Size-related stable isotope changes in Late Cretaceous planktic foraminifera: Implications for paleoecology and photosymbiosis
Size-related stable isotope changes in Late Cretaceous planktic foraminifera: Implications for paleoecology and photosymbiosis
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DOI：
10.1016/j.marmicro.2007.05.005
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发表时间：
2007-10-29
影响因子：
1.9
通讯作者：
Norris, Richard D.
中科院分区：
文献类型：
--
作者：
Bornemann, Andre;Norris, Richard D.
在Cenomanian晚期到Coniacian时期（类似于95-86 Ma）的白垩纪寒武纪有孔虫的古生态学仍然存在争议，因为大部分热带海洋记录保存为白垩和石灰岩，具有不确定的地球化学叠印。在这里，我们提出了三角洲C-13和三角洲O-18的数据，从筛粒度级的单种样品保存异常完好的南极有孔虫在大洋钻探计划腿207（德梅拉拉隆起，热带大西洋西部）。我们的研究结果表明，所有研究的物种（Hedbergella delrioensis，Heterohelix globulosa，Marginotruncana sinuosa，whiteinella baltica）主要生长在表面沃茨，并没有改变他们的生活周期中的深度栖息地。在白垩纪和现代有孔虫的三角洲C-13的大小相关的个体发育趋势的比较进一步表明，甲藻光合共生检测使用三角洲C-13是混淆的有孔虫生长的早期阶段的生理效应，提高了对以前的解释光合共生小有孔虫物种的怀疑。我们建议，专性光共生涉及甲藻可能没有进化，直到坎帕尼亚或马斯特里赫特，因为我们的调查Cenomanian-Coniacian物种没有发现三角洲O-18和三角洲C-13的大小相关的趋势，在现代有孔虫甲藻共生。(c)2007 Elsevier B. V.保留所有权利。
The paleoecology of Cretaceous planktic foraminifera during the Late Cenomanian to Coniacian period (similar to 95-86 Ma) remains controversial since much of the tropical marine record is preserved as chalk and limestone with uncertain geochemical overprints. Here we present delta C-13 and delta O-18 data from sieve size fractions of monospecific samples of exceptionally well preserved planktic foraminifera recovered during Ocean Drilling Program Leg 207 (Demerara Rise, western tropical Atlantic). Our results suggest that all species studied (Hedbergella delrioensis, Heterohelix globulosa, Marginotruncana sinuosa, whiteinella baltica) grew primarily in surface waters and did not change their depth habitat substantially during their life cycle. Comparison of size-related ontogenetic trends in delta C-13 in Cretaceous and modem foraminifera further suggests that detection of dinoflagellate photosymbiosis using delta C-13 is confounded by physiological effects during the early stages of foraminifer growth, raising doubts about previous interpretations of photosymbiosis in small foraminifera species. We propose that obligate photosymbiosis involving dinoflagellates may not have evolved until the Campanian or Maastrichtian since our survey of Cenomanian-Coniacian species does not find the delta O-18 and delta C-13 size-related trends observed in modem foraminifer-dinoflagellate symbioses. (c) 2007 Elsevier B.V. All rights reserved.