Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising...
-
Upload
easter-phebe-nicholson -
Category
Documents
-
view
227 -
download
4
Transcript of Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising...
![Page 1: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/1.jpg)
KarstDefinition by Jennings (1985)
“A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found elsewhere.”
![Page 2: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/2.jpg)
Important Components of Definition
• A distinctive landform developed on highly soluble rocks.
– Most often, limestone.• 60 % CaCO3 before karst will start to
form.
• 90 % CaCO3 before well developed karst will form
– Evaporites (gypsum/halite)
– Quartzite (humid, tropics)
![Page 3: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/3.jpg)
Important Components of Definition
• A unique drainage pattern resulting from the movement of most water into subsurface.
– Holokarst - Precipitation moves directly underground; little, if any, channelized flow.
– Fluviokarst - clear that karst landforms are superimposed on former fluvial landscape.
![Page 4: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/4.jpg)
Calcite Dissolution
From Ritter et al. (1995)
![Page 5: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/5.jpg)
Dissolution Reactionsfor Calcite
CO2 + H2O H2CO3
H2CO3 H+ + HCO3-
CaCO3 Ca2+ + CO3-2
CO3-2 + H+ HCO3
-
Equation 1
Equation 2
Equation 3
Equation 4
CaCO3 + H20 + CO2 Ca2+ + 2HCO3
-
Summary Equation
![Page 6: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/6.jpg)
Controls on Solution Rates
• Degree of saturation: slow rates close to saturation. Change is non-linear.
• Fracture width– 1 to .1 mm: flow is laminar; dissolution rate
based on discharge of water through fracture.
– >5 mm: flow may be turbulent; dissolution rate based on rate of chemical reactions at surface of mineral grain.
– 1-5mm: varies with site conditions; combination of two.
• Other Factors: Pco2; temperature of water
![Page 7: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/7.jpg)
Solution Rates
From Ritter et al. (1995)
![Page 8: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/8.jpg)
Karst LandformsHumid, Temperature Climates
• Dolines (sinkholes): small, shallow depression; commonly wider than they are deep.– Solution Sinkhole: related to subcutaneous
zone
– Collapse Sinkhole: material fails into subsurface cavity previously created by dissolution
• Uvala: large closed depression formed by coalescence of one or more dolines.
• Karst Plain: A plain composed of closed depressions and subterranean drainage in karst region.
• Swallet (swallow hole): A place where water disappears underground in karst region. Swallet commonly used to describe loss of water in stream bed.
![Page 9: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/9.jpg)
Solution Sinkhole Development
From Ritter et al. (1995)
![Page 10: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/10.jpg)
Collapse Sinkhole
From Ritter et al. (1995)
![Page 11: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/11.jpg)
Sinkhole Plain
From Ritter et al. (1995)
![Page 12: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/12.jpg)
Blind and Dry Valleys
From Ritter et al. (1995)
![Page 13: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/13.jpg)
Karst LandformsHumid, Temperature Climates
• Blind Valley: A valley that end abruptly where stream vanishes underground.
• Sinking Stream: stream that vanishes underground, usually at terminus of blind valley.
• Resurgence: point where waters from sinking stream reemerges from underground.
• Dry Valley: Valley that no longer exhibits channelized flow.
• Cave: A natural underground room or series of rooms large enough to be entered by a person.
![Page 14: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/14.jpg)
Karst LandformsHumid, Tropical Climates
• Cockpit Karst: a conglomeration of closed depressions surrounded by conical hills - similar to cone karst where depression are star-shaped.
• Tower karst: Type of karst characterized by isolated, steep-walled hills separated by flat lying plain of alluvium.
![Page 15: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/15.jpg)
Cave Shapes(Reach Scale)
From Ritter et al. (1995)
![Page 16: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/16.jpg)
Cave Patterns
From Ritter et al. (1995)
![Page 17: Karst Definition by Jennings (1985) “A terrain with distinctive landforms and drainage arising from greater rock solubility in natural water that is found.](https://reader036.fdocuments.net/reader036/viewer/2022062800/56649dff5503460f94ae82b0/html5/thumbnails/17.jpg)
Cave Characteristics
• Vadose Caves
– Flow always moves downward along easiest route
– Governed largely by rock structure
– Dominated by canyons and shafts
– Caves tend not to converge unless forced to by rock structure
• Phreatic Caves
– Caves may descend well below water table and then rise to level of water table
– Tend to cut across rock structure
– Dominated by elliptical tubes
– Caves tend to converge , developing along hydraulic efficient paths