ADVANCING ANTARCTIC SEDIMENT CHRONOLOGY THROUGH COMBINED RAMPED PYROLYSIS OXIDATION AND PYROLYSIS-GC-MS

IF 2 3区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS
Radiocarbon Pub Date : 2024-02-08 DOI:10.1017/rdc.2023.116
Catherine E Ginnane, Jocelyn C Turnbull, Sebastian Naeher, Brad E Rosenheim, Ryan A Venturelli, Andy M Phillips, Simon Reeve, Jeremy Parry-Thompson, Albert Zondervan, Richard H Levy, Kyu-Cheul Yoo, Gavin Dunbar, Theo Calkin, Carlota Escutia, Julia Gutierrez Pastor
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引用次数: 0

Abstract

Radiocarbon (14C) dating of sediment deposition around Antarctica is often challenging due to heterogeneity in sources and ages of organic carbon in the sediment. Chemical and thermochemical techniques have been used to separate organic carbon when microfossils are not present. These techniques generally improve on bulk sediment dates, but they necessitate assumptions about the age spectra of specific molecules or compound classes and about the chemical heterogeneity of thermochemical separations. To address this, the Rafter Radiocarbon Laboratory has established parallel ramped pyrolysis oxidation (RPO) and ramped pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) systems to thermochemically separate distinct carbon fractions, diagnose the chemical composition of each fraction, and target suitable RPO fractions for radiocarbon dating. Three case studies of sediment taken from locations around Antarctica are presented to demonstrate the implementation of combined RPO-AMS and Py-GC-MS to provide more robust age determination in detrital sediment stratigraphy. These three depositional environments are good examples of analytical and interpretive challenges related to oceanographic conditions, carbon sources, and other factors. Using parallel RPO-AMS and Py-GC-MS analyses, we reduce the number of radiocarbon measurements required, minimize run times, provide context for unexpected 14C ages, and better support interpretations of radiocarbon measurements in the context of environmental reconstruction.
通过热解氧化和热解-气相色谱-质谱联用技术推进南极沉积物年代学研究
由于沉积物中有机碳的来源和年龄存在差异,对南极洲周围沉积物的放射性碳(14C)年代测定往往具有挑战性。在没有微化石存在的情况下,人们使用化学和热化学技术来分离有机碳。这些技术一般都能改进大量沉积物的年代,但它们必须对特定分子或化合物类别的年代谱以及热化学分离的化学异质性作出假设。为了解决这个问题,拉夫特放射性碳实验室建立了平行的斜坡式热解氧化(RPO)和斜坡式热解-气相色谱-质谱(Py-GC-MS)系统,对不同的碳组分进行热化学分离,诊断每个组分的化学成分,并将合适的 RPO 部分作为放射性碳年代测定的目标。本文介绍了对南极洲周边地区沉积物的三个案例研究,展示了如何结合 RPO-AMS 和 Py-GC-MS,在碎屑沉积地层中提供更可靠的年龄测定。这三种沉积环境很好地说明了与海洋条件、碳源和其他因素有关的分析和解释挑战。利用并行的 RPO-AMS 和 Py-GC-MS 分析,我们减少了所需的放射性碳测量次数,最大限度地缩短了运行时间,为意外的 14C 年龄提供了背景信息,并更好地支持了在环境重建背景下对放射性碳测量结果的解释。
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来源期刊
Radiocarbon
Radiocarbon 地学-地球化学与地球物理
CiteScore
16.20
自引率
6.00%
发文量
85
审稿时长
6-12 weeks
期刊介绍: Radiocarbon serves as the leading international journal for technical and interpretive articles, date lists, and advancements in 14C and other radioisotopes relevant to archaeological, geophysical, oceanographic, and related dating methods. Established in 1959, it has published numerous seminal works and hosts the triennial International Radiocarbon Conference proceedings. The journal also features occasional special issues. Submissions encompass regular articles such as research reports, technical descriptions, and date lists, along with comments, letters to the editor, book reviews, and laboratory lists.
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