Download PDF - Speleogenesis

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NCKRI Special Paper Series No.1
either solute or thermal density differences is important in
hypogenic speleogenesis.
In identifying hypogenic caves, the primary criteria
are morphological (patterns and meso-morphology) and
hydrogeological (hydrostratigraphic position and
recharge/flow pattern viewed from the perspective of the
evolution of a regional groundwater flow system).
Elementary patterns typical for hypogenic caves are
network mazes, spongework mazes, irregular chambers
and isolated passages or crude passage clusters. They
often combine to form composite patterns and complex 3-
D structures. Hypogenic caves are identified in various
geological and tectonic settings, and in various
lithologies. Despite these variations, resultant caves
demonstrate a remarkable similarity in cave patterns and
meso-morphology, which strongly suggests that the
hydrogeologic settings were broadly identical in their
formation. Presence of the characteristic morphologic
suites of rising flow with buoyancy components is one of
the most decisive criteria for identifying hypogenic
speleogenesis, which is much more widespread than was
previously presumed. Hypogenic caves include many of
the largest, by integrated length and by volume,
documented caves in the world.
The refined conceptual framework of hypogenic
speleogenesis has broad implications in applied fields and
promises to create a greater demand for karst and cave
expertise by practicing hydrogeology, geological
engineering, economic geology, and mineral resource
industries. Any generalization of the hydrogeology of
karst aquifers, as well as approaches to practical issues
and resource prospecting in karst regions, should take into
account the different nature and characteristics of
hypogenic and epigenic karst systems. Hydraulic
properties of karst aquifers, evolved in response to
hypogenic speleogenesis, are characteristically different
from epigenic karst aquifers. In hypogenic systems, cave
porosity is roughly an order of magnitude greater, and
areal coverage of caves is five times greater than in
epigenic karst systems. Hypogenic speleogenesis
commonly results in more isotropic conduit permeability
pervasively distributed within highly karstified areas
measuring up to several square kilometers. Although
being vertically and laterally integrated throughout
conduit clusters, hypogenic systems, however, do not
transmit flow laterally for considerable distances.
Hypogenic speleogenesis can affect regional subsurface
fluid flow by greatly enhancing initially available crossformational
permeability structures, providing higher
local vertical hydraulic connections between lateral
stratiform pathways for groundwater flow, and creating
discharge segments of flow systems, the areas of lowfluid
potential recognizable at the regional scale.
Discharge of artesian karst springs, which are modern
outlets of hypogenic karst systems, is often very large and
steady, being moderated by the high karstic storage
developed in the karstified zones and by the hydraulic
capacity of an entire artesian system. Hypogenic
speleogenesis plays an important role in conditioning
related processes such as hydrothermal mineralization,
diagenesis, and hydrocarbon transport and entrapment.
An appreciation of the wide occurrence of hypogenic
karst systems, marked specifics in their origin,
development and characteristics, and their scientific and
practical importance, calls for revisiting and expanding
the current predominantly epigenic paradigm of karst and
cave science.