COLLABORATIVE RESEARCH: Time-Averaging in Mixed Brachiopod-Mollusk Assemblages along a Depth Gradient across a Modern Tropical Shelf

合作研究：现代热带陆架上混合腕足动物-软体动物组合沿深度梯度的时间平均

• 批准号: 0125149
• 负责人: Michal Kowalewski
• 金额: $ 9.92万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0125149&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Time; Averaging; Mixed

The limits to temporal resolution imposed by processes of time-averaging (i.e., age mixing of fossils that determines the temporal resolution of the fossil record) have broad implications for interpretation of the fossil record in a wide variety of types of studies. Almost no information on time-averaging is currently available for brachiopods, the predominant organism comprising Paleozoic and many later marine shell assemblages. We propose to use a combination of amino acid racemization and radiocarbon dating to document time-averaging in surficial accumulations of mixed brachiopod-mollusk shells on the southern Brazilian shelf. The resulting data will provide quantitative estimates of age structures of dated shells of brachiopods and mollusks from seven sites along a depth gradient. The study is expected to produce (1) the first quantitative estimates of time-averaging for brachiopod shell accumulations, (2) the first comparative data on time-averaging for two groups of biomineralized organisms (brachiopods vs. mollusks), and (3) the first estimates of time-averaging along an onshore-offshore bathymetric gradient. By adding taxonomic and environmental dimensions to the current knowledge of time-averaging, this study will provide a significant contribution to our understanding of the temporal resolution of the fossil record.

时间平均过程对时间分辨率施加的限制（即，化石的年龄混合决定了化石记录的时间分辨率）对各种类型的研究中化石记录的解释具有广泛的影响。腕足类动物是古生代和许多后来的海洋贝壳组合的主要生物，目前几乎没有关于腕足类动物平均时间的资料。我们建议使用氨基酸外消旋化和放射性碳定年相结合的方法来记录巴西南部陆架腕足-软体动物混合壳表面堆积的平均时间。所得数据将提供沿深度梯度的7个地点腕足类和软体动物的年代结构的定量估计。该研究预计将产生(1)第一次对腕足类贝壳积累的平均时间进行定量估计，(2)第一次对两组生物矿化生物（腕足类与软体动物）的平均时间进行比较数据，以及(3)第一次对陆上-海上水深梯度的平均时间进行估计。通过将分类学和环境维度添加到目前的时间平均知识中，这项研究将为我们对化石记录的时间分辨率的理解做出重大贡献。