Chemistry and petrography of calcite in the KTB pilot borehole, Bavarian Oberpfalz, Germany
Chemical Geology
By: S.C. Komor
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Abstract
The KTB pilot borehole in northeast Bavaria, Germany, penetrates 4000 m of gneiss, amphibolite, and subordinate calc-silicate, lamprophyre and metagabbro. There are three types of calcite in the drilled section: 1) metamorphic calcite in calc-silicate and marble; 2) crack-filling calcite in all lithologies; and 3) replacement calcite in altered minerals. Crack-filling and replacement calcite postdate metamorphic calcite. Multiple calcite generations in individual cracks suggest that different generations of water repeatedly flowed through the same cracks. Crack-filling mineral assemblages that include calcite originally formed at temperatures of 150-350??C. Presently, crack-filling calcite is in chemical and isotopic equilibrium with saline to brackish water in the borehole at temperatures of ???120??C. The saline to brackish water contains a significant proportion of meteoric water. Re-equilibration of crack-filling calcite to lower temperatures means that calcite chemistry tells us little about water-rock interactions in the crystal section of temperatures higher than ~120??C. -from Author
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Chemistry and petrography of calcite in the KTB pilot borehole, Bavarian Oberpfalz, Germany |
| Series title | Chemical Geology |
| DOI | 10.1016/0009-2541(95)00063-R |
| Volume | 124 |
| Issue | 3-4 |
| Year Published | 1995 |
| Language | English |
| Publisher | Elsevier |
| Contributing office(s) | Minnesota Water Science Center |
| Description | 17 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Chemical Geology |
| First page | 199 |
| Last page | 215 |
| Google Analytic Metrics | Metrics page |