Degassing Rhythms and Fluctuations of Geogenic Gases in A Red Wood-Ant Nest and in Soil in The Neuwied Basin (East Eifel Volcanic Field, Germany).

Gabriele M Berberich,Christian Wöhler,Aaron M Ellison,Martin B Berberich

doi:10.3390/insects9040135

Gabriele M Berberich, Christian Wöhler + Show 2 more

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https://doi.org/10.3390/insects9040135

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Abstract

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 minerals 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.

Highlights

The seismically active East Eifel Volcanic Field (EEVF) and its adjoining Neuwied basin have been the focus of many vulcanological, geochemical, petrochemical, and tectonic investigations
We found that nest gas (NG) appears to be associated with soil gas (SG) indicating fault-related micro-seepage of geogases; the degassing rhythm between the soil and nest is associated with degassing rhythms of three nearby mineral springs; and that degassing patterns are independent of earth tides and meteorological conditions
SG5 (7-M: 10.0; 4-W: 12.5 Vol %); maximum concentrations ranged from 0–15 Vol %

Summary

Introduction

The seismically active East Eifel Volcanic Field (EEVF) and its adjoining Neuwied basin have been the focus of many vulcanological, geochemical, petrochemical, and tectonic investigations.These have focused on dormant but not extinct volcanic activity [1,2,3]; the present-day NW–SE-directed compressional stress field and its related seismic activity [4,5]; gas composition and chemical tracers of mineral waters [6,7,8]; and mofettes along the Laacher See or at Obermendig [9]. Important mechanisms driving fluid flow and keeping fractures open are compressive stress, volume changes of pore fluid or the rock matrix, and fluid movement or buoyancy [16]. He concentrations higher than the atmospheric standard (5.22 ppm; Davidson and Emerson 1990). In the 7-M samples, maximum He concentrations of ≈5.50 ppm occurred in SG2, 3, and 7 (Table 2). Rn concentrations in NG (7-M: ≈7 BqL−1 ; 4-W: ≈16 BqL−1 ), SG 2, and SG3 were at or below background levels (Table 2)

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