Novel calibration for LA-ICP-MS-based fission-track thermochronology
Novel calibration for LA-ICP-MS-based fission-track thermochronology
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DOI：
10.1007/s00269-013-0624-2
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发表时间：
2013
影响因子：
1.4
通讯作者：
C. Soares;S. Guedes;J. Hadler;R. Mertz‐Kraus;T. Zack;P. Iunes
中科院分区：
文献类型：
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作者：
C. Soares;S. Guedes;J. Hadler;R. Mertz‐Kraus;T. Zack;P. Iunes
提出了一种新的用于激光烧蚀电感耦合等离子体质谱裂变径迹年龄测定的年龄方程定标方法。这种新的校准结合了内表面的效率因子[ηQ]IS，它是通过测量预计的裂变径迹长度获得的，允许直接使用推荐的自发裂变衰变常数来确定FT年龄。此外，还使用杜兰戈(DUR-2，7.44g/g·U)晶体和泥浆罐(MT-7，6.88g/g·U)晶体作为铀标准物质，测定了磷灰石样品中的铀浓度。考虑到不必考虑额外的不确定度来源，使用基质匹配的参考物质可以将铀测量的不确定度降低到与计数统计有关的不确定度，约为1%。使用来自杜兰戈、鱼峡谷凝灰岩和林贝格的年代良好的样品作为未知样品，对方程以及与基质匹配的参考物质进行了评估。这些结果与通过其他测年方法确定的各自公布的年龄很好地吻合。此外，结果与使用Zeta方法和绝对方法的传统裂变径迹年龄一致，表明本工作中提出的定标方法可以在地质背景下得到很好的应用。此外，考虑到裂变径迹年龄可以在没有年龄标准样本的情况下确定，这里提出的裂变径迹热年代学方法被认为是一种有价值的测年工具。
We present a novel age-equation calibration for fission-track age determinations by laser ablation inductively coupled plasma mass spectrometry. This new calibration incorporates the efficiency factor of an internal surface, [ηq]is, which is obtained by measuring the projected fission-track length, allowing the determination of FT ages directly using the recommended spontaneous fission decay constant. Also, the uranium concentrations in apatite samples are determined using a Durango (Dur-2, 7.44 μg/g U) crystal and a Mud Tank (MT-7, 6.88 μg/g U) crystal as uranium reference materials. The use of matrix-matched reference materials allows a reduction in the uncertainty of the uranium measurements to those related to counting statistics, which are ca. 1 % taking into account that no extra source of uncertainty has to be considered. The equations as well as the matrix-matched reference materials are evaluated using well-dated samples from Durango, Fish Canyon Tuff, and Limberg as unknown samples. The results compare well with their respective published ages determined through other dating methods. Additionally, the results agree with traditional fission-track ages using both the zeta approach and the absolute approach, suggesting that the calibration presented in this work can be robustly applied in geological context. Furthermore, considering that fission-track ages can be determined without an age standard sample, the fission-track thermochronology approach presented here is assumed to be a valuable dating tool.