SECCO- Chile: The coupled vegetation, weathering, erosion, and sediment-export response to climate change unravelled from novel proxies in Chilean marine sediment

SECCO-智利：智利海洋沉积物中的新代理揭示了植被、风化、侵蚀和沉积物输出对气候变化的耦合响应

• 批准号: 408246516
• 负责人: Professorin Dr. Anne Bernhardt
• 金额: --
• 依托单位: Institut für Geologische Wissenschaften
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/408246516?language=en
• 关键词: SECCO; Chile; coupled; vegetation; weathering

Understanding landscape response to climate change is a central problem in the geosciences today, as substantial future changes in precipitation patterns and intensity are expected. Earth's surface is vulnerable to complex feedbacks between climate, hydrology, vegetation, weathering, erosion, and sediment deposition that affect the evolution of landscapes that we live on. However, precisely how vegetation, weathering and erosion, and associated sediment dynamics, respond to climate change is currently unknown. This gap in knowledge severely obstructs the interpretation of marine sedimentary records as archives of changes in climate and/or surface processes. In Chile, there is published evidence for a direct response between an onshore climatic forcing and the offshore sedimentary archive: following onshore aridification in the last deglacial, turbidite-deposit thickness and frequency strongly decreased offshore.This project seeks to identify the cascade of changes in weathering, erosion, and sediment export to the ocean following hydrologic and vegetation changes from the Last Glacial Maximum (LGM) to the present along the Chilean coast. To achieve this goal, we link the disciplines of sedimentary systems research, geochemistry, and biology to jointly explore the feedbacks between changes in hydrology and vegetation and Earth-surface processes over a large spatial (the Chilean coast) and temporal (LGM to Holocene) scale. We hypothesize that the impact of deglacial climate change on Chilean landscapes is strongly modulated through the presence of vegetation. Hence, we suggest that temporal lags occurred between changes in climate/ hydrology and vegetation, and changes in weathering, erosion, and sediment export.We propose to test this hypothesis by applying a unique combination of novel state-of-the-art proxies that allow the detection of changes in vegetation and hydrology (by lipid biomarker analysis and their delta 13C and delta D isotope composition), weathering (by using Li stable isotopes, delta 7Li), and erosion (by using novel cosmogenic meteoric 10Be/9Be ratios) that followed deglacial aridification. In a first work package (WP1), we will identify present-day spatial differences in the evolution of these proxies along the Chilean climatic gradient, by sampling modern erosion products from riverine and offshore surface sediment from core tops. In WP2, we use the same methods on independently dated marine sedimentary archives that provide the depositional legacy necessary to reconstruct the temporal dynamics of these proxies from the LGM to the present day, as spatially representative archives are mostly absent onshore. This modern calibration (WP1) in combination with the paleo-record (WP2) will allow us to identify and mechanistically understand the sources of variability in and the temporal leads and lags between changes in vegetation, weathering, erosion, and sediment export to the ocean following a major hydrological change.

在当今的地球科学中，了解对气候变化的景观反应是一个核心问题，因为预计降水模式和强度的实质性变化。地球表面容易受到气候，水文学，植被，风化，侵蚀和沉积物沉积之间的复杂反馈，这些反馈影响了我们所生活的景观的演变。然而，目前尚不清楚植被，风化和侵蚀以及相关的沉积物动态如何应对气候变化。知识的这种差距严重阻碍了海洋沉积记录的解释，因为气候和/或表面过程的变化档案。在智利中，有公开的证据表明，陆上气候强迫与近海沉积物档案之间有直接反应：在最后一个冰川，浊度居住的厚度和频率强烈降低的陆上干旱后，该项目旨在确定最大程度地变化，触发效率，雾化，植物的含量最大。现在沿智利海岸。为了实现这一目标，我们将沉积系统研究，地球化学和生物学的学科联系起来，共同探索在大型空间（智利海岸）和颞（LGM到全新世）上的水文和植被变化与植被的变化与地球表面过程之间的反馈。我们假设通过植被的存在，强烈调节了冰川气候变化对智利景观的影响。因此，我们建议在气候/水文学和植被的变化以及风化，侵蚀和沉积物出口的变化之间发生时间滞后。我们提议通过应用新颖的最新最先进的代理来检验这一假设，这些代理允许检测植被和水文的变化（通过Lipid Biomarker Anallys和Delta delta DeLta Desta dista desta desta dista desta dc d d d.稳定的同位素，delta 7li）和侵蚀（通过使用新型的宇宙灭气10BE/9BE比率），遵循冰冰干燥的侵蚀。在第一个工作套餐（WP1）中，我们将通过对河流河流和海上表面沉积物的现代侵蚀产物进行采样，从智利气候梯度沿智利气候梯度沿智利气候梯度的演变中的当今空间差异。在WP2中，我们在独立日期的海洋沉积档案中使用了相同的方法，这些方法提供了从LGM到今天重建这些代理的时间动态所需的沉积遗产，因为空间代表性的档案主要不存在。这种现代校准（WP1）与古纪录（WP2）结合使用，将使我们能够识别并机械理解可变性的来源以及植被，风化，侵蚀和沉积物的变化之间的暂时潜在客户和滞后，并在重大水文变化后向海洋出口到海洋。