Solution caves

Ford, D C., 1976, Development of the principal types of solution caves in limestone, in Proceedings, 6 International Congress of Speleology, pp. 83-84. 

How caves are formed Caves form in limestone regions throughout the world. Limestone is calcium carbonate, which is only slightly soluble in water. The caves that form within these rocks are called solution caves. 

The water phase of oil-base mud can be freshwater, or various solutions of calcium chloride (CaCl ) or sodium chloride (NaCl). The concentration and composition of the water phase in oil-base mud determines its ability to solve the hydratable shale problem. Oil-base muds containing freshwater are very effective in most water-sensitive shales. The external phase of oil-base mud is oil and does not allow the water to contact the formation the shales are thereby prevented from becoming water wet and dispersing into the mud or caving into the hole. 

Gypsum is a relatively soft rock made of calcium sulfate. Rainwater percolates through g q)sum, dissolves some of the rock, and eventually becomes saturated with Ca ions and SOq ions. A geochemist takes a sample of groundwater from a cave and finds that it contains 8.4 X 10 M SO4 and 5.8 X 10 M Ca. (The ratio is not 1 1 because other sulfate rock contributes some of the SOq ions to the solution.) Use these data to determine the solubility product of calcium sulfate. 

Cave, Krotinger and McCaleb [60] worked out a general method for preparing explosives in the form of fine crystals. It consists of introducing a hot solution into a cold diluting liquid. 

Crack through which a mineralized solution of calcium carbonate seeps into roof of cave. 

Limestone is mostly made up of the mineral calcite, or calcium carbonate (CaC03). As the calcium carbonate rock dissolves in the slightly acidic water, spaces and even caves develop underground. If carbonic acid dissolves all the way through the rock and into a cave below the Earth s surface, the resulting solution contains calcium hydrogen carbonate (calcium bicarbonate). 

More recently, Caves and Karplus71 have used diagrammatic techniques to investigate Hartree-Fock perturbation theory. They developed a double perturbation expansion in the perturbing field and the difference between the true electron repulsion potential and the Hartree-Fock potential, V. This is compared with a solution of the coupled Hartree-Fock equations. In their interesting analysis they show that the CPHF equations include all terms first order in V and some types of terms up to infinite order. They propose an alternative iteration procedure which sums an additional set of diagrams and thus should give results more accurate than the CPHF scheme. Calculations on Ha and Be confirmed these conclusions. 

In a warm and semi-arid climate thick calcretes can develop. Alteration in the vadose zone is relatively rapid but not as rapid as in the phreatic zone. Surface karst is present locally, and caves are small and rare. The mineralogical changes follow the pattern of Figure 7.25, but at a rate slower than that for a warm, subtropical climate like Bermuda. Under the extreme of a warm, wet tropical climate, extensive terra-rossa soils can develop, and dissolution features, such as caves, solution pipes and fractures, should be prevalent. Mineralogical stabilization should occur rapidly. 

Reeder, S., Cave, M. R., Entwisle, D. C., and Trick, J. K. (1998). Extraction ofWater and Solutes from Clayey Material A Review and Critical Discussion of Available Techniques. WI/98/4C, British Geological Survey. Keyworth, Nottingham. 

Crystallization. Very often it is necessary to obtain explosives (TNT among them) in readily precipitated form. Cave, Krotinger and McCaleb [61] developed a general method of crystallization which consists essentially in introducing the hot solution of a substance into cold diluting liquid or solid carbon dioxide. 

Solution caverns or caves often contain deposits of recrystallized calcium carbonate, usually in the form of the mineral aragonite. Stalactites, stalagmites, and other cave formations are called speleothems. Created gradually by the precipitation of aragonite from groundwater, many speleothems display a layered structure. Recent study shows that bacteria and other simple life forms may contribute to the formation of cave deposits. 

Deprotonation of 8 is readily achieved by treatment of 8 with Na[Et3BH] in hexane. The sodium 2,4-dicarba-n/db-hexaborate(r) 9 has been characterised in solution by H, nB and 13C NMR, including various 1H 1 B double and 13C H,llB] triple resonance experiments and also in the solid state by X-ray structural analysis.13 In the solid state, 9 crystallises from toluene without solvent as a dimer in which the two sodium cations are imbedded into a cave formed by the ten basal ethyl groups of the two anions. There are numerous close contacts between the sodium cations and the ethyl groups the B-H-B hydrogen atoms are not involved in those contacts. The electron balance of the anion 9 is comparable to that of cyclopentadienyl anions. 

Calcite speleothems are deposited in a cave when downward-percolating, carbonate-saturated grormdwaters, with a partial pressure of CO2 exceeding that of the cave atmosphere, enter a cave and become supersaturated with respect to calcium carbonate. If the degassing of CO2 from solution is slow and isotopic equilibrium is maintained between aqueous carbon phases and deposited carbonate, then two climatically-dependent variables (a fractionation effect and a water effect) will determine the O-isotopic composition of the speleothem calcite deposited in a cave. 

Three common mechanisms for the precipitation of calcite speleothems in caves have been recognized (i) precipitation due to the slow loss of CO2 from solution, (ii) precipitation due to the rapid outgassing of CO2 from solution, and (iii) evaporation. Only the first of these processes results in the deposition of speleothem of calcite that is in... 

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