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HYPOGENIC CAVE FEATURES
condensation-corrosion is occurring in older conduits of a
phreatic origin.
In their recent review of the Alpine karst in Europe,
Audra et al. (2007a) point out that hypogenic
(hydrothermal) karst appears more widespread in the
region than previously assumed. Rising hydrothermal
systems are usually located near thrust and strike-slip
faults. The hydrothermal origin of these caves can be
recognized from their characteristic convection-related
morphology and presence of calcite spar. Ascending
hydrothermal systems create well-connected cave systems,
which later are generally reused and reshaped by
epigenetic speleogenesis, overwriting many marks of their
hypogenic origin. These were conserved, however, when
caves were rapidly fossilized (Audra et al., 2007a).
Instructive examples of densely packed hypogenic
mazes in Western Europe are Fuchslabyrinth Cave (6.4
km; Figure 28-A; Müller et al, 1994) in Baden-
Würtenberg, Germany, and Moestroff Cave (4 km; Figure
28-B; Massen, 1997) in Luxemburg. Both have a main
story and lower story. The caves were developed within
particular beds of the stratified carbonate Muschelkalk
Formation under former artesian conditions. The presence
of low permeability beds in the caprock prevents vertical
downward percolation to the caves, which perfectly
display the morphological suite of rising flow, described in
Section 4.4 (see Plate 1-C, Plate 3-H, Plate 10-A). No
mineralogical evidence is found pointing to the
involvement of H2S waters, but dissolution due to mixing
or rising flow and lateral flow is clearly an option. Largely
similar network mazes are known in the Carboniferous
limestones of the Northern Pennines, United Kingdom,
some of them intercepted by the denudation surface while
others have been encountered by mines (Ryder, 1975). The
multi-story Knock Fell Caverns (4 km; Figure 28-C) has a
substantial overprint of water table and vadose features but
the morphologic suite of rising flow is still easily
recognizable.
Among gypsum caves in Western Europe,
characteristic examples of hypogenic transverse
speleogenesis are Estremera Cave in the Neogene gypsum
of the Madrid Basin, Spain (Almendros and Anton Burgos,
1983), and Denis Parisis Cave in the Tertiary gypsum of
the Paris Basin, France (Beluche et al, 1996). In Estremera
Cave (3.5 km; Figure 29, right) the morphologic suite of
rising flow is firmly identified. Denis Parisis Cave (3.5
km; Figure 29, left), a joint-controlled stratiform cave, is
encountered by a gypsum mine, being totally isolated from
both lateral and downward potential recharge sources.
Based on published photographs, the characteristic
morphology of “ascending” artesian mazes is recognizable.
A type location for hypogenic speleogenesis in
gypsum with cave development at the base of a thick
soluble formation by buoyancy-driven dissolution from the
basal aquifer, is the South Harz in Germany where large
isolated chambers and other irregularly-shaped cavities
(Schlotten) were encountered by mines at depths up to 400
m (Kempe, 1996; Figure 30).
Figure 28. Hypogenic maze caves in Cretaceous (A) and Triassic (B and C) limestones in Western Europe. A = Fuchslabyrinth Cave,
Germany (6.4 km; from Müller et al, 1994); B = Moestrof Cave, Luxembourg (4 km; from Massen, 1997); C = Knock Fell Cavern, UK
(4 km; from Elliot, 1994).
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