Plio-pleistocene marine paleoenvironments and dinoflagellate cyst paleoecology

上更新世海洋古环境与甲藻包囊古生态学

• 批准号: 327150-2006
• 负责人: Head, Martin
• 金额: $ 1.67万
• 依托单位: Brock University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=397606
• 关键词: Plio; pleistocene; marine; paleoenvironments; dinoflagellate

Numerical reconstructions of high-latitude environments in the North Atlantic and adjacent seas during the past 4.9 Myr are a major aim of this proposal.  Such reconstructions are critical for understanding the ocean-climate system and validating computer climate simulations. Organic-walled dinoflagellate cysts, or "dinocysts", are now used frequently in quantitative reconstructions of later Quaternary marine environments, especially at higher latitudes where calcareous microfossil assemblages decline in diversity.  The analysis of their fossil record allows us to reconstruct numerically both summer and winter sea-surface temperature and salinity, the duration of sea-ice cover, and levels of nutrient enrichment.  However, using dinocysts to reconstruct many earlier Quaternary and Pliocene environments is hindered by the increasing presence of extinct species and unusual species associations.  The challenge is to understand the environmental significance of these older assemblages, thereby extending backwards in time the utility of dinocysts for quantitative environmental analysis. The proposed research examines dinocysts at very high resolution across six time intervals (each about 100 kyr duration or less) of critical paleoclimatic interest for the Pliocene and Pleistocene.  Material will be examined from across the North Atlantic region, based on existing deep-sea core material.  Assemblages will be uniquely calibrated throughout by obtaining stable isotopes and Mg/Ca ratios to serve as fully independent proxies for climate change, and allow precise tuning to an orbital timescale.  The aim is to develop a quantitative understanding of Plio-Pleistocene dinocyst ecology, and to apply this to learn more about the time intervals in question.  Results address the dynamics of late Cenozoic climate, especially at higher latitudes where dinocyst reconstructions of sea-ice cover and seasonality will provide new insights into the timing and causes of Northern Hemisphere glaciations.  Results will be relevant to paleoclimate modeling and stratigraphy especially at high latitudes where mineralized microfossil groups are of low diversity.

该方案的主要目标是对过去490万年北大西洋及其邻近海域高纬度环境进行数值重建，这对于理解海洋气候系统和验证计算机气候模拟至关重要。有机壁甲藻孢囊，或“甲藻孢囊”，现在经常被用于定量重建晚第四纪海洋环境，特别是在高纬度地区，钙质微体化石组合的多样性下降。对它们的化石记录的分析使我们能够在数值上重建夏季和冬季的海面温度和盐度，海冰覆盖的持续时间，以及营养盐富集水平。然而，由于越来越多的灭绝物种和不寻常的物种组合的存在，利用dinocysts重建许多早期第四纪和上新世环境受到阻碍。挑战在于了解这些古老组合的环境意义，从而将dinocysts用于定量环境分析的效用向后延伸。这项拟议中的研究在六个时间间隔内以非常高的分辨率检查了dinocysts（每个约100 kyr持续时间或更短）的关键古气候感兴趣的上新世和更新世。材料将被检查从整个北大西洋地区，组合将通过获得稳定同位素和Mg/Al Ca比率作为气候变化的完全独立的代理，并允许精确调整到轨道时间尺度。目的是发展上新世更新世恐龙囊生态学的定量理解，并将其应用于了解更多有关时间间隔的问题。结果解决了晚新生代气候的动态，特别是在高纬度地区，那里的海冰覆盖和季节性的恐龙囊重建将提供新的见解北方半球冰川的时间和原因。结果将与古气候建模和地层学有关，特别是在高纬度地区，矿化微体化石群的多样性低。