✦ LIBER ✦
Uranium-lead geochronology of the Archean Imataca Series, Venezuelan Guayana Shield
✍ Scribed by Carla W. Montgomery
- Publisher
- Springer
- Year
- 1979
- Tongue
- English
- Weight
- 910 KB
- Volume
- 69
- Category
- Article
- ISSN
- 0010-7999
No coin nor oath required. For personal study only.
✦ Synopsis
Uranium and lead isotopic analyses of totalrock and feldspar samples from the Imataca Series indicate an early Archean (3.5 + b,y.) age for the basement gneisses. Lead isotopic evolution in most gneiss samples may approximately be described by a three-stage model. The start of the third stage is marked by a pervasive metamorphic event, locally up to pyroxene-granulite grade, at 2 b.y. ago, which commonly resulted in extensive depletion of uranium relative to lead.