Home – Home – Jornals – Russian Geology and Geophysics 2003 number 12

The paper considers magma-forming fluid systems of continental lithosphere in which T is equal or slightly above the solidus of the newly forming melt. The fluids should have an enthalpy (H, kcal/mole) high enough to maintain melting, and the magma systems should be open to ensure supply of heat carriers. The origin depth and enthalpy of the latter are key elements in the energy balance of the magma source. The most voluminous magma-forming fluids which induce melting in crust and mantle originate in the asthenosphere and in the outer core, two Earth's major fluid-bearing systems. T, P, and H of fluids separated from the outer core and asthenosphere in the period from Archean through Cenozoic were estimated by thermodynamic modeling. The major- and trace-element compositions of fluids were investigated for three stages of plutonism (443 11, 412 6, and 360 20 Ma) that produced the Zerenda complex. Two first stages result from upper mantle depletion, and the latest granites, with prominent rare-metal enrichment, record effects of high-F asthenospheric fluid systems on the preexisting granites.