Gas permeable deep reaching fracture zones encourage site selection of ants

Difficulties with geological mapping of fault patterns occur frequently due to missing outcrops and typically fault mineralization (e.g. crystalline quartz and ore mineralization). Alternatively, in addition to other analyses, soil gas measurements (e.g. helium) can be carried out. Due to fault zone complexity, geologists must often rely on other, in some cases, easier indications of their existence. Geological studies in several areas of central Europe especially in the Middle Rhine Region (Rhenish Massif) indicate that active gas permeable fracture zones are linked to linear distributions of nests of hill-building forest ants. Therefore, the possibility of using formicines as indicators of gas permeable fault patterns was investigated. These preliminary data indicated the possible interaction of site selection and active gas permeable fracture zones. Consequently, regions in the Alps, the Black Forest, the Lower Rhine Embayment, Bavaria, Hesse and South Sweden were chosen, ant nests were mapped, and their sites subsequently compared to geological structures. Most of the investigated ant nests were located on or near active gas permeable faults. Additionally, in the Middle Rhine Region variations in population size of formicines on fault zones and inter fault zones have been observed. These primary data suggest formicines can be applied successfully as an aid to fault pattern location.