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采用~(40)Ar/~(39)Ar激光阶段加热分析技术,对采自澳大利亚昆士兰中部某风化剖面中的钡硬锰矿和隐钾锰矿进行同位素年龄测定,获得可靠的坪年龄和等时线年龄,再次证明可以用40Ar/39Ar测年技术对极细小的表生锰氧化物进行年代学研究.发现Ar同位素在钡硬锰矿和隐钾锰矿中主要赋存于两种不同的位置.第1种位置（晶间空隙）主要赋存大气成因Ar,在激光功率为0.2～0.4W时释放出来,包括40Aratm,38Aratm和36Aratm.第2种位置（即隧道结构或晶内位置）主要赋存放射性成因Ar（40Ar＊）和核反应成因 Ar（39ArK,38ArK）,其去气的激光功率主要在0.5～1.0W之间.当激光功率大于1.0W时,已很少有Ar气从锰氧化物中释放出来,说明赋存放射性成因和核反应成因Ar的隧道结构因持续受热而崩塌、解体.40Ar,39ArK和38ArK的近于完全一致的去气行为意味着它们不仅在锰氧化物中占有相同或相当的晶体位置,同时证明39ArK在样品接受同位素分析之前的中子照射及实验室预热过程中没有反冲出矿物晶体结构.结果表明,尽管表生锰氧化物中含有大量的大气Ar,且这些氧化物的晶体十分细小,但应用40Ar/39Ar激光阶段加热分析技术可以获得有意义的风化年代学信息.
A ~ (40) Ar / ~ (39) Ar laser stage heating analysis technique was used to determine the isotopic ages of barium and cryptomerite from a weathered profile in central Queensland, Australia, and to obtain reliable age and isochron The age again proves that the 40Ar / 39Ar dating technique can be used to chronologically study very fine superficial manganese oxides. It is found that Ar isotopes mainly exist in two different positions in barium and cryptomelane. Arrays (intergranular voids) are mainly responsible for atmospheric genesis Ar and are released at laser powers of 0.2-0.4 W, including 40Aratm, 38Aratm, and 36Aratm. The second location (ie, the tunnel structure or intragranular location) is predominantly radioactive Genesis Ar (40Ar *) and nuclear reaction Ar (39ArK, 38ArK), the laser power to degassing mainly between 0.5 ~ 1.0W.When the laser power is greater than 1.0W, there has been little Ar gas from the manganese oxide Is released, indicating that the tunnel structure of Ar, which causes radioactive causes and nuclear reactions, collapses and disintegrates due to continuous heating.The near-identical degassing behavior of 40Ar, 39ArK and 38ArK means that they not only occupy the same or equivalent part of manganese oxide Crystal Position and at the same time proved that 39ArK did not backfill mineral crystal structure during the neutron irradiation and laboratory preheating before the sample was subjected to isotope analysis.The results show that although the superficial manganese oxide contains a large amount of atmospheric Ar and these oxides The crystals are very small, but the use of 40Ar / 39Ar laser stage heating analysis technology can obtain meaningful weathering chronology information.