Formation and collapse of ejecta plumes from large meteorite impact - a case study at the Ries crater, Germany

大型陨石撞击导致的喷射物羽流的形成和崩溃——以德国里斯陨石坑为例

• 批准号: 35635560
• 负责人: Professor Dr. Wolf Uwe Reimold
• 金额: --
• 依托单位: Museum für Naturkunde - Leibniz-Institut für Evolutions- und Biodiversitätsforschung (MfN)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/35635560?language=en
• 关键词: Formation; collapse; ejecta; plumes; large

This project aims at obtaining better understanding of the enigmatic and extremely dynamic processes related to formation of impact breccias within the evolving impact crater and vapour plume, and their mode(s) of distribution within and outside of the crater. An innovative two-prong investigative approach has been chosen. This comprises comprehensive and comparative petrographic (including textural) analysis of impact breccias drilled along a profile from the interior to the exterior of the Ries impact structure, as well as numerical modeling which allows to trace movement of material from the original target stratigraphy to its final place of deposition. Significant progress has been made with collection of modal, grain size, particle shape and orientation data, and mineralogical composition and textural observations from the groundmass of suevite, on samples from the FBN 1973, Enkingen, Otting and Wörnitzostheim drill cores. Numerical modeling has so far indicated that the amount of impact melt observed in crater suevite and surroundings of the structure does not satisfy the modeled melt volume. Also, the traditional hypothesis that suevitic impact breccias develop by fallout from an impact vapor plume can not be confirmed with our modeling results. Within-crater processes, such as ground-surge along the crater floor, thus attains enhanced significance. A further outcome of our modeling is that an extensive melt pool must develop within the crater interior. As this is not consistent with geophysical and drilling observations, a new approach to solve this problem is required. We apply for a 1-year extension of this project in order to complete petrographic-textural data acquisition as a prerequisite for data synthesis, and to develop a numerical model for post-impact mass transfer caused by phreato-magmatic type of explosions and related deposition of suevite inside and outside of the crater.

该项目旨在更好地了解与不断发展的冲击火山口和蒸气羽流以及其在火山口内外的分布模式相关的神秘和极具动态过程。选择了一种创新的两项调查方法。这完成了沿着从内部到外部到外部影响结构的轮廓的影响角度的全面和比较的岩石学（包括纹理）分析，以及数值建模，该模型允许将材料从原始目标层学界定到其最终沉积位置的材料移动。在FBN 1973，Enkingen，Otting，Otting和Wörnitzostheim钻井中，通过收集模态，晶粒大小，颗粒形状和方向数据的收集以及矿物学组成和纹理观测，取得了重大进展。到目前为止，数值建模表明，在火山口SUEVITE和结构周围观察到的冲击量无法满足建模的熔体体积。同样，我们的建模结果无法确认传统的假设，即影响蒸气羽流的辐射而发展的传统假设。界面的过程，例如沿火山口地面的地面横冲直撞，因此具有增强的意义。我们建模的进一步结果是，在火山口内部必须发展广泛的熔体池。由于这与地球物理和钻探观测不一致，因此需要一种解决此问题的新方法。我们申请该项目的1年延长，以完成岩石学纹理数据获取，作为数据综合的先决条件，并开发由爆炸类型的爆炸类型和相关的SUEVITE内部和外部的相关沉积引起的破坏后大质量的数值模型。