In situ cosmogenic 10Be production-rate calibration from the Southern Alps, New Zealand
In situ cosmogenic 10Be production-rate calibration from the Southern Alps, New Zealand
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DOI：
10.1016/j.quageo.2009.12.001
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发表时间：
2010-08-01
影响因子：
2.7
通讯作者：
Kelley, S. E.
中科院分区：
文献类型：
--
作者：
Putnam, A. E.;Schaefer, J. M.;Kelley, S. E.
我们提出了一个Be-10生产率校准来自早全新世碎屑流存款在海拔约1000米，在南阿尔卑斯山，新西兰，在中纬度南半球。从被存款掩埋的土壤层中提取的大型化石的10个放射性碳年龄将该存款的日期定在公元2008年之前的9690 +/- 50个日历年。部分嵌入稳定表面的存款的七个大漂砾的表面Be-10浓度分布紧密，产生类似于2%的标准偏差。使用五种标准换算方法中的每一种将Be-10测量值转换为海平面/高纬度值，表明Be-10的产生率为3.84 +/- 0.08、3.87 +/-0.08、3.83 +/- 0.08、4.15 +/- 0.09和3.74 +/- 0.08原子g（-1）a（-1），相对于'07 KNSTD' Be-10 AMS标准，仅包括当地时间积分的生产率不确定度。当包括海平面高纬度定标不确定性时，每个速率的总体误差类似于2.5%（1 sigma）。为了测试该生产率校准的区域适用性，我们测量了在公元2008年前18060 +/- 200年前沉积的一组附近冰碛中的Be-10浓度。Be-10年龄仅与使用新生产率计算的最低限度C-14年龄数据一致。这也表明，在新西兰的陆地原位宇宙生成核素生产没有显着变化，从末次盛冰期到全新世的时间。我们的生产率与最近北美东北部的校准研究结果一致，但比其他常用值低12-14%。这里给出的生产率值可用于新西兰其他地区末次冰期或自末次冰期以来暴露的岩石表面。(C)2009爱思唯尔有限公司版权所有。
We present a Be-10 production-rate calibration derived from an early Holocene debris-flow deposit at about 1000 m above sea level in the central Southern Alps, New Zealand, in the mid-latitude Southern Hemisphere. Ten radiocarbon ages on macrofossils from a soil horizon buried by the deposit date the deposit to 9690 +/- 50 calendar years before AD2008. Surface Be-10 concentrations of seven large boulders partially embedded in the stable surface of the deposit are tightly distributed, yielding a standard deviation of similar to 2%. Conversion of the Be-10 measurements to sea level/high-latitude values using each of five standard scaling methods indicates Be-10 production rates of 3.84 +/- 0.08, 3.87 +/- 0.08, 3.83 +/- 0.08, 4.15 +/- 0.09, and 3.74 +/- 0.08 atoms g(-1) a(-1), relative to the '07KNSTD' Be-10 AMS standard, and including only the local time-integrated production-rate uncertainties. When including a sea level high-latitude scaling uncertainty the overall error is similar to 2.5% (1 sigma) for each rate. To test the regional applicability of this production-rate calibration, we measured Be-10 concentrations in a set of nearby moraines deposited before 18060 +/- 200 years before AD2008. The Be-10 ages are only consistent with minimum-limiting C-14 age data when calculated using the new production rates. This also suggests that terrestrial in situ cosmogenic-nuclide production did not change significantly from Last Glacial Maximum to Holocene time in New Zealand. Our production rates agree well with those of a recent calibration study from northeastern North America, but are 12-14% lower than other commonly adopted values. The production-rate values presented here can be used elsewhere in New Zealand for rock surfaces exposed during or since the last glacial period. (C) 2009 Elsevier B.V. All rights reserved.