It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature.Combined with the large size o...It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature.Combined with the large size of certain garnet porphyroblast,this allows investigating variations in metamorphic conditions such as pressure,temperature,deviatoric stress,and fluid composition,which occur during subduction-related metamorphism.Here,one garnet porphyroblast of 6 cm diameter was sampled from the Yardoi schists of Xizang,and the major-,trace-,and Li-Mg isotopic compositions of distinct growth zones were determined in situ.The δ^(7)Li values range from+6.0‰to+4.1‰and follow‘S-shaped’patterns on both sides of the garnet’s core,revealing a two-stage growth process corresponding to the fluid-assisted sequential recrystallization of chlorite and micas during prograde metamorphism.By contrast,once corrected for the overprinting by retrograde metamorphism,theδ^(26)Mg values vary monotonically from−1.73‰in the core to−1.32‰in the outer rim,reflecting a single-step process interpreted to result from increasing temperature and the solid-state recrystallization of chlorite-biotite during prograde metamorphism.This different behavior of Li and Mg isotopes is interpreted to result from the fact that Li is more fluid-mobile than the major element Mg.展开更多
The Himalayan Orogen, resulting from the Tertiary collision of Indian and Asian continents, is a natural laboratory for studying metamorphism, partial melting and granite formation of collisional orogens. However, met...The Himalayan Orogen, resulting from the Tertiary collision of Indian and Asian continents, is a natural laboratory for studying metamorphism, partial melting and granite formation of collisional orogens. However, metamorphic and anatectic conditions and timescales of meta-mafic rocks in the Greater Himalayan Sequences （GHS） in the east-central Himalaya remain controversial, in this paper, we conduct a study of petrology and geochronology of mafic granulite from the Eastern Himalayan Syntaxis （EHS）. The mafic granulite with abundant leucosome bands occurs as layers within felsic granulites and is well deformed. The granulite consists of garnet, plagioclase, amphibole and quartz with minor clinopyroxene, orthopyroxene, biotite, rutile, titanite and ilmenite. The garnet has growth compositional zoning and contains abundant mineral inclusions in its core. Peak metamorphic mineral assemblage of the granulite is garnet, amphibole, plagioclase, quartz, clinopyroxene and futile, recording a high-pressure （HP） and high-temperature （HT） peak-metamorphism under conditions of 14-15.5 kbar and 780-790 ℃ in the presence of melt. The reconstructed clockwise P-T path is characterized by an early heating and burial prograde metamorphism, and late isothermal and cooling decompression retrogression. The granulite witnessed a long lasting HT metamorphism, partial melting and melt crystallization process which began at ca. 39 Ma and lasted to ca. 11 Ma. The present study shows that various high-grade rocks of the GHS in the EHS core experienced similar metamorphic conditions and P-T-t paths, indicating that they occurred as a coherent slab during the subduction and exhumation of Indian lithosphere. The significant melts generated during the prograde metamorphism of the GHS rocks not only contributed to the formation of the Himalayan leucogranite, but also resulted in the rheological weakening and ductile flow of the thickened lower crust of the Himalayan Orogen.展开更多
Although zircon U-Pb geochronometer has been widely used for dating metamorphism in moderate- to high-grade metamorphic rocks, it is still difficult to link the zircon U-Pb age to pressure and temperature （P-T） cond...Although zircon U-Pb geochronometer has been widely used for dating metamorphism in moderate- to high-grade metamorphic rocks, it is still difficult to link the zircon U-Pb age to pressure and temperature （P-T） conditions. In this study, zircon trace elements and Hf isotopes and REE partitioning between zircon and garnet are adopted to track the formation condition of zircon in the granu- lites from North Tongbai Orogen, Central China. Combined with previous metamorphic P-T path results, a quantitative integrated anticlockwise P-T-t path was established for Tongbai granulites. These grauulites recorded an early low-P heating followed by a dramatic pressure increase. Evidence for the prograde history （M1） is provided by cordierite, orthopyroxene and biotite inclusions in garnet. The prograde metamorphism occurred at around 443±3 Ma, with P-T conditions of ca. 730-820 ℃ and 〈6 kbar. The peak metamorphic （M2） condition is 〉920 ℃ and 8.5-10 kbar and the peak metamorphism age is ca. 432±4 Ma. At around 419 Ma, the granulites suffered an amphibolite-facies retrograde metamorphism （M3）, represented by the replacement of garnet by biotite and plagioclase, and clinopyroxene by amphibole, with metamorphic condition of ca. 700℃ and ca. 7 kbar. The last retrograde metamorphism （M4） is a greenschist-facies overprint with an age of ca. 404 Ma. It is concluded that the meta- morphism of Tongbai granulite lasted for more than 40 Ma, including a stage of more than 20 Ma granulitc-facies metamorphism. The prolonged granulite-facies metamorphism resulted from the continuous northward subduction of the Shangdan oceanic crust beneath the North Qinling terrane.展开更多
Zhendong You was born in 1928, in Fujian Province, eastern China in golden September. He graduated from the Department of Geology of Peking University in 1952, and has subsequently been teaching and researching in pet...Zhendong You was born in 1928, in Fujian Province, eastern China in golden September. He graduated from the Department of Geology of Peking University in 1952, and has subsequently been teaching and researching in petrology and optical mineralogy at China University of Geosciences （CUG） and its predecessors, Beijing Institute of Geology and Wuhan Institute of Geology, since 1956. He taught petrology and petrogenesis of metamorphic rocks in School of Earth Sciences, CUG for nearly 50 years as a professor and doctoral supervisor and made out- standing contributions nationally to metamorphic petrology and personnel training. His contributions have been recognized by a Li Siguang Earth Science Teaching Award.展开更多
The absence of ultrahigh pressure(UHP)orogenic eclogite in the geological record older than c.0.6 Ga is problematic for evidence of subduction having begun on Earth during the Archean(4.0-2.5 Ga).Many eclogites in Pha...The absence of ultrahigh pressure(UHP)orogenic eclogite in the geological record older than c.0.6 Ga is problematic for evidence of subduction having begun on Earth during the Archean(4.0-2.5 Ga).Many eclogites in Phanerozoic and Proterozoic terranes occur as mafic boudins encased within low-density felsic crust,which provides positive buoyancy during subduction;however,recent geochemical proxy analysis shows that Archean continental crust was more mafic than previously thought,having greater proportions of basalt and komatiite than modern-day continents.Here,we show via petrological modelling that secular change in the petrology and bulk composition of upper continental crust would make Archean continental terranes negatively buoyant in the mantle before reaching UHP conditions.Subducted or delaminated Archean continental crust passes a point of no return during metamorphism in the mantle prior to the stabilization of coesite,while Proterozoic and Phanerozoic terranes remain positively buoyant at these depths.UHP orogenic eclogite may thus readily have formed on the Archean Earth,but could not have been exhumed,weakening arguments for a Neoproterozoic onset of subduction and plate tectonics.Further,isostatic balance calculations for more mafic Archean continents indicate that the early Earth was covered by a global ocean over 1 km deep,corroborating independent isotopic evidence for large-scale emergence of the continents no earlier than c.3 Ga.Our findings thus weaken arguments that early life on Earth likely emerged in shallow subaerial ponds,and instead support hypotheses involving development at hydrothermal vents in the deep ocean.展开更多
The genesis of Liangguo corundum deposit in the southern Gangdese magmatic arc,east-central Himalaya,remains unknown.The present study shows that the corundum-bearing rocks occur as lenses with variable sizes in the E...The genesis of Liangguo corundum deposit in the southern Gangdese magmatic arc,east-central Himalaya,remains unknown.The present study shows that the corundum-bearing rocks occur as lenses with variable sizes in the Eocene gabbro that intruded into marble.These corundum-bearing rocks have highly variable mineral assemblage and mode.The corundum-rich rocks are characterized by containing abundant corundum,and minor spinel,ilmenite and magnetite,whereas the corundum-poor and corundum-free rocks have variable contents of spinel,plagioclase,sillimanite,cordierite,ilmenite and magnetite.The host gabbro shows variable degrees of hydration and carbonization.The corundum grains are mostly black,and rarely blue,and have minor Fe O and TiO_(2).The spinel is hercynite,with high Fe O and low Mg O contents.The corundum-bearing rocks have variable but high Al_2O_3,FeO and TiO_(2),and low SiO_(2)contents.Inherited magmatic and altered zircons of the corundum-bearing rocks have similar U e Pb ages(~47 Ma)to the magmatic zircons of the host gabbro,indicating corundum-bearing rock formation immediately after the gabbro intrusion.We considered that emplacement of gabbro induced the contact metamorphism of the country-rock marble and the formation of silica-poor fluid.The channeled infiltration of generated fluid in turn resulted in the hydrothermal metasomatism of the gabbro,which characterized by considerable loss of Si from the gabbro and strong residual enrichment of Al.The metasomatic alteration probably formed under Pe T conditions of~2.2-2.8 kbar and~650-700℃.We speculate that SiO_(2),CaO and Na_2O were mobile,and Al_(2)O_(3),FeO,TiO_(2)and high field strength elements remained immobile during the metasomatic process of the gabbro.The Liangguo corundum deposit,together with metamorphic corundum deposits in Central and Southeast Asia,were related to the Cenozoic Himalayan orogeny,and therefore are plate tectonic indicators.展开更多
[Objectives]To investigate the serum metabolomic characteristics of primary dysmenorrhea rat model induced by estradiol benzoate combined with oxytocin,and to reveal its material basis.[Methods]20 female SD rats were ...[Objectives]To investigate the serum metabolomic characteristics of primary dysmenorrhea rat model induced by estradiol benzoate combined with oxytocin,and to reveal its material basis.[Methods]20 female SD rats were randomly divided into control group and model group.The primary dysmenorrhea rat model was established by subcutaneous injection of estradiol benzoate for 10 consecutive days and intraperitoneal injection of oxytocin on the last day.The serum samples of rats in control group and model group were collected by ultra-performance liquid chromatography(UPLC)quadrupole time-of-flight mass spectrometry(Q-TOF-MS).The differential metabolites were identified by multivariable pattern recognition method and endogenous metabolite database,and the metabolic pathways were enriched by Metaboanalyst 5.0 platform.[Results]There were significant differences in serum metabolic profiles between the two groups.A total of 36 potential biomarkers of primary dysmenorrhea including L-tyrosine,glycocholic acid,citric acid,palmitoyl carnitine and cholesterol were screened and identified,mainly involving metabolic pathways such as phenylalanine,tyrosine and tryptophan biosynthesis,glycerophospholipid metabolism,and primary bile acid biosynthesis.[Conclusions]The serum metabolic profile of primary dysmenorrhea rats deviates significantly from that of healthy rats,and there are multiple metabolic pathway disorders,which are mainly related to phenylalanine,tyrosine and tryptophan biosynthesis,glycerophospholipid metabolism,and primary bile acid biosynthesis.展开更多
Alternative splicing plays a vital role in plant immunity,but how plants stringently and selectively regulate alternative splicing to coordinate immunity and growth is poorly understood.Here,we report that H_(2)O_(2)-...Alternative splicing plays a vital role in plant immunity,but how plants stringently and selectively regulate alternative splicing to coordinate immunity and growth is poorly understood.Here,we report that H_(2)O_(2)-triggered phosphorylation of the RNA-binding protein RRM2R releases a retained-intron brake in OsMAPKKK18 encoding a mitogen-activated protein kinase kinase kinase to orchestrate plant immunity and growth in rice.We found that,without pathogen infection,OsMAPKKK18βtranscripts containing a retained intron are subjected to nonsense-mediated mRNA decay to promote plant growth.Upon Magnaporthe oryzae pathogen invasion,H_(2)O_(2)activates the protein kinase OsCLK1 to phosphorylate and stabilize RRM2R,which interacts with OsRNPS1A/B to recruit spliceosome machinery and promote the production of OsMAPKKK18αtranscripts without the retained intron to promote rice immunity.Furthermore,we revealed that after the endogenous H_(2)O_(2)is consumed or degraded by peroxidases or catalases,decreased abundance of RRM2R reduces the accumulation of OsMAPKKK18αtranscripts to avoid autoimmunity in rice.Taken together,the results of our study uncover H_(2)O_(2)-controlled OsMAPKKK18 intron retention as a novel molecular switch for orchestrating immunity and growth in rice.展开更多
The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd is...The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd isotopic data yield a whole rock-garnet-omphacite isochron of (500 ?10) Ma. The U-Pb isotopic measurements of zircons show that the four展开更多
The architecture and growth history of Precambrian crustal basements in the Central Tianshan Block play a key role in understanding the tectonic evolution of the Chinese Tianshan Orogenic Belt.In this study,we present...The architecture and growth history of Precambrian crustal basements in the Central Tianshan Block play a key role in understanding the tectonic evolution of the Chinese Tianshan Orogenic Belt.In this study,we present precise LA-ICP-MS zircon U–Pb dating and LAMC-ICPMS zircon Hf isotopic data for two granitic gneisses from Alatage area in the Central Tianshan Block.The magmatic zircons from both samples yield similar protolith ages of 945±6 and 942±6 Ma,indicating that the early Neoproterozoic magmatism is prevailed in the Alatage area.These zircons have crustal Hf model ages of1.82–2.22 and 1.70–2.03 Ga,respectively,which are significantly older than their crystallization ages.It indicates that their parental magmas were derived from the reworking of ancient crust.However,we suggest that these Paleoproterozoic Hf model ages might result from mixing of continental materials with different ages in the Neoproterozoic crust.The inherited(detrital)zircon cores not only yield a wide age range of ca.989–1617 Ma,but also exhibit large Hf-isotope variations with Hf model ages of1.54–2.30 Ga.In particular,some 1.4–1.6 Ga zircons show high initial176Hf/177Hf ratios,consistent with those of depleted mantle,which indicates that the Mesoproterozoic event involved both reworking of older crust and generation of juvenile crust.The Central Tianshan Block has different Precambrian crustal growth history from the Tarim Craton.Therefore,it would not be a fragment of the Precambrian basement of the Tarim Craton.展开更多
Aiming at the interception problem of noncooperative evader spacecraft adopting random maneuver strategy in one-to-one orbital pursuit-evasion problem,an interception strategy with decision-making training mechanism f...Aiming at the interception problem of noncooperative evader spacecraft adopting random maneuver strategy in one-to-one orbital pursuit-evasion problem,an interception strategy with decision-making training mechanism for the pursuer based on deep reinforcement learning is proposed.Its core purpose is to improve the success rate of interception in the environment with high uncertainty.First of all,a multi-impulse orbit transfer model of pursuer and evader is established,and a modular deep reinforcement learning training method is built.Second,an effective reward mechanism is proposed to train the pursuer to choose the impulse direction and impulse interval of the orbit transfer and to learn the successful interception strategy with the optimal fuel and time.Finally,with the evader taking a random maneuver decision in each episode of training,the trained decision-making strategy is applied to the pursuer,the corresponding interception success rate of which is further analyzed.The results show that the pursuer trained can obtain universal and variable interception strategy.In each round of pursuit-evasion,with random maneuver strategy of the evader,the pursuer can adopt similar optimal decisions to deal with high-dimensional environments and thoroughly random state space,maintaining high interception success rate.展开更多
Herein,the 2,4-dinitrophenyl functional group acting as the thiophenol reactive site was introduced into a carbazole-chalcone fluorophore to synthesize probe-CCF2,which could result in a remarkable increase in fluores...Herein,the 2,4-dinitrophenyl functional group acting as the thiophenol reactive site was introduced into a carbazole-chalcone fluorophore to synthesize probe-CCF2,which could result in a remarkable increase in fluorescence when reacting with thiophenols.The selectivity and accuracy of probe-CCF2 were investigated with thiophenols,hydrosulphide salt,aliphatic thiols,glutathione,cysteine,anions and metal cations.Probe-CCF2 exhibited a detection limit of 37 nmol/L(R^(2)=0.9951),a remarkable Stokes shift of approximately 130 nm,and a brief response time of 9 min with a remarkable increase in fluorescence of 90-fold.Probe-CCF2 was applied for thiophenol detection in water samples and imaging in living cells successfully,with high sensitivity and excellent selectivity.展开更多
Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concer...Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concerning the formation and evolution of rocks.There are a growing number of reports of zircon existing in mantle peridotite.However,it is generally considered that zircon is unlikely crystallized in ultrabasic rocks due to SiO_(2)-unsaturation.In this paper,the SiO_(2) activity and zircon/baddeleyite transition curve at different conditions were calculated through thermodynamic phase equilibrium modeling,to reveal the main factors affecting the SiO_(2) activity and the stability of zircon/baddeleyite in ultrabasic and basic rocks,especially in mantle peridotite.These results provide a thermodynamic basis for interpreting the genesis and significance of zircon in mantle rocks.That is,the SiO_(2) activity is mainly controlled by stable mineral assemblages and temperature-pressure conditions.The orthopyroxene+olivine assemblage in peridotite as an effective buffer restricts the SiO_(2) activity in a relatively high range with a small variation.The upper temperature limit of zircon can reach more than 1500℃ with this mineral assemblage.During the low-temperature serpentinization of peridotite,the replacement of olivine and pyroxene by serpentine can result in a significant decrease of SiO_(2) activity,and baddeleyite can be stabilized at<530℃ and<2.7 GPa.When peridotite is strongly metasomatized by the SiO_(2)-bearing fluid,the addition of SiO_(2) can increase its activity and make zircon stable at low temperatures.The SiO_(2) activity in ultrabasic-basic rocks is not only positively correlated with the SiO_(2) content but also negatively correlated with the Ca and Na contents of rocks.This is because Ca and Na preferentially combine with Si and Al to form Si-rich minerals,such as clinopyroxene and feldspar.This process will consume excessive SiO_(2),decreasing the SiO_(2) activity.This may be the reason why zircon can be found in ultrabasic rocks,while baddeleyite can exist in some basic and alkaline rocks.The thermodynamic modeling can also reasonably explain the mutual transformation between zircon and baddeleyite in ultrabasic-basic rocks.Our results indicate that zircon can exist stably in mantle peridotite in a wide range of temperature-pressure conditions and its formation is related to melt/fluid metasomatism.That is,the presence of zircon in mantle peridotite is an important information carrier of crust-mantle interaction for deep material cycling.展开更多
基金supported by the National Natural Science Foundation of China(Nos.41729001,42073003,41673031).
文摘It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature.Combined with the large size of certain garnet porphyroblast,this allows investigating variations in metamorphic conditions such as pressure,temperature,deviatoric stress,and fluid composition,which occur during subduction-related metamorphism.Here,one garnet porphyroblast of 6 cm diameter was sampled from the Yardoi schists of Xizang,and the major-,trace-,and Li-Mg isotopic compositions of distinct growth zones were determined in situ.The δ^(7)Li values range from+6.0‰to+4.1‰and follow‘S-shaped’patterns on both sides of the garnet’s core,revealing a two-stage growth process corresponding to the fluid-assisted sequential recrystallization of chlorite and micas during prograde metamorphism.By contrast,once corrected for the overprinting by retrograde metamorphism,theδ^(26)Mg values vary monotonically from−1.73‰in the core to−1.32‰in the outer rim,reflecting a single-step process interpreted to result from increasing temperature and the solid-state recrystallization of chlorite-biotite during prograde metamorphism.This different behavior of Li and Mg isotopes is interpreted to result from the fact that Li is more fluid-mobile than the major element Mg.
基金co-supported by the National Key Research and Development Project of China (No. 2016YFC0600310)the National Natural Science Foundation of China (Nos. 41230205 and 41602062)the China Geological Survey (No. DD20160122)
文摘The Himalayan Orogen, resulting from the Tertiary collision of Indian and Asian continents, is a natural laboratory for studying metamorphism, partial melting and granite formation of collisional orogens. However, metamorphic and anatectic conditions and timescales of meta-mafic rocks in the Greater Himalayan Sequences （GHS） in the east-central Himalaya remain controversial, in this paper, we conduct a study of petrology and geochronology of mafic granulite from the Eastern Himalayan Syntaxis （EHS）. The mafic granulite with abundant leucosome bands occurs as layers within felsic granulites and is well deformed. The granulite consists of garnet, plagioclase, amphibole and quartz with minor clinopyroxene, orthopyroxene, biotite, rutile, titanite and ilmenite. The garnet has growth compositional zoning and contains abundant mineral inclusions in its core. Peak metamorphic mineral assemblage of the granulite is garnet, amphibole, plagioclase, quartz, clinopyroxene and futile, recording a high-pressure （HP） and high-temperature （HT） peak-metamorphism under conditions of 14-15.5 kbar and 780-790 ℃ in the presence of melt. The reconstructed clockwise P-T path is characterized by an early heating and burial prograde metamorphism, and late isothermal and cooling decompression retrogression. The granulite witnessed a long lasting HT metamorphism, partial melting and melt crystallization process which began at ca. 39 Ma and lasted to ca. 11 Ma. The present study shows that various high-grade rocks of the GHS in the EHS core experienced similar metamorphic conditions and P-T-t paths, indicating that they occurred as a coherent slab during the subduction and exhumation of Indian lithosphere. The significant melts generated during the prograde metamorphism of the GHS rocks not only contributed to the formation of the Himalayan leucogranite, but also resulted in the rheological weakening and ductile flow of the thickened lower crust of the Himalayan Orogen.
基金supported by the National Natural Science Foundation of China (No. 41302040)the China Geological Survey (No. DD20160201)
文摘Although zircon U-Pb geochronometer has been widely used for dating metamorphism in moderate- to high-grade metamorphic rocks, it is still difficult to link the zircon U-Pb age to pressure and temperature （P-T） conditions. In this study, zircon trace elements and Hf isotopes and REE partitioning between zircon and garnet are adopted to track the formation condition of zircon in the granu- lites from North Tongbai Orogen, Central China. Combined with previous metamorphic P-T path results, a quantitative integrated anticlockwise P-T-t path was established for Tongbai granulites. These grauulites recorded an early low-P heating followed by a dramatic pressure increase. Evidence for the prograde history （M1） is provided by cordierite, orthopyroxene and biotite inclusions in garnet. The prograde metamorphism occurred at around 443±3 Ma, with P-T conditions of ca. 730-820 ℃ and 〈6 kbar. The peak metamorphic （M2） condition is 〉920 ℃ and 8.5-10 kbar and the peak metamorphism age is ca. 432±4 Ma. At around 419 Ma, the granulites suffered an amphibolite-facies retrograde metamorphism （M3）, represented by the replacement of garnet by biotite and plagioclase, and clinopyroxene by amphibole, with metamorphic condition of ca. 700℃ and ca. 7 kbar. The last retrograde metamorphism （M4） is a greenschist-facies overprint with an age of ca. 404 Ma. It is concluded that the meta- morphism of Tongbai granulite lasted for more than 40 Ma, including a stage of more than 20 Ma granulitc-facies metamorphism. The prolonged granulite-facies metamorphism resulted from the continuous northward subduction of the Shangdan oceanic crust beneath the North Qinling terrane.
文摘Zhendong You was born in 1928, in Fujian Province, eastern China in golden September. He graduated from the Department of Geology of Peking University in 1952, and has subsequently been teaching and researching in petrology and optical mineralogy at China University of Geosciences （CUG） and its predecessors, Beijing Institute of Geology and Wuhan Institute of Geology, since 1956. He taught petrology and petrogenesis of metamorphic rocks in School of Earth Sciences, CUG for nearly 50 years as a professor and doctoral supervisor and made out- standing contributions nationally to metamorphic petrology and personnel training. His contributions have been recognized by a Li Siguang Earth Science Teaching Award.
文摘The absence of ultrahigh pressure(UHP)orogenic eclogite in the geological record older than c.0.6 Ga is problematic for evidence of subduction having begun on Earth during the Archean(4.0-2.5 Ga).Many eclogites in Phanerozoic and Proterozoic terranes occur as mafic boudins encased within low-density felsic crust,which provides positive buoyancy during subduction;however,recent geochemical proxy analysis shows that Archean continental crust was more mafic than previously thought,having greater proportions of basalt and komatiite than modern-day continents.Here,we show via petrological modelling that secular change in the petrology and bulk composition of upper continental crust would make Archean continental terranes negatively buoyant in the mantle before reaching UHP conditions.Subducted or delaminated Archean continental crust passes a point of no return during metamorphism in the mantle prior to the stabilization of coesite,while Proterozoic and Phanerozoic terranes remain positively buoyant at these depths.UHP orogenic eclogite may thus readily have formed on the Archean Earth,but could not have been exhumed,weakening arguments for a Neoproterozoic onset of subduction and plate tectonics.Further,isostatic balance calculations for more mafic Archean continents indicate that the early Earth was covered by a global ocean over 1 km deep,corroborating independent isotopic evidence for large-scale emergence of the continents no earlier than c.3 Ga.Our findings thus weaken arguments that early life on Earth likely emerged in shallow subaerial ponds,and instead support hypotheses involving development at hydrothermal vents in the deep ocean.
基金co-supported by the National Key Research and Development Project of China(Grant No.2016YFC0600310)the National Natural Science Foundation of China(Grant Nos.41230205,41472056,41202035 and 41602062)+1 种基金China Postdoctoral Science Foundation(Grant Nos.2017T100099 and 2016M601086)the China Geological Survey(Grant No.DD20160201)
文摘The genesis of Liangguo corundum deposit in the southern Gangdese magmatic arc,east-central Himalaya,remains unknown.The present study shows that the corundum-bearing rocks occur as lenses with variable sizes in the Eocene gabbro that intruded into marble.These corundum-bearing rocks have highly variable mineral assemblage and mode.The corundum-rich rocks are characterized by containing abundant corundum,and minor spinel,ilmenite and magnetite,whereas the corundum-poor and corundum-free rocks have variable contents of spinel,plagioclase,sillimanite,cordierite,ilmenite and magnetite.The host gabbro shows variable degrees of hydration and carbonization.The corundum grains are mostly black,and rarely blue,and have minor Fe O and TiO_(2).The spinel is hercynite,with high Fe O and low Mg O contents.The corundum-bearing rocks have variable but high Al_2O_3,FeO and TiO_(2),and low SiO_(2)contents.Inherited magmatic and altered zircons of the corundum-bearing rocks have similar U e Pb ages(~47 Ma)to the magmatic zircons of the host gabbro,indicating corundum-bearing rock formation immediately after the gabbro intrusion.We considered that emplacement of gabbro induced the contact metamorphism of the country-rock marble and the formation of silica-poor fluid.The channeled infiltration of generated fluid in turn resulted in the hydrothermal metasomatism of the gabbro,which characterized by considerable loss of Si from the gabbro and strong residual enrichment of Al.The metasomatic alteration probably formed under Pe T conditions of~2.2-2.8 kbar and~650-700℃.We speculate that SiO_(2),CaO and Na_2O were mobile,and Al_(2)O_(3),FeO,TiO_(2)and high field strength elements remained immobile during the metasomatic process of the gabbro.The Liangguo corundum deposit,together with metamorphic corundum deposits in Central and Southeast Asia,were related to the Cenozoic Himalayan orogeny,and therefore are plate tectonic indicators.
基金Supported by the Natural Science Foundation for the Youth funded by the Natural Science Foundation of China(82104384)the Science and Technology Project of Hebei Education Department(QN2021008)+5 种基金the Research Fund for the Doctoral Program Funded by the Chengde Medical University(202103)Key Discipline Construction Project of Colleges and Universities in Hebei Province(Ji Jiao Gao[2013]4)Technology Innovation Guidance Project-Science and Technology Work Conference of Hebei Provincial Department of Science and TechnologyPharmacodynamic Material Basis Team of Traditional Chinese Medicine of the Youth PI(Principle Investigator)Science and Technology Innovation Team Project of Chengde Medical UniversityChengde Medical University Student Innovation and Entrepreneurship Training Program(202203)Hebei Key Laboratory of Nerve Injury and Repair(NJKF202202)。
文摘[Objectives]To investigate the serum metabolomic characteristics of primary dysmenorrhea rat model induced by estradiol benzoate combined with oxytocin,and to reveal its material basis.[Methods]20 female SD rats were randomly divided into control group and model group.The primary dysmenorrhea rat model was established by subcutaneous injection of estradiol benzoate for 10 consecutive days and intraperitoneal injection of oxytocin on the last day.The serum samples of rats in control group and model group were collected by ultra-performance liquid chromatography(UPLC)quadrupole time-of-flight mass spectrometry(Q-TOF-MS).The differential metabolites were identified by multivariable pattern recognition method and endogenous metabolite database,and the metabolic pathways were enriched by Metaboanalyst 5.0 platform.[Results]There were significant differences in serum metabolic profiles between the two groups.A total of 36 potential biomarkers of primary dysmenorrhea including L-tyrosine,glycocholic acid,citric acid,palmitoyl carnitine and cholesterol were screened and identified,mainly involving metabolic pathways such as phenylalanine,tyrosine and tryptophan biosynthesis,glycerophospholipid metabolism,and primary bile acid biosynthesis.[Conclusions]The serum metabolic profile of primary dysmenorrhea rats deviates significantly from that of healthy rats,and there are multiple metabolic pathway disorders,which are mainly related to phenylalanine,tyrosine and tryptophan biosynthesis,glycerophospholipid metabolism,and primary bile acid biosynthesis.
基金funded by grants from the National Natural Science Foundation of China(32121003 and 32425005 to Xuewei Chen,32572382 to X.L.,32102227 to Q.X.,and 32272116 and 32072043 to J.W.)New Cornerstone Science Foundation(grant to Xuewei Chen),Central Guidance for Local Science and Technology Development Fund of Sichuan Province(2024ZYD0200 to X.L.)+1 种基金Biological Breeding-National Science and Technology Major Project(2023ZD04070 to J.W.)Natural Science Science Foundation of Sichuan Province(2024NSFTD0022 to J.W.,2024YFNH0014 to J.Yin,and 2023NSFSC1996 to W.Li).
文摘Alternative splicing plays a vital role in plant immunity,but how plants stringently and selectively regulate alternative splicing to coordinate immunity and growth is poorly understood.Here,we report that H_(2)O_(2)-triggered phosphorylation of the RNA-binding protein RRM2R releases a retained-intron brake in OsMAPKKK18 encoding a mitogen-activated protein kinase kinase kinase to orchestrate plant immunity and growth in rice.We found that,without pathogen infection,OsMAPKKK18βtranscripts containing a retained intron are subjected to nonsense-mediated mRNA decay to promote plant growth.Upon Magnaporthe oryzae pathogen invasion,H_(2)O_(2)activates the protein kinase OsCLK1 to phosphorylate and stabilize RRM2R,which interacts with OsRNPS1A/B to recruit spliceosome machinery and promote the production of OsMAPKKK18αtranscripts without the retained intron to promote rice immunity.Furthermore,we revealed that after the endogenous H_(2)O_(2)is consumed or degraded by peroxidases or catalases,decreased abundance of RRM2R reduces the accumulation of OsMAPKKK18αtranscripts to avoid autoimmunity in rice.Taken together,the results of our study uncover H_(2)O_(2)-controlled OsMAPKKK18 intron retention as a novel molecular switch for orchestrating immunity and growth in rice.
文摘The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd isotopic data yield a whole rock-garnet-omphacite isochron of (500 ?10) Ma. The U-Pb isotopic measurements of zircons show that the four
基金supported by the Program of Excellent Young Geologists of China Geological Survey(QNYC2-2012-21)the Ministry of Land and Resources of China(201011034)the Chinese Geological Survey Project(12120113096400)
文摘The architecture and growth history of Precambrian crustal basements in the Central Tianshan Block play a key role in understanding the tectonic evolution of the Chinese Tianshan Orogenic Belt.In this study,we present precise LA-ICP-MS zircon U–Pb dating and LAMC-ICPMS zircon Hf isotopic data for two granitic gneisses from Alatage area in the Central Tianshan Block.The magmatic zircons from both samples yield similar protolith ages of 945±6 and 942±6 Ma,indicating that the early Neoproterozoic magmatism is prevailed in the Alatage area.These zircons have crustal Hf model ages of1.82–2.22 and 1.70–2.03 Ga,respectively,which are significantly older than their crystallization ages.It indicates that their parental magmas were derived from the reworking of ancient crust.However,we suggest that these Paleoproterozoic Hf model ages might result from mixing of continental materials with different ages in the Neoproterozoic crust.The inherited(detrital)zircon cores not only yield a wide age range of ca.989–1617 Ma,but also exhibit large Hf-isotope variations with Hf model ages of1.54–2.30 Ga.In particular,some 1.4–1.6 Ga zircons show high initial176Hf/177Hf ratios,consistent with those of depleted mantle,which indicates that the Mesoproterozoic event involved both reworking of older crust and generation of juvenile crust.The Central Tianshan Block has different Precambrian crustal growth history from the Tarim Craton.Therefore,it would not be a fragment of the Precambrian basement of the Tarim Craton.
基金supported by the National Natural Science Foundation of China(grant nos.62073102 and 62203145).
文摘Aiming at the interception problem of noncooperative evader spacecraft adopting random maneuver strategy in one-to-one orbital pursuit-evasion problem,an interception strategy with decision-making training mechanism for the pursuer based on deep reinforcement learning is proposed.Its core purpose is to improve the success rate of interception in the environment with high uncertainty.First of all,a multi-impulse orbit transfer model of pursuer and evader is established,and a modular deep reinforcement learning training method is built.Second,an effective reward mechanism is proposed to train the pursuer to choose the impulse direction and impulse interval of the orbit transfer and to learn the successful interception strategy with the optimal fuel and time.Finally,with the evader taking a random maneuver decision in each episode of training,the trained decision-making strategy is applied to the pursuer,the corresponding interception success rate of which is further analyzed.The results show that the pursuer trained can obtain universal and variable interception strategy.In each round of pursuit-evasion,with random maneuver strategy of the evader,the pursuer can adopt similar optimal decisions to deal with high-dimensional environments and thoroughly random state space,maintaining high interception success rate.
基金supported by Natural Science Foundation of Zhejiang Province(LQ21C200002)Zhejiang Provincial Key Research and Development Program(2021CO2062,2022C02028)Key Research and Development Program of Ningbo(2021Z056,2022S163)
文摘Herein,the 2,4-dinitrophenyl functional group acting as the thiophenol reactive site was introduced into a carbazole-chalcone fluorophore to synthesize probe-CCF2,which could result in a remarkable increase in fluorescence when reacting with thiophenols.The selectivity and accuracy of probe-CCF2 were investigated with thiophenols,hydrosulphide salt,aliphatic thiols,glutathione,cysteine,anions and metal cations.Probe-CCF2 exhibited a detection limit of 37 nmol/L(R^(2)=0.9951),a remarkable Stokes shift of approximately 130 nm,and a brief response time of 9 min with a remarkable increase in fluorescence of 90-fold.Probe-CCF2 was applied for thiophenol detection in water samples and imaging in living cells successfully,with high sensitivity and excellent selectivity.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41972067&41930215)the Fund from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources(Grant No.J1901-11).
文摘Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concerning the formation and evolution of rocks.There are a growing number of reports of zircon existing in mantle peridotite.However,it is generally considered that zircon is unlikely crystallized in ultrabasic rocks due to SiO_(2)-unsaturation.In this paper,the SiO_(2) activity and zircon/baddeleyite transition curve at different conditions were calculated through thermodynamic phase equilibrium modeling,to reveal the main factors affecting the SiO_(2) activity and the stability of zircon/baddeleyite in ultrabasic and basic rocks,especially in mantle peridotite.These results provide a thermodynamic basis for interpreting the genesis and significance of zircon in mantle rocks.That is,the SiO_(2) activity is mainly controlled by stable mineral assemblages and temperature-pressure conditions.The orthopyroxene+olivine assemblage in peridotite as an effective buffer restricts the SiO_(2) activity in a relatively high range with a small variation.The upper temperature limit of zircon can reach more than 1500℃ with this mineral assemblage.During the low-temperature serpentinization of peridotite,the replacement of olivine and pyroxene by serpentine can result in a significant decrease of SiO_(2) activity,and baddeleyite can be stabilized at<530℃ and<2.7 GPa.When peridotite is strongly metasomatized by the SiO_(2)-bearing fluid,the addition of SiO_(2) can increase its activity and make zircon stable at low temperatures.The SiO_(2) activity in ultrabasic-basic rocks is not only positively correlated with the SiO_(2) content but also negatively correlated with the Ca and Na contents of rocks.This is because Ca and Na preferentially combine with Si and Al to form Si-rich minerals,such as clinopyroxene and feldspar.This process will consume excessive SiO_(2),decreasing the SiO_(2) activity.This may be the reason why zircon can be found in ultrabasic rocks,while baddeleyite can exist in some basic and alkaline rocks.The thermodynamic modeling can also reasonably explain the mutual transformation between zircon and baddeleyite in ultrabasic-basic rocks.Our results indicate that zircon can exist stably in mantle peridotite in a wide range of temperature-pressure conditions and its formation is related to melt/fluid metasomatism.That is,the presence of zircon in mantle peridotite is an important information carrier of crust-mantle interaction for deep material cycling.
