A new method for determining the partial melting depth of mantle-derived magma and lithospheric thickness in continental regions is derived from REE geochemistry. This effective technique uses variations in the Ce/Yb ...A new method for determining the partial melting depth of mantle-derived magma and lithospheric thickness in continental regions is derived from REE geochemistry. This effective technique uses variations in the Ce/Yb and Sm/Yb ratios found in mainly volcanic rocks in continental China. The ratios change with the depth of origin consistent with the correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios found in oceanic basalt. These ratios increase exponentially with the depth of origin, the lithospheric thickness, of a wide variety of Cenozoic volcanic basalt and Paleozoic kimberlite in the North China Craton, northeastern China continent and vicinity. This functional relationship with depth is shown in a plot of the ratios that forms a concordia curve, which is closely expressed by formulas using 8–degree polynomials. These provide a more accurate gage in measuring the lithospheric thickness than the traditional geophysical methods. When applied to volcanic rock of different ages it also reveals how the thickness has changed over time and thus, greatly aids the understanding of the tectonic history. Relations between the COcontent, mineral reactions and pressure in the upper asthenosphere beneath the base of the lithosphere appears to affect the proportions of REE in partial melts and brings about a close correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios in mantle–derived magmatic rock. This thickness gauge, for both continental and oceanic lithosphere, provides a new approach in analyzing the lithospheric thickness in different tectonic settings and geologic times.展开更多
Our previous work first reported the cooperative sensitized luminescence from Cu2＋ or Pb2＋ by three clustered Yb^3＋ ions, in which three NIR photons can be converted into a high energy photon. Could a reverse proce...Our previous work first reported the cooperative sensitized luminescence from Cu2＋ or Pb2＋ by three clustered Yb^3＋ ions, in which three NIR photons can be converted into a high energy photon. Could a reverse process happen that a high energy photon is cut into three NIR photons？ This work demonstrated an example of three-photon quantum cutting （QC） phosphor, CaF2：Ce^3＋,Yb^3＋, in which three clustered Yb^3＋ ions （Yb^3＋-trimer） cooperatively and indirectly received a 306 nm ultraviolet （UV） photon energy transferred from a Ce^3＋ ion in 5d excited state and emitted three 975 nm near-infrared （NIR） photons. The cluster destruction experiments were designed to verify the necessity of the presence of Yb^3＋-trimers for QC. The dynamical analysis on luminescence of Ce^3＋ ions confirmed the energy transfer from Ce^3＋ ions to Yb^3＋-trimers. The doping concentration effect on luminescence was investigated. Furthermore, the maximum energy transfer （ET） efficiency and the corresponding QC efficiency were estimated to be 61% and 222%, respectively. Therefore, the reported three-photon QC phosphor has an attractive prospect in efficiently harvesting solar energy for silicon solar cells.展开更多
基金supported by the Ministry of Land and Resources of China under grant No.201211095
文摘A new method for determining the partial melting depth of mantle-derived magma and lithospheric thickness in continental regions is derived from REE geochemistry. This effective technique uses variations in the Ce/Yb and Sm/Yb ratios found in mainly volcanic rocks in continental China. The ratios change with the depth of origin consistent with the correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios found in oceanic basalt. These ratios increase exponentially with the depth of origin, the lithospheric thickness, of a wide variety of Cenozoic volcanic basalt and Paleozoic kimberlite in the North China Craton, northeastern China continent and vicinity. This functional relationship with depth is shown in a plot of the ratios that forms a concordia curve, which is closely expressed by formulas using 8–degree polynomials. These provide a more accurate gage in measuring the lithospheric thickness than the traditional geophysical methods. When applied to volcanic rock of different ages it also reveals how the thickness has changed over time and thus, greatly aids the understanding of the tectonic history. Relations between the COcontent, mineral reactions and pressure in the upper asthenosphere beneath the base of the lithosphere appears to affect the proportions of REE in partial melts and brings about a close correlation between lithospheric thickness and the Ce/Yb and Sm/Yb ratios in mantle–derived magmatic rock. This thickness gauge, for both continental and oceanic lithosphere, provides a new approach in analyzing the lithospheric thickness in different tectonic settings and geologic times.
基金Project supported by the National Natural Science Foundation of China(11274139)
文摘Our previous work first reported the cooperative sensitized luminescence from Cu2＋ or Pb2＋ by three clustered Yb^3＋ ions, in which three NIR photons can be converted into a high energy photon. Could a reverse process happen that a high energy photon is cut into three NIR photons？ This work demonstrated an example of three-photon quantum cutting （QC） phosphor, CaF2：Ce^3＋,Yb^3＋, in which three clustered Yb^3＋ ions （Yb^3＋-trimer） cooperatively and indirectly received a 306 nm ultraviolet （UV） photon energy transferred from a Ce^3＋ ion in 5d excited state and emitted three 975 nm near-infrared （NIR） photons. The cluster destruction experiments were designed to verify the necessity of the presence of Yb^3＋-trimers for QC. The dynamical analysis on luminescence of Ce^3＋ ions confirmed the energy transfer from Ce^3＋ ions to Yb^3＋-trimers. The doping concentration effect on luminescence was investigated. Furthermore, the maximum energy transfer （ET） efficiency and the corresponding QC efficiency were estimated to be 61% and 222%, respectively. Therefore, the reported three-photon QC phosphor has an attractive prospect in efficiently harvesting solar energy for silicon solar cells.
