Towards ε-Precision of U-series Age Determinations of Secondary Carbonates
Towards ε-Precision of U-series Age Determinations of Secondary Carbonates
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次生碳酸盐 U 系列年龄测定的 ε 精度
DOI：
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发表时间：
2017
期刊：
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通讯作者：
J. Arps
中科院分区：
文献类型：
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作者：
J. Arps
在本论文中，描述了在 MC-ICP 质谱仪上以可达到的最高精度进行 U 系列测年的测量协议和数据校正。具有高于 6 ppt 的高 [U] 和 [Th] 的样品溶液的 U 和 Th 同位素比可以在 6 e 尺度 (e = 1·10−4) 上重复测量。具有中等 [U] 和 [Th] 的样品溶液的 U 和 Th 同位素比通常以 8 至 18 e 精度测定。各种质谱仪的测量结果在其不确定性范围内是可重复的，证实了我们的约会结果的可信度。利用高分辨率测年，将斯潘纳格尔洞穴（北阿尔卑斯山）倒数第二次冰川消融的开始日期推迟了 2,000 年，位于距今 133,183 ± 833 年，与之前公布的结果相比，精度提高了 400 年。这个年龄区间与北方夏季日照的增加大致一致，
似乎更符合米兰科维奇假设。此外，还以 Δt = 220 a 的分辨率比较了瑞士阿尔卑斯山相邻洞穴中两个石笋在过去 6,500 a 中的生长速率。两种生长率都显示了个体的生长历史，但是当与林线记录相结合时，可以提供对当地植被历史的更多了解。
In this thesis the measurement protocols and data corrections for U-series dating with the highest achievable precision on a MC-ICP mass spectrometer are described. U and Th isotope ratios of sample solutions with high [U] and [Th] above 6 ppt can be measured reproducibly on a 6 e-scale (e = 1·10−4). U and Th isotope ratios of sample solutions with moderate [U] and [Th] are routinely determined with 8 to 18 e-precision. Results from measurements on various mass spectrometers were reproducible within their uncertainties, confirming the credibility of our dating results. Using high-resolution dating, the beginning of the penultimate deglaciation at the Spannagel Cave (Northern Alps) was dated delayed by 2,000 a at 133,183 ± 833 a BP achieving a higher precision of 400 a compared to formerly published results. This age interval is broadly coincident with the rise in boreal summer insolation and
seems more concordant to Milankovitch hypothesis. Furthermore, the growth rates of two stalagmites from adjacent caves in the Swiss Alps were compared on a resolution of Δt = 220 a in the last 6,500 a. Both growth rates show individual growth histories, however when combined with a tree-line record, provide additional insights into the local vegetation history.