Travertines spring-deposited

Carbonates CaC03 Stalactite, travertine, spring deposit. K-T boundary, Antarctic and fault carbonates ... 

Fouke, B. W., G. T. Bonheyo, E. Sanzenbacher and J. Frias-Lopez, 2003, Partitioning of bacterial communities between travertine depositional facies at Mammoth Hot Springs, Yellowstone National Park, USA. Canadian Journal Earth Sciences 40,1531-1548. 

Travertine is layered calcite that forms around hot springs. These deposits are sometimes hundreds of feet deep, and may be used as decorative or building stone. Mexican onyx is one of the many common names used for this material. 

Travertine is composed of calcite deposited by chemical precipitation from natural hot-water springs. It has a characteristic banded appearance and is used as a decorative building stone. 

Tufa is also produced by chemical precipitation from natural springs. It is typically deposited over rocks and is softer and more porous than travertine. 

Travertine 1) Any finely crystalline massive concretionary limestone formed by surface or groundwater evaporation. 2) Any flowstone deposit, hence the usage travertine implying stalagmitic flowstone. 3) Any carbonate deposit formed within a cave or karst system by secondary precipitation. 4) Massive, hard, dense carbonate deposits formed in association with open-air springs, streams, lakes, or marshes that precipitate carbonate. 

Tufa 1) A chemical sedimentary rock composed of calcium carbonate, which form in nonmarine settings. 2) Any snbaerial travertine deposit formed near a spring mouth, along a stream, in a marsh or lake. The term often refers to thin, porous, or soft deposits, as opposed to travertine used for massive, hard, dense deposits. 

Travertine stone is a natural chemical precipitate of carbonate minerals deposited from the water of mineral springs saturated with dissolved calcium bicarbonate (Gauri Bandyopadhyay, 1999). It consists of calcite or aragonite, of low to moderate intercrystalline porosity and often high mouldic porosity (Pentecost, 2005). Precipitation results primarily through the transfer of carbon dioxide from or to a groundwater source leading to calcium carbonate (CaCOj) supersaturation. 

Geologists have discovered that water in a spring near the ancient site of the oracle contains the hydrocarbons methane, ethane, and ethylene (ethene). Ethane and methane were found in pieces of travertine, a limestone stalactite deposited by an ancient spring. In the days of the Pythia, colliding tectonic plates near the Temple of Apollo are believed to have generated sufficient heat to vaporize the hydrocarbons, which were extruded as vapors in the chamber of the oracle. If those vapors included ethylene, the Pythia may have been in a state of ethylene narcosis. Ethylene may produce states of euphoria and memory disturbances. Overexposure can lead to loss of consciousness and even death due to hypoxia. ... 

Elemental sulftn- may occur in a number of crystalline and non-crystalline forms, both natural and synthetic in origin. Of these the most important are the amorphous and orthorhombic (Sg) forms. Sulftn is commonly associated with volcanic deposits, particularly during the late stages of vulcanicity around hot springs and pools where it is associated with travertine (. v. a form of limestone), siliceous sinter and borates. It is also found in association with gypsum in sedimentary rocks and particularly with black shales where it is a product of an anaerobic environment and found associated with pyrite (qq.v.). It is also found associated with aerially weathered pyrite (and other similar sulfides) where the rate of oxidation is increased due to the presence of thiobacteria. In these cases it is associated with a range of iron sulfate compounds as well as sulfuric acid. 

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