Experimental Studies on K-Rich Rocks - Origin of Potassium-rich Silica-deficient Igneous Rocks - page 410

C

E K-Ti-SIL

+ CPX +
GNT + AMPH
+ MICA

7

K-Ti-SIL + COESITE
+ CPX + GNT + L

?

6

B

L

A

CPX + GNT + L

?

?

5

D

K-SPAR + CPX
AMPH + MICA + L

CPX + L

4

1000 1200 1400 1600

T o

Fig. 13.22 Experimentally determined phase relationships of the sanidine phlogopite lamproite
(after Mitchell 1995). Abbreviations Cpx: clinopyroxene, Gnt: garnet, K-spar: K-felspar,
K - Ti - SIL: potassium-titanium-silicate, AMPH: amphebol

Fig. 13.23 Experimentally
determined phase relationship
of the Oscar lamproite. L
liquid, OPX orthopyroxene.
PHL phlogopite, COES
coesite, GNT garnet, RU
rutile. (after Mitchell and
Edger 2002)

cant control on the nature of the
initial liquidus phases, with orthopyroxene occurring at low pressure (<4 GPa) in
the relatively calcium-poor Oscar and Cancarix lamproites. At higher pressure
(>6 GPa) orthopyroxene is replaced by garnet plus clinopyroxene as near-liquidus
phases in the Oscar lamproite and by orthopyroxene plus clinopyroxene in the

They showed that bulk composition has a signi