Experimental Studies on K-Rich Rocks - Origin of Potassium-rich Silica-deficient Igneous Rocks - page 412

Cancrix sample. Clinopyroxene is a near-liquidus phase at all pressures in the
Middle Table Mountain lamproite. Near solidus phase assemblages at high pres-

sure (>5 GPa) are: clinopyroxene + phlogopite + coesite + rutile + garnet (Oscar);
clinopyroxene + garnet + coesite + K

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Ti-silicate (Canccarix); clinopyrox-

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ene + phlogopite + apatite + K Ti-silicate (Middle Table Mountain). In all com-

positions olivine is never found as a liquidus phase at any of the temperatures or
pressures studied here. The phase relationships are interpreted to suggest that silica-
rich lampriotes cannot be derived by the partial melting of lherzolitic sources.
According to them their genesis was involved with high degree of partial melting of
ancient metasomatic veins within a harzburgitic-lherzolitic lithospheric substrate
mantle. They considered the veins to haver mineralogy similar to that of an
experimentally-observed, high pressure, near-solidus phase assemblages.

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13.2.14 Experimental Study on an Olivine Leucitite
up to 3.5 GPa at Variable Temperatures

Elkines-Tanton and Grove (2003) made experimental investigation on a Pliocene
olivine leucitite (WC-1) from the central Sierra-Navada, California. The chemical
composition of the rock has been given in Table 13.2 :
Phase relation on this composition (Wc-1) is shown in Fig. 13.26 .

Fig. 13.26 Phase equilibrium
experiments on synthetic
analogue of Sierra Navada
olivine leucitite WC-1.
Experiments numbers are
marked. The solid oval marks
the multiple saturation point
(after Elkines-Tanton and
Grove 2003)