Linking biocalcification to the global carbon cycle: carbonate systems during the Paleogene

要了解碳循环与生物钙化速率变化之间的联系，一个基本步骤是在d13C发生重大偏移时，限制碳酸盐环境中生物钙化剂的扩张/限制。我们建议在西班牙研究古近系碳酸盐岩体系来解决这个问题，在那里，露头的质量和该地区以前的研究数量为该项目提供了很好的前提条件。古近纪是一个理想的时期，因为它包含了影响生物钙化和碳循环的大型事件。在古近纪，碳酸盐环境见证了大型底栖有孔虫的快速多样化、最大多样性和后来的灭绝。古近纪早期，海相碳酸盐在d13C发生了一次大偏移，偏移幅度为30°/ 60°（新生代最大），表明全球碳循环发生了重大变化。这也为整个古新世的高分辨率化学地层学提供了基础。我们打算构建陆架到盆地的综合样带，在那里我们将整合碳酸盐相的时空分布数据（以限制海平面变化和生物钙化的变异性）与同位素和地球化学数据（通过化学地层学和古环境变化来限制年龄）。这将有助于确定生物钙化模式，并最终将碳分配的变化与气候变化联系起来。

A fundamental step to understand the link between the carbon cycle and changes in biocalcification rates requires constraining the controls on the expansion/restrictions of biocalcifiers in carbonate environments at times of major d13C excursion. We propose to tackle this problem investigating Paleogene carbonate systems in Spain, where the qualities of outcrops and the number of previous studies in the area provide excellent preconditions for the project. The Paleogene is an ideal time because it contains large magnitude events affecting both biocalcification and the carbon cycle. During the Paleogene, carbonate environments witnessed the rapid diversification, maximum diversity and later extinction of larger benthic foraminifera. In the early Paleogene, marine carbonate record a major excursion in d13C, a 3o/oo shift (the largest in the Cenozoic), indicating major changes in the global carbon cycle. This also provides the basis for a high-resolution chemostratigraphy troughout the Paleocene. We intend to construct integrated shelf to basins transects where we will integrate data on the distribution in time and space of carbonate facies (to constrain sea level changes and variability in biocalcification) with isotopic and geochemical data (to constrain ages via chemostratigraphy, and paleonvironmental changes). This will allow to identify biocalcification patterns and ultimately relate variations in carbon partitioning to climatic changes.