Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of...Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of liquid rather than solid phases.The physicochemical property of liquid phases is determined by the dehydration behavior of crustal rocks at the slab-mantle interface in subduction channels.Because of the significant fractionation in incompatible trace elements but the full inheritance in radiogenic isotopes relative to their crustal sources,the production of liquid phases is crucial to the geochemical transfer from the subducting crust into the mantle.In this process,the stability of specific minerals in subducting crustal rocks exerts a primary control on the enrichment of given trace elements in the liquid phases.For this reason,geochemically enriched oceanic basalts can be categorized into two types in terms of their trace element distribution patterns in the primitive mantle-normalized diagram.One is island arc basalts(IAB),showing enrichment in LILE,Pb and LREE but depletion in HFSE such as Nb and Ta relative to HREE,The other is ocean island basalts(OIB),exhibiting enrichment in LILE and LREE,enrichment or non-depletion in HFSE but depletion in Pb relative to HREE.In either types,these basalts show the enhanced enrichment of LILE and LREE with increasing their incompatibility relative to normal mid-ocean ridge basalts(MORB).The thermal regime of subduction zones can be categorized into two stages in both time and space,The first stage is characterized by compressional tectonism at low thermal gradients.As a consequence,metamorphic dehydration of the subducting crust prevails at forearc to subarc depths due to the breakdown of hydrous minerals such as mica and amphibole in the stability field of garnet and rutile,resulting in the liberation of aqueous solutions with the trace element composition that is considerably enriched in LILE,Pb and LREE but depleted in HFSE and HREE relative to normal M展开更多
Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates....Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates. GSZ are closey related to gravity Moho gradient zones and lithospheric thickness. The GSZ between the Yangtze and Cathaysian plates is consistent with the Shizong-Mile tectonic belt, where island are basalts are well developed. The Yangtze-Indo-China GSZ is parallel to the Jingdong-Mojiang volcanic belt in rift-island are environments. The evidence of geology, geophysics and geochemistry all indicates that Cathaysia was subducted towards the Yangtze plate and that the Yangtze plate was underthrust beneath the Indo-China, which took place from the Early Carboniferous to the Early Triassic.展开更多
The meta-basic volcanic rocks in the Tengtiaohe Zone yield zircon U–Pb ages of 258.8±2.5 Ma and 259.2±1.8 Ma, respectively which agree with the ages of flood basalts of ELIP and are similar to the basaltic ...The meta-basic volcanic rocks in the Tengtiaohe Zone yield zircon U–Pb ages of 258.8±2.5 Ma and 259.2±1.8 Ma, respectively which agree with the ages of flood basalts of ELIP and are similar to the basaltic rocks and komatiites from the Song Da Zone in northern Vietnam. The results suggest that the age of meta-basic volcanic rocks is Late Permian, rather than the Early Permian or Early Carboniferous ages as previously inferred. Most meta-basic volcanic rocks are strongly enriched in LREEs relative to HREEs and display trace element patterns similar to the ELIP high-Ti basalts, and are enriched in LILEs with negative Sr anomalies. Their initial 87^Sr/86^Sr ratios range from 0.705974 to 0.706188 and εNd（t） from-0.82 to-2.11. Their magmas were derived from an enriched and deep mantle source without significant crustal contamination. These meta-basic volcanic rocks formed in ELIP. Therefore, the Tengtiaohe Zone is not an ophiolite zone and can link to the Song Da Zone in northern Vietnam.展开更多
One major consequence of global warming in the Antarctic region is increased ice-free zones.Subsequent colonization of these ice-free areas by penguins alters their biogeochemistry,with one prominent example being ele...One major consequence of global warming in the Antarctic region is increased ice-free zones.Subsequent colonization of these ice-free areas by penguins alters their biogeochemistry,with one prominent example being elevation of inorganic phosphate concentrations around feces depositions.The complex soil biochemistry in the region makes it difficult to define the causal factors of these changes using common research approaches.Here,we addressed the effects of phosphate alone on microbiome structure and dynamics over time by adding external phosphate to selected soils in the Antarctic region.We then analyzed the soil bacterial community composition and diversity using 16S rRNA amplicon sequencing and compared these data with phosphate levels.Parallel geochemical analysis revealed changes in nine soil geochemical factors upon phosphate addition,all of which were relevant to microbiome structure,with soil pH showing the highest correlation.Links between geochemical factors and composition were identified,as were interactions between bacterial taxa.Additionally,Sphingobacteriia,Sphingobacteriales and Chitinophagaceae were found to be more abundant in phosphate-treated soils.Co-occurrence network analysis revealed significantly increased levels of associations in all major network properties over time after phosphate supplementation.Therefore,we conclude phosphate addition has diverse effects on Antarctic soil microbiomes.展开更多
The geochemical characteristics of rare earth elements (REEs) in intertidal sediments in Tianjin coastal zone were systematically studied. The environmental behaviors of REEs in polluted river were also examined. The ...The geochemical characteristics of rare earth elements (REEs) in intertidal sediments in Tianjin coastal zone were systematically studied. The environmental behaviors of REEs in polluted river were also examined. The source of REEs in intertidal sediments was discussed on the basis of distribution pattern of REEs. The results can be summed up in the following aspects: (1) The average content of total REEs in the intertidal sediments is 164.5 mg·kg -1, and different in different sections of the coast. (2) Residual REEs in the coastal zone decrease from north to south, and Fe-Mn oxides and organic matter-bound REEs increase. Compared with those in Changjiang River, ratio between residual and carbonate REEs is obviously low. (3) Distribution patterns of REEs show that light REEs is relatively high and Eu-anomaly is slightly negative. They are similar to the patterns in coastal and inland rivers and different from those in continental shelf.展开更多
基金supported by funds from the Chinese Academy of Sciences(XDB18020303)the Chinese Ministry of Science and Technology(2015CB856100)the National Natural ScienceFoundation of China(41590620)
文摘Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of liquid rather than solid phases.The physicochemical property of liquid phases is determined by the dehydration behavior of crustal rocks at the slab-mantle interface in subduction channels.Because of the significant fractionation in incompatible trace elements but the full inheritance in radiogenic isotopes relative to their crustal sources,the production of liquid phases is crucial to the geochemical transfer from the subducting crust into the mantle.In this process,the stability of specific minerals in subducting crustal rocks exerts a primary control on the enrichment of given trace elements in the liquid phases.For this reason,geochemically enriched oceanic basalts can be categorized into two types in terms of their trace element distribution patterns in the primitive mantle-normalized diagram.One is island arc basalts(IAB),showing enrichment in LILE,Pb and LREE but depletion in HFSE such as Nb and Ta relative to HREE,The other is ocean island basalts(OIB),exhibiting enrichment in LILE and LREE,enrichment or non-depletion in HFSE but depletion in Pb relative to HREE.In either types,these basalts show the enhanced enrichment of LILE and LREE with increasing their incompatibility relative to normal mid-ocean ridge basalts(MORB).The thermal regime of subduction zones can be categorized into two stages in both time and space,The first stage is characterized by compressional tectonism at low thermal gradients.As a consequence,metamorphic dehydration of the subducting crust prevails at forearc to subarc depths due to the breakdown of hydrous minerals such as mica and amphibole in the stability field of garnet and rutile,resulting in the liberation of aqueous solutions with the trace element composition that is considerably enriched in LILE,Pb and LREE but depleted in HFSE and HREE relative to normal M
基金This study was supported by the key project of Chinese Academy of Sciences KZ951-B1-413Project No.973 of the National Commission of Science and Technology(G1999043213).
文摘Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates. GSZ are closey related to gravity Moho gradient zones and lithospheric thickness. The GSZ between the Yangtze and Cathaysian plates is consistent with the Shizong-Mile tectonic belt, where island are basalts are well developed. The Yangtze-Indo-China GSZ is parallel to the Jingdong-Mojiang volcanic belt in rift-island are environments. The evidence of geology, geophysics and geochemistry all indicates that Cathaysia was subducted towards the Yangtze plate and that the Yangtze plate was underthrust beneath the Indo-China, which took place from the Early Carboniferous to the Early Triassic.
基金supported by National Natural Science Foundation of China(Grant No.41172202,No.41190073 and No.41302178)China Geological Survey(Grant No.1212011121256)+2 种基金National Basic Research Program of China(2014CB440901)the Fundamental Research Funds for the Central Universities to SYSUState Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences in Wuhan(MSFGPMR201402)
文摘The meta-basic volcanic rocks in the Tengtiaohe Zone yield zircon U–Pb ages of 258.8±2.5 Ma and 259.2±1.8 Ma, respectively which agree with the ages of flood basalts of ELIP and are similar to the basaltic rocks and komatiites from the Song Da Zone in northern Vietnam. The results suggest that the age of meta-basic volcanic rocks is Late Permian, rather than the Early Permian or Early Carboniferous ages as previously inferred. Most meta-basic volcanic rocks are strongly enriched in LREEs relative to HREEs and display trace element patterns similar to the ELIP high-Ti basalts, and are enriched in LILEs with negative Sr anomalies. Their initial 87^Sr/86^Sr ratios range from 0.705974 to 0.706188 and εNd（t） from-0.82 to-2.11. Their magmas were derived from an enriched and deep mantle source without significant crustal contamination. These meta-basic volcanic rocks formed in ELIP. Therefore, the Tengtiaohe Zone is not an ophiolite zone and can link to the Song Da Zone in northern Vietnam.
基金funded by the National Key R&D Program of China(Grant no.2018YFC1406700)the National Natural Science Foundation of China(Grant no.41776198)the Basic Scientific Fund for National Public Research Institutes of China(Grant no.GY0219Q10)。
文摘One major consequence of global warming in the Antarctic region is increased ice-free zones.Subsequent colonization of these ice-free areas by penguins alters their biogeochemistry,with one prominent example being elevation of inorganic phosphate concentrations around feces depositions.The complex soil biochemistry in the region makes it difficult to define the causal factors of these changes using common research approaches.Here,we addressed the effects of phosphate alone on microbiome structure and dynamics over time by adding external phosphate to selected soils in the Antarctic region.We then analyzed the soil bacterial community composition and diversity using 16S rRNA amplicon sequencing and compared these data with phosphate levels.Parallel geochemical analysis revealed changes in nine soil geochemical factors upon phosphate addition,all of which were relevant to microbiome structure,with soil pH showing the highest correlation.Links between geochemical factors and composition were identified,as were interactions between bacterial taxa.Additionally,Sphingobacteriia,Sphingobacteriales and Chitinophagaceae were found to be more abundant in phosphate-treated soils.Co-occurrence network analysis revealed significantly increased levels of associations in all major network properties over time after phosphate supplementation.Therefore,we conclude phosphate addition has diverse effects on Antarctic soil microbiomes.
文摘The geochemical characteristics of rare earth elements (REEs) in intertidal sediments in Tianjin coastal zone were systematically studied. The environmental behaviors of REEs in polluted river were also examined. The source of REEs in intertidal sediments was discussed on the basis of distribution pattern of REEs. The results can be summed up in the following aspects: (1) The average content of total REEs in the intertidal sediments is 164.5 mg·kg -1, and different in different sections of the coast. (2) Residual REEs in the coastal zone decrease from north to south, and Fe-Mn oxides and organic matter-bound REEs increase. Compared with those in Changjiang River, ratio between residual and carbonate REEs is obviously low. (3) Distribution patterns of REEs show that light REEs is relatively high and Eu-anomaly is slightly negative. They are similar to the patterns in coastal and inland rivers and different from those in continental shelf.
