Response of East African climate to orbital forcing during the last two glacial-interglacial cycles: The Lake Naivasha Coring Project

东非气候对最近两个冰期-间冰期循环期间轨道强迫的响应：奈瓦沙湖取芯项目

• 批准号: 5399684
• 负责人: Professor Dr. Martin Trauth
• 金额: --
• 依托单位: Institut für Geowissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2003
• 资助国家: 德国
• 起止时间: 2002-12-31 至 2006-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5399684?language=en
• 关键词: Response; East; African; climate; orbital

High-quality chronologies of late Pleistocene tropical climate have become increasingly important in discussions concerning tropical forcing of deglaciation, i.e., the transition from a glacial to an interglacial. The key argument of this hypothesis is that tropical climate leads high-latitude ice volumes by several thousand years. A tropical forcing of deglaciation would also help to explain why ice ages occur in both hemispheres simultaneously, although the changes in solar irradiance from orbital variations have opposite effects in the two hemispheres. Lake Naivasha provides a unique opportunity to study a continuous record of tropical climate changes during the last two glacial-interglacial cycles (approximately 175 kyr) through sedimentologic and paleoecologic changes reflected in the sediments. We propose a two-step strategy to reconstruct the lake history during this period: (A) a high-resolution seismic survey to characterize the depositional setting, lake-level fluctuations and neotectonics in the Naivasha basin. This survey will also guide up to the best sites for (B) two 50- and 40-m-long sediment cores from the present lake area. These sediment records are expected to fill the gap between a well-studied section exposed south of the present lake (175 to 60 kyr before present) and two sediment cores studied in the 1960's (25 kyr to present).

在有关热带脱胶冰期强迫的讨论中，即从冰川到冰川间的过渡到冰期的过渡时，更新世热带气候晚期的高质量年表变得越来越重要。这一假设的主要论点是，热带气候导致高纬度冰量增加了数千年。热带脱气的强迫也有助于解释为什么同时在两个半球上发生冰年的冰期，尽管轨道变化的太阳辐照度的变化在两个半球中具有相反的作用。 Naivasha湖提供了一个独特的机会，可以通过沉积物中反映在沉积学和古生物学上的变化来研究最后两个冰川间间冰循环（约175 kyr）中热带气候变化的连续记录。我们提出了一项两步策略，以在此期间重建湖泊历史：（a）一项高分辨率的地震调查，以表征Naivasha盆地中的沉积环境，湖泊水平的波动和新神经学。这项调查还将指导（b）目前湖区的两个50米和40米长的沉积物核心。预计这些沉积物记录将填补当前湖南以南的一个充分的部分（现在175至60 kyr）和在1960年代研究的两个沉积物岩心（现在为25 kyr）之间的空白。