Assessing the reliability of U-series and 10Be dating techniques on alluvial fans in the Anza Borrego Desert, California
Assessing the reliability of U-series and 10Be dating techniques on alluvial fans in the Anza Borrego Desert, California
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DOI：
10.1016/j.quageo.2012.08.004
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发表时间：
2012-12-01
影响因子：
2.7
通讯作者：
Sharp, Warren
中科院分区：
文献类型：
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作者：
Blisniuk, Kimberly;Oskin, Michael;Sharp, Warren
我们将地下碎屑涂层的成土碳酸盐的联合收割机Be-10暴露测年与U系列测年相结合，确定了加州安扎博雷戈沙漠四个地点中全新世至晚更新世冲积扇沉积的年代。由于每种测年技术都有不同的假设，它们的系统不确定性在很大程度上是独立的。因此，我们认为Be-10和U系列的日期是一致的，是高度可靠的。如果沉积后的侵蚀没有显著改变扇表面，暴露日期应产生最大年龄时，没有校正的继承。相比之下，U系测年提供了最小的年代，因为成壤碳酸盐形成后，风扇沉积。因此，两种技术的日期之间的一致性（或缺乏一致性）为其可靠性提供了严格的测试。我们的研究结果表明：（1）对大多数扇体测得了一致的Be-10和U-系列年龄，从而提供了可靠的年龄估计，（2）成壤碳酸盐的U-系列年龄可以成功地应用于全新世中期的冲积层，（3）所研究的全新世扇体沉积物的Be-10继承性似乎明显低于活动冲洗沉积物中Be-10浓度所暗示的。(C)2012爱思唯尔有限公司版权所有。
We combine Be-10 exposure dating with U-series dating of pedogenic carbonate from subsurface clast-coatings to date deposition of mid-Holocene to late Pleistocene alluvial fans at four sites in the Anza Borrego desert of California. Since each dating technique is subject to distinct assumptions, their systematic uncertainties are largely independent. We therefore consider Be-10 and U-series dates that are consistent to be highly reliable. If post-depositional erosion has not significantly modified a fan surface, exposure dates should yield maximum ages when no correction is made for inheritance. U-series dating, in contrast, provides minimum dates because pedogenic carbonate forms after fan deposition. Accordingly, agreement between dates from the two techniques (or lack thereof) provides a stringent test of their reliability. Our results show that: (1) concordant Be-10 and U-series dates were measured for most fans, thereby providing robust age estimates, (2) U-series dating of pedogenic carbonate can be successfully applied to alluvium as young as mid-Holocene and (3) Be-10 inheritance of the studied Holocene fan deposits appears to be significantly lower than implied by Be-10 concentrations in active wash deposits. (C) 2012 Elsevier B.V. All rights reserved.