La-Ba and La-Ce geochronometers and Ce-138 as a geochemical tracer, developed to study origin and evolution of terrestrial materials

本研究开发了<^(138)La> - <^(138)Ce>和<^(138)La> - <^(138)Ba>两个新的地球时计系统，并在Re-Os、Rb-Sr和sm - nd等地球时计中取得了一些技术和/或科学成果。(1)通过对格陵兰Amitsoq片麻岩和芬兰Mustikkamaki片麻岩的La- ce年龄与Sm-Nd年龄的拟合，计算出<^(138)La>的< β ^->衰变常数为2.94x <10^(-12)> <yr^(-1)>。(2) Ce同位素研究表明，14310样品的正Ce异常可能在月球早期经历了氧（热液/水/冰）蚀变。(3)对太古宙Amitsoq片麻岩进行了Ce、Nb同位素比值和REE丰度分析。结果表明，Amitsoq片麻岩母质的Ce和Nd同位素比值接近其形成时的球粒值（约3800 Ma）。(4) <^(138)Ce> / <^(142)Ce>和<^(143)Nd> / <^(144)Nd>。揭示了大陆地壳岩石的直接成因，具有球粒型或液态型稀土元素模式。(5)太平洋各地区锰铁结核的Nd和Ce同位素比值表明，这些锰铁结核中Nd的主要来源是大陆，而Ce主要来自深海火山。2. La-Ba系统：<^(138)La> - <^(138)Ba>衰变的地质年代学应用已被证明可用于富ree矿物，如allanite， monazite和绿帘石。Korsnas方铅矿样品和Mustikkamaki辉晶岩样品的La- ba年龄与Sm-Nb年龄拟合得到<lambda> <_(EC)> <^(138)La>值为4.15x <10^(-12)> <yr^(-1)>。3. Re-Os分系统：用电感耦合等离子体质谱仪测量了3种Os试剂、4种陆生Os- ir合金（彩虹胺）和5种铁陨石中的锇同位素，<^(187)Os> / <^(192)Os>的精度约为1%。我们对铁陨石的研究表明，铁陨石的形成年龄值得重新考证。此外，对辉钼矿样品进行了Re-Os年龄测定。4. Rb-Sr分系统：确定了闪长岩的Rb-Sr年龄为4400 ma，比长辉长岩的形成年龄小100Ma。少

two new geochronometers, <^(138)La> - <^(138)Ce> and <^(138)La> - <^(138)Ba> systems, have been developed in this study, with some technical and/or scientific achievments in other geochronometers, Re-Os, Rb-Sr and Sm-Nd.1. La-Ce systematics: (1) The <beta^-> decay constant of <^(138)La> was calculated to be 2.94x <10^(-12)> <yr^(-1)> by fitting of La-Ce ages to Sm-Nd ages for the Amitsoq gneiss, Greenland, and the Mustikkamaki pegmatite, Finland. (2) Ce isotopic study suggested that the positive Ce anomaly observed for lunar sample 14310 is considered to have been subjected to some oxic (hydrothermal/aqueous/ice) alteration in the early stage of the lunar history. (3) The Archean Amitsoq gneisses have been analyzed for Ce and Nb isotopic ratios and REE abundances. It was suggested that parent material of the Amitsoq gneisses had Ce and Nd isotopic ratios close to chondritic values at the time of their formation (ca. 3,800 Ma). (4) <^(138)Ce> / <^(142)Ce> and <^(143)Nd> / <^(144)Nd> rat … More ios in nineteen terrestrial rocks including MORB and metamorphic rocks from continental crust have been determined. It was disclosed that the rocks from continental crust were derived directly from the source with chondritic or liquid-type REE patterns. (5) Nd and Ce isotopic ratios for ferromanganese nodules from various Pacific regions indicate that the major source of Nd in these ferromanganese nodules is continental, while Ce is supplied mainly from abyssal volcanics. 2. La-Ba systematics: The geochronological utility of the <^(138)La> - <^(138)Ba> decay has been demonstrated for REE-rich minerals such as allanite, monazite and epidote. Fitting of La-Ba ages to Sm-Nb ages for Korsnas galena mine samples and Mustikkamaki pegmatite samples yielded the <lambda> <_(EC)> <^(138)La> value of 4.15x <10^(-12)> <yr^(-1)> . 3. Re-Os systematics: Osmium isotopes in three Os reagents, four terrestrial Os-Ir alloys (iridosmines) and five iron meteorites have been measured on the inductively coupled plasma mass spectrometer, with the precision of around 1% for <^(187)Os> / <^(192)Os> . Our studies on iron meteorites suggest that the formation ages for iron meteorites merit re-examination. Further, Re-Os ages were reported for molybdenite samples. 4. Rb-Sr systematics: Rb-Sr age for diogenite have been determined to be 4,400Ma which is 100Ma younger than the formation age of eucrite. Less