Volcanism in the Vitim Volcanic Field, Siberia: geochemical evidence for a mantle plume beneath the Baikal rift
The Baikal Rift is a zone of active lithospheric extension adjacent to the Siberian Craton. The 6–16 Myr old Vitim Volcanic Field (VVF) lies approximately 200 km east of the rift axis and consists of 5000 km3 of melanephelinites, basanites, alkali and tholeiitic basalts, and minor nephelinites. In t...
| Main Authors: | , , , |
|---|---|
| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.559.8823 http://petrology.oxfordjournals.org/content/early/2005/03/04/petrology.egi016.full.pdf |
| Summary: | The Baikal Rift is a zone of active lithospheric extension adjacent to the Siberian Craton. The 6–16 Myr old Vitim Volcanic Field (VVF) lies approximately 200 km east of the rift axis and consists of 5000 km3 of melanephelinites, basanites, alkali and tholeiitic basalts, and minor nephelinites. In the volcanic pile, 142 drill core samples were used to study temporal and spatial variations. Vari-ations in major element abundances (e.g. MgO 33–146 wt %) reflect polybaric fractional crystallization of olivine, clinopyroxene and plagioclase. 87Sr/86Sri (07039–07049), 143Nd/144Ndi (05127–05129) and 176Hf/177Hfi (02829–02830) ratios are similar to those for ocean island basalts and suggest that the magmas have not assimilated significant amounts of continental crust. Variable degrees of partial melting appear to be responsible for differences in Na2O, P2O5, K2O and incompatible trace element abundances in the most primitive (high-MgO) magmas. Fraction- |
|---|