Democrat Creek

The complex at Democrat Creek covers 9 km2 and is composed predominantly of quartz syenites together with breccias and a mass of mafic and ultramafic rocks to the south. The largest area of breccia to the southeast of the syenite is approximately 800x450 m and is cut by the syenite, but of five smaller breccia pipes occurring nearby three are older than the syenite (Heinrich and Dahlem, 1966, p. 39). The mafic and ultramafic rocks include gabbros and pyroxenites that contain both ortho- and clinopyroxene, variable plagioclase, two interstitial amphiboles, and a little biotite and quartz; they are all hypersthene-normative rocks. The most abundant rocks are quartz syenites averaging 15% modal quartz, together with microperthite, microcline, albite, sodic amphibole, a little biotite, and accessory fluorite, zircon and magnetite. Dykes of syenite, melasyenite, lamprophyre, dolerite and carbonatite are found in the vicinity, and Th veins are numerous and widespread particularly to the south of the complex. REE and Sr isotope data are given by Armbrustmacher and Hedge (1982) and rock analyses by Armbrustmacher (1984a).