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HYPOGENIC CAVE FEATURES
4.5 Selected examples of caves formed by
hypogenic transverse speleogenesis
In this section, a brief overview is provided of some
exemplary caves for which hypogene transverse origin is
firmly established or suspected based on available
publications and personal observations by the author. Not
all of them have been previously interpreted in this way,
but their morphological and geological characteristics,
consistent with the criteria discussed above, strongly
suggest their development by rising flow in confined
settings.
In no way should this overview be considered as
exhaustive for hypogenic caves. The number of such caves
recognized around the world is rapidly growing, and it is
going to expand dramatically by re-interpretation of many
caves, based on the new approach suggested in this book.
Rather, this is a list of reference cases to use in relating,
refining or revising the origin of a great number of caves in
many regions, and an illustration of the variety of
geographic and geologic settings in which ascending
hypogenic speleogenesis occurs.
Central and Western Europe
Hypogenic transverse caves are abundant throughout
Central and Western Europe, occurring in both cratonic
and disrupted (folded) settings.
Probably the most well known and early recognized as
hypogenic (hydrothermal) are caves in the Buda
Mountains, Hungary (e.g. Müller and Sarvary, 1977. There
is abundant literature on Hungarian hydrothermal caves,
summarized in Takács-Bolner and Kraus (1989) and
Dublyansky, Yu. (1995, 2000c). Triassic cherty limestones
are overlain by 40-60 m of Eocene limestones covered by
marls that form a largely impermeable cap. Denudation
and fluvial erosion imposed over the complex block-fault
geologic structure created various situations of breaching
and draining of the cave-hosting limestones. Mean
temperatures of descending waters invading the caves are
8-13 o C. Different thermal springs have mean temperatures
between 20-60 o C, indicating that differing amounts of
mixing take place (Ford and Williams, 2007). Almost the
full range of thermal cave types and evolutionary stages of
development can be found in Budapest, including 2-D and
3-D mazes, relict shafts, chambers, and modern caves
discharging rising thermal waters at the level of the
Danube River.
Ford and Williams (2007) refer to a series of
illustrative examples of the Buda Mountains caves.
Pálvölgyi (Figure 22, A) and Ferenc-hegy caves are multistory
mazes. Szemlöhegy Cave is a more simple outlet rift
from along joints; it has abundant subaqueous calcite
crusts. Molnár János is a modern outlet; its warm waters
have been dove to -70 m, discovering ~4 km of maze at
depth. Jószefhegy Cave is a shaft descending to ramiform
chambers with abundant secondary gypsum deposits,
where Ford and Williams (2007) point out that CO2
(hydrothermal) and H2S dissolution mechanisms may
mingle within a small geographical area.
Sátorkö-puszta Cave and Bátori Cave (Figure 22, B)
are examples of basal chambers with a tree-like branching
pattern of rising passages containing sequences of
spherical cupolas. These passages extend for about 40 m
above the chamber in Sátorkö-puszta. The origin of
cupolas had been attributed earlier to the convectional
condensation mechanism operating above the water table
(Szunyogh, 1989). The chamber walls are largely
converted to gypsum. Ford and Williams (2007) believe
these caves are monogenetic H2S systems, major
enlargements by H2S processes of earlier rising water
shafts.
Figure 22. Patterns of hydrothermal caves of the Buda Mountains, Hungary. A = maze pattern, plan view of Pálvölgyi Cave (by J. Kárpát
and K. Takácsne-Bolner); B = bush-like patterns, 1 = profile of Sátorkö-puszta Cave (by M. Juhasz), 2 = profile of Bátori Cave (by P. Borka
and J. Kárpát). From Dublyansky Yu. (2000c).
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