Chapter 5 Soluble rocks

1. Chapter 5 Soluble rocks Solubility – threatens water storage and water conveyance projects with sever problems involving potential leakage and ground collapse

2. Question: What is the most common soluble rock type?

3. Question: What are the 3 groups or classes of limestone? The divisions are based on their mode of formation? • Biochemical • Chemical • Detrital

4. Calcareous algae Upper Tertiary Dhofar, Southern Oman Biochemical limestone Rocks formed from living organisms – shells of microscopic planktonic foraminifera and plates of calcareous algae

6. Ammonite and tubiphythes in "Treuchtlingen Marble"; trade name: Jura Gelb Upper Jurassic (Malm Delta) Treuchtlingen, Germany

7. Oolith Lower Aptian Near Doman, Recita Zone, Southern Carpaten, Rumania

8. Belemnite and tubiphythes "Treuchtlingen Marble" Upper Jurassic (Malm Delta) Treuchtlingen, Germany

9. Sponge Devonian ? Bucchan Caves?, Australia

10. Belemnite battlefield Lower? Jurassic Mistelgau, Northern Bavaria, Germany

11. fossiliferous limestone, very rich in crinoids; trade name: Derbyshire Fossil Carboniferous Coahill, Derbyshire, England, Great Britain

12. Beige limestone with rounded intraclasts and fossils (gastropods, corals)

13. Red limestone with bivalve shells and other molluscs, brachiopods? Helvetikum Grünten, Allgäu, Germany

14. Recrystallized stromatopore-reef limestone (Lahn-Marble) with stromatopores, crinoids und tabulate corals (Thamnopora or Heliolites); grey ruditic lime is normal background sedimentation; red is storm sediment Middle Devonian Bongard-Quarry (?), Villmar, Kreis Limburg-Weilburg, Germany

15. Reddish coral limestone Carboniferous Avon Gorge, Bristol, UK

16. Brown-reddish coral limestone ?, probably Carboniferous or Devonian Beach fortification near the bunkers from WWII, Dunkerque, France

17. Biochemical limestone • Bedded and jointed • Hardness 3 to 4, mineral calcite and dolomite Chert horizons • hardness 6 - silica

18. Chert concretion from Boom Clay Belgium

19. cherts are formed from the tiny (0.5 to 1.5 mm) silica shells of radiolaria. Chert

20. Chalk • one unusual example of biochemical limestone is chalk – compacted but not lithified

21. Chalk • white friable and very porous • shells of microscopic planktonic foraminifera and calcareous algae

22. Chalk • massive uniform layers or • very thick beds separated by shale partings • not typical to be jointed as is most limestone Horizons of chert concretions common

23. Chalk

24. Chalk Other names dependent upon content of clay and chalk Chalk > 95% CaCO3 Clay Chalk >5%<13% clay Clay Marl >13%<25% clay Calcareous mudstone >25%clay

25. Chemical limestone Precipitate of calcite CaCO3 (uncommon), occurs in warm CaCO3 rich seas oolites.

26. Oolites • Concentric radial structure

27. 1. Precipitation of CaCo3 sea water is almost saturated in CaCO2 – decrease in the content of CO2 by warming or by the action of plants in shallow water can cause calcium carbonate to precipitate

28. 2. Precipitation of CaCo3 rivers saturated in CaCO2 precipitate it when they enter saline environments, called travertine

29. 3. Precipitation of CaCo3 groundwater saturated in CaCO3 precipitates it when the groundwater emerges into the atmosphere, springs called tufa brick in a church

30. 4. Precipitation of CaCo3 evaporation in arid and semiarid regions leads to the precipitation of CaCO3 called caliche

31. Detrital limestone • particles of CaCO3 cemented together, very porous • Names are dependent upon the size and nature of the particles • clay – calcilutite • sand – calcarenite • gravel – calcirudite • shell fragments – coquina or shell-hash limestone

32. calclutite

33. calcarenite • sand size grains of CaCO3

34. calcirudite

35. Question: • Compare the strength of calcarenite with orthoquartzite with respect to their particles, and cement. • What is the expected difference in porosity?

36. Dolostone or Dolomite recrystallized limestone which contains Mg • composed 90%of the mineral dolomite, • less soluble than calcite • composition changes after deposition – type of chemical re crystallization

37. Dolostone or Dolomite dolomitization is not always uniform

38. Dolostone or Dolomite Fractures in the dolostone bedrock  conduct groundwater

39. Dolostone or Dolomite Mountain range called dolomites

40. Marble What type of rock is it? Marble – metamorphic rock formed from limestone – complete recrystallization

41. Evaporate rocks • Gypsum CaSO4 2H2O • Anhydrite CaSO4 • Halite NaCl

42. Evaporate rocks • Gypsum CaSO4 2H2O • Anhydrite CaSO4 • Halite NaCl

43. Evaporate rocks • Gypsum CaSO4 2H2O • Anhydrite CaSO4 • Halite NaCl

44. Gypsum • massive or bedded • associated with rock salt, shale, dolomite and limestone • bituminous material common • often intensely folded and brecciated – due to its formation: Anhydrite + hydration results in Gypsum and EXPANSION and deformation • highly soluble – 170 times more soluble than calcite but only 1% that of NaCl • lacks strength for caverns to form

45. Anhydrite • stable form of CaSO4 above 43 degrees • stable at any temperature when there is no H2O present • Hydration – volume expansion of 35% • Hydration depth is less than 150 m (fig 5.9) • Hydration changes the anhydrite to Gypsum • 3.5 Mpa pressure due to hydration

46. Halite or Rock Salt • massive beds with inclusions of brine • salt dome formation – diapirs Fig. 5.8 – intrusions of salt into overlying rocks • salt domes – up to 3 km diameter • steep and vertical joints • impermeable – trap for oil • cap rock deformed • source as much as 5 km deep • salt diapirs that pierce the ground become salt glaciers

47. salt dome

48. Salt glacier

49. Solution processes and effects Common in limestone, dolostone and marble

50. Stages of Karstification Youth Maturity Old age