Amino acid geochronology of foraminifera test from north Queensland margin

In this study, we demonstrate the utility of amino acid geochronology based on single-foraminiferal tests in Quaternary sediment cores from the Queensland margin, Australia. The large planktonic foraminifer Pulleniatina obliquiloculata is ubiquitous in shelf, slope, and basin sediments of north Queensland as well as pantropical oceans. Fossil tests are resistant to dissolution, and retain substantial concentrations of amino acids (2-4 nmol/mg of shell) over hundreds of thousands of years. Amino acid D and L isomers of aspartic acid (Asp) and glutamic acid (Glu) were separated using reverse phase chromatography, which is sensitive enough to analyze individual foraminifera tests. In all, 462 Pulleniatina tests from 80 horizons in 11 cores exhibit a systematic increase in D/L ratios down core. D/L ratios were determined in 32 samples whose ages are known from AMS 14C analyses. In all cases, the Asp and Glu D/L ratios are concordant with 14C age. […]

在本研究中，我们展示了基于单个有孔虫测试的氨基酸地质年代学在澳大利亚昆士兰州边缘第四纪沉积岩心中的实用性。大型浮游有孔虫普伦尼亚有孔虫（Pulleniatina obliquiloculata）在北昆士兰州的近岸、斜坡和盆地沉积物中普遍存在，以及泛热带洋中亦然。化石测试对溶解具有抵抗力，并在数百万年内保持壳体中氨基酸（每毫克壳体2-4纳摩尔）的显著浓度。通过反相色谱法分离了天冬氨酸（Asp）和谷氨酸（Glu）的D和L异构体，该方法对分析单个有孔虫测试具有足够的灵敏度。总计，来自11个岩心的80个层面的462个普伦尼亚有孔虫测试呈现出随岩心深度的系统性的D/L比值增加。在已知AMS 14C年代分析的32个样本中，确定了D/L比值。在所有情况下，天冬氨酸和谷氨酸的D/L比值与14C年龄相吻合。