Problems of Developing the Pleistocene Radiocarbon Chronology within high Mountain Terranes by the Example of Russian Altai
Problems of Developing the Pleistocene Radiocarbon Chronology within high Mountain Terranes by the Example of Russian Altai
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DOI：
10.1017/rdc.2019.83
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发表时间：
2019-07
期刊：
影响因子：
8.3
通讯作者：
A. Agatova;R. Nepop;E. Zazovskaya;I. Ovchinnikov;P. Moska
中科院分区：
文献类型：
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作者：
A. Agatova;R. Nepop;E. Zazovskaya;I. Ovchinnikov;P. Moska
摘要本文讨论了俄罗斯阿尔泰山山间洼地和山谷中各种成因沉积物中有机物质的24个放射性碳（14 C）年龄。这些明显的14 C年龄（有时接近14 C测年方法的上限）与其他代理数据和光释光（OSL）日期相矛盾。用14 C测年法恢复古代沉积物遇到两个问题：（1）错误地将先前未知的第三纪沉积物的近地表位置解释为具有再沉积的古植物群的更新世沉积物;（2）错误地估计具有再沉积的石炭纪、侏罗纪和新近纪有机物质（以包裹体为代表）的更新世-全新世沉积物的年龄。14 C年龄的显着分散，在一个部分内的反转，并与其他代理数据的差异表明渗透的“年轻”的碳到古老的有机物质，其存在于一个独特的（每个样品）的比例。目前，这种污染无法通过标准的预处理技术消除。“年轻”碳的流入与沉积后的构造和外源过程有关，这在阿尔泰等构造活跃的山区省份很常见。报告的问题并不是一个新的问题，虽然在俄罗斯阿尔泰地区的方法研究尚未进行。
ABSTRACT The paper presents a discussion of 24 radiocarbon (14C) dates of organic material from deposits of various genesis within the intermountain depressions and valleys of the Russian Altai. These apparent 14C ages (sometimes near the upper time limit of the 14C dating method) contradict to other proxy data and optically stimulated luminescence (OSL) dates. Rejuvenation of ancient deposits by 14C dating encountered two problems: (1) wrong interpretation of previously unknown near-surface location of Tertiary deposits as being of the Pleistocene ones with the redeposited ancient flora; and (2) wrong age estimation of the Pleistocene-Holocene deposits with redeposited Carboniferous, Jurassic, and Neogene organic material, which is represented as inclusions. Significant scattering of 14C ages, their inversion within a section, and discrepancy with other proxy data indicate penetrating of the “young” carbon into ancient organic material, and its presence in a unique (for each sample) ratio. Today such contamination cannot be eliminated utilizing standard pre-treatment techniques. The influx of “young” carbon is related to post-sedimentation tectonic and exogenous processes, which are common for tectonically active mountain provinces including Altai. The reported problem is not a new one, although methodological studies in the Russian Altai have not yet been carried out earlier.