MagmaCourse: Fluid pathways below the Eger Rift constrained by numerical and analog simulations.

MagmaCourse：埃格尔裂谷下方的流体路径受到数值和模拟模拟的约束。

• 批准号: 344745229
• 负责人: Professorin Dr. Eleonora Rivalta, Ph.D.
• 金额: --
• 依托单位: Lehrstuhl für Mineralogie und Petrologie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/344745229?language=en
• 关键词: MagmaCourse; Fluid; pathways; below; Eger

The aim of this proposal is to obtain a conceptual model of deep fluid pathways consistent with observations, especially seismic and magnetotelluric (MT) observations that are sensitive to fluids, mineralization and presence of magma (Q1 and Q2). We plan for the first time to combine mechanical models (numerical simulations and complementary laboratory analog models) with constrained MT inversions and geochemical models in a loop process where the output of one model is used as input for the next step.The Vogtland/West Bohemia seismic swarms are a prominent example of crustal seismicity where fluids are playing a primary role, and relate to one of the few intra-plate seismically active regions of Europe. Many debates and unanswered questions revolve around these seismic swarms, here we list a selection: Q1) The role played by the intra-continental tectonics of the area. The area is a Paleozoic suture that was reactivated by Cenozoic post-orogenic extension, creating the 300km long and 50km wide Eger Graben and the Cheb-Domazlice Graben. Abundant, spatially distributed alkaline volcanism is associated with this area. What controls the spatial distribution of the volcanism and its geochemistry? How are seismicity and volcanism linked?Q2) Deep fluid pathways. Isotope ratios reveal that the high CO2 flux, reaching the surface in the form of CO2 rich mofettes and hydrothermal activity, originates directly from the upper mantle. What are the pathways followed by the magma and by the other fluids, and what factors are controlling them? What are the composition and the physicochemical properties of the fluids while they are migrating?Q3) Channeling of the fluids into pre-existing faults and the triggering factors for the seismicity. In the last 30 years multiple swarms have occurred in the area. What is the mechanics of the pressurized fluids entering into the pre-existing fault zone? What are the mechanisms supporting fluid movement? What is the composition of the crustal fluids reaching the seismogenic volume? What are their physical properties, and how do they evolve with time? How is the fluid-rock coupling converting fluid pressurization into rock stressing?These interconnected questions represent key questions for the ICDP Eger Rift project. We will develop new numerical and analog mechanical and geochemical models, and use them to constrain the model space of existing 2D inversion models, that are now non-unique. We will use available deep crustal seismic data and MT data acquired along 2 perpendicular profiles (autumn 2015) and on a dense grid (spring 2016) in the area of earthquake swarms and mofettes. A close cooperation with the MT group aimed at directly countercheck individual assumptions is novel and pioneering. The generation of the seismicity in the seismogenic zone will be addressed in a follow-up proposal.

本建议的目的是获得一个与观测相一致的深部流体路径的概念模型，特别是对流体、矿化和岩浆存在敏感的地震和大地电磁（MT）观测（Q1和Q2）。我们计划首次将力学模型（数值模拟和互补的实验室模拟模型）与约束MT反演和地球化学模型结合在一个循环过程中，其中一个模型的输出用作下一步的输入。沃格特兰/西波西米亚地震群是地壳地震活动的一个突出例子，流体在其中起着主要作用，并且与欧洲为数不多的板块内地震活跃区域之一有关。围绕这些地震群有许多争论和未解决的问题，在这里我们列出一些选择：Q1)该地区大陆内部构造所起的作用。该地区是一个古生代缝合带，在新生代造山后伸展作用下重新激活，形成了长300公里、宽50公里的Eger地堑和Cheb-Domazlice地堑。丰富、空间分布的碱性火山活动与本区有关。是什么控制了火山活动及其地球化学的空间分布？地震活动性和火山活动是如何联系在一起的？Q2)深层流体通路。同位素比值表明，以富CO2颗粒和热液活动的形式到达地表的高CO2通量直接来自上地幔。岩浆和其他流体的流动路径是什么，又是什么因素控制着它们？当流体迁移时，它们的组成和物理化学性质是什么？Q3)流体进入已存在断层的通道和地震活动性的触发因素。在过去的30年里，该地区发生了多次蜂群。加压流体进入已存在的断裂带的机制是什么？支持流体运动的机制是什么？到达发震体积的地壳流体的成分是什么？它们的物理性质是什么？它们是如何随时间演变的？流体-岩石耦合如何将流体压力转化为岩石应力？这些相互关联的问题代表了ICDP Eger Rift项目的关键问题。建立新的数值模拟力学和地球化学模型，并利用它们约束现有的非唯一性二维反演模型的模型空间。我们将使用沿两条垂直剖面（2015年秋季）和密集网格（2016年春季）在地震群和mofete区域获得的深部地壳地震数据和MT数据。与MT集团的密切合作旨在直接反制个人假设是新颖和开创性的。孕震带地震活动性的产生将在后续的建议中讨论。