Zircon is a key accessary mineral for metamorphic geochronology and geochemical tracing,but it has been a challenge to interpret its complex chemical zoning and age record acquired during multiple episodes of anatecti...Zircon is a key accessary mineral for metamorphic geochronology and geochemical tracing,but it has been a challenge to interpret its complex chemical zoning and age record acquired during multiple episodes of anatectic metamorphism in collisional orogens.This is illustrated by a combined study of petrography,phase equilibrium modeling and metamorphic P-T-t determination for granulites from the Bohemian Massif in the Variscan Orogen.These rocks record multiple episodes of zircon growth during anatectic metamorphism.They started from the compressional heating for prograde metamorphism to high-pressure(HP)to ultrahigh-pressure(UHP)eclogite facies with low degrees of partial melting.Afterwards,they underwent a decompressional stage from UHP eclogite facies to HP granulite facies for dehydration melting.These were followed by a further decompressional stage either to kyanite granulite facies or to sillimanite granulite facies at ultrahigh-temperature(UHT)conditions.Episodes of zircon growth are linked to specific metamorphic conditions for peritectic reactions on the basis of zoning patterns,trace element signatures,index mineral inclusions in dated domains and textural relationships to coexisting minerals.The results indicate that relict zircon domains are preserved even at UHT granulite facies conditions.A few zircon domains in the kyanite granulite grew during the prograde to peak UHP metamorphism,possibly corresponding to consumption of biotite and plagioclase but growth of garnet.During the decompressional exhumation to the HP granulite-facies,relict or prograde zircon domains were mostly dissolved into anatectic melts produced by muscovite breakdown.Most zircon grains grew during this transition to the HP granulite-facies in the kyanite granulite and are chemically related to continuous growth of garnet,whereas abundant zircon grains grew subsequently at the UHT granulite facies in the sillimanite granulite and are chemically related to garnet breakdown reactions.Another peak of zircon growth occurred at the final crystallization of anatectic melts in the sillimanite granulite rather than in the kyanite granulite,and these zircon grains mostly show oscillatory zoning,low HREE+Y contents and significantly negative Eu anomalies.In terms of the inference for protolith nature,it appears that zircon in metasedimentary rocks can grow at a short timescale in different stages of anatectic metamorphism,and its dissolution and growth are mainly dictated by anatectic conditions and extent,the property of peritectic reactions,and the stability of Ti-rich minerals.展开更多
Machine learning(ML)applications in weather and climate are gaining momentum as big data and the immense increase in High-performance computing(HPC)power are paving the way.Ensuring FAIR data and reproducible ML pract...Machine learning(ML)applications in weather and climate are gaining momentum as big data and the immense increase in High-performance computing(HPC)power are paving the way.Ensuring FAIR data and reproducible ML practices are significant challenges for Earth system researchers.Even though the FAIR principle is well known to many scientists,research communities are slow to adopt them.Canonical Workflow Framework for Research(CWFR)provides a platform to ensure the FAIRness and reproducibility of these practices without overwhelming researchers.This conceptual paper envisions a holistic CWFR approach towards ML applications in weather and climate,focusing on HPC and big data.Specifically,we discuss Fair Digital Object(FDO)and Research Object(RO)in the DeepRain project to achieve granular reproducibility.DeepRain is a project that aims to improve precipitation forecast in Germany by using ML.Our concept envisages the raster datacube to provide data harmonization and fast and scalable data access.We suggest the Juypter notebook as a single reproducible experiment.In addition,we envision JuypterHub as a scalable and distributed central platform that connects all these elements and the HPC resources to the researchers via an easy-to-use graphical interface.展开更多
Five hybrid tetrapeptides,each consisting a central dipeptide segment ofα-amino acid residues flanked by two aromaticγ-amino acid residues,are found to fold into well-definedβ-hairpin conformations as shown by NMR,...Five hybrid tetrapeptides,each consisting a central dipeptide segment ofα-amino acid residues flanked by two aromaticγ-amino acid residues,are found to fold into well-definedβ-hairpin conformations as shown by NMR,computational study,and X-ray structures.The turn loop of thisβ-hairpin motif accommodates different two-residueα-amino acid sequences from the highly flexible Gly-Gly,to the more restricted D-Pro-Gly.The presence ofα-amino acid side chains enhances the stabilities of theβ-hairpins with the exception of D-Pro-Gly-which results in destabilization.Based on this hairpin/turn motif,a variety of different dipeptide sequences ofα-amino acids which rarely occur inβ-turns can be introduced and presented as two-residue loops.展开更多
This is a report of carbon isotope anomaly in marbles associated with the UHP eclogites from the Dabie Mountains. The results place constraints on the degree of crust_mantle interaction during the UHP metamorphism.
基金supported by the Natural Science Foundation of China(Nos.41673030,41590624)the Strategy Guide Project B of the Chinese Academy of Sciences(No.XDB18020303)+1 种基金the Youth Innovation Promotion Association of CAS(No.2013283)the Fundamental Research Programs for the Central Universities。
文摘Zircon is a key accessary mineral for metamorphic geochronology and geochemical tracing,but it has been a challenge to interpret its complex chemical zoning and age record acquired during multiple episodes of anatectic metamorphism in collisional orogens.This is illustrated by a combined study of petrography,phase equilibrium modeling and metamorphic P-T-t determination for granulites from the Bohemian Massif in the Variscan Orogen.These rocks record multiple episodes of zircon growth during anatectic metamorphism.They started from the compressional heating for prograde metamorphism to high-pressure(HP)to ultrahigh-pressure(UHP)eclogite facies with low degrees of partial melting.Afterwards,they underwent a decompressional stage from UHP eclogite facies to HP granulite facies for dehydration melting.These were followed by a further decompressional stage either to kyanite granulite facies or to sillimanite granulite facies at ultrahigh-temperature(UHT)conditions.Episodes of zircon growth are linked to specific metamorphic conditions for peritectic reactions on the basis of zoning patterns,trace element signatures,index mineral inclusions in dated domains and textural relationships to coexisting minerals.The results indicate that relict zircon domains are preserved even at UHT granulite facies conditions.A few zircon domains in the kyanite granulite grew during the prograde to peak UHP metamorphism,possibly corresponding to consumption of biotite and plagioclase but growth of garnet.During the decompressional exhumation to the HP granulite-facies,relict or prograde zircon domains were mostly dissolved into anatectic melts produced by muscovite breakdown.Most zircon grains grew during this transition to the HP granulite-facies in the kyanite granulite and are chemically related to continuous growth of garnet,whereas abundant zircon grains grew subsequently at the UHT granulite facies in the sillimanite granulite and are chemically related to garnet breakdown reactions.Another peak of zircon growth occurred at the final crystallization of anatectic melts in the sillimanite granulite rather than in the kyanite granulite,and these zircon grains mostly show oscillatory zoning,low HREE+Y contents and significantly negative Eu anomalies.In terms of the inference for protolith nature,it appears that zircon in metasedimentary rocks can grow at a short timescale in different stages of anatectic metamorphism,and its dissolution and growth are mainly dictated by anatectic conditions and extent,the property of peritectic reactions,and the stability of Ti-rich minerals.
基金German Bundesministerium fuer Bildung und Forschung(BMBF)for funding the DeepRain project under grant agreement 01 IS18047A-E.
文摘Machine learning(ML)applications in weather and climate are gaining momentum as big data and the immense increase in High-performance computing(HPC)power are paving the way.Ensuring FAIR data and reproducible ML practices are significant challenges for Earth system researchers.Even though the FAIR principle is well known to many scientists,research communities are slow to adopt them.Canonical Workflow Framework for Research(CWFR)provides a platform to ensure the FAIRness and reproducibility of these practices without overwhelming researchers.This conceptual paper envisions a holistic CWFR approach towards ML applications in weather and climate,focusing on HPC and big data.Specifically,we discuss Fair Digital Object(FDO)and Research Object(RO)in the DeepRain project to achieve granular reproducibility.DeepRain is a project that aims to improve precipitation forecast in Germany by using ML.Our concept envisages the raster datacube to provide data harmonization and fast and scalable data access.We suggest the Juypter notebook as a single reproducible experiment.In addition,we envision JuypterHub as a scalable and distributed central platform that connects all these elements and the HPC resources to the researchers via an easy-to-use graphical interface.
基金supported by the National Natural Science Foundation of China(No.21778012 to Z.L.Lu,21801020 to R.Liu)the American Chemical Society–Petroleum Research Fund(PRF#58364-ND7,to B.Gong)+1 种基金the Center for Computational Research(CCR)(to D.P.Miller and E.Zurek)Hofstra University(to D.P.Miller)。
文摘Five hybrid tetrapeptides,each consisting a central dipeptide segment ofα-amino acid residues flanked by two aromaticγ-amino acid residues,are found to fold into well-definedβ-hairpin conformations as shown by NMR,computational study,and X-ray structures.The turn loop of thisβ-hairpin motif accommodates different two-residueα-amino acid sequences from the highly flexible Gly-Gly,to the more restricted D-Pro-Gly.The presence ofα-amino acid side chains enhances the stabilities of theβ-hairpins with the exception of D-Pro-Gly-which results in destabilization.Based on this hairpin/turn motif,a variety of different dipeptide sequences ofα-amino acids which rarely occur inβ-turns can be introduced and presented as two-residue loops.
文摘This is a report of carbon isotope anomaly in marbles associated with the UHP eclogites from the Dabie Mountains. The results place constraints on the degree of crust_mantle interaction during the UHP metamorphism.
