Ejecta erosion, thermal and chemical lake evolution of the Ries impact structure

Ries 撞击结构的喷射物侵蚀、热湖和化学湖演化

• 批准号: 432460462
• 负责人: Professor Dr. Gernot Arp
• 金额: --
• 依托单位: Rieskrater-Museum Nördlingen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/432460462?language=en
• 关键词: Ejecta; erosion; thermal; chemical; lake

The 15 Ma old Nördlinger Ries is one of the most important terrestrial analogue sites for impact structures and their sedimentary crater fills on other planets and moons. The precise reconstruction of its post-impact erosional and sedimentary history helps to understand aquatic sedimentation and climate evolution on planets such as Mars. With respect to the Miocene Ries crater basin, the hypothesis is that chemical changes in inflowing solutions, changes in hydrology, and the temperature decline of the crater floor were major controlling factors of sedimentation, while climatic changes are responsible for superimposed fluctuations. Therefore, the present proposal focuses on tracing the successive erosion of the primary and secondary ejecta layer and the thermal evolution of the crater floor by analyzing the 87Sr/86Sr, carbon and oxygen (d13C, d18O, D'17O) isotopic composition of post-impact carbonates throughout a well-preserved drill core of the central crater basin. In addition, present-day surface and subsurface waters are analysed as references for weathering solutions of different lithological units (crystalline basement rocks, suevite, Bunte Breccia, Triassic and Jurassic sedimentary rocks). Specifically, strontium isotopic ratios are used to reconstruct changes in the provenance of solutes and hydrological changes with time. Oxygen isotope ratios are used to reveal trends in water temperatures, especially in early parts of the sedimentary succession. The reason for anomalously high carbonate d13C values will be elucidated.The aim and expected outcome is a precise reconstruction of processes affecting the chemical evolution of the Ries crater lake, a model to distinguish external (climatic) versus intrinsic (erosion and crater floor temperature decline) factors in planetary crater fill successions.

15 Ma的诺德林格山脉是最重要的地球撞击构造和其他行星和卫星上沉积火山口填充的类似地点之一。精确重建其撞击后的侵蚀和沉积历史有助于了解火星等行星上的水生沉积和气候演变。关于中新世里斯火山口盆地，假设是流入溶液的化学变化，水文变化和火山口底部的温度下降是沉积的主要控制因素，而气候变化是叠加波动的原因。因此，本提案的重点是跟踪连续侵蚀的初级和次级喷出物层和火山口底部的热演化，通过分析87 Sr/86 Sr，碳和氧（d13 C，d18 O，D '17 O）同位素组成的影响后的碳酸盐岩在整个保存完好的中央火山口盆地的钻孔芯。此外，还分析了现今地表和地下沃茨，作为不同岩性单元（结晶基底岩、苏云铁、本特角砾岩、三叠纪和侏罗纪沉积岩）风化溶液的参考。具体而言，锶同位素比值被用来重建溶质的来源和水文变化随时间的变化。氧同位素比值被用来揭示水温的趋势，特别是在沉积序列的早期。碳酸盐d13 C值异常高的原因将阐明。目的和预期的结果是一个精确的重建过程影响的里斯火山口湖的化学演变，一个模型来区分外部（气候）与内在（侵蚀和火山口底部温度下降）的因素在行星陨石坑填充序列。