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GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany).

Berberich G, Schreiber U - Animals (Basel) (2013)

Bottom Line: The results showed linear alignments and clusters of approx. 3,000 RWA mounds.A possible cause can be found in occasionally occurring H₂S in the fault systems, which is toxic at miniscule concentrations to the ants.Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.

View Article: PubMed Central - PubMed

Affiliation: Department of Geology, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany. gabriele.berberich@uni-due.de.

ABSTRACT
In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO₂, Helium, Radon and H₂S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H₂S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.

No MeSH data available.


Related in: MedlinePlus

Hough transform analyses of spatial distribution of RWA mounds (degrees from N) in the 1,140 km² West Eifel study area (a) in comparison with fault zones (degrees from N) (b) and in a map presentation (c) show that the RWA mounds are not randomly distributed but that there are preferential alignment directions of RWA mounds that correspond to those of the main fault directions.
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animals-03-00475-f007: Hough transform analyses of spatial distribution of RWA mounds (degrees from N) in the 1,140 km² West Eifel study area (a) in comparison with fault zones (degrees from N) (b) and in a map presentation (c) show that the RWA mounds are not randomly distributed but that there are preferential alignment directions of RWA mounds that correspond to those of the main fault directions.

Mentions: Furthermore, the spatial distribution of RWA mounds shows that they are not statistically randomly distributed, but follow a certain shaped pattern [28,31]. This could be verified by the Hough transform (a well-established algorithm for identifying linear structures in sets of points [25]) applied on the spatial distribution of RWA mounds in entire the study area (cf.Figure 7(a)) in comparison with fault zones [26,27] (cf.Figure 7(b)). Statistical analyses show that the center’s of the modes, i.e., the local maxima in the histograms, denote the preferential alignment directions, while their widths indicate the corresponding directional variations. In both histograms (cf.Figure 7(a,b)), the local maxima are separated by vertical black lines. For each mode, the average value is indicated by a solid vertical red line combined with direction (i.e., NW-SE) and the ±1 standard deviation interval surrounded by two dashed vertical red lines. Each blue bar represents a 3°-step-degree from N. More specifically, the azimuthal directions in which the RWA mound positions are aligned correspond to those of the main fault directions.


GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany).

Berberich G, Schreiber U - Animals (Basel) (2013)

Hough transform analyses of spatial distribution of RWA mounds (degrees from N) in the 1,140 km² West Eifel study area (a) in comparison with fault zones (degrees from N) (b) and in a map presentation (c) show that the RWA mounds are not randomly distributed but that there are preferential alignment directions of RWA mounds that correspond to those of the main fault directions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494391&req=5

animals-03-00475-f007: Hough transform analyses of spatial distribution of RWA mounds (degrees from N) in the 1,140 km² West Eifel study area (a) in comparison with fault zones (degrees from N) (b) and in a map presentation (c) show that the RWA mounds are not randomly distributed but that there are preferential alignment directions of RWA mounds that correspond to those of the main fault directions.
Mentions: Furthermore, the spatial distribution of RWA mounds shows that they are not statistically randomly distributed, but follow a certain shaped pattern [28,31]. This could be verified by the Hough transform (a well-established algorithm for identifying linear structures in sets of points [25]) applied on the spatial distribution of RWA mounds in entire the study area (cf.Figure 7(a)) in comparison with fault zones [26,27] (cf.Figure 7(b)). Statistical analyses show that the center’s of the modes, i.e., the local maxima in the histograms, denote the preferential alignment directions, while their widths indicate the corresponding directional variations. In both histograms (cf.Figure 7(a,b)), the local maxima are separated by vertical black lines. For each mode, the average value is indicated by a solid vertical red line combined with direction (i.e., NW-SE) and the ±1 standard deviation interval surrounded by two dashed vertical red lines. Each blue bar represents a 3°-step-degree from N. More specifically, the azimuthal directions in which the RWA mound positions are aligned correspond to those of the main fault directions.

Bottom Line: The results showed linear alignments and clusters of approx. 3,000 RWA mounds.A possible cause can be found in occasionally occurring H₂S in the fault systems, which is toxic at miniscule concentrations to the ants.Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.

View Article: PubMed Central - PubMed

Affiliation: Department of Geology, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany. gabriele.berberich@uni-due.de.

ABSTRACT
In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO₂, Helium, Radon and H₂S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H₂S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.

No MeSH data available.


Related in: MedlinePlus