Ages and stable-isotope compositions of secondary calcite and opal in drill cores from Tertiary volcanic rocks of the Yucca Mountain area, Nevada
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Abstract
Stable-isotope compositions of fracture-and cavity-filling calcite from the unsaturated zone of three drill cores at Yucca Mountain Tertiary volcanic complex indicate that the water from which the minerals precipitated was probably meteoric in origin. A decrease in 18O in the calcite with depth is interpreted as being due to the increase in temperature in drill holes corresponding to an estimated average geothermal gradient of 34° per kilometer. A few of the calcite samples and all of the opal samples yielded uranium-series ages older than 400,000 yr, although most of the calcite samples yielded ages between 26,000 and 310,000 yr. The stable-isotope and uranium- series dates from precipitated calcite and opal of this reconnaissance study suggest a complex history of fluid movement through the volcanic pile, and episodes of fracture filling predominantly from meteoric water during at least the past 400,000 yr.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Ages and stable-isotope compositions of secondary calcite and opal in drill cores from Tertiary volcanic rocks of the Yucca Mountain area, Nevada |
| Series title | Geological Society of America Bulletin |
| DOI | 10.1130/0016-7606(1990)102<1714:AASICO>2.3.CO;2 |
| Volume | 102 |
| Issue | 12 |
| Year Published | 1990 |
| Language | English |
| Publisher | Geological Society of America |
| Description | 6 p. |
| First page | 1714 |
| Last page | 1719 |
| Country | United States |
| State | Nevada |
| Other Geospatial | Yucca Mountain area |