Red Sea deep-water ventilation and climate variability during the past 200,000 years (REVENT)

过去 20 万年的红海深水通风和气候变化 (REVENT)

• 批准号: 457158703
• 负责人: Professor Dr. Werner Ehrmann
• 金额: --
• 依托单位: Abteilung Geologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/457158703?language=en
• 关键词: Red; Sea; deep; water; ventilation

The Red Sea is a landlocked basin, bordered by the semiarid to arid regions of northeastern Africa and the Arabian Peninsula. The exchange of water masses with the Indian Ocean is restricted to the narrow and shallow strait of Bab al-Mandab and the basin receives major dust input from the borderlands. Consequently, the oceanography and sedimentation processes of the Red Sea respond to even subtle climate and sea-level changes. In the proposed project we want to investigate how the Red Sea overturning circulation and oxygen minimum zone (OMZ) responded to orbital and millennial-scale climate changes during the past 200,000 years and if the oceanographic responses were in phase with hydrological changes and dust fluxes of the borderlands. Specifically, we want to address the hypotheses that 1) the Red Sea deep-water ventilation is linked to global sea-level and is regionally modulated by the influence of the Mediterranean and monsoon climate regimes, 2) millennial-scale climate changes, such as cold and hyper-arid events provoke contemporaneous changes in deep-water circulation and hydrology on the borderlands, 3) the dust fluxes monitor time-transgressive shifts of the African tropical rain belt reflecting thresholds in vegetation and the exposure of dust particles. The sediment archive of the deep Red Sea appears suitable to test these hypotheses since the basin extends SSE-NNW between approximately 12.5° and 30°N and thus is influenced by high- and low-latitude climate regimes. We will investigate three sediment cores along a N-S transect. Benthic foraminiferal stable isotope and pore density records from various parts of the Red Sea will be used for correlation and reconstruction of basin-wide and local changes in deep-water ventilation and OMZ strength. Geochemical records from the same archives will be used to reconstruct the hydrological changes on land, particularly the exposure and deflation of dust particles, but also biogeochemical processes in the Red Sea. The comparison of these proxy records will allow for the evaluation of regional contrasts and time-transgressive nature of humid and dry periods and oceanographic responses. This information is also relevant for the identification and characterization of potential time windows for the migration of anatomically modern humans across North Africa and the Arabian Peninsula into the Mediterranean region and Asia.

红海是一个内陆盆地，与非洲东北部和阿拉伯半岛的半干旱至干旱地区接壤。与印度洋的水团交换仅限于狭窄而浅的曼德海峡，该盆地接收来自边境的主要沙尘输入。因此，红海的海洋学和沉积过程甚至会对微妙的气候和海平面变化做出反应。在拟议的项目中，我们想要调查红海翻转环流和最低氧气区 (OMZ) 在过去 20 万年中如何响应轨道和千年尺度的气候变化，以及海洋学响应是否与边境地区的水文变化和尘埃通量同步。具体来说，我们想要解决以下假设：1）红海深水通风与全球海平面相关，并受到地中海和季风气候制度的影响进行区域调节，2）千禧年规模的气候变化，例如寒冷和极度干旱事件，会引起边境地区深水循环和水文的同时变化，3）尘埃通量监测着 非洲热带雨带反映了植被的阈值和灰尘颗粒的暴露。红海深处的沉积物档案似乎适合检验这些假设，因为该盆地在北纬 12.5° 至 30° 之间延伸 SSE-NNW，因此受到高纬度和低纬度气候状况的影响。我们将沿着南北横断面调查三个沉积岩芯。红海各地的底栖有孔虫稳定同位素和孔隙密度记录将用于关联和重建全盆地和局部深水通风和 OMZ 强度的变化。来自同一档案的地球化学记录将用于重建陆地上的水文变化，特别是灰尘颗粒的暴露和收缩，以及红海的生物地球化学过程。这些代理记录的比较将有助于评估潮湿和干旱时期的区域对比和时间海侵性质以及海洋响应。该信息还与识别和描述解剖学上的现代人类穿越北非和阿拉伯半岛迁移到地中海地区和亚洲的潜在时间窗有关。