Geogenic Gases in a Red Wood-Ant Nest and Soil in the Neuwied Basin, Germany 2016

Geochemical tracers of crustal fluids (CO2, He, Rn) provide a useful tool for the identification of buried fault structures. We acquired geochemical data during 7 months of continual sampling to identify causal processes underlying correlations between ambient air and degassing patterns of three gases (CO2, He, Rn) in a nest of red wood ants (Formica polyctena; “RWA”) and the soil at Goloring in the Neuwied Basin, a part of the East Eifel Volcanic Field (EEVF). We explored whether temporal relations and degassing rhythms in soil and nest gas concentrations could be indicators of hidden faults through which the gases migrate to the surface from depth. In nest gas, the coupled system of CO2-He and He concentrations exceeding atmospheric standards 2-3 fold suggested that RWA nests may be biological indicators of hidden degassing faults and fractures at small scales. Equivalently periodic degassing infradian rhythms in the RWA nest, soil, and three nearby mineral springs suggested NW-SE and NE-SW tectonic linkages. Because volcanic activity in the EEVF is dormant, more detailed information on the EEVF’s tectonic, magmatic, and degassing systems and its active tectonic fault zones are needed. Such data could provide additional insights into earthquake processes that are related to magmatic processes at the lower crust.

地壳流体（CO₂、He、Rn）的地球化学示踪剂，为隐伏断层构造的识别提供了有效工具。本研究通过7个月的连续采样获取地球化学数据，旨在厘清新维德盆地（Neuwied Basin，隶属于东埃菲尔火山场（East Eifel Volcanic Field，EEVF））戈洛林（Goloring）地区，赤木蚁（Formica polyctena，简称"RWA"）蚁巢与周边土壤中，周边环境空气与三类气体（CO₂、He、Rn）脱气模式间的关联背后的因果过程。本研究探讨了土壤与蚁巢内的气体浓度的时序关联及脱气节律，能否作为气体从深部运移至地表的隐伏断层的指示指标。蚁巢气体中，CO₂-He耦合体系与He浓度超出大气标准2~3倍，这一现象表明赤木蚁蚁巢可作为小型隐伏脱气断层及裂隙的生物指示物。同理，赤木蚁蚁巢、土壤及附近三处矿泉的脱气亚昼夜节律（infradian rhythms）呈现周期性特征，暗示了NW-SE与NE-SW向的构造联动关系。鉴于东埃菲尔火山场（EEVF）的火山活动处于休眠状态，亟需获取该区域构造、岩浆、脱气系统以及活动构造断层带的详尽资料。此类数据可进一步深化对与下地壳岩浆活动相关的地震活动过程的认知。