A protocol was established for simultaneous measurements of zircon U-Pb ages and trace elements by LA-ICP-MS at spot sizes of 16 32 μm.This was accomplished by introducing N 2 into ICP to increase the sensitivity.The...A protocol was established for simultaneous measurements of zircon U-Pb ages and trace elements by LA-ICP-MS at spot sizes of 16 32 μm.This was accomplished by introducing N 2 into ICP to increase the sensitivity.The obtained U-Pb ages for zircon standards GJ-1,TEMORA and SK10-2 are consistent with the preferred values within about 1% uncertainty (2σ) by simple external calibration against zircon standard 91500.Different data reduction softwares could yield different uncertainties for calculation of U-Pb ages.The commercially available program GLITTER4.4 could apply an improper uncertainty calculation strategy,but it may yield artificial high precisions for single analyses.Our trace element analyses indicate that Si is not an ideal internal standard for zircon when calibrated against the NIST glasses.Calibration against the NIST glasses using Si as an internal standard,a systematic deviation of 10% 30% was found for most trace elements including Zr.However,the trace element compositions of zircon can be accurately measured by calibration against multiple reference materials with natural compositions (e.g.,BCR-2G,BHVO-2G and BIR-1G),or calibration against NIST SRM 610 and using Zr as an internal standard.Analyses of two pieces of GJ-1 demonstrate that it is relatively homogenous for most trace elements (except for Ti).展开更多
Zircon U-Pb dating is the most commonly used method for isotopic geochronology. However, it has been a difficult issue when relating zircon U-Pb ages to metamor- phic conditions in complex metamorphic rocks. Much pro-...Zircon U-Pb dating is the most commonly used method for isotopic geochronology. However, it has been a difficult issue when relating zircon U-Pb ages to metamor- phic conditions in complex metamorphic rocks. Much pro- gress has been made in the past decade with respect to the genesis of zircon and its constraints on interpretation of U-Pb age. Three methods have been proposed to link zircon U-Pb age to metamorphic conditions: (ⅰ) internal structure; (ⅱ) trace element feature; (ⅲ) mineral inclusion composition. Magmatic zircon shows typical oscillatory zoning and/or sector zoning, whereas metamorphic zircon has internal structures such as no zoned, weakly zoned, cloudy zoned, sector zoned, planar zoned, and patched zoned ones. Zircons formed in different geological environments generally have characteristic internal structures. Magmatic zircons from different rock types have variable trace element abundances, with a general trend of increasing trace element abundances in zircons from ultramafic through mafic to granitic rocks. Zircons formed under different metamorphic conditions have different trace element characteristics that can be used to relate their formation to metamorphic conditions. It is an effective way to relate zircon growth to certain P-T condi- tions by studying the trace element partitioning between coexisting metamorphic zircon and garnet in high-grade metamorphic rocks containing both zircon and garnet. Pri- mary mineral inclusions in zircon can also provide unambi- guous constraints on its formation conditions. Therefore, interpretation of zircon U-Pb ages can be constrained by its internal structure, trace element composition, mineral inclu- sion and so on.展开更多
山东省是中国蔬菜的主要产区，常年蔬菜种植面积占全国的10％以上，设施蔬菜的面积占全国的近50％。1994-1997年山东设施蔬菜年平均施肥量达到N1351 kg hm^-2、P2O51701kg hm^-2和K20539．6kg hm^-2，在这段时间内施肥量逐年增加，2004...山东省是中国蔬菜的主要产区，常年蔬菜种植面积占全国的10％以上，设施蔬菜的面积占全国的近50％。1994-1997年山东设施蔬菜年平均施肥量达到N1351 kg hm^-2、P2O51701kg hm^-2和K20539．6kg hm^-2，在这段时间内施肥量逐年增加，2004年的施肥量与1997年相比氮肥和磷肥的用量有所减少，钾肥的用量有所增加，有机养分占总养分的比例明显增加。设施蔬菜土壤养分表观平衡为氮磷钾均盈余，且盈余量较大。设施蔬菜在大量施肥的情况下，肥料的利用率较低，1997年寿光设施蔬菜氮肥的表观利用率为21．33％，磷肥的表观利用率只有2．82％，钾肥的利用率较高达到61．34％。大棚蔬菜土壤pH值与露地相比有降低的趋势，土壤有机质含量高于露地土壤。山东省不同地区大棚土壤中碱解氮含量差异较大，以地处鲁西的德州最低，寿光的最高，平均达到205．4mgkg^-1。不同地区大棚土壤中有效磷含量差异很大，寿光设施蔬菜土壤中有效磷含量最高，平均为225．2mgkg^-1，土壤有效磷具有明显的积累效应，设施种植时间与土壤有效磷含量之间存在极显著的正相关性（r=0．550＊＊，n=35）。土壤母质类型对土壤速效钾具有一定的影响，寿光设施蔬菜土壤中速效钾含量最高，平均为369．7mgkg^-1。土壤速效钾也具有明显的积累效应，设施种植时间与土壤速效钾含量之间具有极显著的正相关性（r=0．502＊＊，n=35）。设施表层土壤中水溶性钙的含量平均为337．9mgkg^-1，土壤水溶性镁的含量平均为67．8mgkg^-1，明显高于露地土壤。设施蔬菜土壤中微量元素含量均高于露地土壤。展开更多
Simultaneous in-situ determination of U-Pb ages and 20 trace elements of three international zircon standards(91500,GJ1 and TEMORA 1) and one laboratory zircon standard(SK10-2) separated from Cenozoic fine-grained gab...Simultaneous in-situ determination of U-Pb ages and 20 trace elements of three international zircon standards(91500,GJ1 and TEMORA 1) and one laboratory zircon standard(SK10-2) separated from Cenozoic fine-grained gabbro was carried out on quadrupole ICP-MS equipped with 193 nm excimer laser in 20 μm spot size. The weighted mean 206Pb/238U ages of 91500,GJ1 and TEMORA 1 are 1064.4±4.8 Ma(2σ ),603.2±2.4 Ma(2σ ) and 418.2±2.4 Ma(2σ ),respectively. The relative standard de-viations(RSDs) of 206Pb/238U ages(2σ ) are less than 2.2% for single measurements and 0.6% for weighted means. The obtained weighted mean 206Pb/238U ages of three standard zircons agree with the recommended values within 2σ error. The weighted mean 206Pb/238U age of SK10-2 is 31.42±0.25 Ma(2σ ) and the RSDs of 206Pb/238U ages(2σ ) are between 2.4% and 5.7% for single measurements and less than 0.8% for weighted mean. The obtained weighted mean 206Pb/238U age is in good agreement with the age obtained by Yuan(2004). Trace element concentrations of NIST612 and NIST614 obtained under the same LA-ICP-MS operating conditions agree with the recommended values within analytical error. The results indicate that it is possible to measure U-Pb age and trace elements simultaneously by LA-ICP-MS in a small spot size of 20 μm.展开更多
基金supported by the National Natural Science Foundation of China (GrantNos. 40821061,90914007,40576030 and 90714010)the State Administration of Foreign Expert Affairs of China (Grant No. B07039)the Special Fund for Basic Scientific Research of Central Colleges,China University of Geosciences
文摘A protocol was established for simultaneous measurements of zircon U-Pb ages and trace elements by LA-ICP-MS at spot sizes of 16 32 μm.This was accomplished by introducing N 2 into ICP to increase the sensitivity.The obtained U-Pb ages for zircon standards GJ-1,TEMORA and SK10-2 are consistent with the preferred values within about 1% uncertainty (2σ) by simple external calibration against zircon standard 91500.Different data reduction softwares could yield different uncertainties for calculation of U-Pb ages.The commercially available program GLITTER4.4 could apply an improper uncertainty calculation strategy,but it may yield artificial high precisions for single analyses.Our trace element analyses indicate that Si is not an ideal internal standard for zircon when calibrated against the NIST glasses.Calibration against the NIST glasses using Si as an internal standard,a systematic deviation of 10% 30% was found for most trace elements including Zr.However,the trace element compositions of zircon can be accurately measured by calibration against multiple reference materials with natural compositions (e.g.,BCR-2G,BHVO-2G and BIR-1G),or calibration against NIST SRM 610 and using Zr as an internal standard.Analyses of two pieces of GJ-1 demonstrate that it is relatively homogenous for most trace elements (except for Ti).
文摘Zircon U-Pb dating is the most commonly used method for isotopic geochronology. However, it has been a difficult issue when relating zircon U-Pb ages to metamor- phic conditions in complex metamorphic rocks. Much pro- gress has been made in the past decade with respect to the genesis of zircon and its constraints on interpretation of U-Pb age. Three methods have been proposed to link zircon U-Pb age to metamorphic conditions: (ⅰ) internal structure; (ⅱ) trace element feature; (ⅲ) mineral inclusion composition. Magmatic zircon shows typical oscillatory zoning and/or sector zoning, whereas metamorphic zircon has internal structures such as no zoned, weakly zoned, cloudy zoned, sector zoned, planar zoned, and patched zoned ones. Zircons formed in different geological environments generally have characteristic internal structures. Magmatic zircons from different rock types have variable trace element abundances, with a general trend of increasing trace element abundances in zircons from ultramafic through mafic to granitic rocks. Zircons formed under different metamorphic conditions have different trace element characteristics that can be used to relate their formation to metamorphic conditions. It is an effective way to relate zircon growth to certain P-T condi- tions by studying the trace element partitioning between coexisting metamorphic zircon and garnet in high-grade metamorphic rocks containing both zircon and garnet. Pri- mary mineral inclusions in zircon can also provide unambi- guous constraints on its formation conditions. Therefore, interpretation of zircon U-Pb ages can be constrained by its internal structure, trace element composition, mineral inclu- sion and so on.
文摘山东省是中国蔬菜的主要产区，常年蔬菜种植面积占全国的10％以上，设施蔬菜的面积占全国的近50％。1994-1997年山东设施蔬菜年平均施肥量达到N1351 kg hm^-2、P2O51701kg hm^-2和K20539．6kg hm^-2，在这段时间内施肥量逐年增加，2004年的施肥量与1997年相比氮肥和磷肥的用量有所减少，钾肥的用量有所增加，有机养分占总养分的比例明显增加。设施蔬菜土壤养分表观平衡为氮磷钾均盈余，且盈余量较大。设施蔬菜在大量施肥的情况下，肥料的利用率较低，1997年寿光设施蔬菜氮肥的表观利用率为21．33％，磷肥的表观利用率只有2．82％，钾肥的利用率较高达到61．34％。大棚蔬菜土壤pH值与露地相比有降低的趋势，土壤有机质含量高于露地土壤。山东省不同地区大棚土壤中碱解氮含量差异较大，以地处鲁西的德州最低，寿光的最高，平均达到205．4mgkg^-1。不同地区大棚土壤中有效磷含量差异很大，寿光设施蔬菜土壤中有效磷含量最高，平均为225．2mgkg^-1，土壤有效磷具有明显的积累效应，设施种植时间与土壤有效磷含量之间存在极显著的正相关性（r=0．550＊＊，n=35）。土壤母质类型对土壤速效钾具有一定的影响，寿光设施蔬菜土壤中速效钾含量最高，平均为369．7mgkg^-1。土壤速效钾也具有明显的积累效应，设施种植时间与土壤速效钾含量之间具有极显著的正相关性（r=0．502＊＊，n=35）。设施表层土壤中水溶性钙的含量平均为337．9mgkg^-1，土壤水溶性镁的含量平均为67．8mgkg^-1，明显高于露地土壤。设施蔬菜土壤中微量元素含量均高于露地土壤。
基金Supported by the National Natural Science Foundation of China (Grant Nos.40472099, 40521001 and 40673019)Chinese Ministry of Education (Grant Nos.IRT0441 and 306021)
文摘Simultaneous in-situ determination of U-Pb ages and 20 trace elements of three international zircon standards(91500,GJ1 and TEMORA 1) and one laboratory zircon standard(SK10-2) separated from Cenozoic fine-grained gabbro was carried out on quadrupole ICP-MS equipped with 193 nm excimer laser in 20 μm spot size. The weighted mean 206Pb/238U ages of 91500,GJ1 and TEMORA 1 are 1064.4±4.8 Ma(2σ ),603.2±2.4 Ma(2σ ) and 418.2±2.4 Ma(2σ ),respectively. The relative standard de-viations(RSDs) of 206Pb/238U ages(2σ ) are less than 2.2% for single measurements and 0.6% for weighted means. The obtained weighted mean 206Pb/238U ages of three standard zircons agree with the recommended values within 2σ error. The weighted mean 206Pb/238U age of SK10-2 is 31.42±0.25 Ma(2σ ) and the RSDs of 206Pb/238U ages(2σ ) are between 2.4% and 5.7% for single measurements and less than 0.8% for weighted mean. The obtained weighted mean 206Pb/238U age is in good agreement with the age obtained by Yuan(2004). Trace element concentrations of NIST612 and NIST614 obtained under the same LA-ICP-MS operating conditions agree with the recommended values within analytical error. The results indicate that it is possible to measure U-Pb age and trace elements simultaneously by LA-ICP-MS in a small spot size of 20 μm.
