I believe that the fractures play a major role in the initiation and enhancement of the karst features.
Article Fracture systems and dissolution cavities in Wadi As Sir For...
I believe that the fracture system is from the main factors that initiate the karstification
The non-uniformity and heterogeneity of the geological, geographical, and therefore hydrogeological settings account for the large diversity of karst types identified over the world. As we know, the rocks have different hydrogeological behaviors as a result of factors that controlling karstification in the extending area such as lithostratigraphy, energy gradient, tectonic activity, erosion base, and climate change, followed by a number of other factors. The tectonic activity is the one of the major factor in karstification. As you know, the primary porosity is very low in carbonate rocks. The discontinuities (fault plane, fracture system, etc.) comprise secondary porosity in these rocks. Thus, secondary porosity host presences of water and create suitable pathway for water circulation in carbonate rocks. I think that it is important to initiation of karstification. You should keep in mind other factors in evaluation of karst.
Horizontal Cave systems tend to form at the intersection of
vertical fractures and horizontal seams between depositional
layers. As rivers downcut, the caves, form sequentially in layers
from the top down. The abandoned conduits are higher in elevation,
and actively forming conduits are at or below the water table.
Mammoth Cave Kentucky, Jewel Cave South Dakota, and Wind
Cave South Dakota were, and, are being formed in this manner.
Other types of caves are more vertically oriented with a series of
vertical parallel fractures ( Tectonic cracks ). Caves that form in
reefs form with stagnant water and dilute Sulfuric acid. They form
a network similar to the interior of bones, followed by collapse
when the supporting water is removed.
in many ways Caves are natures storm sewers. They get rid of
excess water by moving it underground along the path of least
resistance, and in the process the conduits grow larger, and
can change course, and can change elevation.
in all of these, the formation of limestone at a prior geologic time period,
at an elevation that is now higher than the current global sea
level. After the oceans recede, Tectonics, water and acids work
on the limestone to remove some of it leaving caves, conduits,
cracks, and " bone Yards ".
It depends on what you mean by important.... As limestone is an impervious rock the possibility for water to circulate in a block depends on the presence of open cracks and joints. Meanwhile their orientation is not the main factor for karst developpment. For epigenic caves, the most important is the hydraulic gradient. (It is like electricity that uses the less resistive way). The water runs from a feeding part (unique or diffuse) to an outlet (spring) whose position is determined by the respective geometry of base level (river, lake, sea), limestone block and impervoius series. Fractures are just a possible way to reach the outlet. Water will preferentially use the fractures that are open and whose orientation is close to the flow direction. If a main fracture is perpendicular to the circulation it will be poorly enlarged.
As most systems are polyphase karst, the variations of base level position and tectonics strengths may change the water circulation.
See the numerous publication by Paul L. Broughton on the subject of underlying salt dissolution tectonics controlling the collapse of hypogene karst in western Canada
Yea, its correct. Fracture systems are very important in karstification but fractures must connected with together. fractures that are not connected to each other do not have great importance in karstification.
It depends on its density and occurrences in the area of interest.
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