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File Created: 08-Nov-1991 by Keith J. Mountjoy (KJM)
Last Edit:  08-Nov-1991 by Keith J. Mountjoy (KJM)

Summary Help Help

NMI
Name HOWARD CREEK SYENITE, HOWARD CREEK, TOP 1-4, TOP 1, 7803, 7804 Mining Division Kamloops
BCGS Map 083D036
Status Showing NTS Map 083D07W
Latitude 052º 22' 40'' UTM 11 (NAD 83)
Longitude 118º 51' 54'' Northing 5804694
Easting 373053
Commodities Nepheline Syenite, Sodalite, Niobium, Tantalum, Uranium Deposit Types R13 : Nepheline syenite
N01 : Carbonatite-hosted deposits
Tectonic Belt Omineca Terrane Kootenay
Capsule Geology

The Howard Creek Syenite showing is located at the headwaters of Howard Creek, 13 kilometres west of McNaughton Lake and 41 kilometres northeast of Blue River. The Verity carbonatite showing (083D 005) lies approximately 4.5 kilometres to the east. This showing is only accessible by helicopter support from Valemount or Blue River, as no trail exists in to the area from lower elevations.

A nepheline syenite gneiss outcrop, measuring 5 by 20 metres, occurs in a south-facing cirque, adjacent to the Howard Creek carbonatite showing (083D 043). The syenite gneiss occurs as a sill within quartz-hornblende-mica schist of the Semipelite Amphibolite division of the Hadrynian Horsethief Creek Group. The syenite is composed of grey weathering, medium grained, layered and foliated gneiss. It is locally migmatitic, with massive, medium to coarse grained, lensoidal leucosomes.

The relationship between syenite and carbonatite is unknown due to structural complications but a slightly discordant uranium/lead isotopic age of 340 Ma and lead/lead ages of 351 and 363 Ma suggest that they are penecontemporaneous intrusives of Devono-Mississippian (circa 350 Ma) age (Bulletin 86, in press). The regional foliation generally strikes 120 degrees and dips 15 to 30 degrees southwest. Two major orientations of faults occur locally with the more prominent striking 345 degrees and dipping steeply to the west. Motion on these faults is west side down. The other orientation strikes east-west dipping near vertical. Structures to the north and northwest of Howard Creek indicate the area has undergone regional doming.

The major constituents of the syenite are: microcline, plagioclase, nepheline and biotite. Accessory minerals include muscovite, sodalite, cancranite, zircon and perthite. Trace minerals present are: calcite, magnetite, pyrrhotite, pyrochlore and uranopyrochlore (Open File 1987-17).

Strontium content of the nepheline syenite is 0.070 percent (Fieldwork 1984).

Bibliography
EM EXPL 2001-73-82
EMPR BULL *86 (in press)
EMPR FIELDWORK *1984, pp. 84-94; 95-100
EMPR OF *1987, pp. 41-48
GSC MAP 15-1967
GSC OF 2324
GSC P 89-1E, pp. 95-100
CJES 1988 Vol. 25, No. 8, pp. 1323-1337
Canadian Mineralogist 1961, Vol. 6, pp. 610-633
Pell, J. and Hora, Z.D. (1990): Rifting, alkaline rocks and related magmatic deposits in the southern Canadian Cordillera; Ministry of Energy, Mines and Petroleum Resources, Geological Survey Branch, 8th IAGOD paper, 1990.

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