Upper-crust magma tracers

+ See all authors and affiliations

Science  28 Nov 1997:
Vol. 278, Issue 5343, pp. 1541k
DOI: 10.1126/science.278.5343.1541k

The platinum-group elements (PGEs) have been used as tracers of magma dynamics and mantle differentiation in Earth's interior because their depletions and enrichments relative to each other indicate how much melting, mixing, and water-rock interaction a magma may have experienced during its solidification. However, because the PGEs represent parts-per-billion concentrations in most rocks, an accurate determination of their abundance has been difficult. Rehkämper et al. measured the abundances of platinum, palladium, iridium, and ruthenium in a set of Cameroon and northern Tanzania xenoliths. From this limited but precise data, they infer that the magmas that formed the northern Tanzanian crust were extracted from a fluid-rich, deep subduction zone, whereas those magmas that produced the Cameroon crust melted and were extracted under anhydrous conditions; these results imply different mantle environments rather than varying degrees of partial melting to produce these different rock suites.

Related Content

Navigate This Article