Timing and trigger mechanisms of abrupt cold events during the Holsteinian interglacial based on analyses of annually laminated sediments

荷尔斯泰因间冰期与11c亚阶段的海洋同位素相关联，该亚阶段集中在约40000yr BP （Beaulieu et al. 2001, Tzedakis et al. 2003）。在此期间，气候强迫，即轨道驱动的日照和温室气体浓度，与目前的情况最为相似（Berger & Loutre 2002， ERICA成员2004）。因此，海洋同位素第11c次阶段及其陆地等效阶段，即荷斯泰因期，被认为äs是全新世的最佳古气候类似物（McManus et al. 2003, Kukla 2003）。在这种背景下，在欧洲西北部的几个地点（如Turner 1970年，H. m<e:1> ller 1974年，Binka & Nitychoruk 1995年），在荷尔斯泰因间冰期几个嗜热树种的突然减少所表现出的两个寒冷事件获得了新的相关性。这些发生在间冰期的突发性寒冷事件与我们现在的全新世最相似，它们的起源和时间是什么？本文拟通过对德国德特林根（Dethlingen）年层状湖泊沉积物的分析，探讨这些事件的确切时间和触发机制。由于自己的初步工作，核心材料已经可用，并进行了低分辨率花粉分析，以确保核心确实包括荷尔斯泰因人。现在建议对整个记录进行阀计数和高分辨率（十年至百年尺度）花粉分析。特别是，建议对两个冷事件的临界温度进行花粉、地球化学和地球物理参数的超高分辨率（年分辨率）分析。对每年层状沉积物的超高分辨率分析将提供关于确切时间的信息，从而提供关于在间冰期边界条件下触发突然冷却的机制的信息。

The Holsteinian interglacial has been correlated with marine Isotope substage 11 c, which is centred at around 400,000 yr BP (Beaulieu et al. 2001, Tzedakis et al. 2003). During that time the climate forcing, i.e. the orbitally driven Insolation and concentration of greenhouse gases, was most similar to the present Situation (Berger & Loutre 2002, ERICA members 2004). Therefore, marine isotope substage 11 c and its terrestriai equivalent, the Holsteinian, are considered äs the best paleoclimatic analogues for the Holocene (McManus et al. 2003, Kukla 2003). In this context, two cold events manifested by the abrupt decline of several thermophile tree species within the Holsteinian interglacial at several sites across NW-Europe (e.g. Turner 1970, H. Müller 1974, Binka & Nitychoruk 1995), gain new relevance. What was the origin and timing of these abrupt cold events which occurred during an interglacial that represents the best analogue to our present Holocene? Here it is proposed to investigate the exact timing and trigger mechanisms of these events based on analyses of annually laminated lake Sediments from Dethlingen (N-Germany). Due to own preliminary work, the core material is already available and low-resolution pollen analyses have been performed to ensure the core indeed comprises the Holsteinian. Now it is proposed to perform varve counting and high-resolution (decadal to centennial scale) pollen analyses for the entire record. In particular, it is proposed to perform ultra-high-resolution (annual resolution) analyses of pollen, geochemical, and geophysicai parameters on the critical inten/als of the two cold events. The ultra-high-resolution analyses of the annually laminated sediment will provide information about the exact timing and thus information about the mechanisms that triggered the abrupt coolings within interglacial boundary conditions.