The Experts below are selected from a list of 3315 Experts worldwide ranked by ideXlab platform
Jean Sulem - One of the best experts on this subject based on the ideXlab platform.
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Thermal decomposition of carbonates in fault zones: slip-weakening and temperature limiting effects
Journal of Geophysical Research : Solid Earth, 2009Co-Authors: Jean SulemAbstract:During an earthquake, the heat generated by fault friction may be large enough to activate the devolatilization of minerals forming the fault rocks. In this paper, we model the mechanical effects of calcite thermal decomposition on the slip behavior of a fault zone during an earthquake. To do so, we introduce the coupled effects of calcite volume loss, heat consumption and CO2 production in the theoretical analysis of shear heating and thermal pressurization of pore fluids. We consider a rapidly deforming shear band consisting of a fluid saturated carbonate rock. The equations that govern the evolution of pore pressure and temperature inside the band and the mass of emitted CO2 are deduced from the mass and energy balance of the multi-phases saturated medium and from the kinetics of the chemical decomposition of calcite. Numerical simulation of seismic slip at depths of 5 – 8km show that Decarbonation has two critical consequences on fault slip. First, the endothermic reaction of calcite decomposition limits the coseismic temperature increase to less than ~800°C (corresponding to the initiation of the chemical reaction) inside the shear band. Second, the rapid emission of CO2 by Decarbonation significantly increases the slip-weakening effect of thermal pressurization. The pore pressure reaches a maximum and then decreases due to the reduction of solid volume, causing a re-strengthening of the shear stress. Our theoretical study shows, on the example of Decarbonation, that the thermal decomposition of minerals is an important slip-weakening process, and that a large part of the frictional heat of earthquakes may go into endothermic devolatilization reactions.
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Thermal decomposition of carbonates in fault zones: Slip-weakening and temperature-limiting effects
Journal of Geophysical Research, 2009Co-Authors: Jean Sulem, Vincent FaminAbstract:During an earthquake, the heat generated by fault friction may be large enough to activate the devolatilization of minerals forming the fault rocks. In this paper, we model the mechanical effects of calcite thermal decomposition on the slip behavior of a fault zone during an earthquake. To do so, we introduce the coupled effects of calcite volume loss, heat consumption, and CO 2 production in the theoretical analysis of shear heating and thermal pressurization of pore fluids. We consider a rapidly deforming shear band consisting of a fluid-saturated carbonate rock. The equations that govern the evolution of pore pressure and temperature inside the band and the mass of emitted CO 2 are deduced from the mass and energy balance of the multiphase-saturated medium and from the kinetics of the chemical decomposition of calcite. Numerical simulation of seismic slip at depths of 5 to 8 km show that Decarbonation has two critical consequences on fault slip. First, the endothermic reaction of calcite decomposition limits the coseismic temperature increase to less than ~800°C (corresponding to the initiation of the chemical reaction) inside the shear band. Second, the rapid emission of CO 2 by Decarbonation significantly increases the slip-weakening effect of thermal pressurization. The pore pressure reaches a maximum and then decreases due to the reduction of solid volume, causing a restrengthening of shear stress. Our theoretical study shows, on the example of Decarbonation, that the thermal decomposition of minerals is an important slip-weakening process and that a large part of the frictional heat of earthquakes may go into endothermic devolatilization reactions.
Weronika Gorczyk - One of the best experts on this subject based on the ideXlab platform.
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Decarbonation in an intracratonic setting: Insight from petrological–thermomechanical modeling†
Journal of Geophysical Research: Solid Earth, 2017Co-Authors: Christopher M. Gonzalez, Weronika GorczykAbstract:Cratons form the stable core roots of the continental crust. Despite long term stability, cratons have failed in the past. Cratonic destruction (e.g., North Atlantic craton) due to chemical rejuvenation at the base of the lithosphere remains poorly constrained numerically. We use 2D petrological–thermomechanical models to assess cratonic rifting characteristics and mantle CO2 degassing in the presence of a carbonated subcontinental lithospheric mantle (SCLM). We test two tectonothermal SCLM compositions: Archon (depleted) and Tecton (fertilized) using 2 CO2 wt.% in the bulk composition to represent a metasomatized SCLM. We parameterize cratonic breakup via extensional duration (7-12 Ma; full breakup), tectonothermal age, TMoho(300-600∘C), and crustal rheology. The two compositions with metasomatized SCLMs share similar rifting features and Decarbonation trends during initial extension. However, we show long-term (>67 Ma) stability differences due to lithospheric density contrasts between SCLM compositions. The Tecton model shows convective removal and thinning of the metasomatized SCLM during failed rifting. The Archon composition remained stable, highlighting the primary role for SCLM density even when metasomatized at its base. In the short-term, three failed rifting characteristics emerge: failed rifting without Decarbonation, failed rifting with Decarbonation, and semiâĂŞfailed rifting with dry asthenospheric melting and Decarbonation. Decarbonation trends were greatest in the failed rifts, reaching peak fluxes of 94x104 kg m−3. Increased TMoho did not alter the effects of rifting or Decarbonation. Lastly, we show mantle regions where Decarbonation, mantle melting in the presence of carbonate, and preservation of carbonated mantle occur during rifting.
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Decarbonation in an intracratonic setting insight from petrological thermomechanical modeling
Journal of Geophysical Research, 2017Co-Authors: Christopher M. Gonzalez, Weronika GorczykAbstract:Cratons form the stable core roots of the continental crust. Despite long term stability, cratons have failed in the past. Cratonic destruction (e.g., North Atlantic craton) due to chemical rejuvenation at the base of the lithosphere remains poorly constrained numerically. We use 2D petrological–thermomechanical models to assess cratonic rifting characteristics and mantle CO2 degassing in the presence of a carbonated subcontinental lithospheric mantle (SCLM). We test two tectonothermal SCLM compositions: Archon (depleted) and Tecton (fertilized) using 2 CO2 wt.% in the bulk composition to represent a metasomatized SCLM. We parameterize cratonic breakup via extensional duration (7-12 Ma; full breakup), tectonothermal age, TMoho(300-600∘C), and crustal rheology. The two compositions with metasomatized SCLMs share similar rifting features and Decarbonation trends during initial extension. However, we show long-term (>67 Ma) stability differences due to lithospheric density contrasts between SCLM compositions. The Tecton model shows convective removal and thinning of the metasomatized SCLM during failed rifting. The Archon composition remained stable, highlighting the primary role for SCLM density even when metasomatized at its base. In the short-term, three failed rifting characteristics emerge: failed rifting without Decarbonation, failed rifting with Decarbonation, and semiâĂŞfailed rifting with dry asthenospheric melting and Decarbonation. Decarbonation trends were greatest in the failed rifts, reaching peak fluxes of 94x104 kg m−3. Increased TMoho did not alter the effects of rifting or Decarbonation. Lastly, we show mantle regions where Decarbonation, mantle melting in the presence of carbonate, and preservation of carbonated mantle occur during rifting.
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Decarbonation of subducting slabs insight from petrological thermomechanical modeling
Gondwana Research, 2016Co-Authors: Christopher M. Gonzalez, Weronika Gorczyk, Taras GeryaAbstract:Abstract Subduction of heterogeneous lithologies (sediments and altered basalts) carries a mixture of volatile components (H 2 O ± CO 2 ) into the mantle, which are later mobilized during episodes of devolatilization and flux melting. Several petrologic and thermodynamic studies investigated CO 2 Decarbonation to better understand carbon cycling at convergent margins. A paradox arose when investigations showed little to no Decarbonation along present day subduction geotherms at subarc depths despite field based observations. Sediment diapirism is invoked as one of several methods for carbon transfer from the subducting slab. We employ high-resolution 2D petrological–thermomechanical modeling to elucidate the role subduction dynamics has with respect to slab Decarbonation and the sediment diapirism hypothesis. Our thermodynamic database is modified to account for H 2 O–CO 2 binary fluids via the following lithologies: GLOSS average sediments (H 2 O: 7.29 wt.% & CO 2 : 3.01 wt.%), carbonated altered basalts (H 2 O: 2.63 wt.% & CO 2 : 2.90 wt.%), and carbonated peridotites (H 2 O: 1.98 wt.% & CO 2 : 1.50 wt.%). We include a CO 2 solubility P–x[H 2 O wt.%] parameterization for sediment melts. We parameterize our model by varying two components: slab age (20, 40, 60, 80 Ma) and convergence velocity (1, 2, 3, 4, 5, 6 cm year − 1 ). 59 numerical models were run and show excellent agreement with the original code base. Three geodynamic regimes showed significant Decarbonation. 1) Sedimentary diapirism acts as an efficient physical mechanism for CO 2 removal from the slab as it advects into the hotter mantle wedge. 2) If subduction rates are slow, frictional coupling between the subducting and overriding plate occurs. Mafic crust is mechanically incorporated into a section of the lower crust and undergoes Decarbonation. 3) During extension and slab rollback, interaction between hot asthenosphere and sediments at shallow depths result in a small window (~ 12.5 Ma) of high integrated CO 2 fluxes (205 kg m − 3 Ma − 1 ).
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Decarbonation of subducting slabs: Insight from petrological–thermomechanical modeling
Gondwana Research, 2016Co-Authors: Christopher M. Gonzalez, Weronika Gorczyk, Taras GeryaAbstract:Abstract Subduction of heterogeneous lithologies (sediments and altered basalts) carries a mixture of volatile components (H 2 O ± CO 2 ) into the mantle, which are later mobilized during episodes of devolatilization and flux melting. Several petrologic and thermodynamic studies investigated CO 2 Decarbonation to better understand carbon cycling at convergent margins. A paradox arose when investigations showed little to no Decarbonation along present day subduction geotherms at subarc depths despite field based observations. Sediment diapirism is invoked as one of several methods for carbon transfer from the subducting slab. We employ high-resolution 2D petrological–thermomechanical modeling to elucidate the role subduction dynamics has with respect to slab Decarbonation and the sediment diapirism hypothesis. Our thermodynamic database is modified to account for H 2 O–CO 2 binary fluids via the following lithologies: GLOSS average sediments (H 2 O: 7.29 wt.% & CO 2 : 3.01 wt.%), carbonated altered basalts (H 2 O: 2.63 wt.% & CO 2 : 2.90 wt.%), and carbonated peridotites (H 2 O: 1.98 wt.% & CO 2 : 1.50 wt.%). We include a CO 2 solubility P–x[H 2 O wt.%] parameterization for sediment melts. We parameterize our model by varying two components: slab age (20, 40, 60, 80 Ma) and convergence velocity (1, 2, 3, 4, 5, 6 cm year − 1 ). 59 numerical models were run and show excellent agreement with the original code base. Three geodynamic regimes showed significant Decarbonation. 1) Sedimentary diapirism acts as an efficient physical mechanism for CO 2 removal from the slab as it advects into the hotter mantle wedge. 2) If subduction rates are slow, frictional coupling between the subducting and overriding plate occurs. Mafic crust is mechanically incorporated into a section of the lower crust and undergoes Decarbonation. 3) During extension and slab rollback, interaction between hot asthenosphere and sediments at shallow depths result in a small window (~ 12.5 Ma) of high integrated CO 2 fluxes (205 kg m − 3 Ma − 1 ).
Vincent Famin - One of the best experts on this subject based on the ideXlab platform.
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Thermal decomposition of carbonates in fault zones: Slip-weakening and temperature-limiting effects
Journal of Geophysical Research, 2009Co-Authors: Jean Sulem, Vincent FaminAbstract:During an earthquake, the heat generated by fault friction may be large enough to activate the devolatilization of minerals forming the fault rocks. In this paper, we model the mechanical effects of calcite thermal decomposition on the slip behavior of a fault zone during an earthquake. To do so, we introduce the coupled effects of calcite volume loss, heat consumption, and CO 2 production in the theoretical analysis of shear heating and thermal pressurization of pore fluids. We consider a rapidly deforming shear band consisting of a fluid-saturated carbonate rock. The equations that govern the evolution of pore pressure and temperature inside the band and the mass of emitted CO 2 are deduced from the mass and energy balance of the multiphase-saturated medium and from the kinetics of the chemical decomposition of calcite. Numerical simulation of seismic slip at depths of 5 to 8 km show that Decarbonation has two critical consequences on fault slip. First, the endothermic reaction of calcite decomposition limits the coseismic temperature increase to less than ~800°C (corresponding to the initiation of the chemical reaction) inside the shear band. Second, the rapid emission of CO 2 by Decarbonation significantly increases the slip-weakening effect of thermal pressurization. The pore pressure reaches a maximum and then decreases due to the reduction of solid volume, causing a restrengthening of shear stress. Our theoretical study shows, on the example of Decarbonation, that the thermal decomposition of minerals is an important slip-weakening process and that a large part of the frictional heat of earthquakes may go into endothermic devolatilization reactions.
Heriberto Pfeiffer - One of the best experts on this subject based on the ideXlab platform.
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thermogravimetric study of sequential carbonation and Decarbonation processes over na2zro3 at low temperatures 30 80 c relative humidity effect
RSC Advances, 2016Co-Authors: Arturo J Mendozanieto, Heriberto PfeifferAbstract:In the present work, Na2ZrO3 was synthetized via a solid-state reaction and characterized by powder X-ray diffraction and N2 physisorption techniques, where desired structural and microstructural characteristics were confirmed. Then, the ceramic material was tested dynamically and isothermally in a low temperature range (30–80 °C) for carbonation and Decarbonation processes using relative humidity (RH) values between 0 and 80%. Thermogravimetric results indicate that humidity has a positive influence over the carbonation process, thus the amount of CO2 captured increases as a function of relative humidity. When high values of humidity (70 and 80%) were used, the increase in sample weight was higher than the theoretical amount of 57.2 wt% expected in wet conditions. This result was attributed to the formation of NaHCO3 with a mesoporous microstructure. Then, the relative humidity effect was studied during the Decarbonation stage as a sequential step after the carbonation process, using a N2 flow. Infrared spectroscopy and thermogravimetric results showed that NaHCO3 decomposition took place in this process. At low RH values, 0 and 20%, NaHCO3 is decomposed in Na2O and Na2CO3; whereas, when RH was increased between 40 and 80%, only the presence of Na2CO3 was observed. This result indicates that at high humidity conditions the Na2O formation is avoided. Thermal curves show that Na2CO3 decomposition presented a maximum efficiency at 40% of RH, which seems to be the optimal condition for the Decarbonation step. Finally, sequential carbonation–Decarbonation tests were performed with sodium zirconate samples. Infrared and thermal analyses confirm that it is possible to accomplish successively at least eight cycles of carbonation and Decarbonation steps and to obtain high NaHCO3 and Na2CO3 regenerations.
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Thermogravimetric study of sequential carbonation and Decarbonation processes over Na2ZrO3 at low temperatures (30–80 °C): relative humidity effect
RSC Advances, 2016Co-Authors: J. Arturo Mendoza-nieto, Heriberto PfeifferAbstract:In the present work, Na2ZrO3 was synthetized via a solid-state reaction and characterized by powder X-ray diffraction and N2 physisorption techniques, where desired structural and microstructural characteristics were confirmed. Then, the ceramic material was tested dynamically and isothermally in a low temperature range (30–80 °C) for carbonation and Decarbonation processes using relative humidity (RH) values between 0 and 80%. Thermogravimetric results indicate that humidity has a positive influence over the carbonation process, thus the amount of CO2 captured increases as a function of relative humidity. When high values of humidity (70 and 80%) were used, the increase in sample weight was higher than the theoretical amount of 57.2 wt% expected in wet conditions. This result was attributed to the formation of NaHCO3 with a mesoporous microstructure. Then, the relative humidity effect was studied during the Decarbonation stage as a sequential step after the carbonation process, using a N2 flow. Infrared spectroscopy and thermogravimetric results showed that NaHCO3 decomposition took place in this process. At low RH values, 0 and 20%, NaHCO3 is decomposed in Na2O and Na2CO3; whereas, when RH was increased between 40 and 80%, only the presence of Na2CO3 was observed. This result indicates that at high humidity conditions the Na2O formation is avoided. Thermal curves show that Na2CO3 decomposition presented a maximum efficiency at 40% of RH, which seems to be the optimal condition for the Decarbonation step. Finally, sequential carbonation–Decarbonation tests were performed with sodium zirconate samples. Infrared and thermal analyses confirm that it is possible to accomplish successively at least eight cycles of carbonation and Decarbonation steps and to obtain high NaHCO3 and Na2CO3 regenerations.
Christopher M. Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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Decarbonation in an intracratonic setting: Insight from petrological–thermomechanical modeling†
Journal of Geophysical Research: Solid Earth, 2017Co-Authors: Christopher M. Gonzalez, Weronika GorczykAbstract:Cratons form the stable core roots of the continental crust. Despite long term stability, cratons have failed in the past. Cratonic destruction (e.g., North Atlantic craton) due to chemical rejuvenation at the base of the lithosphere remains poorly constrained numerically. We use 2D petrological–thermomechanical models to assess cratonic rifting characteristics and mantle CO2 degassing in the presence of a carbonated subcontinental lithospheric mantle (SCLM). We test two tectonothermal SCLM compositions: Archon (depleted) and Tecton (fertilized) using 2 CO2 wt.% in the bulk composition to represent a metasomatized SCLM. We parameterize cratonic breakup via extensional duration (7-12 Ma; full breakup), tectonothermal age, TMoho(300-600∘C), and crustal rheology. The two compositions with metasomatized SCLMs share similar rifting features and Decarbonation trends during initial extension. However, we show long-term (>67 Ma) stability differences due to lithospheric density contrasts between SCLM compositions. The Tecton model shows convective removal and thinning of the metasomatized SCLM during failed rifting. The Archon composition remained stable, highlighting the primary role for SCLM density even when metasomatized at its base. In the short-term, three failed rifting characteristics emerge: failed rifting without Decarbonation, failed rifting with Decarbonation, and semiâĂŞfailed rifting with dry asthenospheric melting and Decarbonation. Decarbonation trends were greatest in the failed rifts, reaching peak fluxes of 94x104 kg m−3. Increased TMoho did not alter the effects of rifting or Decarbonation. Lastly, we show mantle regions where Decarbonation, mantle melting in the presence of carbonate, and preservation of carbonated mantle occur during rifting.
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Decarbonation in an intracratonic setting insight from petrological thermomechanical modeling
Journal of Geophysical Research, 2017Co-Authors: Christopher M. Gonzalez, Weronika GorczykAbstract:Cratons form the stable core roots of the continental crust. Despite long term stability, cratons have failed in the past. Cratonic destruction (e.g., North Atlantic craton) due to chemical rejuvenation at the base of the lithosphere remains poorly constrained numerically. We use 2D petrological–thermomechanical models to assess cratonic rifting characteristics and mantle CO2 degassing in the presence of a carbonated subcontinental lithospheric mantle (SCLM). We test two tectonothermal SCLM compositions: Archon (depleted) and Tecton (fertilized) using 2 CO2 wt.% in the bulk composition to represent a metasomatized SCLM. We parameterize cratonic breakup via extensional duration (7-12 Ma; full breakup), tectonothermal age, TMoho(300-600∘C), and crustal rheology. The two compositions with metasomatized SCLMs share similar rifting features and Decarbonation trends during initial extension. However, we show long-term (>67 Ma) stability differences due to lithospheric density contrasts between SCLM compositions. The Tecton model shows convective removal and thinning of the metasomatized SCLM during failed rifting. The Archon composition remained stable, highlighting the primary role for SCLM density even when metasomatized at its base. In the short-term, three failed rifting characteristics emerge: failed rifting without Decarbonation, failed rifting with Decarbonation, and semiâĂŞfailed rifting with dry asthenospheric melting and Decarbonation. Decarbonation trends were greatest in the failed rifts, reaching peak fluxes of 94x104 kg m−3. Increased TMoho did not alter the effects of rifting or Decarbonation. Lastly, we show mantle regions where Decarbonation, mantle melting in the presence of carbonate, and preservation of carbonated mantle occur during rifting.
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Decarbonation of subducting slabs insight from petrological thermomechanical modeling
Gondwana Research, 2016Co-Authors: Christopher M. Gonzalez, Weronika Gorczyk, Taras GeryaAbstract:Abstract Subduction of heterogeneous lithologies (sediments and altered basalts) carries a mixture of volatile components (H 2 O ± CO 2 ) into the mantle, which are later mobilized during episodes of devolatilization and flux melting. Several petrologic and thermodynamic studies investigated CO 2 Decarbonation to better understand carbon cycling at convergent margins. A paradox arose when investigations showed little to no Decarbonation along present day subduction geotherms at subarc depths despite field based observations. Sediment diapirism is invoked as one of several methods for carbon transfer from the subducting slab. We employ high-resolution 2D petrological–thermomechanical modeling to elucidate the role subduction dynamics has with respect to slab Decarbonation and the sediment diapirism hypothesis. Our thermodynamic database is modified to account for H 2 O–CO 2 binary fluids via the following lithologies: GLOSS average sediments (H 2 O: 7.29 wt.% & CO 2 : 3.01 wt.%), carbonated altered basalts (H 2 O: 2.63 wt.% & CO 2 : 2.90 wt.%), and carbonated peridotites (H 2 O: 1.98 wt.% & CO 2 : 1.50 wt.%). We include a CO 2 solubility P–x[H 2 O wt.%] parameterization for sediment melts. We parameterize our model by varying two components: slab age (20, 40, 60, 80 Ma) and convergence velocity (1, 2, 3, 4, 5, 6 cm year − 1 ). 59 numerical models were run and show excellent agreement with the original code base. Three geodynamic regimes showed significant Decarbonation. 1) Sedimentary diapirism acts as an efficient physical mechanism for CO 2 removal from the slab as it advects into the hotter mantle wedge. 2) If subduction rates are slow, frictional coupling between the subducting and overriding plate occurs. Mafic crust is mechanically incorporated into a section of the lower crust and undergoes Decarbonation. 3) During extension and slab rollback, interaction between hot asthenosphere and sediments at shallow depths result in a small window (~ 12.5 Ma) of high integrated CO 2 fluxes (205 kg m − 3 Ma − 1 ).
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Decarbonation of subducting slabs: Insight from petrological–thermomechanical modeling
Gondwana Research, 2016Co-Authors: Christopher M. Gonzalez, Weronika Gorczyk, Taras GeryaAbstract:Abstract Subduction of heterogeneous lithologies (sediments and altered basalts) carries a mixture of volatile components (H 2 O ± CO 2 ) into the mantle, which are later mobilized during episodes of devolatilization and flux melting. Several petrologic and thermodynamic studies investigated CO 2 Decarbonation to better understand carbon cycling at convergent margins. A paradox arose when investigations showed little to no Decarbonation along present day subduction geotherms at subarc depths despite field based observations. Sediment diapirism is invoked as one of several methods for carbon transfer from the subducting slab. We employ high-resolution 2D petrological–thermomechanical modeling to elucidate the role subduction dynamics has with respect to slab Decarbonation and the sediment diapirism hypothesis. Our thermodynamic database is modified to account for H 2 O–CO 2 binary fluids via the following lithologies: GLOSS average sediments (H 2 O: 7.29 wt.% & CO 2 : 3.01 wt.%), carbonated altered basalts (H 2 O: 2.63 wt.% & CO 2 : 2.90 wt.%), and carbonated peridotites (H 2 O: 1.98 wt.% & CO 2 : 1.50 wt.%). We include a CO 2 solubility P–x[H 2 O wt.%] parameterization for sediment melts. We parameterize our model by varying two components: slab age (20, 40, 60, 80 Ma) and convergence velocity (1, 2, 3, 4, 5, 6 cm year − 1 ). 59 numerical models were run and show excellent agreement with the original code base. Three geodynamic regimes showed significant Decarbonation. 1) Sedimentary diapirism acts as an efficient physical mechanism for CO 2 removal from the slab as it advects into the hotter mantle wedge. 2) If subduction rates are slow, frictional coupling between the subducting and overriding plate occurs. Mafic crust is mechanically incorporated into a section of the lower crust and undergoes Decarbonation. 3) During extension and slab rollback, interaction between hot asthenosphere and sediments at shallow depths result in a small window (~ 12.5 Ma) of high integrated CO 2 fluxes (205 kg m − 3 Ma − 1 ).
