The current state of the hidden magmatic process beneath the western Eger Rift after the 2011 earthquake swarm traced by isotope studies

通过同位素研究追踪 2011 年群震后埃格尔裂谷西部隐藏岩浆过程的现状

基本信息

批准号：
252970106
负责人：
Dr. Karin Bräuer
金额：
--
依托单位：
Department Hydrogeologie
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/252970106?language=en
关键词：
current state hidden magmatic process

项目摘要

As a result of the detailed isotope-geochemical studies of the mantle-derived fluids related to the 2000 and 2008 earthquake swarms the temporal seismically induced release of crustal derived components could be identified at degassing locations along the Pocatky Plesna Fault Zone (PPZ) and at degassing sites along the Marianske Lazne Fault (MLF), but was also observed in the Vogtland area. Both, after the swarms 2000 and 2008, the admixture of crustal derived components to the steady mantle-derived fluid flow were repeatedly detected for about two years. Besides that a clear increase of mantle-derived helium (up to 6 Ra) was observed at locations in the Cheb basin at least since 2000. This increase indicates the existence of an active magmatic reservoir in the upper mantle beneath the Cheb basin. Superimposed to the progressive increase of mantle-derived helium further temporal increased portions of mantle-derived helium (to 6.3 Ra) were observed before the 2000 and 2008 earthquake swarms at locations close to the Novy Kostel focal zone (NKFZ). The recorded anomalies indicate that both, the 2000 and the 2008 swarm, seems to be linked with supply of fresh magma from a less degassed reservoir in the upper mantle. That means from the view of fluids both swarms seems to be triggered by hidden magma intrusions within the lithosphere. No fluid data could be recorded accompanying the earthquake swarm 2011. Thus, it is yet unknown whether the portion of mantle-derived gas has increased or decreased in the western Eger Rift area in relation to the latest earthquake swarm, and whether indications exist for a further spatial expansion of the area with increased portions of mantle-derived gas in the western Eger Rift, respectively?Therefore, the proposal is mainly focussed on two aims: (1) to evaluate and compare the geodynamic situation within the three degassing centres Cheb Basin (CB), Marianske Lazne and surroundings (ML) and Karlovy Vary (KV) after the earthquake swarm 2011, and (2) to evaluate the fluid signatures at the degassing locations close to the piece of the planned seismic and geoelectric profile together. As a result of the planned fluid studies an update of the distribution pattern of mantle-derived gas is to expect in comparison to situation about 20 years ago. The new fluid data, regional and close of the profiles of geophysical research, allow the evaluation the permeability of fluid migration paths supplying the respective sites by their gas characteristic at the surface and provide information on the current state of the magmatic reservoir. The final discussion of all data will assist the interpretation of spatial anomalies and indications of ascending fluid paths, respectively identified in geophysical studies and will supply essential information for a future ICDP drilling in the western Eger Rift.

通过对与 2000 年和 2008 年地震群相关的地幔衍生流体进行详细同位素地球化学研究，可以在 Pocatky Plesna 断层带 (PPZ) 沿线的脱气位置和在沿玛丽亚温泉断层 (MLF) 的排气点，但也在沃格特兰地区观察到。在 2000 年和 2008 年的群聚之后，在大约两年的时间里，重复检测到地壳衍生成分与稳定的地幔衍生流体流的混合。此外，至少自 2000 年以来，在切布盆地的某些位置观察到源自地幔的氦明显增加（高达 6 Ra）。这种增加表明在切布盆地下方的上地幔中存在活跃的岩浆储层。与地幔衍生氦气的逐渐增加相叠加，在 2000 年和 2008 年地震群发生之前，在靠近 Novy Kostel 震源区 (NKFZ) 的位置观察到地幔衍生氦气的比例在时间上进一步增加（达到 6.3 Ra）。记录的异常表明，2000 年和 2008 年的岩浆群似乎都与来自上地幔脱气程度较低的储层的新鲜岩浆供应有关。这意味着从流体的角度来看，这两个群似乎都是由岩石圈内隐藏的岩浆侵入引发的。没有记录到 2011 年地震群伴随的流体数据。因此，目前尚不清楚埃格尔裂谷西部地区与最近的地震群相关的幔源气体部分是否增加或减少，以及是否存在迹象。埃格尔裂谷西部幔源天然气含量增加的区域是否进一步空间扩张？因此，该建议主要集中在两个目的：（1）评价和比较三个区域内的地球动力学情况2011 年地震群发生后，Cheb 盆地 (CB)、玛丽亚温泉市及周边地区 (ML) 和卡罗维发利 (KV) 脱气中心，以及 (2) 评估靠近计划地震和地电部分的脱气位置的流体特征一起配置文件。作为计划中的流体研究的结果，与大约 20 年前的情况相比，预计地幔衍生气体的分布模式将得到更新。新的流体数据，区域性的和接近地球物理研究的概况，允许通过地表的气体特征来评估供应各个地点的流体运移路径的渗透性，并提供有关岩浆储层当前状态的信息。所有数据的最终讨论将有助于解释分别在地球物理研究中确定的空间异常和上升流体路径的指示，并将为未来在埃格尔裂谷西部进行 ICDP 钻探提供重要信息。