Radiometric Dating

放射性约会
  • 文章类型: Historical Article
    The dating of organic findings is a fundamental task for many scientific fields. Radiocarbon dating is currently the most commonly used method. For wood, dendrochronology is another state-of-the-art method. Both methods suffer from systematic restrictions, leading to samples that have not yet been able to be dated. Molecular changes over time are reported for many materials under different preservation conditions. Many of them are intrinsically monotonous. These monotonous molecular decay (MD) patterns can be understood as clocks that start at the time when a given molecule was formed. Factors that influence these clocks include input material composition and preservation conditions. Different wood species, degrees of pyrolysis, and pretreatments lead to different prediction models. Preservation conditions might change the speed of a given clock and lead to different prediction models. Currently published models for predicting the age of wood, paper, and parchment depend on infrared spectroscopy. In contrast to radiocarbon dating, dating via MD does not comprise a single methodology. Some clocks may deliver less precise results than the others. Ultimately, developing a completely different, new dating strategy-such as MD dating-will help to bring to light a treasure trove of information hidden in the darkness of organic findings.
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  • 文章类型: Journal Article
    在死亡前信息有限的情况下,作为长期失踪人员案件调查的一部分,对身份不明的遗体进行检查是一项复杂的工作,因此需要多学科的方法。炸弹脉冲约会,其中涉及14C浓度的分析和解释,是一种可以通过提供出生年份和死亡年份的估计来帮助这些调查的技术。这篇评论研究了炸弹脉冲测年技术及其在识别不同保存的未知人类遗骸中的使用。实施炸弹脉冲测年的研究和案例研究主要在北半球进行,并证明了可靠和准确的结果。局限性是,然而,在整个文献中确定。这些包括以前研究/案例研究中使用的小样本量,这些样本量影响了研究结果的统计意义,以及特定技术的问题。这种局限性凸显了未来研究的必要性。
    In cases where there is limited antemortem information, the examination of unidentified human remains as part of the investigation of long-term missing person\'s cases is a complex endeavor and consequently requires a multidisciplinary approach. Bomb pulse dating, which involves the analysis and interpretation of 14C concentration, is one technique that may assist in these investigations by providing an estimate of year of birth and year of death. This review examines the technique of bomb pulse dating and its use in the identification of differentially preserved unknown human remains. Research and case studies implementing bomb pulse dating have predominantly been undertaken in the Northern Hemisphere and have demonstrated reliable and accurate results. Limitations were, however, identified throughout the literature. These included the small sample sizes used in previous research/case studies which impacted on the statistical significance of the findings, as well as technique-specific issues. Such limitations highlight the need for future research.
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  • 文章类型: Journal Article
    More than ten years of paleontological fieldwork during the enlargement of the Can Mata Landfill (Abocador de Can Mata [ACM]), in els Hostalets de Pierola (Vallès-Penedès Basin, NE Iberian Peninsula) led to the recovery of >60,000 Miocene vertebrate remains. The huge sampling effort (due to continuous surveillance of heavy machinery digging activity, coupled with manual excavation and screen-washing of sediments) enabled generally rare faunal elements such as pliopithecoid and hominoid primates to be found. Thanks to detailed litho-, bio- and magnetostratigraphic controls, accurate dating is possible for all the recovered primate remains from 19 of the 235 localities defined along the 234 m-thick composite stratigraphic sequence of the ACM. Here we report updated estimated (interpolated) ages for these paleontological localities and review the timing of the primate succession in this area. Our results indicate that the whole ACM sequence is late Aragonian in age (MN6 and MN7+8) and includes seven magnetozones that are correlated to subchrons C5Ar.1r to C5r.2r (ca. 12.6 to 11.4 Ma). Great apes (dryopithecines) are first recorded at 12.4-12.3 Ma, but most of the finds (Anoiapithecus, Pierolapithecus and Dryopithecus) cluster between 12.0 and 11.9 Ma, followed by some indeterminate dryopithecine remains between 11.7 and 11.6 Ma. Pliopithecoids first appear at 12.1 Ma, being subsequently represented by Pliopithecus between 11.9 and 11.7 Ma. The small-bodied hominoid Pliobates is the youngest ACM primate, with an estimated age of 11.6 Ma. Although these primates probably overlapped in time, their co-occurrence is recorded only twice, at 11.9 Ma (a dryopithecine with Pliopithecus) and at 11.6 Ma (a dryopithecine with Pliobates). The rare co-occurrence between great apes and small-bodied catarrhines might be attributable to sampling biases and/or to presumed diverging ecological preferences of these groups. In the future, more detailed analyses of the fauna recovered from the long and densely-sampled ACM sequence will hopefully throw new light on this long-standing, unresolved question.
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