The chemistry and mineralogy of a CO sub 2 -rich travertine depositing spring in the California Coast Range

Journal Article · Sun Nov 01 04:00:00 EST 1987 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(87)90364-4· OSTI ID:5180277

Amundson, R; Kelly, E ^[1]

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1. Univ. of California, Berkeley (USA)

A CO{sub 2}-rich (> 1 atm PCO{sub 2}) travertine-depositing spring was studied to determine how it equilibrated, both chemically and isotopically, with conditions at the earth's surface. The water degassed rapidly along a 47 m section of its channel. Small quantities of siderite- and aragonite-rich precipitates were present along the first few meters and larger quantities of aragonite-rich precipitates were present in the later sections of the channel. CO{sub 2} degassing increased the {delta}{sup 13}C of dissolved C from {minus}9.7 {per thousand} near the spring orifice to +0.7 {per thousand} 47 m downstream. Along the first portion of the stream, the isotopic effect of degassing could be explained by a Rayleigh distillation process. Along the latter portion of the stream, photosynthesis may have enriched the dissolved C in {sup 13}C. The carbonate minerals appear to have formed in approximate isotopic equilibrium with the dissolved C. Older travertine samples from the terrace differ chemically, mineralogically, and isotopically from the more recently deposited minerals suggesting a possible alteration of the originally deposited material.

• OSTI ID: 5180277
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 51:11; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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