In studying the petrogenesis of intra-plate ocean island basalts(OIB) associated with hotspots or mantle plumes, we hypothesized that the two large-low-shear-wave-velocity provinces(LLSVPs) at the base of the mantle b...In studying the petrogenesis of intra-plate ocean island basalts(OIB) associated with hotspots or mantle plumes, we hypothesized that the two large-low-shear-wave-velocity provinces(LLSVPs) at the base of the mantle beneath the Pacific(Jason) and Africa(Tuzo) are piles of subducted ocean crust(SOC)accumulated over Earth's history. This hypothesis was formulated using petrology, geochemistry and mineral physics in the context of plate tectonics and mantle circulation. Because the current debate on the origin of the LLSVPs is limited to the geophysical community and modelling discipline and because it is apparent that such debate cannot be resolved without considering relevant petrological and geochemical information, it is my motivation here to objectively discuss such information in a readily accessible manner with new perspectives in light of most recent discoveries. The hypothesis has the following elements:(1) subduction of the ocean crust of basaltic composition to the lower mantle is irreversible because(2) SOC is denser than the ambience of peridotitic composition under lower mantle conditions in both solid state and liquid form;(3) this understanding differs from the widespread view that OIB come from ancient SOC that returns from the lower mantle by mantle plumes, but is fully consistent with the understanding that OIB is not derived from SOC because SOC is chemically and isotopically too depleted to meet the requirement for any known OIB suite on Earth;(4) SOC is thus the best candidate for the LLSVPs, which are, in turn, the permanent graveyard of SOC;(5) the LLSVPs act as thermal insulators, making core-heating induced mantle diapirs or plumes initiated at their edges, which explains why the large igneous provinces(LIPs) are associated with the edges of the LLSVPs;(6) the antipodal positioning of Jason and Tuzo represents the optimal momentum of inertia, which explains why the LLSVPs are stable in the spinning Earth.展开更多
Paleogeography can be reconstructed using various crust-or mantle-based reference frames that make fundamentally different assumptions.The various reconstruction models differ significantly in continental paleolongitu...Paleogeography can be reconstructed using various crust-or mantle-based reference frames that make fundamentally different assumptions.The various reconstruction models differ significantly in continental paleolongitude,but it has been difficult to assess which models are more valid.We suggest here a "LLSVP test",where an assumed correlation between present-day large low velocity shear-wave provinces and the paleogeography of supercontinent Pangea at breakup ca.200 million years ago can be used to assess the relative accuracy of published reconstructions.Closest correlations between continental paleolongitude and the African LLSVP are achieved with mantle-based reference frames(moving hotspots and true polar wander),whereas shallower crustbased reference frames are shown to be invalid.The relative success of mantle-based frames,and thus the importance of the depth of reference frame,supports the notion that mantle convection is largely vertical compared to the horizontal plate motion of tectonics.展开更多
The Dupal anomaly has attracted widespread attention since being discovered and is regarded as the most direct manifestation of mantle inhomogeneity at present. From the initially defined anomalies limited to the sout...The Dupal anomaly has attracted widespread attention since being discovered and is regarded as the most direct manifestation of mantle inhomogeneity at present. From the initially defined anomalies limited to the southern hemisphere to the global scale, the criteria for identifying anomalies defined by Pb isotopes have also been adjusted, providing an important method and reference for the study of the mantle evolution. Pearce and Peate(1995) proposed the method of NdHf isotope and element ratio to identify the Dupal anomaly. The Nd-Hf method also offers a possible way to discriminate the mantle region of arc magmatism through the correction of Nd in the subduction process. This paper introduces the concepts and determination methods of the Dupal anomaly, and reports new Hf isotopic data of MORB-type rocks with Dupal signature in the several Tethys ophiolites. Our results of Nd-Hf method are in good agreement with those of previous Pb isotope identification. Moreover, origins and their controversy of Dupal anomaly are reviewed, and possible internal connections between Dupal anomalies and the two Large Low Shear Velocity Provinces(LLSVPs) in the lower mantle are discussed in depth. Further studies on origin and evolution of the Dupal anomaly are suggested, especially using integrated approach of Hf-Nd and Pb isotopes.展开更多
A compilation of 178 more precise ages on 10 potential Large Igneous Provinces(LIPs)across southern Africa,is compared to Earth’s supercontinental cycles,where 5 more prominent LIP-events all formed during the assemb...A compilation of 178 more precise ages on 10 potential Large Igneous Provinces(LIPs)across southern Africa,is compared to Earth’s supercontinental cycles,where 5 more prominent LIP-events all formed during the assembly of supercontinents,rather than during breakup.This temporal bias is confirmed by a focused review of field relationships,where these syn-assembly LIPs formed behind active continental arcs;whereas,the remaining postassembly-and likely breakup-related-LIPs never share such associations.Exploring the possibility of two radically different LIP-types,only the two younger breakup events(the Karoo LIP and Gannakouriep Suite)produced basalts with more enriched asthenospheric OIB-signatures;whereas,all assembly LIPs produced basalts with stronger lithospheric,as well as more or less primitive asthenospheric,signatures.A counterintuitive observation of Precambrian breakup LIPs outcropping as smaller fragments that are more peripherally located along craton margins,compared to assembly LIPs as well as the Phanerozoic Karoo breakup LIP,is explained by different preservation potentials during subsequent supercontinental cycles.Thus,further accentuating radical differences between(1)breakup LIPs,preferentially intruding along what evolves to become volcanic rifted margins that are more susceptible to deformation within subsequent orogens,and(2)assembly LIPs,typically emplaced along backarc rifts within more protected cratonic interiors.A conditioned duality is proposed,where assembly LIPs are primarily sustained by thermal blanketing(as well as local arc hydration and rifting)below assembling supercontinents and breakup LIPs more typically form above impinging mantle plumes.Such a duality is further related to an overall dynamic Earth model whereby predominantly supercontinent-orientated ocean lithospheric subduction establishes/revitalizes large low shear velocity provinces(LLSVPs)during assembly LIP-activity,and heating of such LLSVPs by the Earth’s core subsequently leads to a derivation of mantle plumes during supercontinental breakup.展开更多
Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes.Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been ...Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes.Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been suggested to explain the space-time distribution of magmatism in east Africa.We devise paleogeographically constrained global models of mantle convection and,based on the evolution of flow in the deepest lower mantle,show that the Afar plume migrated southward throughout its lifetime.The models suggest that the mobile Afar plume provides a dynamically consistent explanation for the spatial extent of the southward propagation of the east African rift system(EARS),which is difficult to explain by the northeastward migration of Africa over one or more fixed plumes alone,over the last≈45 Myr.We further show that the age-progression of volcanism associated with the southward propagation of EARS is consistent with the apparent surface hotspot motion that results from southward motion of the modelled Afar plume beneath the northeastward migrating African plate.The models suggest that the Afar plume became weaker as it migrated southwards,consistent with trends observed in the geochemical record.展开更多
Mantle heterogeneity has revealed systematic differences in Pb isotopic compositions between the Indian OceanSouth Atlantic mantle in the Southern Hemisphere and the Pacific Ocean-North Atlantic mantle in the Northern...Mantle heterogeneity has revealed systematic differences in Pb isotopic compositions between the Indian OceanSouth Atlantic mantle in the Southern Hemisphere and the Pacific Ocean-North Atlantic mantle in the Northern Hemisphere.This large-scale difference in mantle isotopes in the Southern Hemisphere is known as the DUPAL anomaly,but its origin remains controversial.Based on a systematic review of the Nd-Pb isotopic evolution of the Tethyan mantle domain,this study identified the long-term presence of the DUPAL anomaly in this domain since the early Paleozoic,characterized by long-term and high mantle thorium/uranium(Th/U)ratios.By comparing the Nd-Pb isotopic compositions of the Tethyan mantle domain with the Panthalassic-Pacific mantle domain(the Paleo-Asian,Paleo-Pacific,and modern Pacific oceans),it is shown that the mantle initially had low Th/U features due to early Earth crust-mantle differentiation,with the crust having high Th/U ratios.As such,the mantle initially had uniformly low Th/U ratios that were inherited throughout the Panthalassic-Pacific mantle domain.However,the plate tectonics and continental collisions in the Tethyan domain affected its characteristics,leading to the long-term and large-scale DUPAL anomaly.During the opening of and subduction in the Tethys Ocean,Gondwanaland fragmentation and frequent continent-continent collisions led to long-term and extensive crust-mantle interactions and the continuous input of highTh/U mantle sources,which thus modified the mantle.This process formed not only the unique DUPAL anomaly in the Tethyan mantle domain,but also the Tethyan tectonic domain dominated by continental collisions.Moreover,the high DUPAL anomaly in the Proto-and Paleo-Tethyan mantle domains records the effects of mantle plumes,which might have occurred primarily during the formation of the Proto-and Paleo-Tethys oceans during the early evolution of the Tethyan domain.Therefore,the inherent coupling of mantle domain properties and plate tectonic mechanisms provides important insights for understanding plate tectonics and geodynamic processes in the Tethyan domain.展开更多
Thermal conductivity plays an important role in the thermochemical evolution of Earth’s mantle.Recent mineral physics studies suggest that the thermal conductivity of the mantle varies with pressure and composition,a...Thermal conductivity plays an important role in the thermochemical evolution of Earth’s mantle.Recent mineral physics studies suggest that the thermal conductivity of the mantle varies with pressure and composition,and this may play an important role in the evolution of the Earth’s mantle.Meanwhile,the rheology of the deep mantle is also supposed to be composition-dependent.However,the dynamic influences of these factors remain not well understood.In this study,we performed numerical experiments of thermochemical mantle convection in 2-D spherical annulus geometry to systematically investigate the effects of depth-and composition-dependent thermal conductivity and the compositional viscosity ratio on the long-term evolution of the large thermochemical structure of primordial material in Earth’s mantle.Our results show that increasing the depth-dependent thermal conductivity leads to a larger core-mantle boundary(CMB)heat flow and allows the formation of more stable large thermochemical piles(e.g.,Large Low Shear Velocity Provinces,LLSVPs);while decreasing the composition-dependent thermal conductivity would slightly destabilize the primordial thermochemical piles,increase the altitude of these piles and the temperature differences between the piles and the ambient mantle.If the primordial mantle material is compositionally more viscous(e.g.,20 times than that of the ambient mantle),the long-term stability of the thermochemical piles of primordial material decreases,and this destabilizing effect will be enhanced by decreasing the composition-dependent thermal conductivity.As a result,the thermochemical piles would be unstable in the core-mantle boundary region.Therefore,our study indicates that the combined effects of depth-and composition-dependent thermal conductivity and compositional viscosity ratio are pronounced to the thermochemical evolution of the mantle.展开更多
Seismic tomography observations have shown that there are two large low shear velocity provinces(LLSVPs)above the core-mantle boundary beneath Africa and the Pacific.The thermal and compositional properties of these t...Seismic tomography observations have shown that there are two large low shear velocity provinces(LLSVPs)above the core-mantle boundary beneath Africa and the Pacific.The thermal and compositional properties of these two LLSVPs may differ from those of the ambient mantle,and they are suggested to be thermochemical piles of primordial material in the lower mantle.Their evolution is of great importance to our understanding of mantle dynamics.In this study,we systematically conducted numerical experiments to investigate the effects of the buoyancy ratio(B),compositional viscosity ratio(Δη_(c)),and heat-producing ratio(Λ)of the primordial material on the long-term evolution of thermochemical piles.Our results show that the buoyancy ratio plays the most important role in the stability of these piles.When the buoyancy ratio is small,and the primordial material is enriched in heat-producing elements(Λ>1),the stability of these piles decreases with increasing compositional viscosity ratio or heat-producing ratio.For cases with homogeneous heat production(Λ=1),the stability of these piles increases with increasingΔηc.We further compare constant internal heating with radioactive decay internal heating,and find that the longterm stability of thermochemical piles slightly decreases with radioactive decay heating,but the overall differences between these two internal heating modes are relatively small.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41630968, 41130314 and 91014003)the National Natural Science Foundation of Chinae Shandong (Grant No. U1606401)+2 种基金Qingdao National Laboratory for Marine Science and Technology (Grant No. 2015ASKJ03)grants from regional and local authorities (Shandong Province and City of Qingdao), Chinese Academy of Sciences (Innovation Grant No. Y42217101L)China University of Geosciences (Beijing)
文摘In studying the petrogenesis of intra-plate ocean island basalts(OIB) associated with hotspots or mantle plumes, we hypothesized that the two large-low-shear-wave-velocity provinces(LLSVPs) at the base of the mantle beneath the Pacific(Jason) and Africa(Tuzo) are piles of subducted ocean crust(SOC)accumulated over Earth's history. This hypothesis was formulated using petrology, geochemistry and mineral physics in the context of plate tectonics and mantle circulation. Because the current debate on the origin of the LLSVPs is limited to the geophysical community and modelling discipline and because it is apparent that such debate cannot be resolved without considering relevant petrological and geochemical information, it is my motivation here to objectively discuss such information in a readily accessible manner with new perspectives in light of most recent discoveries. The hypothesis has the following elements:(1) subduction of the ocean crust of basaltic composition to the lower mantle is irreversible because(2) SOC is denser than the ambience of peridotitic composition under lower mantle conditions in both solid state and liquid form;(3) this understanding differs from the widespread view that OIB come from ancient SOC that returns from the lower mantle by mantle plumes, but is fully consistent with the understanding that OIB is not derived from SOC because SOC is chemically and isotopically too depleted to meet the requirement for any known OIB suite on Earth;(4) SOC is thus the best candidate for the LLSVPs, which are, in turn, the permanent graveyard of SOC;(5) the LLSVPs act as thermal insulators, making core-heating induced mantle diapirs or plumes initiated at their edges, which explains why the large igneous provinces(LIPs) are associated with the edges of the LLSVPs;(6) the antipodal positioning of Jason and Tuzo represents the optimal momentum of inertia, which explains why the LLSVPs are stable in the spinning Earth.
基金This work was supported by the Australian Research Council Laureate Fellowship grant to Z.X.L.(FL150100133)the Key Research Program of the Institute of Geology & Geophysics,CAS,grant to R.N.M.(No. IGGCAS-201905)
文摘Paleogeography can be reconstructed using various crust-or mantle-based reference frames that make fundamentally different assumptions.The various reconstruction models differ significantly in continental paleolongitude,but it has been difficult to assess which models are more valid.We suggest here a "LLSVP test",where an assumed correlation between present-day large low velocity shear-wave provinces and the paleogeography of supercontinent Pangea at breakup ca.200 million years ago can be used to assess the relative accuracy of published reconstructions.Closest correlations between continental paleolongitude and the African LLSVP are achieved with mantle-based reference frames(moving hotspots and true polar wander),whereas shallower crustbased reference frames are shown to be invalid.The relative success of mantle-based frames,and thus the importance of the depth of reference frame,supports the notion that mantle convection is largely vertical compared to the horizontal plate motion of tectonics.
基金funded by the National Key Research and Development Project of China (Project 2020YFA0714800)。
文摘The Dupal anomaly has attracted widespread attention since being discovered and is regarded as the most direct manifestation of mantle inhomogeneity at present. From the initially defined anomalies limited to the southern hemisphere to the global scale, the criteria for identifying anomalies defined by Pb isotopes have also been adjusted, providing an important method and reference for the study of the mantle evolution. Pearce and Peate(1995) proposed the method of NdHf isotope and element ratio to identify the Dupal anomaly. The Nd-Hf method also offers a possible way to discriminate the mantle region of arc magmatism through the correction of Nd in the subduction process. This paper introduces the concepts and determination methods of the Dupal anomaly, and reports new Hf isotopic data of MORB-type rocks with Dupal signature in the several Tethys ophiolites. Our results of Nd-Hf method are in good agreement with those of previous Pb isotope identification. Moreover, origins and their controversy of Dupal anomaly are reviewed, and possible internal connections between Dupal anomalies and the two Large Low Shear Velocity Provinces(LLSVPs) in the lower mantle are discussed in depth. Further studies on origin and evolution of the Dupal anomaly are suggested, especially using integrated approach of Hf-Nd and Pb isotopes.
基金supported by South Africa’s National Research Foundation。
文摘A compilation of 178 more precise ages on 10 potential Large Igneous Provinces(LIPs)across southern Africa,is compared to Earth’s supercontinental cycles,where 5 more prominent LIP-events all formed during the assembly of supercontinents,rather than during breakup.This temporal bias is confirmed by a focused review of field relationships,where these syn-assembly LIPs formed behind active continental arcs;whereas,the remaining postassembly-and likely breakup-related-LIPs never share such associations.Exploring the possibility of two radically different LIP-types,only the two younger breakup events(the Karoo LIP and Gannakouriep Suite)produced basalts with more enriched asthenospheric OIB-signatures;whereas,all assembly LIPs produced basalts with stronger lithospheric,as well as more or less primitive asthenospheric,signatures.A counterintuitive observation of Precambrian breakup LIPs outcropping as smaller fragments that are more peripherally located along craton margins,compared to assembly LIPs as well as the Phanerozoic Karoo breakup LIP,is explained by different preservation potentials during subsequent supercontinental cycles.Thus,further accentuating radical differences between(1)breakup LIPs,preferentially intruding along what evolves to become volcanic rifted margins that are more susceptible to deformation within subsequent orogens,and(2)assembly LIPs,typically emplaced along backarc rifts within more protected cratonic interiors.A conditioned duality is proposed,where assembly LIPs are primarily sustained by thermal blanketing(as well as local arc hydration and rifting)below assembling supercontinents and breakup LIPs more typically form above impinging mantle plumes.Such a duality is further related to an overall dynamic Earth model whereby predominantly supercontinent-orientated ocean lithospheric subduction establishes/revitalizes large low shear velocity provinces(LLSVPs)during assembly LIP-activity,and heating of such LLSVPs by the Earth’s core subsequently leads to a derivation of mantle plumes during supercontinental breakup.
基金supported by ARC grants IH130200012 and DP130101946supported by the National Science Foundation under award EAR-1645775undertaken with the assistance of resources from the National Computational Infrastructure(NCI),which is supported by the Australian Government。
文摘Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes.Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been suggested to explain the space-time distribution of magmatism in east Africa.We devise paleogeographically constrained global models of mantle convection and,based on the evolution of flow in the deepest lower mantle,show that the Afar plume migrated southward throughout its lifetime.The models suggest that the mobile Afar plume provides a dynamically consistent explanation for the spatial extent of the southward propagation of the east African rift system(EARS),which is difficult to explain by the northeastward migration of Africa over one or more fixed plumes alone,over the last≈45 Myr.We further show that the age-progression of volcanism associated with the southward propagation of EARS is consistent with the apparent surface hotspot motion that results from southward motion of the modelled Afar plume beneath the northeastward migrating African plate.The models suggest that the Afar plume became weaker as it migrated southwards,consistent with trends observed in the geochemical record.
基金supported by the National Natural Science Foundation of China (Grant No. 92055208)the Guangxi Science Innovation Base Construction Foundation (Grant No. GuikeZY21195031)+2 种基金the Fifth Bagui Scholar Innovation Project of Guangxi Province (to Xu Jifeng)the Xinjiang Tianchi Distinguished Expert grant awarded to Xijun LIUthe Guangxi Key Mineral Resources Deep Exploration Talent Highland
文摘Mantle heterogeneity has revealed systematic differences in Pb isotopic compositions between the Indian OceanSouth Atlantic mantle in the Southern Hemisphere and the Pacific Ocean-North Atlantic mantle in the Northern Hemisphere.This large-scale difference in mantle isotopes in the Southern Hemisphere is known as the DUPAL anomaly,but its origin remains controversial.Based on a systematic review of the Nd-Pb isotopic evolution of the Tethyan mantle domain,this study identified the long-term presence of the DUPAL anomaly in this domain since the early Paleozoic,characterized by long-term and high mantle thorium/uranium(Th/U)ratios.By comparing the Nd-Pb isotopic compositions of the Tethyan mantle domain with the Panthalassic-Pacific mantle domain(the Paleo-Asian,Paleo-Pacific,and modern Pacific oceans),it is shown that the mantle initially had low Th/U features due to early Earth crust-mantle differentiation,with the crust having high Th/U ratios.As such,the mantle initially had uniformly low Th/U ratios that were inherited throughout the Panthalassic-Pacific mantle domain.However,the plate tectonics and continental collisions in the Tethyan domain affected its characteristics,leading to the long-term and large-scale DUPAL anomaly.During the opening of and subduction in the Tethys Ocean,Gondwanaland fragmentation and frequent continent-continent collisions led to long-term and extensive crust-mantle interactions and the continuous input of highTh/U mantle sources,which thus modified the mantle.This process formed not only the unique DUPAL anomaly in the Tethyan mantle domain,but also the Tethyan tectonic domain dominated by continental collisions.Moreover,the high DUPAL anomaly in the Proto-and Paleo-Tethyan mantle domains records the effects of mantle plumes,which might have occurred primarily during the formation of the Proto-and Paleo-Tethys oceans during the early evolution of the Tethyan domain.Therefore,the inherent coupling of mantle domain properties and plate tectonic mechanisms provides important insights for understanding plate tectonics and geodynamic processes in the Tethyan domain.
基金supported by the National Natural Science Foundation of China(Grant No.41888101)the International Partnership Program of Chinese Academy of Sciences(Grant Nos.132A11KYSB20200019,GJHZ1776)+1 种基金the Key Research Program of the Institute of Geology and Geophysics CAS(Grant Nos.IGGCAS-201904,IGGCAS-202204)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.311021003)。
文摘Thermal conductivity plays an important role in the thermochemical evolution of Earth’s mantle.Recent mineral physics studies suggest that the thermal conductivity of the mantle varies with pressure and composition,and this may play an important role in the evolution of the Earth’s mantle.Meanwhile,the rheology of the deep mantle is also supposed to be composition-dependent.However,the dynamic influences of these factors remain not well understood.In this study,we performed numerical experiments of thermochemical mantle convection in 2-D spherical annulus geometry to systematically investigate the effects of depth-and composition-dependent thermal conductivity and the compositional viscosity ratio on the long-term evolution of the large thermochemical structure of primordial material in Earth’s mantle.Our results show that increasing the depth-dependent thermal conductivity leads to a larger core-mantle boundary(CMB)heat flow and allows the formation of more stable large thermochemical piles(e.g.,Large Low Shear Velocity Provinces,LLSVPs);while decreasing the composition-dependent thermal conductivity would slightly destabilize the primordial thermochemical piles,increase the altitude of these piles and the temperature differences between the piles and the ambient mantle.If the primordial mantle material is compositionally more viscous(e.g.,20 times than that of the ambient mantle),the long-term stability of the thermochemical piles of primordial material decreases,and this destabilizing effect will be enhanced by decreasing the composition-dependent thermal conductivity.As a result,the thermochemical piles would be unstable in the core-mantle boundary region.Therefore,our study indicates that the combined effects of depth-and composition-dependent thermal conductivity and compositional viscosity ratio are pronounced to the thermochemical evolution of the mantle.
基金supported by the National Natural Science Foundation of China(Grant Nos.41888101,41625016)the International Partnership Program of Chinese Academy of Sciences(Grant No.132A11KYSB20200019)+2 种基金the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.311021003)the Key Research Program of the Institute of Geology and Geophysics CAS(Grant No.IGGCAS-201904)the Pioneer Hundred Talents Program of Chinese Academy of Sciences.
文摘Seismic tomography observations have shown that there are two large low shear velocity provinces(LLSVPs)above the core-mantle boundary beneath Africa and the Pacific.The thermal and compositional properties of these two LLSVPs may differ from those of the ambient mantle,and they are suggested to be thermochemical piles of primordial material in the lower mantle.Their evolution is of great importance to our understanding of mantle dynamics.In this study,we systematically conducted numerical experiments to investigate the effects of the buoyancy ratio(B),compositional viscosity ratio(Δη_(c)),and heat-producing ratio(Λ)of the primordial material on the long-term evolution of thermochemical piles.Our results show that the buoyancy ratio plays the most important role in the stability of these piles.When the buoyancy ratio is small,and the primordial material is enriched in heat-producing elements(Λ>1),the stability of these piles decreases with increasing compositional viscosity ratio or heat-producing ratio.For cases with homogeneous heat production(Λ=1),the stability of these piles increases with increasingΔηc.We further compare constant internal heating with radioactive decay internal heating,and find that the longterm stability of thermochemical piles slightly decreases with radioactive decay heating,but the overall differences between these two internal heating modes are relatively small.
