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File Created: 29-Aug-1990 by Mary McLean (MM)
Last Edit:  11-Apr-2021 by Karl A. Flower (KAF)

Summary Help Help

NMI
Name DEM, DEM LAKE, TEZZ Mining Division Omineca
BCGS Map 093K078
Status Showing NTS Map 093K16W
Latitude 054º 45' 06'' UTM 10 (NAD 83)
Longitude 124º 26' 48'' Northing 6068118
Easting 406891
Commodities Arsenic, Gold, Silver Deposit Types K04 : Au skarn
Tectonic Belt Intermontane Terrane Quesnel, Cache Creek
Capsule Geology

The Dem showing is located 1 kilometre south of Dem Lake and about 50 kilometres northwest of Fort Fraser.

The region is underlain by sedimentary and volcanic rocks of the Upper Triassic to Lower Jurassic Takla Group within the Quesnellia Terrane. The group comprises the informally named Inzana Lake, Rainbow, Witch Lake and Chuchi Lake Formations.

The Inzana Lake Formation is a sequence of epiclastic sediments derived from a volcanic source. It is underlain by fine-grained slates and sediments of the Rainbow Formation derived (in part) from a continental source. In turn, it is overlain by augite porphyry flows and agglomerates of the Witch Lake Formation and the subaerial maroon and green flows of the Chuchi Lake Formation.

The Dem showing is hosted in metasomatically altered sediments of the Inzana Lake Formation. Well laminated sandstones and siltstones are intruded and altered by syenomonzonite dikes. Original concordant bedding strikes 144 degrees and dips 70 degrees north. Areally, extensive alteration in the sediments ranges from local massive epidote-tremolite skarning to biotite-diopside hornfelsing.

The main Dem showing is a pod shaped subcrop exposure (20 centimetres by 1 metre) of brecciated quartz vein. The vein contains between 5 and 10 per cent arsenopyrite that occurs in clumps with epidote and tremolite. Another massive skarn pod (0.5 metres wide) occurs within the sediments in close proximity to syenomonzonite dikes, approximately 500 metres south of the arsenopyrite quartz breccia vein. Skarn mineralization consists of pyrite and pyrrhotite with secondary biotite and actinolite veinlets.

These brecciated quartz veins containing up to 10 per cent arsenopyrite assayed up to 0.36 gram per tonne gold plus pyrite-pyrrhotite skarn assaying up to 0.2 gram per tonne gold (Assessment Report 22277).

Work History

The Dem showing was discovered by the B.C. Geological Survey in 1990 and subsequently staked and held by Noranda Exploration Company Limited. In 1991, Noranda explored their Tezz 1 and Dem 1-4 claims by grid soil geochemical survey (collecting 822 samples) and mapping. Several multi-element anomalies were outlined with highs of 2.1 parts per million gold, 160 parts per million silver, 0.5 per cent lead and 0.41 per cent zinc (Assessment Report 22277). Outcrops of pyritized, hornfelsed and propylitic-altered andesitic volcanics and sediments are reported to have yielded up to 0.84 gram per tonne gold (Assessment Report 22277).

In 2005, Uwe Schmidt prospected his Dem claim which was staked to cover the lapsed THE Dem showing. A total of 8 rock samples and 1 basal till sample were collected and sent for geochemical analysis. Analyzed samples were not considered significant.

In 2011, Xstrata completed a 75.6 line-kilometre induced polarization survey on the Hat Super Block property. The following year, 10 diamond drill holes, totalling 2326.3 metres were completed on the Hat, Axis and Mags claims of the Hat Super Block property.

In 2017, a 2.3 line-kilometre induced polarization survey and an 87.0 line-kilometre airborne magnetic survey was completed on the Dem property.

Bibliography
EMPR ASS RPT *22277, *28280, 32883, 33677, 36880
EMPR BULL 99
EMPR EXPL 1992-69-106
EMPR FIELDWORK *1990, pp. 89-110; 1992, pp. 475-482
EMPR MP MAP 1992-4
EMPR OF *1991-3
EMPR PFD 256, 670225
GSC OF 2593, 2801, 2846
GSC P 90-1F, pp. 115-120; 91-1A, pp. 7-13

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