Magnetostratigraphy of Pleistocene Sediments from the Republic of Georgia - Dating and Correlation of Climate Signals

格鲁吉亚共和国更新世沉积物的磁性地层学 - 气候信号的年代测定和相关性

• 批准号: 245125135
• 负责人: Professor Dr. Valerian Bachtadse
• 金额: --
• 依托单位: Sektion Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/245125135?language=en
• 关键词: Magnetostratigraphy; Pleistocene; Sediments; Republic; Georgia

The discovery of hominin remains of as many as six individuals, approx. 1.8 Ma in age, in Dmanisi, Southern Georgia, marks the first appearance of human occupation in Eurasia, significantly earlier than previously thought and thus changed our understanding of the causes of the first wave of emigration out of Africa substantially. Recent studies have shown, that the only African elements in the Dmanisi site are the remains of Homo Georgicus itself and associated tools. Unambiguous European affinities of the Dmanisi fauna do not support the idea, that the early hominins followed the migration patterns of large herbivores to ensure their food supply. The details of the Dmanisi hominins furthermore suggest, that local or global changes in climate are the key driving factor for early humans to venture towards Europe, because other hypothesis are disproved. In the early Pleistocene, rapid changes of warm/cold periods are documented based on global oxygen isotope records. It has been proposed, that during one of the warm periods the onset of desertification in eastern Africa forced early hominins to migrate into Europe. It is debated, however, whether the human remains in Georgia demonstrate favorable climatic conditions for early hominins and prove a long term occupation of this area, or the Caucasus represents a stepping stone along a migration path into Eurasia. For investigation of local climatic conditions, high resolution palynology is an ideal technique to map the paleoenvironmental conditions and local responses to global climate. For such studies, however, very precise age control isinevitable.High resolution magnetostratigraphy has been shown to be a very precise correlation and dating tool especially concerning young sediments. Thus, magnetostratigraphy provides the basis for successful studies of short term variations of the paleoenvironment.In Western Georgia there are a number of sedimentary sections with proposed deposition ages from ~3 million years up to the present. This time span includes the hominid bearing deposits at Dmanisi as well as lake sediments from Armenia studied earlier (Ba1210/14-1). What makes the Georgian shallow marine sections special, however, is the extremely large amounts of pollen which can give a high resolution picture of the paleoenvironmental conditions during times of human migration through the Caucasus. Correlating the magnetostratigraphic data from Georgia with those from Armenia will allow us to compare the climatic situation in Western Georgia and Armenia during the Pleistocene.It is therefore planned to study two large sections in Guria which cover a sufficiently long time span to include the 1.8 Ma time mark (age of the Dmanisi hominins) and the southern Armenian sections. The results of this study will contribute to a precise reconstruction of the paleoclimate and paleoenvironment of the Caucasus during a crucial phase of hominin occupation in the area.

发现的古人类遗骸多达六人，约。乔治亚州南部德马尼西的1.8 Ma年龄标志着欧亚大陆首次出现人类占领，比之前认为的要早得多，从而大大改变了我们对第一波非洲移民潮原因的理解。最近的研究表明，德马尼西遗址中唯一的非洲元素是乔治人本身和相关工具的遗骸。德马尼西动物群与欧洲的明确联系并不支持早期人类遵循大型食草动物的迁徙模式以确保食物供应的观点。德马尼西古人类的细节进一步表明，局部或全球气候变化是早期人类冒险前往欧洲的关键驱动因素，因为其他假设被证明是错误的。在更新世早期，根据全球氧同位素记录记录了暖/冷期的快速变化。有人提出，在某个温暖时期，东非沙漠化的爆发迫使早期人类迁徙到欧洲。然而，格鲁吉亚的人类遗骸是否证明了早期人类的有利气候条件并证明了该地区的长期居住，或者高加索地区是否代表了进入欧亚大陆的迁徙道路上的垫脚石，这一点仍存在争议。对于当地气候条件的调查，高分辨率孢粉学是绘制古环境条件和当地对全球气候的响应的理想技术。然而，对于此类研究，非常精确的年龄控制是不可避免的。高分辨率磁地层学已被证明是一种非常精确的相关和测年工具，特别是对于年轻的沉积物。因此，磁性地层学为古环境短期变化的成功研究提供了基础。在乔治亚州西部，有许多沉积部分的沉积年龄从约 300 万年至今。该时间跨度包括德马尼西的原始人类沉积物以及早期研究的亚美尼亚湖泊沉积物（Ba1210/14-1）。然而，格鲁吉亚浅海部分的特殊之处在于其大量的花粉，可以提供人类穿越高加索迁徙期间古环境条件的高分辨率图像。将格鲁吉亚的磁性地层数据与亚美尼亚的磁性地层数据进行关联，将使我们能够比较更新世期间格鲁吉亚西部和亚美尼亚的气候状况。因此，计划研究古里亚的两个大区域，这两个区域覆盖足够长的时间跨度，包括 1.8 Ma 时间标记（德马尼西古人类的年龄）和亚美尼亚南部区域。这项研究的结果将有助于精确重建高加索地区古人类占领的关键阶段的古气候和古环境。