ISSN:
1432-0967
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract Peridotite xenoliths from the Pello tuff cone in the Rift Valley of northern Tanzania, bear witness to upper mantle veining and metasomatism. Veins of katungite composition, with an asthenospheric signature, have imposed K, Fe, Ti, OH and REE metasomatism upon previously depleted peridotite. Chemical and mineralogical gradients are present in the peridotite wall rocks, and hydrous phases developed in the peridotite are generally lower in Ti and Fe, but higher in Mg and Cr, than those in the veins. The metasomatism has reduced the density of affected peridotite by up to 4.5%, supporting earlier geophysical models for low-density mantle beneath the Rift Valley. Age constraints for the metasomatically-induced density decrease permit correlation with Recent faulting in the Rift Valley, but not with the major upwarp of the Kenya Dome in the late Tertiary.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00371380
