| Abstract: | Two calcium-magnesium carbonate solid solutions form Holocene travertines and conglomerate cements in fresh water stream channels of the Coast Range of California. Calcite does not yield the {015} diffraction maximum. The {006} diffraction maximum is lacking over most of the range of composition of calcite. Calcite has compositions from CaCO3 to Ca0.5Mg0.5CO3. Dolomite yields both the {006} and {015} diffraction maxima over its entire composition range, Ca0.6Mg0.4CO3 to Ca0.5Mg0.5CO3. The Ca-Mg carbonates form in isotopic equilibrium and thermodynamic disequilibrium from dispersion of Ca2+-rich water into CO32--rich water within the alluvium. The stable isotope data suggest that all the Mg-rich carbonates are primary precipitates and not a result of Mg-substitution in precursor CaCO3. There is a correlation between ??C13 and Mg content of the carbonates which predicts a 5%. fractionation of C13 between dolomite and calcite at sedimentary temperatures. C14 is incorporated in Ca-Mg carbonates forming from C13-poor meteoric waters and C13-rich waters from Cretaceous sediments. C14 ages of the Ca-Mg carbonates are apparent, and cannot be corrected to absolute values. Solution rates of calcite decrease with increasing MgCO3 content; dolomite dissolves slower than any calcite. ?? 1971. |
| Genre: | Article |
| ProdID: | 70010380 |
| Citation Author: | Barnes, I.; O'Neil, J. R. |
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| Citation End Page: | 718 |
| Citation Issue: | 7 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geochimica et Cosmochimica Acta |
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| Citation Number Of Pages: | 20 |
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| Citation Search Results Text: | Calcium-magnesium carbonate solid solutions from Holocene conglomerate cements and travertines in the Coast Range of California; 1971; Article; Journal; Geochimica et Cosmochimica Acta; Barnes, I.; O‘Neil, J. R. |
| Citation Start Page: | 699 |
| Citation Volume: | 35 |
| Citation Year: | 1971 |
| Type: | citation/reference |
| Text: | Calcium-magnesium carbonate solid solutions from Holocene conglomerate cements and travertines in the Coast Range of California; 1971; Article; Journal; Geochimica et Cosmochimica Acta; Barnes, I.; O‘Neil, J. R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Fri, 1 Jan 1971 00:00 -0600 |
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