust. The rheology is non-Newtonian and temperature-, pressure-, and water content-dependent. For low strength reduction associated to water content, the upper plate is locally thinned by an enhanced corner flow. For larger strength reductions, small convection cells rapidly thin the upper plate ( in less than 15 Myr) over the area in the overriding lithosphere hydrated by slab-derived water fluxes. As a result, the thinned region location depends on the subducting plate thermal state, and it increases with high convergence rates and low subduction dip angles. Other simulations are performed to test the sole effect of hydrous rock weakening on the upper plate/mantle convective interaction. They show that the thinning process is not influenced by the corner flow, but develops at the favor of a decoupling level induced by the formation of hydroxylated minerals inside the hydrated lithosphere. The erosion mechanism identified in these simulations allows us to explain the characteristic duration of erosion as a function of the hydrous strength reduction. We find that the presence of amphibole in the upper lithosphere in significant proportions is required down to a temperature of about 980 degrees C, corresponding to an initial depth of similar to 70 km, to strongly decrease the strength of the base of the lithosphere and trigger a rapid erosion (< 15 Myr). Y1 - 2006 UR - http://g-cubed.org/ U6 - https://doi.org/10.1029/2005gc001061 SN - 1525-2027 ER - TY - JOUR A1 - Düsterhöft, Erik A1 - de Capitani, Christian T1 - Theriak_D - an add-on to implement equilibrium computations in geodynamic models JF - Geochemistry, geophysics, geosystems N2 - This study presents the theory, applicability, and merits of the new THERIAK_D add-on for the open source Theriak/Domino software package. The add-on works as an interface between Theriak and user-generated scripts, providing the opportunity to process phase equilibrium computation parameters in a programming environment (e. g., C or MATLABV (R)). THERIAK_D supports a wide range of features such as calculating the solid rock density or testing the stability of mineral phases along any pressure-temperature (P-T) path and P-T grid. To demonstrate applicability, an example is given in which the solid rock density of a 2-D-temperature-pressure field is calculated, portraying a simplified subduction zone. Consequently, the add-on effectively combines thermodynamics and geodynamic modeling. The carefully documented examples could be easily adapted for a broad range of applications. THERIAK_D is free, and the program, user manual, and source codes may be downloaded from http://www.min.unikiel.de/similar to ed/theriakd/. KW - geodynamic modeling KW - thermodynamic modeling KW - Theriak/Domino KW - equilibrium assemblage KW - software Y1 - 2013 U6 - https://doi.org/10.1002/ggge.20286 SN - 1525-2027 VL - 14 IS - 11 SP - 4962 EP - 4967 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Duesterhoeft, Erik A1 - Quinteros, Javier A1 - Oberhänsli, Roland A1 - Bousquet, Romain A1 - de Capitani, Christian T1 - Relative impact of mantle densification and eclogitization of slabs on subduction dynamics: A numerical thermodynamic/thermokinematic investigation of metamorphic density evolution JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - Understanding the relationships between density and spatio-thermal variations at convergent plate boundaries is important for deciphering the present-day dynamics and evolution of subduction zones. In particular, the interaction between densification due to mineralogical phase transitions and slab pull forces is subject to ongoing investigations. We have developed a two-dimensional subduction zone model that is based on thermodynamic equilibrium assemblage calculations and includes the effects of melting processes on the density distribution in the lithosphere. Our model calculates the "metamorphic density" of rocks as a function of pressure, temperature and chemical composition in a subduction zone down to 250 km. We have used this model to show how the hydration, dehydration, partial melting and fractionation processes of rocks all influence the metamorphic density and greatly depend on the temperature field within the subduction system. These processes are largely neglected by other approaches that reproduce the density distribution within this complex tectonic setting. Our model demonstrates that the initiation of edogitization (i.e., when crustal rocks reach higher densities than the ambient mantle) of the slab is not the only significant process that makes the descending slab denser and generates the slab pull force. Instead, the densification of the lithospheric mantle of the sinking slab starts earlier than eclogitization and contributes significantly to slab pull in the early stages of subduction. Accordingly, the complex metamorphic structure of the slab and the mantle wedge has an important impact on the development of subduction zones. (C) 2014 Elsevier B.V. All rights reserved. KW - Density KW - Melt KW - Metamorphism KW - Subduction KW - Thermodynamic modeling KW - Thermo-mechanical modeling Y1 - 2014 U6 - https://doi.org/10.1016/j.tecto.2014.09.009 SN - 0040-1951 SN - 1879-3266 VL - 637 SP - 20 EP - 29 PB - Elsevier CY - Amsterdam ER -