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Site characterization of the PIER-ICDP drill locations to understand the relation between earthquake swarms, mofette fields and crustal fluid pathways by imaging the electrical conductivity structure

对 PIER-ICDP 钻探位置进行现场表征，通过对电导率结构进行成像来了解地震群、mofette 场和地壳流体通道之间的关系

基本信息

批准号：
271050501
负责人：
Privatdozentin Dr. Ute Weckmann
金额：
--
依托单位：
Sektion 2.2: Geophysikalische Abbildung des Untergrunds
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/271050501?language=en
关键词：
Site characterization PIER ICDP drill

项目摘要

The area around Nový Kostel/NW-Bohemia is part of the geodynamically active Variscan orogenic belt in Europe, and experiences repeated occurrence of intra-plate earthquake swarms and is characterized by numerous mineral springs and CO2 emissions. These phenomena are usually related to volcanic activity. To better understand the underlying processes, the Eger rift and the Cheb Basin are favored as a possible location for several scientific drillings. Magnetotelluric (MT) data sense the electrical resistivity of the Earth, a physical parameter that is particularly sensitive to the presence of low-resistivity phases such as aqueous fluids, partial melts or metallic compounds. Fluid phases have electrical resistivities orders of magnitude lower than that of the rock matrix, and relatively small amount of fluids, when interconnected, can thus decrease bulk rock resistivity by several orders of magnitude. Measurements of electrical resistivity can therefore be used to constrain the volume of subsurface fluids, their interconnectivity and the rheology of the crust and mantle. I propose a passive MT experiment centred on the location where earthquake swarms occur and mofette fields are observed. The major objectives are (i) imaging the regional electrical conductivity on crustal scale, including tectonic features such as fault zones, (ii) providing a site characterization for drilling locations, (iii) studying the behavior of rocks and fluids from the surface down to the source region of earthquake swarms, (iv) imaging fluid pathways, their hydraulic properties and their interconnection, in particular in relation to mofette fields (v) investigate existence and characteristics of possible lower crustal magmatic sources.

11月Kstel/NW-Bohemia周围地区是欧洲地球动力学活动的瓦里斯坎造山带的一部分，板块内地震群反复发生，以大量矿泉和二氧化碳排放为特征。这些现象通常与火山活动有关。为了更好地了解潜在的过程，埃格尔裂谷和切布盆地被认为是几个科学钻探的可能地点。大地电磁(MT)数据检测地球的电阻率，这是一种对低电阻率相(如水溶液、部分熔体或金属化合物)的存在特别敏感的物理参数。流体相的电阻率比岩石基质的电阻率低几个数量级，而相对少量的流体，当相互连接时，可以使整体岩石的电阻率降低几个数量级。因此，测量电阻率可以用来限制地下流体的体积、它们的相互连通性以及地壳和地幔的流变性。我提出了一个被动的MT实验，以震群发生和观测到的莫菲特磁场为中心。主要目标是：(1)成像地壳规模的区域电导率，包括断裂带等构造特征；(2)提供钻探地点的场地特征；(3)研究从地表到震群源区的岩石和流体的行为；(4)成像流体路径、其水力性质及其相互联系，特别是与莫菲特磁场有关；(5)调查可能的下地壳岩浆源的存在和特征。