Hypogene Karst: principal features and implications for geosciences

Abstract

Principal features of hypogene karst and its implications for geosciences

Full text

Alexander Klimchouk
National Academy
of Sciences of Ukraine, Kyiv
klimchouk.2020@gmail.com
Hypogene Karst: principal features Hypogene Karst: principal features
and implications and implications for for geosciencesgeosciences
Highlights of Highlights of GeoscientificGeoscientific Cave ResearchCave Research
November 11-12, 2022, Austrian Academy of Sciences, Vienna

Hypogene karst: principal features
and implications to geosciences
Hypogene karst:
•the notion
•distinctions with epigene k.
•fluids, flow drives,
dissolution mechanisms
•types
•patterns and morphs
•settings
•implications for geosciences
www.360parks.com

Traditional karst paradigm = epigene (hypergene) karst
- karstifiable rocks – those readily soluble under normal conditions (limestone, gypsum, salt, …);
- unconfined (open) conditions, recharge from the surface, direct genetic and functional
relationship with the surface, variable flow rates and high flow velocities;
- predominantly lateral (stratiform) groundwater circulation in the phreatic zone;
- highly competitive conduits development (strong dissolution / flow feedback).
Focused recharge
Concentrated discharge
direct genetic and functional relationship with the surface
Goldscheider & Drew (2007)

Traditional karst paradigm = epigene (hypergene) karst
The general notion of karst is commonly defined through specific features of landscapes and
of shallow groundwater circulation.
Exposure of soluble rocks was considered a necessary pre-requisite for karst.
In reverse, karstified intervals found in deep settings were deemed paleokarst and an indication
of surface exposure in the past.
GypsumGypsum,, TienTien Shan, Shan,
UzbekistanUzbekistan
Limestones, Limestones, ChatyrdagChatyrdag Plateau, Plateau,
Crimea, UkraineCrimea, Ukraine LimestonesLimestones, South , South ChinaChina
LimestonesLimestones, UK, UK Salt, Zagros, Iran
Limestones, Limestones,
West West Caucasus. GeorgiaCaucasus. Georgia

The concept of hypogene speleogenesis refers to the origin of the cave-forming agency
(i.e. fluid flow and its aggressiveness) from depth.
Hypogene speleogenesis is defined as the formation of dissolution-enlarged permeability
structures (void-conduit systems) by upwelling fluids that recharge the cave-forming zone from
below, whereas fluids originate from distant, estranged (by low-permeability units), or internal
sources, independent of recharge from the overlying or immediately adjacent surface.
The notion of hypogene karst - no genetic and functional relationship with the surface

The notion of hypogene karst
•rock solubility is a function of PT conditions and fluid composition; as these conditions vary with depth,
hypogene karst may develop in a wide range of rocks, including igneous and siliciclastic;
•diverse origins of fluids (meteoric, metamorphic, magmatic) and flow drives/regimes (gravitational,
compaction, convection, tectonic squeeze, thermobaric, endogenic);
•diverse dissolution mechanisms;
•rising flow; recharge and discharge occur through vertically adjacent formations; low flow velocities;
•specific mechanism of speleogenesis – suppression of competition between alternative flow paths,
high role of natural convection; phantomisation (alteration) of rocks along flow paths;
•karst development may occur at great depths (up to 8 km) and may not manifest at the surface.
- no genetic and functional relationship with the surface

Hypogene karst – Diverse origins of fluids
In hydrogeology, the origin of aqueous fluids
is distinguished either:
- according to ways by which they penetrate
into the lithosphere, or
- according to processes by which they are
released or generated within the lithosphere.
Common fluids in hypogene karstification:
- Meteoric fluids of deep circulation (thermal);
- Metamorphic fluids;
- Magmatic fluids.
Modified from Pinneker (1980), in Klimchouk (2017)
Geological cycle
Hydrological cycle

Types according to dissolution mechanisms involved:
•hydrothermal speleogenesis by carbonic acid, - due to the retrograde
solubility of calcite in rising and cooling waters;
•sulfuric acid speleogenesis (SAS) – where H2S-waters are oxidized;
•“mixing corrosion” speleogenesis (mixing of two waters saturated under
different conditions may generate additional aggressiveness);
•simple dissociation speleogenesis (evaporites), etc.
Hypogene karst – Genetic types
In deep settings where magmatic fluids are involved, other acids, such as
hydrochloric and hydrofluoric, may play the role in dissolution of rocks

Hypogene karst – Genetic types
1. Artesian speleogenesis, related to upwelling
cross-unit communication between aquifers
Types according to hydrogeological environments - driving forces / conditions for ascending flow:
2. Endogenous, fault-aligned speleogenesis,
related to rising cross-formational flow along
basement-rooted faults
- dispersed recharge from the underlying aquifer;
- stratiform, commonly maze-like, cave systems;
- distribution is controlled by the hydrodynamics
of topography-driven flow in multi-story aquifer
systems (i.e. upward flow below topographic
lows) .
- strong structural control by faults and deeply-rooted
fracture zones; geodynamic control over fluid flow;
- cross-formational, sub-vertical void-conduit
systems, linear-localized distribution;
- involvement of deep fluids.

3. Mixed, artesian/endogenous speleogenesis, where deep fluids ascend along faults or fracture
corridors and interact with stratiform aquifers;
- may have characteristics of both, type 1 and type 2.
Sulfuric acid speleogenesis (SAS)at the water table:
- carbonate rocks;
- water table control;
- condensation-corrosion above the water table.
Coastal speleogenesis at the fresh/saline water interface:
- carbonate rocks;
- controlled by the position of the mixing zone and
the sea level / water table fluctuations.
4. Speleogenesis at hydrogeological interfaces in open settings
water table –
H2S oxidation
H2S
Galdensi, 2017 Mylroie and Carew, 1995
fresh water lens
saline water
mixing zone
Hypogene karst – Genetic types
Types according to hydrogeological environments - driving forces / conditions for ascending flow:

Groups of patterns Patterns (structures)
Dominantly stratiform (concordant)
Intrastratal, - along networks of strata-bound joints
or touching vugs
– single story (in a single mechanical unit)
– multi-story (in multiple mechanical units)
Isolated linear (rift-like) conduits
Isolated rising tubes (chimneys)
Network maze
Spongework maze
Rudimentary clusters of linear conduits
Clusters and patches of karst breccia
Basal-contact, - at and above the lower contact
of soluble beds or sequences
Isolated chambers
Anastomotic, spongework, and ramiform
Clusters and patches of karst breccia
Dominantly cross-formational (discordant)
Karstic, patchy-linear, - along faults and large
throughgoing fractures
Isolated linear rift conduits
Clusters of isolated or connected rift conduits
Isolated rising conduits (shafts)
Isolated chambers, cavernous fringe of fractures and rifts
Karstic-gravitational Collapse shafts and breccia pipes
Compound
Compound Stair-case
Complex 3D
Hypogene karst – Patterns
Klimchouk, 2013

-Stratiform structures
(conformable with the enclosing layered sequence)
Isolated linear conduits
and their clusters
Hypogene karst – Patterns
N
Klimchouk et al., 2010
Numerous isolated karst
conduits and conduit clusters
intercepted by historic mines
in Odessa, South Ukraine
(Pliocene limestones)
Enlarged are fractures connected to the lower
contact (i.e. receiving recharge from below),
especially those connected to both, the lower and
upper contacts (i.e. allow transverse through flow)

-Stratiform structures
(conformable with the enclosing layered sequence)
Isolated linear conduits
and their clusters
Hypogene karst – Patterns
Stochastic fracture models showing different sizes and
shapes of finite fracture networks - bundles of
interconnected fractures embedded in a sea of isolated
fractures (Ozkaya & Al-Fakmi, 2022)
N
Klimchouk et al., 2010
Numerous isolated karst
conduits and conduit bundles
intercepted by historic mines
in Odessa, South Ukraine
(Pliocene limestones)
Clusters of conduits form where bungles of laterally
interconnected fractures are available and at least
some fractures receive recharge at the lower contact
and have output points at the upper contact.
Ozkaya & Al-Fakmi, 2022

Network mazes, often multi-storey
Western
Ukraine
Budapest
Brazil
USA
East Siberia
Ozerna Cave, Western Ukraine
Hudgill Cave, United Kingdom
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns

Network mazes, often multi-storey
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns
Fracture connectivity –
Finite fracture networks
Klimchouk & Andreychouk, 2017
Ozkaya & Al-Fakmi, 2022
But… fracture stratigraphy also matters ↓
5х magnification

Mechanical Unit
Mechanical Interface
Mechanical Interface
Fracture stratigraphy
Network mazes, often multi-storey
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns
Klimchouk, 2003
Klimchouk & Andreychouk, 2017
5х magnification
Rising flow and speleogenesis in
superimposed networks of fractures
with limited vertical connectivity

Mechanical Unit
Mechanical Interface
Mechanical Interface
Fracture stratigraphy
Network mazes, often multi-storey
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns
Klimchouk, 2003
Klimchouk & Andreychouk, 2017
Gross & Eyal, 2007
Strata-bound (confined) fractures
Throughgoing fractures
5х magnification
Rising flow and speleogenesis in
superimposed networks of fractures
with limited vertical connectivity

Network mazes, often multi-storey
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns
Klimchouk & Andreychouk, 2017
5х magnification
Necessary conditions for extensive
multi-storey mazes to form:
•Confining unit (constrained discharge);
•Recharge from below in many points;
•Fracture stratigraphy;
•Lateral fracture connectivity in some units

Network mazes, often multi-storey
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns
Klimchouk & Andreychouk, 2017
5х magnification
The impression that such extensive mazes
supported lateral through-flow during
speleogenesis is a misconception.
Instead, largely independent flow
compartments operated, with limited
hydraulic interaction between them.

Mazes with combined, spongework/network pattern
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns
Combined, basal-contact and intrastratal patterns
•The lower level (black) is the master level –
spongework pattern of passages developed just above
the contact with the underlying aquifer;
•The passages at the upper level (yellow) form where
the growing master passage intercepts from below
a fracture in the upper unit.
•Fracture-controlled passages at the upper level are
commonly isolated laterally but may form the network
mazes (green outlines 1-3) where interconnected and
are fed from different master passages.
•There are only three documented outlets (discharge
points; red dots) in the mapped part of the system,
where passages reach the upper aquifer.
Klimchouk & Andreychouk, 2017
2
1
3

Plan
145 km
Network mazes, often multi-storey
-Stratiform structures
(conformable with the enclosing layered sequence)
Hypogene karst – Patterns
Rising flow through a fracture corridor
related to a deep fault
Profile
Toca da Boa Vista – Barriguda
Cave System in Neoproterozoic
limestones, the largest cave system
in the South America
Lower level
Master level
Upper level
(outlets)
Klimchouk et al., 2015
The master level is
defined by fracture
stratigraphy – the densely
fractured units (3-4)
below the “seal”, the
barely fractured unit 5

Karst rifts
-Cross-formational structures - karstic
Hypogene karst – Patterns
Texas, USATexas, USA BudapestBudapest
BudapestBudapest New Mexico, USANew Mexico, USA UKUK
Swabian Alb
Belgium
Rifts
in quarries
Saxony, Saxony,
GermanyGermany
Germany
N.CapeN.Cape,, S.AfricaS.Africa
AlgerieAlgerie
Audra, 2015 photo I. Urban
Homuth et al., 2011
photo A.Palmer

Karst rifts
-Cross-formational structures - karstic
Hypogene karst – Patterns
Underwater rifts -
maximum explored
depth - 282 m
SE AustraliaSE Australia
BahamasBahamas
Mallorca, Spain Mallorca, Spain
BudapestBudapest
Budapest, Hungary
BudapestBudapest
photo A.Kalinovic
photo: Internet
photo: Internet
photo A.Kalinovic
photo J.Gines

Karst rifts
-Cross-formational structures - karstic
Hypogene karst – Patterns
Armageddon Cave – a large karst rift,
260 m deep and over 2 km long
«Earth fissures» are common in geodynamically active regions
with thick carbonates and sandstones
- Beginning of exhumation of a rift-dominated
hypogene cave system
Northern Cape,
South Africa –
Karst rifts opened
up to the surface
on Jan 6th 2017
2 km
Interception of karst rifts by the denudational surface
N.CapeN.Cape,, S.AfricaS.Africa
Photo by André Doussy
Modified from Tucker, 2015
plan

Karst rifts
-Cross-formational structures - karstic
Hypogene karst – Patterns
Armageddon Cave – a large karst rift,
260 m deep and over 2 km long
«Earth fissures» are common in geodynamically active regions
with thick carbonates and sandstones
- Beginning of exhumation of a rift-dominated
hypogene cave system
Northern Cape,
South Africa –
Karst rifts opened
up to the surface
on Jan 6th 2017
2 km
Interception of karst rifts by the denudational surface
N.CapeN.Cape,, S.AfricaS.Africa
Photo by André Doussy
Modified from Tucker, 2015
plan

Rising shafts
-Cross-formational structures - karstic
Hypogene karst – Patterns
Relict shafts exposed in cliffs
SandstonesSandstones, ,
Campos Campos GeraisGerais, Brazil, Brazil
Limestones,
Crimean
Piedmont,
Ukraine
SandstonesSandstones, ,
Sydney Basin, AustraliaSydney Basin, Australia
Rising chimney
in the cave ceiling
3 м3 м
Active shafts with rising waters
Auler (2009) , Garamana (2002), Hranicka Propast
Group
Relict rising shaft
LimestonesLimestones, ,
MexicoMexico
Internet
Internet
Internet

Rising shafts
-Cross-formational structures - karstic
Hypogene karst – Patterns
Numerous relict rising shafts in the Cretaceous limestones,
in the vicinity of the Antamina porphyry intrusion
emplaced 9-10 Ma,
high Peruvian Andes
Klimchouk et al., 2022

Karstic-gravitational,
collapse shafts and breccia pipes
-Cross-formational structures
Hypogene karst – Patterns
Collapse shafts form over large
hypogene karst chambers
Typical of regions of young volcanism
and deep-seated evaporite karst:
– Konya Basin in Turkey,
– Zakaton area in Mexico,
– Gabrier Mnt. area in S. Australia,
– Kavminvod region, N.Caucasus, Russia,
– Western Canadian Basin
Zacaton System, Mexica
Gabrier Mt region, Australia
Cherik-Kel,
Russia
Kizoran,
Turkey

-Cross-formational structures
Hypogene karst – Patterns
700 m
Северный Китай
Arizona, USA
300300--900 900 mm
350 350 mm
Vertically exposed
breccia pipe in
the Grand Canyon
,
Arizona
North China
Huntoon, 1996
Xiang et al., 1993
limestone
limestone
Karstic-gravitational,
collapse shafts and breccia pipes
photo K.Wenrich

-Cross-formational structures
Hypogene karst – Patterns
Distribution of over 1000
breccia pipes mapped
in the Delaware Basin, USA
Distribution of over 2500 breccia pipes mapped in
the Northern Arizona (Grand Canyon area), USA
Spencer et al., 2015
Castil
pipes
Stafford et al., 2008
Karstic-gravitational,
collapse shafts and breccia pipes
photo K.Wenrich

Large isolated chambers
-Basal-contact
Hypogene karst – Patterns
Kempe, 1996
South Harz, Germany
Large chambers
at the base of
evaporite sequence
Large chambers form:
1) at the base of evaporite sequences
underlain by prolific aquifers
(dissolution by free convection);
2) where recharge and a source
of aggressive fluids (e.g. deep CO2)
are localized and intense.
Rodope Mnts, Bulgaria
Giant chamber in
Proterozoic marbles
Volume 237.6 mln m3
Sebev, 1970
1200 m

Complex 3-D structures
-Compound
Hypogene karst – Patterns
1200 m
490 m
National Park Service, USA
930 м
Monte Cucco System, Apennines, Italy
Lechuguilla Cave,
NM, USA
profile
plan
Combination of cross-formational
and stratiform components
and various patterns in a complex
3-d array of conduits and voids
www.360parks.com

Diagnostic morphological features of caves
Hypogene karst – Meso-morphology
Hypogene caves formed in different lithologies and by
different dissolution processes demonstrate remarkable
similarity in their patterns, morphologies, hydrostratigraphic
occurrence, and hydrogeologic functioning.
Specific meso-forms are indicative of hypogene speleogenesis
and are diagnostic if occur in spatially related assemblages
(“morphological suits of rising flow”)
Audra et al., 2009
Klimchouk, 2007
Klimchouk, 2013

Large sedimentary (artesian) basins
Hypogene karst – Settings
Stratiform (artesian)
Hydrodynamic zones
Gravitational
(topography-driven)
flow systems
transitional
Fluid-geodynamic
(endogenic)
influence
Cross-formational (endogenic
)
Distribution of hypogene karst
is governed by the regional
hydrodynamics in the upper
zone and by cross-formational
fluid-conducting structures in
the deep part of basins Types of hypogene karst:
Combined
1
22
3

Large sedimentary (artesian) basins
Hypogene karst – Settings
Audra, 2015
1
2
3

Regions of young volcanism
Hypogene karst – Settings
Kavminvody area, North Caucasus, Russia
– over 30 collapse shafts up to 368 m deep
Konya Basin, Turkey – over 140 collapse shafts up to 160 m deep
-anomalous geothermal regime;
- specific groundwater chemistry;
- intense CO2inflows;
- highly localized input from below.
Large chambers at the lower contact, which collapse
to form large breakdown shafts and breccia pipes
up to a few hundred meters in depth and diameter.
Kizoran – depth 160 m
Bayari et al., 2009
Modified from Vakhrushev, 2009, in Klimchouk, 2013

Regions of young volcanism
Hypogene karst – Settings
•Yellowstone – volcanic caldera with a mantle plum at the base;
•Numerous geysers fed by large rising conduits;
•Thermal alkaline waters (pH >8), aggressive with respect to
silicates – a mix of meteoric waters with brines rising from the
depth of about 5 km, where they have temperature of 340-370 oC.
Blackwood et al., 2018
Hypogene karst in rhyolites in the volcanic caldera – Yellowstone, Wyoming, USA
Hurwitz et al., 2014

Regions of young volcanism
Hypogene karst – Settings
Hypogene karst in rhyolites in the volcanic caldera – Yellowstone, Wyoming, USA
Old Faithful geyser and its
feeding void-conduit system
•Using download cameras and seismic tomography revealed
large cavities with characteristic hypogene morphology;
•A functional model is developed that accounts for the dynamic
of a gas-vapor fluid in the given configuration of the void-
conduit system.
Blackwood et al., 2018
Hurwitz et al., 2014

Hypogene karst – Settings Hypogene karst in the seafloor
Hypogene karst can develop beneath the seafloor
beyond the continental shelf.
Hypogene karst at the ocean bottom, Carnegie
Range, Pacific Ocean, at depth of 1500-2600 m
- Closed depressions 1-4 km in widths and 100-400 m
in depth.
- Carbonate rocks of the Upper Miocene-Pleistocene,
400-500 m thick, resting on a volcanogenic
basement.
- «Hot spot» near the Galapagos Rift.
- The area with closed depressions has never been
exposed to subaerial conditions.
Michaud et al., 2005

Hypogene karst – Settings Hypogene karst in the seafloor
Betzler et al., (2005)
The sea bottom at 400 м
Large depressions
up to 200 m deep.
Related to vertical
conduits penetrating
across a carbonate
platform. Sun et al., 2013
220 breccia pipes rooted
in a thick carbonate
sequence, formed by
collapses of large
hydrothermal cavities.
Heights – up to 1000 m,
diameters from 100 to
700 m.
South China Sea, Dongsha Massif
Maldives, Indian Ocean

Paradigm shift
Hypogene karst – Implications for karst science
•Hypogene karst studies have dramatically changed the paradigm of karst – the traditional,
essentially geomorphological paradigm evolves to the essentially geological one.
•Karst (karstification) is a geological process that encompasses the whole upper (brittle)
crust and strongly influences petrophysical rock properties and the functioning of fluid flow
systems.
•Karst occurs in both continental and oceanic crust. Hypogene karst can develop beneath
the seafloor beyond the continental shelf.
•The notion of “karstifiable”, or “soluble” rocks is blurred; the solubility is the function of
temperature and pressure that widely vary across the upper crust, so many types of rocks
may support karstification under certain conditions.
•Karst may develop without any surface expression. When exhumed, it may have
manifestation quite different from traditional karst geomorphology.
•Not all deep-seated karst features are paleokarst, i.e. buried and fossilized inactive epigene
karst. A big part of such features represents hypogene karst, either active or relict.

Hypogene karst – Implications for geosciences
•Sedimentology, lithology, economic geology – HK as an agency of diagenesis (e.g.
hydrothermal dolomitization) and the formation of ore deposits (e.g. MWT lead-zinc).
•Petrophysics, fluid geology – HK enhances porosity (reservoir capacity) and creates cross-
formational plumbing structures, including seal bypass systems. As such, it has important
implications for hydrogeology, petroleum geology, the use of geothermal resources, geological
sequestration of CO2and hazardous wastes etc.
•Petroleum geology, carbonate reservoirs - Over 60% of global reserves of oil and about 40%
of global reserves of gas are contained in carbonate reservoirs, many of which are
of hypogene karst origin, not paleo(epigenic) karst.
•Geomorphology – When exhumed, hypogene karst may have manifestation in the landscape
quite different from traditional karst geomorphology.
•Geological engineering, mining geology – hypogene karst may develop without any surface
expression, hence associated hazards may be unexpected as such areas are commonly not
mapped as karstic.

Hypogene karst – the take-home message
There are fundamental distinctions between hypogene and epigene karst,
particularly in:
- conditions of development,
- evolutionary trajectories,
- distribution,
- speleogenetic mechanisms,
- patterns and morphology of cave systems,
- hydrogeological functioning,
- and ecosystems
Hypogene karst is a fundamental category of karst, of at least equal importance
to more familiar epigene karst.
Consequently, the genetic (speleogenetic) and evolutionary approach in studying
karst is crucial for all practical geoscience applications including prospecting,
developing, and managing various resources and assessing karst-related hazards
and risks.

Thanks for your attention!