Genesis of Ultrapotassic Rocks - Origin of Potassium-rich Silica-deficient Igneous Rocks - page 450

Table 15.1 Subsolidus assemblages as obtained by different petrologists in their experiments on
various K-rich rock types
Sr
No.

Rock type investigated Subsolidus assemblage (phases shown in

brackets are accessory minerals)

References

1. Alban hills leucite

basanite
(synthetic)

Garnet - phlogopite pyroxenite Gupta et al.

(1976)

2. Melilite nepheline leu-

citite (synthetic)

K-richterite phlogopite pyroxenite Gupta et al.

(1976)

- -

3. Katungite Phlogopite pyroxenite (perovskite, Ti-

magnetite)

Arima and
Edgar (1983)

4. Madupite Garnet apatite phlogopite pyroxenite as Barton and

Hamilton
(1979)

- -

a source rock

5. Leucite lamproite Phlogopite lherzolite Foley (1989)

6. Jarangdih lamproite Phlogopite harzburgite

(apatite + ilmanite + carbonate)

Gupta et al.
(2002)

7. Raniganj lamproite Phlogopite harzburgite

(apatite + chromite + carbonate)

Gupta et al.
(2002)

8. Mohanpur lamproite Phlogopite - harzburgite

(apatite + chromite + rutile + carbonate)

Gupta et al.
(2002)

9. Wolgidite Phlogopite websterite (rutile) Arima and

Edgar (1983)

10. Biotite mafurite Phlogopite wehrlite (ilmanite) Ryabchikov

and Green
(1978)

11. Olivine ugandite Phlogopite wehrlite Edgar et al.

(1980)

Phlogopite wehrlite ( ± orthopyroxene) 12. Phlogoite minette Edgar et al.

(1980)

13. Armalcolite - phlogopite

lamproite

Phlogopite websterite ( ± richterite,
armalcolite)

Edgar et al.
(1992)

14. Olivine lamproite Phlogopite harzburgite Foley (1993)

15. Sanidite phlogopite

lamproite.

Phlogopite richterite pyroxenite Mitchell

(1995)

- -

4 fluid is considered to have been formed

by less than 0.5 % melt of the MORB source rock.
Arima and Edgar (1980) and Dubeau and Edgar (1985) showed that wadeite and
priderite are stable at pressures up to at least 2.5 GPa in the mantle. Whereas
wadeite can be a source of Zr, and K, priderite may supply K, Ba, and Ti in the
mantle in an alumina-de

- 10 % metsomatic fluid. This metasomatic

cient environment. They are therefore, not expected in the
mantle source rock for tephritic and basanitic liquid. Experimental study of ar-
malcolite-bearing K-rich rock shows that it may be stable under mantle pressure up
to 2.0 GPa, and at still higher P-T

T condition, it breaks down to rutile and other

-

phases.