Étude expérimentale du fractionnement des éléments Rb, Cs, Sr et Ba entre feldspaths alcalins, solutions hydrothermales et liquides silicatés dans le système Q.Ab.Or.H2O à 2 kbar entre 700 et 800 °C
Abstrak
The fractionation of the trace elements Rb, Cs, Sr, Ba was measured by the radiotracers technique, between hydrothermal solution, Ab . Or feldspars and silicate melts ranging from Q₄₀Ab₆₀ to Q₄₀Or₆₀. The partition coefficient D between melts and solutions are close to the unit, and they are nearly independent from the composition. The values of D between crystals and solution are quite different from the unit, and are strongly dependent on the feldspar composition : alkali earth elements enter preferably the minerals, while alkali elements remain in the solutions. Some simplifications make it possible to calculate the fractionation coefficient between solids and melt, in the range of temperatures 700-800 °C, and for normative quartz values between 30 % and 40 %. The extreme values of D may reach 250 (D[Cs]melt/Ab) and 0.01 (D[Sr]melt/Or). For two liquids close to the Q.Ab and Q.Or sides of the Q.Ab.Or triangle, we discuss the variation of the bulk partition coefficient during a fractional crystallisation process, and the evolution of the trace elements contents in the residual melts.
Penulis (2)
Jean-Paul Carron
Martine Lagache
Format Sitasi
Akses Cepat
- Tahun Terbit
- 1980
- Bahasa
- fr
- Total Sitasi
- 29×
- Sumber Database
- CrossRef
- DOI
- 10.3406/bulmi.1980.7422
- Akses
- Terbatas