Karst Processes, Landforms, and Landscapes

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Transcript Karst Processes, Landforms, and Landscapes

Karst Processes, Landforms, and Landscapes

Karst Flow

 Diffuse vs. conduit flow  Primary vs. secondary porosity

Karst Materials

   Carbonate Rocks  Limestone  Dolomite Other materials     Salt Gypsum Ice Permafrost?

GEOMORPHLIST  Sandstone?

Porosity and Permeability

 Recrystallization of carbonate  Calcite/ aragonite  Faulting, jointing  Bedding

Carbonate Geochemistry

 Low-temperature geochemistry  Calcite and water; pH ~ 10, 12-15 ppm  Effectively insoluble!

 Calcite, water, and air CO 2 ; pH ~ 8.4, 50 ppm  Very slow – like soil formation  Calcite, water, and soil CO 2 ; pH ~ 4-7, <700 ppm  H 2 O + CO 2  H 2 CO 3 [carbonic acid]     H 2 CO 3  CaCO 3  H + + HCO 3 Ca ++ + CO 3 - CO 3 - + H + Now

that

 HCO 3 will eat rock!

Variables Affecting Karst Formation

    Precipitation Temperature Organic matter Turbulence

Effects of mixing

 “Two waters meetin’, limestone is eaten.”  Water sources  Water table  Lakes, etc.

 Acid sources  Cave types   Meteoric (CO 2 ) Hydrothermal (H 2 S)

  Where max. solution?

 Surface   Water table Confluence Effects of lithology/ structure

Cavern Formation

Cave Networks – Wind Cave Note structural control!

Lechuguilla Cave (Carlsbad, NM)

http://www.esri.com/industries/cavekarst/graphics/lech_3d_bg.jpg

Geochemical transitions Degassing Precipitation of CaCO 3 Charging w/ soil CO 2

Speleothems

 Stalactites  Stalagmites  Columns  Flowstone  Cave bacon  Cave popcorn  Helictites  Shields…

http://www.cumberlandadventures.com/cave/form.html

Distribution of Karst

 Typical of cratons  Carbonate + evaporite deposition at high sea-stands

Distribution of Karst

 Typical of cratons  Carbonate + evaporite deposition at high sea-stands  Horizontal (diapirs?)  Floridan, Interior plateaus, Edwards; Madison

    

Cvijic (1893) - “krs [karst]” – bleak, waterless Davis, Penck, Bretz Karren, lapies, grike and clint “Sinkholes”    Dolines, cenotes, cockpits… Polje, Uvalas Kegelkarst, tower karst Drainage   Sinks/springs Valleys – dry, pocket, blind, through

Karst landscapes

Inputs and outputs

Fundamental Karst Landforms

 Doline (sinkhole, cenote)  Origins  Solution  Subsidence  Collapse

Winter Park sinkhole (1981)

 100 m across  One day  During drought (water table lowering?)  On city Web page; now an urban lake.

Winter Park sinkhole.kmz

Cenotes

 Yucatan, Florida…  Developed during glaciations  Flooded during interglaciations  Explored by diving

Complex Forms

 Polje (oval); uvala (complex)

Karst Landscapes

 Cockpit karst  Tower karst

What types of karst depression does each of the following lakes occupy?

Lake Altamaha Lake Serena Twin Lakes Crystal Lake

solution or subsidence uvala Crystal Lake Lake Serena Lake Belle solution doline subsidence doline solution or subsidence uvala

Karst Hydrology

  Sinks, Swallets, Swallow holes… EX: Popo Agie Sinks.kmz

 Map view

Karst Hydrology

  Sinks, Swallets, Swallow holes, Ponors… EX: Popo Agie Sinks.kmz

  Map view Sink  Resurgence/spring

Case Study: Mammoth Cave

 Interior low plateaus  Sinkholes and uvala  Sinks and springs

Case Study: Mammoth Cave

 Interior low plateaus  Sinkholes and uvala  Sinks and springs Mammoth Cave, Kentucky.kmz

Sinkholes, Uvalas, and Caves

http://www.esri.com/industries/cavekarst/

Geology

 Stratigraphy  Structure

Block Diagram

Cave Exploration

 “The Longest Cave”  Now over 300 miles of interconnected passages  Best explored in drought!

Cave Exploration

 “The Longest Cave”  Now over 300 miles of interconnected passages  Best explored in drought!

Mammoth Cave Evolution

 Theoretical evolution (undated)  Upper = older, lower = younger  Incision = interglacial, stability/infilling = glacial

TIME