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)对在各种类型的研究中解释化石记录具有广泛的影响。目前几乎没有关于腕足类时间平均的信息，腕足类是由古生代和许多后来的海壳组合组成的主要生物体。我们建议使用氨基酸消旋和放射性碳测年相结合的方法来记录巴西南部陆架上腕足类和软体动物混合贝壳表面堆积的时间平均。由此产生的数据将提供沿深度梯度的七个地点腕足类和软体动物的年代贝壳的定量估计。这项研究预计将产生(1)腕足类贝壳累积时间平均的第一个定量估计，(2)两组生物矿化生物(腕足类与软体动物)时间平均的第一个比较数据，以及(3)沿陆上-近海水深梯度的第一个时间平均估计。通过将分类学和环境维度添加到当前的时间平均知识中，这项研究将为我们理解化石记录的时间分辨率做出重大贡献。