Micrometer-scale biomarker and elemental imaging on sediments from the northeastern Arabian Sea – reconstruction of the Indian monsoon evolution on a sub-decadal scale in the Holocene and the Bølling-Allerød interstadial

阿拉伯海东北部沉积物的微米级生物标志物和元素成像——全新世和贝尔林-阿勒德间质层亚十年尺度印度季风演化的重建

• 批准号: 464898428
• 负责人: Dr. Igor Obreht
• 金额: --
• 依托单位: Zentrum für Marine Umweltwissenschaften (MARUM)
• 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/464898428?language=en
• 关键词: Micrometer; scale; biomarker; elemental; imaging

The Indian monsoon is one of the most important large-scale coupled land-ocean-atmosphere phenomena in the low latitudes. However, the forcing mechanisms of the decadal-scale monsoon variability are not well understood because knowledge of short-term climate oscillations is mostly limited to periods covered by instrumental records. Understanding of the short-scale climate evolution in the more distant past is hampered by the small number of records that preserve undisturbed signals and by methodological limitations to obtain highly resolved records. However, recent developments that interrogate laminated sediments with novel imaging techniques showed great potential to overcome these limitations. In order to reveal subdecadal-scale paleoclimate evolution of the tropics, I propose to apply biomarker and elemental imaging on finely laminated sediment sections from the Arabian Sea spanning the major part of Holocene (from 11.7-2 ka) and Bølling-Allerød interstadial (B-A; 14.7-12.9 ka). The goal of this project is to explore the interplay of the Intertropical Convergence Zone (ITCZ), Indian monsoon intensity and related environmental responses on the subdecadal and decadal-scale during the Holocene and B-A.Sediment core SO130-289KL from the Arabian Sea preserves an undisturbed, laminated record for proposed time intervals, providing an excellent archive for high-resolution studies. I propose to apply mass spectrometry imaging, a novel technique in paleoclimate research that collects mass spectra of organic compounds and visualizes their spatial distribution at the µm-scale, and combine it with congruent µXRF data from sediments deposited during the Holocene and B-A interstadial. The aim is to combine independent biomarker proxies for sea-surface temperature (SST) with proxies of terrestrial vegetation response, aquatic primary productivity and water column anoxia in 200 µm (i.e. annual) resolution and relate this data to elemental ratios indicative of environmental conditions acquired at 50 µm resolution. Obtained annually resolved biomarker and elemental records will reveal previously inaccessible information on monsoon intensity and its relation to ITCZ in interglacial and interstadial climate states, as well as precisely establish monsoon forcing on the environment by detecting leads and lags in the responses of the ocean, atmosphere and land to climate change in an unprecedented level of details. A conservative approach in establishing dominant frequencies of climate variability in warm climate states of the past ~15 ka will be applied to test for the existence of quasi-persistent decadal oscillations. This project will also constrain the rate of SST change and its variability in the tropics over the Holocene and B-A. In summary, this project will provide highly-resolved biomarker and elemental data that could serve as a reference record for subdecadal climate evolution in the tropics during the Holocene and the B-A.

印度季风是低纬度地区最重要的大尺度陆-海-气耦合现象之一。然而，年代际季风变率的强迫机制尚不清楚，因为对短期气候振荡的了解大多局限于仪器记录所涵盖的时期。由于保存未受干扰信号的记录数量少，以及在获得高分辨率记录方面的方法限制，对较遥远过去的短尺度气候演变的认识受到阻碍。然而，最近利用新型成像技术研究层状沉积物的进展显示出克服这些限制的巨大潜力。为了揭示热带地区亚年代际尺度的古气候演化，作者建议对阿拉伯海全新世大部分时间（11.7-2 ka）和b ølling- allero ød间期（B-A; 14.7-12.9 ka）的精细层状沉积物剖面进行生物标志物和元素成像。本项目的目的是在全新世和B-A年的年代际和年代际尺度上探讨热带辐合带（ITCZ）与印度季风强度及其相关环境响应的相互作用。来自阿拉伯海的沉积物岩心SO130-289KL保留了未受干扰的层压记录，为高分辨率研究提供了极好的档案。本文拟应用质谱成像这一古气候研究的新技术，在微米尺度上收集有机化合物的质谱并可视化其空间分布，并将其与全新世和B-A间期沉积沉积物的一致μ XRF数据相结合。目的是将海面温度（SST）的独立生物标志物代理与陆地植被响应、水生初级生产力和水柱缺氧的代理在200微米（即年）分辨率下结合起来，并将这些数据与在50微米分辨率下获得的指示环境条件的元素比率联系起来。每年获得的生物标志物和元素记录将揭示以前无法获得的关于间冰期和间冰期气候状态下季风强度及其与ITCZ关系的信息，并通过探测海洋、大气和陆地对气候变化的响应的领先和滞后，以前所未有的细节水平精确地建立季风对环境的强迫。在过去~15 ka温暖气候状态中建立气候变率主导频率的保守方法将用于检验准持续年代际振荡的存在。该项目还将限制全新世和B-A期间热带海温的变化速率及其变率。总之，该项目将提供高分辨率的生物标志物和元素数据，可作为全新世和B-A期间热带地区年代际气候演变的参考记录。