The aragonite, an index mineral of glaucophane schist facies, has not been confirmed in the Dabie Mountains high pressure and ultrahigh pressure metamorphic belts. The Mulanshan glaucophane schist in Huangpi County,...The aragonite, an index mineral of glaucophane schist facies, has not been confirmed in the Dabie Mountains high pressure and ultrahigh pressure metamorphic belts. The Mulanshan glaucophane schist in Huangpi County, Hubei Province is located in the southwestern Dabie Mountains, Central China. The micron sized intergranular aragonite is confirmed with optical microscope (OM) and electron probe microanalysis (EPMA) in the glaucophane schist. The submicrometer sized ellipse aragonite inclusion is observed by using bright field image (BFI), X ray energy damage spectrograph (EDS) and selected area electron diffraction (SAED) with transmission electron microscope in the quartz lens of glaucophane albite epidote chlorite schist from Mulanshan. The presence of aragonite indicates not only the average geothermal gradient of the Mulanshan glaucophane schist less than 10 ℃/km, which is very close to that of eclogite in the Dabie Mountains metamorphic belts, but also the relatively higher concentration of CO2 during the metamorphic process. In addition, the glaucophane schist free of such index minerals as lawsonite, prehnite and pumpellyite, has been attributed to the effect of CO2 on the stability of calcium aluminum silicate minerals during the low grade metamorphism. EDS and SAED analysis results show that the host of aragonite inclusion is amorphous SiO2. The occurrence of amorphous SiO2 indicates a quick cooling process during the exhumation of the Mulanshan glaucophane schist. These results suggest that the rapid exhumation mechanism of the glaucophane schist, the same as that of eclogite in the Dabie Mountains metamorphic belts, occurred in the geodynamic context of subduction obduction.展开更多
Using the constant addition technique,the coprecipitation of lanthanum,gadolinium,and lutetium with aragonite in seawater was experimentally investigated at 25 ℃.Their concentrations in aragonite overgrowths were det...Using the constant addition technique,the coprecipitation of lanthanum,gadolinium,and lutetium with aragonite in seawater was experimentally investigated at 25 ℃.Their concentrations in aragonite overgrowths were determined by inductive coupled plasma mass spectrometer.All these lanthanides were strongly enriched in aragonite overgrowths.The amount of lanthanum,gadolinium,and lutetium incorporated into aragonite accounted for 57%–99%,50%–89%,and 40%–91% of their initial total amount,respectively.With the in...展开更多
Growth of phytoplankton, zooplankton and probably most other marine organisms as well, is likely to be affected by the pH of seawater. Growth of calcareous shells and skeletons is less likely to be affect ed by the sa...Growth of phytoplankton, zooplankton and probably most other marine organisms as well, is likely to be affected by the pH of seawater. Growth of calcareous shells and skeletons is less likely to be affect ed by the saturation states of calcite and aragonite but the dissolution is. The increase of CO2 in the oceans due to burning of fossil fuel and clearing of forests is decreasing the pH of seawater and the degress of saturation for calcite and aragonite worldwide. This paper presents the results of the first attempt to estimate the vertical distribution of anthropogenic CO2, and the decreases in pH and the degrees of saturation of calcite and aragonite in seawater near Taiwan. Most ef fects are very small except for the possible dissolution of aragonite on the upper continental slope starting around 2050 AD.展开更多
Highly oriented calcium carbonate lamellas are exquisite structure produced by biomineralization. Strategies mimicking nature have been developed to synthesize inorganic materials with excellent structures and optimal...Highly oriented calcium carbonate lamellas are exquisite structure produced by biomineralization. Strategies mimicking nature have been developed to synthesize inorganic materials with excellent structures and optimal properties. In our strategy, egg white protein and zinc ion were employed in the solution to induce the crystallization of calcium carbonate, resulting in the macroscopic aragonite laminate with an average length of 1.5 mm, which was comprised of single-crystalline tablets. During the crystallization at initial stage, it was found that the particles displayed the characteristics of amorphous calcium carbonate, which was then transformed into the sophisticated structured aragonite through a multistage assembly process. The rebuilt nacre structure in vitro was achieved owing to the synergistic effects of egg white protein and zinc ion.展开更多
The 13C-18O bonds in carbonates are potential single-phase geo-thermometers. However, their theoretical distributions (noted as Δ47s) in CO2 degassed from calcite and aragonite with phosphoric acid are unclear. Thus,...The 13C-18O bonds in carbonates are potential single-phase geo-thermometers. However, their theoretical distributions (noted as Δ47s) in CO2 degassed from calcite and aragonite with phosphoric acid are unclear. Thus, the isotope reactions of 13C-18O bonds on the growing surfaces of calcite (0001) and aragonite (001) planes were investigated using ab initio techniques. It was found that these reactions determined 13C-18O clumped isotope signatures in bulk calcite and aragonite minerals with novel Δ47 polynomials: and for temperatures ranging from 260 to 1500 K. These theoretical results were in good agreement with the experimental data. In addition, the influence of phosphoric acid on these polynomials was at the level of 0.01‰.展开更多
Aragonite calcium carbonate whisker was prepared by thermal decomposition of Ca（HCO3）2 in aqueous solution in the presence of chloride salts. The influences of reaction temperature, time and concentrations of CaCl2,...Aragonite calcium carbonate whisker was prepared by thermal decomposition of Ca（HCO3）2 in aqueous solution in the presence of chloride salts. The influences of reaction temperature, time and concentrations of CaCl2, MgCl2 and KCl on the morphology of CaCO3 whiskers were studied. The structure characteristics of CaCO3 whiskers were analyzed by XRD and SEM. The results indicate that the optimum conditions are 80～100 ℃, 50～60 min and the suitable concentrations of Ca（HCO3）2, KCl, MgCl2, CaCl2 are 6.0 mmol/L, 14.0 mmol/L, 1.0 mmol/L, 1.5 mmol/L respectively. The purity of the whiskers is 99.53% and the average aspect ratio is 24.1.展开更多
基金theNationalNaturalScienceFoundationofChina (No .4980 2 0 0 4)
文摘The aragonite, an index mineral of glaucophane schist facies, has not been confirmed in the Dabie Mountains high pressure and ultrahigh pressure metamorphic belts. The Mulanshan glaucophane schist in Huangpi County, Hubei Province is located in the southwestern Dabie Mountains, Central China. The micron sized intergranular aragonite is confirmed with optical microscope (OM) and electron probe microanalysis (EPMA) in the glaucophane schist. The submicrometer sized ellipse aragonite inclusion is observed by using bright field image (BFI), X ray energy damage spectrograph (EDS) and selected area electron diffraction (SAED) with transmission electron microscope in the quartz lens of glaucophane albite epidote chlorite schist from Mulanshan. The presence of aragonite indicates not only the average geothermal gradient of the Mulanshan glaucophane schist less than 10 ℃/km, which is very close to that of eclogite in the Dabie Mountains metamorphic belts, but also the relatively higher concentration of CO2 during the metamorphic process. In addition, the glaucophane schist free of such index minerals as lawsonite, prehnite and pumpellyite, has been attributed to the effect of CO2 on the stability of calcium aluminum silicate minerals during the low grade metamorphism. EDS and SAED analysis results show that the host of aragonite inclusion is amorphous SiO2. The occurrence of amorphous SiO2 indicates a quick cooling process during the exhumation of the Mulanshan glaucophane schist. These results suggest that the rapid exhumation mechanism of the glaucophane schist, the same as that of eclogite in the Dabie Mountains metamorphic belts, occurred in the geodynamic context of subduction obduction.
基金supported by the National Natural Science Foundation of China (40376038)
文摘Using the constant addition technique,the coprecipitation of lanthanum,gadolinium,and lutetium with aragonite in seawater was experimentally investigated at 25 ℃.Their concentrations in aragonite overgrowths were determined by inductive coupled plasma mass spectrometer.All these lanthanides were strongly enriched in aragonite overgrowths.The amount of lanthanum,gadolinium,and lutetium incorporated into aragonite accounted for 57%–99%,50%–89%,and 40%–91% of their initial total amount,respectively.With the in...
文摘Growth of phytoplankton, zooplankton and probably most other marine organisms as well, is likely to be affected by the pH of seawater. Growth of calcareous shells and skeletons is less likely to be affect ed by the saturation states of calcite and aragonite but the dissolution is. The increase of CO2 in the oceans due to burning of fossil fuel and clearing of forests is decreasing the pH of seawater and the degress of saturation for calcite and aragonite worldwide. This paper presents the results of the first attempt to estimate the vertical distribution of anthropogenic CO2, and the decreases in pH and the degrees of saturation of calcite and aragonite in seawater near Taiwan. Most ef fects are very small except for the possible dissolution of aragonite on the upper continental slope starting around 2050 AD.
基金Funded by the National Natural Science Foundation of China(No.51161140399)
文摘Highly oriented calcium carbonate lamellas are exquisite structure produced by biomineralization. Strategies mimicking nature have been developed to synthesize inorganic materials with excellent structures and optimal properties. In our strategy, egg white protein and zinc ion were employed in the solution to induce the crystallization of calcium carbonate, resulting in the macroscopic aragonite laminate with an average length of 1.5 mm, which was comprised of single-crystalline tablets. During the crystallization at initial stage, it was found that the particles displayed the characteristics of amorphous calcium carbonate, which was then transformed into the sophisticated structured aragonite through a multistage assembly process. The rebuilt nacre structure in vitro was achieved owing to the synergistic effects of egg white protein and zinc ion.
文摘The 13C-18O bonds in carbonates are potential single-phase geo-thermometers. However, their theoretical distributions (noted as Δ47s) in CO2 degassed from calcite and aragonite with phosphoric acid are unclear. Thus, the isotope reactions of 13C-18O bonds on the growing surfaces of calcite (0001) and aragonite (001) planes were investigated using ab initio techniques. It was found that these reactions determined 13C-18O clumped isotope signatures in bulk calcite and aragonite minerals with novel Δ47 polynomials: and for temperatures ranging from 260 to 1500 K. These theoretical results were in good agreement with the experimental data. In addition, the influence of phosphoric acid on these polynomials was at the level of 0.01‰.
文摘Aragonite calcium carbonate whisker was prepared by thermal decomposition of Ca（HCO3）2 in aqueous solution in the presence of chloride salts. The influences of reaction temperature, time and concentrations of CaCl2, MgCl2 and KCl on the morphology of CaCO3 whiskers were studied. The structure characteristics of CaCO3 whiskers were analyzed by XRD and SEM. The results indicate that the optimum conditions are 80～100 ℃, 50～60 min and the suitable concentrations of Ca（HCO3）2, KCl, MgCl2, CaCl2 are 6.0 mmol/L, 14.0 mmol/L, 1.0 mmol/L, 1.5 mmol/L respectively. The purity of the whiskers is 99.53% and the average aspect ratio is 24.1.
