Plio-pleistocene dinoflagellate cysts and paleoceanography of the North Atlantic region

上更新世甲藻包囊和北大西洋地区的古海洋学

• 批准号: 327150-2011
• 负责人: Head, Martin
• 金额: $ 2.04万
• 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: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=571936
• 关键词: Plio; pleistocene; dinoflagellate; cysts; paleoceanography

Described as an early failed attempt by the climate system to reach a full glacial state, marine isotope stage (MIS) M2 occurring 3.29 million years ago represents the first severely cold episode of the Pliocene. Yet it was followed immediately by an interval of exceptional and sustained warmth that has attracted intense interest owing to its relevance for modeling future climate. MIS M2 in contrast has been largely overlooked. Our research focuses on the cold event MIS M2, its inception, (in)stability, recovery, and transition to sustained warmth, and we are the first to have published specifically and in detail on it. Our results show an abrupt southward shift of the North Atlantic Current (NAC) that allowed the Greenland ice sheet to expand. Yet the causes of NAC instability remain uncertain, although they are critical to the modeling of future as well as past climates. The proposed research expands our spatial coverage by analyzing new sites in the North Atlantic at millennial-scale resolution. We use a novel combination of proxies (dinoflagellate cysts, geochemistry, ice-rafted debris) to reconstruct sea-surface temperature, salinity, evidence of ice melting, and NAC strength. MIS 16 at 0.65 million years ago saw the first major climatic deterioration of the Middle Pleistocene and first massive release of icebergs into the North Atlantic. Paradoxically, global atmospheric CO2 levels and geochemically-based paleotemperatures increased well before the termination of MIS 16, implying an unknown amplification mechanism. We propose the first millennial-scale study of dinoflagellate cysts through MIS 16 to assess NAC influence and quantify sea-surface temperatures and salinities from two strategically located sites in the North Atlantic. An expanding data set of Pliocene dinoflagellate cyst assemblages linked to geochemical paleotemperatures based on our novel same-sample method will uniquely allow us to determine numerical temperature requirements of extinct Pliocene taxa and to compare present-day with Pliocene temperature distributions of extant taxa, improving the utility of Pliocene dinoflagellate cysts for paleoenvironmental reconstructions.

海洋同位素阶段（MIS）M2发生在329万年前，被描述为气候系统达到完整冰川状态的早期失败尝试，代表了上新世的第一个严重寒冷时期。 然而，紧接着是一段异常和持续的温暖时期，由于其与模拟未来气候的相关性，引起了人们的强烈兴趣。 而M2在很大程度上被忽视了。 我们的研究重点是冷事件MIS M2，它的开始，（在）稳定性，恢复，并过渡到持续的温暖，我们是第一个已经发表了具体和详细的。我们的研究结果显示，北大西洋电流（NAC）突然向南移动，使格陵兰冰盖扩大。 然而，NAC不稳定的原因仍然不确定，尽管它们对未来和过去气候的建模至关重要。 拟议的研究通过以千年尺度分辨率分析北大西洋的新站点来扩大我们的空间覆盖范围。 我们使用一种新的组合代理（甲藻孢囊，地球化学，冰筏碎片）重建海面温度，盐度，冰融化的证据，和NAC的强度。 MIS 16在0.65百万年前见证了中更新世第一次重大的气候恶化和第一次大规模的冰山释放到北大西洋。 巧合的是，全球大气CO2水平和地球化学为基础的古温度增加之前终止MIS 16，这意味着一个未知的放大机制。 我们提出了第一个千年规模的研究甲藻孢囊通过MIS 16评估NAC的影响和量化海表面温度和盐度从两个战略位置在北大西洋。 一个不断扩大的数据集上新世甲藻孢囊组合的地球化学古温度的基础上，我们的新的相同的样品的方法将唯一允许我们确定灭绝上新世类群的数值温度要求，并比较现今与上新世现存类群的温度分布，提高实用的上新世甲藻孢囊古环境重建。