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个人，大约。1.8格鲁吉亚南部德马尼西的Ma in age标志着欧亚大陆首次出现人类占领，比以前认为的要早得多，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亚人本身和相关工具的遗骸。德马尼西动物群的非纳米比亚欧洲亲缘关系并不支持这种观点，即早期人类遵循大型食草动物的迁移模式，以确保他们的食物供应。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，因为其他假设被推翻。在早更新世，全球氧同位素记录证明了暖/冷时期的快速变化。有人提出，在一个温暖的时期，东非荒漠化的开始迫使早期人类迁移到欧洲。然而，有争议的是，是否在格鲁吉亚的人类遗骸证明了早期人类的有利气候条件，并证明了这一地区的长期占领，或者高加索代表了一个踏脚石沿着迁移到欧亚大陆的路径。高分辨率孢粉学是研究局部气候条件的理想技术，可用于研究古环境条件和局部对全球气候的响应。然而，对于这样的研究，非常精确的年龄控制是不可避免的。高分辨率磁性地层学已被证明是一种非常精确的对比和定年工具，特别是对于年轻的沉积物。因此，磁性地层学为成功研究古环境的短期变化提供了基础。在格鲁吉亚西部，有许多沉积剖面，推测沉积年龄从300万年到现在。这一时间跨度包括德马尼西的人科沉积物以及之前研究过的亚美尼亚湖泊沉积物（Ba 1210/14-1）。然而，格鲁吉亚浅海部分的特殊之处在于，它含有大量的花粉，这些花粉可以提供人类通过高加索迁移期间古环境条件的高分辨率图像。将来自格鲁吉亚和亚美尼亚的磁性地层学数据进行对比，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剖面，这两个剖面覆盖了足够长的时间跨度，包括1.8 Ma时间标记（Dmanisi人类的年龄）和亚美尼亚南部剖面。这项研究的结果将有助于精确重建的古气候和古环境的高加索地区的人类占领的关键阶段。