Mount Prindle
Located 34 km west of Mount Prindle and southeast of the White Mountains is a small badly exposed complex of syenites and nepheline syenites for which few data are available. Drilling indicates gradational contacts between rock types.
The present list of occurrences of alkaline rocks in the United States was based initially on the compilation of Barker (1974), who also discussed the distribution in space and time of North American feldspathoidal rocks (Barker, 1969). The present compilation contains not only newly discovered occurrences but also a number of peralkaline syenite and granite localities which were omitted earlier, althoughBarker himself pointed outthat a number of such occurrences had probably escaped his notice. There are probably still omissions because rocks of this type are often found in non-peralkaline environments and so easily missed during bibliographic searches. However, it is likely that coverage of the pantelleritic and comenditic rocks is relatively comprehensive, apart from as yet unknown occurrences, because of the thorough compilation of Noble and Parker (1975).
Future discoveries in the United States are likely to be in the Cordillera, and the large number of localities already known from there, when combined with the considerable numbers coming to light in British Columbia and Alaska, would suggest that western North America could become a particularly important area for exploring the relationship between alkaline igneous activity and orogenesis.
Located 34 km west of Mount Prindle and southeast of the White Mountains is a small badly exposed complex of syenites and nepheline syenites for which few data are available. Drilling indicates gradational contacts between rock types.
In the area south-southeast of Tenakee nepheline and sodalite syenites occur in a 220 km2 complex which is composed predominantly of hornblende and biotite syenites, monzonite, granodiorite, granite, trondhjemite and syenodiorite. Loney et al. (1975, p.
Located near the southern end of Prince of Wales Island, Bokan is a complex of peralkaline granites, syenites and aplites covering 28. 5 km2, emplaced into graphitic slates in the south and west and metavolcanics and non-alkaline plutonic rocks elsewhere.
The Golden Horn batholith is an approximately rectangular intrusion of 37x11 km in the Northern Cascades (Misch, 1966, Plate 7-1). The rocks are generally leucocratic and include a peralkaline granite and biotite granites.
Lying to the south of the Kruger intrusion (031-00-037), in Okanogan County, is an area of alkaline rocks which are marginal to the Similkameen pluton and probably related to the Kruger occurrence.
Lying some 4 km east of the Similkameen pluton, the Shankers Bend diatreme is an irregularly shaped, concentrically zoned body about 1 km across, consisting of malignite, fenite and other alkaline rocks.
A syenite intrusion, probably sheet-like in form (referred to as a chonolith by Daly, 1912), covers about 10 km2 along Rock Creek, just above its confluence with the Kettle River.
Three irregular plugs and a number of associated dykes extend over 6. 5 km in the Curlew Quadrangle of Ferry County.
The Bobtail Creek stock is exposed over an area of 3. 2 km2 and is in contact with Precambrian schists. It is composed predominantly of syenites containing aegirine-augite.
This small (1.3 km2) multiple intrusion of syenite, monzonite and granite contains aegirine-augite. It is cut by pegmatites, aplitic dykes and quartz veins, and there is some fenitization of the country rocks. Rock analyses are available in Fleshman and Siegmund (1982, Table 6).