The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic...The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic field polarity reversals,the oceanic lithosphere has significant remanent magnetization,which causes magnetic anomaly stripes parallel to the mid-ocean ridges.However,it is difficult to construct a high-resolution lithospheric magnetic field model in oceanic regions with relatively sparse data or no data.Using forward calculated lithospheric magnetic field data based on an oceanic remanent magnetization(ORM) model with physical and geological foundations as a supplement is a feasible approach.We first collect the latest available oceanic crust age grid,plate motion model,geomagnetic polarity timescale,and oceanic lithosphere thermal structure.Combining the assumptions that the paleo geomagnetic field is a geocentric axial dipole field and that the normal oceanic crust moves only in the horizontal direction,we construct a vertically integrated ORM model of the normal oceanic crust with a known age,including the intensity,inclination,and declination.Both the ORM model and the global induced magnetization(GIM) model are then scaled from two aspects between their forward calculated results and the lithospheric magnetic field model LCS-1.One aspect is the difference in their spherical harmonic power spectra,and the other is the misfit between the grid data over the oceans.We last compare the forward calculated lithospheric magnetic anomaly from the scaled ORM and GIM models with the Macao Science Satellite-1(MSS-1) observed data.The comparison results show that the magnetic anomalies over the normal oceanic crust regions at satellite altitude are mainly contributed by the high-intensity remanent magnetization corresponding to the Cretaceous magnetic quiet period.In these regions,the predicted and observed anomalies show good consistency in spatial distribution,whereas their amplitude differences vary across regions.This result suggests that regional ORM construction should be attempted in future work to address these amplitude discrepancies.展开更多
A subducted continental slab is sometimes torn during collision,yet the exact impact of slab-tearing on the overlying lithosphere remains unclear.Here,we image the structure and architecture of the Asian lithosphere a...A subducted continental slab is sometimes torn during collision,yet the exact impact of slab-tearing on the overlying lithosphere remains unclear.Here,we image the structure and architecture of the Asian lithosphere above the Indian slab in the eastern Tibetan Plateau using multiscale seismic tomography models and zircon Hf isotopic mapping,respectively.Our mantle V_(p)model shows that a large low-velocity anomaly extends laterally beneath the thinned Asian lithosphere above the tear zone roughly along the 26°N.The V_(s)images,magmatic records and Hf isotopic mapping indicate that this low-velocity anomaly recorded an asthenosphere flow eastward along the tear zone,which thermally eroded and refertilized the overlying Asian lithosphere,leading to the lithospheric melting,thinning and root delaminating.The vertical tear also generated a tectonic weak zone with associated Cenozoic potassic and carbonatitic magma suites.We argue that such a hot lithosphere discontinuity provided a reasonable mechanism for the abrupt change of crust thickness and the transformation of crust-mantle deformation from coupling to decoupling across the tear zone.展开更多
As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal vari...As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal variations in the lithosphere.Traditional approaches either do not consider the non-axial dipolar terms of the inducing field and its radial variation or do so by means of complicated formulae.Moreover,existing methods treat the magnetic lithosphere either as an infinitesimally thin layer or as a radially uniform spherical shell of constant thickness.Here,we present alternative forward formulae that account for an arbitrarily high maximum degree of the inducing field and for a magnetic lithosphere of variable thickness.Our simulations based on these formulae suggest that the satellite magnetic anomaly field is sensitive to the non-axial dipolar terms of the inducing field but not to its radial variation.Therefore,in forward and inverse calculations of satellite magnetic anomaly data,the non-axial dipolar terms of the inducing field should not be ignored.Furthermore,our results show that the satellite magnetic anomaly field is sensitive to variability in the lateral thickness of the magnetized shell.In particular,we show that for a given vertically integrated susceptibility distribution,underestimating the thickness of the magnetic layer overestimates the induced magnetic field.This discovery bridges the greatest part of the alleged gap between the susceptibility values measured from rock samples and the susceptibility values required to match the observed magnetic field signal.We expect the formulae and conclusions of this study to be a valuable tool for the quantitative interpretation of the Earth's global lithospheric magnetic field,through an inverse or forward modelling approach.展开更多
Subducting slabs transport carbon to deep mantle depths and release it into the overlying mantle wedge and lithospheric mantle through multiple mechanisms,including mechanical removal via diapirism,metamorphic decarbo...Subducting slabs transport carbon to deep mantle depths and release it into the overlying mantle wedge and lithospheric mantle through multiple mechanisms,including mechanical removal via diapirism,metamorphic decarbonization,carbonate dissolution and parting melting.Identifying the dominant carbon recycling mechanism responsible for carbonation of subcontinental lithospheric mantle(SCLM)remains challenging,yet it is critical for understanding the genesis of post-collisional carbonatites and associated rare earth element deposits.To address this issue,we investigate the Li isotopic systematics of typical post-collisional carbonatite-alkalic complexes from Mianning-Dechang(MD),Southeast Xizang.Our results show that the less-evolved magmas(lamprophyres)have mantle-like or slightly lowerδ^(7)Li values(0.3‰–3.6‰)with limited variability,contrasting sharply with the widerδ^(7)Li range observed in associated carbonatites and syenites.We interpret this dichotomy as reflecting distinct processes:while the variable and anomalousδ^(7)Li values in differentiated rocks(carbonatites and syenites)were caused by late-stage magmatic-hydrothermal processes(including biotite fractionation,fluid exsolution and hydrothermal alteration),the lamprophyres retain the primary Li isotopic signature of their mantle source.Together with their arc-like trace element and EM1-EM2-type Sr-Nd-Pb isotopic signatures,such mantle-like or slightly lowerδ^(7)Li values of the lamprophyres preclude carbon derivation from high-δ^(7)Li reservoirs(altered oceanic crust,serpentinites)and recycling of sedimentary carbon through metamorphic decarbonization or dissolution.Instead,these features indicate that the carbon was predominantly transported into the mantle source via partial melting of subducted carbonate-bearing sediments.This study demonstrates that Li isotopes can serve as a tracer for identifying the mechanism of carbon recycling in collision zones.展开更多
Geodynamic processes following the Indo-Eurasian plate collision remain a key research focus,and the Jinshajiang-Red River tectonic zone(JRTZ),situated along this collision boundary,provides critical insights into pos...Geodynamic processes following the Indo-Eurasian plate collision remain a key research focus,and the Jinshajiang-Red River tectonic zone(JRTZ),situated along this collision boundary,provides critical insights into post-collision tectonic evolution.In this study,we identify a lithological assemblage in the JRTZ,including amphibolite,granite gneiss,and migmatite.These rocks exhibit contrasting geochemical signatures,reflecting multiple source regions:asthenospheric mantle,lithospheric mantle,mafic lower and upper crust.Specifically,amphibolite(28.5 Ma)formed through the partial melting of OIB-like mantle source,whereas S-type granite gneiss(28.2 Ma)originated from the dehydration melting of metamorphosed sedimentary rocks.Amphibole monzonite(28.9 Ma)records the mixing of ancient crustal material with mantle-derived components,while migmatite(37.9 Ma)resulted from deep melting processes of metasedimentary rocks under shear conditions.We propose that the ongoing Indo-Eurasian convergence progressively thickened the crust,ultimately driving large-scale lithospheric delamination between the Eocene and Oligocene.This delamination triggered asthenospheric upwelling,which provided the thermal input required for widespread melting.This lithospheric delamination event started around 38-37 Ma and lasted at least until 28 Ma.展开更多
In the author list,the corresponding author indicator(*)was inadvertently omitted from HOU Zengqian’s name.This has now been corrected to:“HOU Zengqian¹,*”.The online version of this article was corrected.
To study the bending deformation of the lithosphere, the simplification of replacing a spherical shell by a plate model is usually made. Based on the differential equations for the bending of plates and shallow spheri...To study the bending deformation of the lithosphere, the simplification of replacing a spherical shell by a plate model is usually made. Based on the differential equations for the bending of plates and shallow spherical shells, an expression for the error caused by such a simplification is derived in this paper. The effect of model sizes on the error is discussed. It is proved that if we replace the shallow spherical shell by a plate model to solve the bending deformation of lithospheric plate, a large error will be caused. In contrast, if we use a plate on an elastic foundation instead, an approximate solution closer to that of spherical shell can be obtained. In such a way, the error can be reduced effectively and the actual geological condition can be modeled more closely.展开更多
The Xinjiang region is situated between the Tethyan and Central Asian orogenic belts.It has undergone multiple episodes of accretionary orogenesis and was tectonically reactivated during the Cenozoic by the far-field ...The Xinjiang region is situated between the Tethyan and Central Asian orogenic belts.It has undergone multiple episodes of accretionary orogenesis and was tectonically reactivated during the Cenozoic by the far-field compressional effects of the India-Eurasia continental collision.These processes have generated pronounced seismicity and recurrent earthquake-related hazards in this region.A high-resolution three-dimensional velocity model is essential for multi-scale velocity model construction,source-parameter inversion,simulation of strong ground motion,and seismic hazard assessment.In this study,we collected first-arrival body-wave travel-time data recorded by permanent stations in and around Xinjiang and processed both ambient-noise and regional-earthquake surface-wave records.The resulting dataset comprises~8.1 million body-wave travel-time picks-including absolute arrival times and event-pair differential times-and~5,000 surface-wave dispersion curves(5-50 s period).By joint inversion of these complementary body and surface wave datasets,we determined a high-resolution three-dimensional V_(p) and V_(s) model for the crust and uppermost mantle beneath Xinjiang(XJVM-1.0)with a lateral resolution of 50-100 km and a vertical resolution of~10 km.XJVM-1.0 reveals that the Tianshan orogen exhibits a relatively rigid upper crust that hosts abundant seismicity under far-field compression,whereas its middle-lower crust accommodates the majority of compressional stress through plastic deformation and/or partial melting.In contrast,the interiors of the Junggar and Tarim basins have experienced negligible internal deformation and are inferred to underthrust beneath the Tianshan orogen in response to the India-Eurasia collision.Relocated seismicity indicates that earthquakes are predominantly concentrated within the Tianshan range,with a notable proportion occurring in the middle-lower crust,implying whole-crust tectonic activity and highlighting the potential for great earthquakes in this region.展开更多
Application of reliable thermobarometer on garnet-bearing mantle xenoliths and granulite xenoliths entrained by Cenozoic basalts in eastern China reveals two main types of geotherm. The first type, as exampled by Hann...Application of reliable thermobarometer on garnet-bearing mantle xenoliths and granulite xenoliths entrained by Cenozoic basalts in eastern China reveals two main types of geotherm. The first type, as exampled by Hannuoba （汉若坝）, Mingxi （明溪） and probably Northeast China, is characterized by constant slope of data in the P-T space. The second type, as exampled by the high geotherms of Niishan （女山） and probably Xinchang （新昌）, is characterized by variable slopes, with the samples with pressure 〈2 MPa defining a slow slope, whereas the samples with pressure 〉2 MPa define a virtually vertical slope. The different slopes in the second type of geotherm may correspond to different heat transfer mechanisms, with conductive transfer for the shallow upper mantle and advective transfer for the deep mantle. This observed transition in thermal transfer mechanism is consistent with theoretical modeling. The two types of geotherm are not mutually exclusive, because the second type may characterize the thermal state of whole lithospheric section including both mechanical boundary layer （MBL） and thermal boundary layer （TBL）, while the first type may only depict the MBL. The variable geotherms for different regions are indicative of a heterogeneous lithospheric structure in eastern China. （a） Eastern North China craton （NCC） is characterized by a second-type geotherm, corresponding to a thin lithosphere （-70 km）. Comparison of the equilibrium temperatures of spinel peridotites with this geotherm constrains the depth to Moho in eastern North China craton to be 30 kin. In contrast, western NCC （Hannuoba： the first-type geotherm） possesses a relatively low thermal gradient, indicative of a thick lithosphere （〉90-100 km） and a thick crust-mantle transition zone. The dramatic change in crustal and mantle structure across the DTGL （Daxing＇anling （大兴安岭）- Talhangshan （太行山） gravity lineament） is consistent with recent seismic studies. （b） There is a decrease in thermal gradient and in lithospheric thickness from the coast （Xinchang： the second-type geotherm） to the inland （Mingxi： the first-type geotherm） in South China （from -80 km to 〉90 kin）, which is collaborated with westward variation in basalt geochemistry. （c） The weak convex-upward pattern of the geo- therm in Qilin （麒麟） and Leizhou （雷州） Peninsula is peculiar, probably reflecting a transitional feature between conductive and advective heat transfer. It may result from impregnation of mantle plume on the base of the lithosphere. These new results not only provide a basic framework for the ongoing 4-D lithosphere mapping project in eastern China, but also yield important implications for deep processes that operated over the past.展开更多
基金supported by the National Natural Science Foundation of China (41804067, 42174090, 42250101, and 42250103)the Science Research Project of the Hebei Education Department (BJK2024107)+3 种基金the Hebei Natural Science Foundation (D2022403044)the Opening Fund of the Key Laboratory of Geological Survey and Evaluation of the Ministry of Education (GLAB2023ZR02)the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources (MSFGPMR2022-4)the Excellent Young Scientist Fund of Hebei GEO University (YQ202403)。
文摘The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic field polarity reversals,the oceanic lithosphere has significant remanent magnetization,which causes magnetic anomaly stripes parallel to the mid-ocean ridges.However,it is difficult to construct a high-resolution lithospheric magnetic field model in oceanic regions with relatively sparse data or no data.Using forward calculated lithospheric magnetic field data based on an oceanic remanent magnetization(ORM) model with physical and geological foundations as a supplement is a feasible approach.We first collect the latest available oceanic crust age grid,plate motion model,geomagnetic polarity timescale,and oceanic lithosphere thermal structure.Combining the assumptions that the paleo geomagnetic field is a geocentric axial dipole field and that the normal oceanic crust moves only in the horizontal direction,we construct a vertically integrated ORM model of the normal oceanic crust with a known age,including the intensity,inclination,and declination.Both the ORM model and the global induced magnetization(GIM) model are then scaled from two aspects between their forward calculated results and the lithospheric magnetic field model LCS-1.One aspect is the difference in their spherical harmonic power spectra,and the other is the misfit between the grid data over the oceans.We last compare the forward calculated lithospheric magnetic anomaly from the scaled ORM and GIM models with the Macao Science Satellite-1(MSS-1) observed data.The comparison results show that the magnetic anomalies over the normal oceanic crust regions at satellite altitude are mainly contributed by the high-intensity remanent magnetization corresponding to the Cretaceous magnetic quiet period.In these regions,the predicted and observed anomalies show good consistency in spatial distribution,whereas their amplitude differences vary across regions.This result suggests that regional ORM construction should be attempted in future work to address these amplitude discrepancies.
基金supported by the National Natural Science Foundation of China(92462304)National Key Technologies R&D Program(2022YFF0800903)。
文摘A subducted continental slab is sometimes torn during collision,yet the exact impact of slab-tearing on the overlying lithosphere remains unclear.Here,we image the structure and architecture of the Asian lithosphere above the Indian slab in the eastern Tibetan Plateau using multiscale seismic tomography models and zircon Hf isotopic mapping,respectively.Our mantle V_(p)model shows that a large low-velocity anomaly extends laterally beneath the thinned Asian lithosphere above the tear zone roughly along the 26°N.The V_(s)images,magmatic records and Hf isotopic mapping indicate that this low-velocity anomaly recorded an asthenosphere flow eastward along the tear zone,which thermally eroded and refertilized the overlying Asian lithosphere,leading to the lithospheric melting,thinning and root delaminating.The vertical tear also generated a tectonic weak zone with associated Cenozoic potassic and carbonatitic magma suites.We argue that such a hot lithosphere discontinuity provided a reasonable mechanism for the abrupt change of crust thickness and the transformation of crust-mantle deformation from coupling to decoupling across the tear zone.
基金supported by the National Natural Science Foundation of China(Grant Nos.42250103 and 42174090)the Opening Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(Grant No.GLAB2023ZR02)the Ministry of Science and Technology(MOST)Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR2022-4)。
文摘As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal variations in the lithosphere.Traditional approaches either do not consider the non-axial dipolar terms of the inducing field and its radial variation or do so by means of complicated formulae.Moreover,existing methods treat the magnetic lithosphere either as an infinitesimally thin layer or as a radially uniform spherical shell of constant thickness.Here,we present alternative forward formulae that account for an arbitrarily high maximum degree of the inducing field and for a magnetic lithosphere of variable thickness.Our simulations based on these formulae suggest that the satellite magnetic anomaly field is sensitive to the non-axial dipolar terms of the inducing field but not to its radial variation.Therefore,in forward and inverse calculations of satellite magnetic anomaly data,the non-axial dipolar terms of the inducing field should not be ignored.Furthermore,our results show that the satellite magnetic anomaly field is sensitive to variability in the lateral thickness of the magnetized shell.In particular,we show that for a given vertically integrated susceptibility distribution,underestimating the thickness of the magnetic layer overestimates the induced magnetic field.This discovery bridges the greatest part of the alleged gap between the susceptibility values measured from rock samples and the susceptibility values required to match the observed magnetic field signal.We expect the formulae and conclusions of this study to be a valuable tool for the quantitative interpretation of the Earth's global lithospheric magnetic field,through an inverse or forward modelling approach.
基金funded by the National Natural Science Foundation of China(42263006)Open Fund from the Jiangxi Province,China(Grant No.20224ACB203011 and 2020101003)East China University of Technology(DHYC-202401 and 1410000874).
文摘Subducting slabs transport carbon to deep mantle depths and release it into the overlying mantle wedge and lithospheric mantle through multiple mechanisms,including mechanical removal via diapirism,metamorphic decarbonization,carbonate dissolution and parting melting.Identifying the dominant carbon recycling mechanism responsible for carbonation of subcontinental lithospheric mantle(SCLM)remains challenging,yet it is critical for understanding the genesis of post-collisional carbonatites and associated rare earth element deposits.To address this issue,we investigate the Li isotopic systematics of typical post-collisional carbonatite-alkalic complexes from Mianning-Dechang(MD),Southeast Xizang.Our results show that the less-evolved magmas(lamprophyres)have mantle-like or slightly lowerδ^(7)Li values(0.3‰–3.6‰)with limited variability,contrasting sharply with the widerδ^(7)Li range observed in associated carbonatites and syenites.We interpret this dichotomy as reflecting distinct processes:while the variable and anomalousδ^(7)Li values in differentiated rocks(carbonatites and syenites)were caused by late-stage magmatic-hydrothermal processes(including biotite fractionation,fluid exsolution and hydrothermal alteration),the lamprophyres retain the primary Li isotopic signature of their mantle source.Together with their arc-like trace element and EM1-EM2-type Sr-Nd-Pb isotopic signatures,such mantle-like or slightly lowerδ^(7)Li values of the lamprophyres preclude carbon derivation from high-δ^(7)Li reservoirs(altered oceanic crust,serpentinites)and recycling of sedimentary carbon through metamorphic decarbonization or dissolution.Instead,these features indicate that the carbon was predominantly transported into the mantle source via partial melting of subducted carbonate-bearing sediments.This study demonstrates that Li isotopes can serve as a tracer for identifying the mechanism of carbon recycling in collision zones.
基金supported by the National Natural Science Foundation of China(Grant No.42472181)the National Key Research and Development Program of China(Grant No.2021YFA0719000)CNPC Innovation Fund(Grant No.2021DQ02-0103).
文摘Geodynamic processes following the Indo-Eurasian plate collision remain a key research focus,and the Jinshajiang-Red River tectonic zone(JRTZ),situated along this collision boundary,provides critical insights into post-collision tectonic evolution.In this study,we identify a lithological assemblage in the JRTZ,including amphibolite,granite gneiss,and migmatite.These rocks exhibit contrasting geochemical signatures,reflecting multiple source regions:asthenospheric mantle,lithospheric mantle,mafic lower and upper crust.Specifically,amphibolite(28.5 Ma)formed through the partial melting of OIB-like mantle source,whereas S-type granite gneiss(28.2 Ma)originated from the dehydration melting of metamorphosed sedimentary rocks.Amphibole monzonite(28.9 Ma)records the mixing of ancient crustal material with mantle-derived components,while migmatite(37.9 Ma)resulted from deep melting processes of metasedimentary rocks under shear conditions.We propose that the ongoing Indo-Eurasian convergence progressively thickened the crust,ultimately driving large-scale lithospheric delamination between the Eocene and Oligocene.This delamination triggered asthenospheric upwelling,which provided the thermal input required for widespread melting.This lithospheric delamination event started around 38-37 Ma and lasted at least until 28 Ma.
文摘In the author list,the corresponding author indicator(*)was inadvertently omitted from HOU Zengqian’s name.This has now been corrected to:“HOU Zengqian¹,*”.The online version of this article was corrected.
文摘To study the bending deformation of the lithosphere, the simplification of replacing a spherical shell by a plate model is usually made. Based on the differential equations for the bending of plates and shallow spherical shells, an expression for the error caused by such a simplification is derived in this paper. The effect of model sizes on the error is discussed. It is proved that if we replace the shallow spherical shell by a plate model to solve the bending deformation of lithospheric plate, a large error will be caused. In contrast, if we use a plate on an elastic foundation instead, an approximate solution closer to that of spherical shell can be obtained. In such a way, the error can be reduced effectively and the actual geological condition can be modeled more closely.
基金supported by the National Key R&D Program of China(Grant No.2022YFC3003701)the National Natural Science Foundation of China(Grant No.42488301)the Xinjiang Uygur Autonomous Region Key R&D Project(Grant No.2022B03001-1).
文摘The Xinjiang region is situated between the Tethyan and Central Asian orogenic belts.It has undergone multiple episodes of accretionary orogenesis and was tectonically reactivated during the Cenozoic by the far-field compressional effects of the India-Eurasia continental collision.These processes have generated pronounced seismicity and recurrent earthquake-related hazards in this region.A high-resolution three-dimensional velocity model is essential for multi-scale velocity model construction,source-parameter inversion,simulation of strong ground motion,and seismic hazard assessment.In this study,we collected first-arrival body-wave travel-time data recorded by permanent stations in and around Xinjiang and processed both ambient-noise and regional-earthquake surface-wave records.The resulting dataset comprises~8.1 million body-wave travel-time picks-including absolute arrival times and event-pair differential times-and~5,000 surface-wave dispersion curves(5-50 s period).By joint inversion of these complementary body and surface wave datasets,we determined a high-resolution three-dimensional V_(p) and V_(s) model for the crust and uppermost mantle beneath Xinjiang(XJVM-1.0)with a lateral resolution of 50-100 km and a vertical resolution of~10 km.XJVM-1.0 reveals that the Tianshan orogen exhibits a relatively rigid upper crust that hosts abundant seismicity under far-field compression,whereas its middle-lower crust accommodates the majority of compressional stress through plastic deformation and/or partial melting.In contrast,the interiors of the Junggar and Tarim basins have experienced negligible internal deformation and are inferred to underthrust beneath the Tianshan orogen in response to the India-Eurasia collision.Relocated seismicity indicates that earthquakes are predominantly concentrated within the Tianshan range,with a notable proportion occurring in the middle-lower crust,implying whole-crust tectonic activity and highlighting the potential for great earthquakes in this region.
基金supported by the Knowledge Inno-vation Project of the Chinese Academy of Sciences (No. KZCX2-YW-Q08-3-6)the National Natural Science Founda-tion of China (Nos. 90714001, 40773015)the CAS/SAFEA International Partnership Program for Creative Research Teams (No. KZCX2-YW-Q04-06)
文摘Application of reliable thermobarometer on garnet-bearing mantle xenoliths and granulite xenoliths entrained by Cenozoic basalts in eastern China reveals two main types of geotherm. The first type, as exampled by Hannuoba （汉若坝）, Mingxi （明溪） and probably Northeast China, is characterized by constant slope of data in the P-T space. The second type, as exampled by the high geotherms of Niishan （女山） and probably Xinchang （新昌）, is characterized by variable slopes, with the samples with pressure 〈2 MPa defining a slow slope, whereas the samples with pressure 〉2 MPa define a virtually vertical slope. The different slopes in the second type of geotherm may correspond to different heat transfer mechanisms, with conductive transfer for the shallow upper mantle and advective transfer for the deep mantle. This observed transition in thermal transfer mechanism is consistent with theoretical modeling. The two types of geotherm are not mutually exclusive, because the second type may characterize the thermal state of whole lithospheric section including both mechanical boundary layer （MBL） and thermal boundary layer （TBL）, while the first type may only depict the MBL. The variable geotherms for different regions are indicative of a heterogeneous lithospheric structure in eastern China. （a） Eastern North China craton （NCC） is characterized by a second-type geotherm, corresponding to a thin lithosphere （-70 km）. Comparison of the equilibrium temperatures of spinel peridotites with this geotherm constrains the depth to Moho in eastern North China craton to be 30 kin. In contrast, western NCC （Hannuoba： the first-type geotherm） possesses a relatively low thermal gradient, indicative of a thick lithosphere （〉90-100 km） and a thick crust-mantle transition zone. The dramatic change in crustal and mantle structure across the DTGL （Daxing＇anling （大兴安岭）- Talhangshan （太行山） gravity lineament） is consistent with recent seismic studies. （b） There is a decrease in thermal gradient and in lithospheric thickness from the coast （Xinchang： the second-type geotherm） to the inland （Mingxi： the first-type geotherm） in South China （from -80 km to 〉90 kin）, which is collaborated with westward variation in basalt geochemistry. （c） The weak convex-upward pattern of the geo- therm in Qilin （麒麟） and Leizhou （雷州） Peninsula is peculiar, probably reflecting a transitional feature between conductive and advective heat transfer. It may result from impregnation of mantle plume on the base of the lithosphere. These new results not only provide a basic framework for the ongoing 4-D lithosphere mapping project in eastern China, but also yield important implications for deep processes that operated over the past.
