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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  22-May-14 by Nicole Barlow(NB)

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NMI 092H12 Au2
Name DOCTORS POINT, NAGY, HARRISON LAKE, CRYSTAL Mining Division New Westminster
BCGS Map 092H061
Status Developed Prospect NTS Map 092H12W
Latitude 49º 39' 03" N UTM 10 (NAD 83)
Longitude 121º 59' 23" W Northing 5500300
Easting 572926
Commodities Gold, Silver, Lead, Zinc, Copper, Bismuth Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
I01 : Au-quartz veins
Tectonic Belt Coast Crystalline Terrane Gambier, Plutonic Rocks
Capsule Geology

The Doctors Point prospect is situated on the southwest shores of Harrison Lake, approximately 36 kilometres north of the Seneca deposit (092HSW013) and 86 kilometres northeast of Vancouver.

The prospect is situated close to the Harrison Lake shear zone, a right-lateral transcurrent fault that splays northward into an imbricate fan of high-angle brittle faults. In part, it passes along and parallel to Harrison Lake, separating the Early and Middle Jurassic Harrison Lake Formation and Cretaceous Fire Lake Group on the west side of the lake from the Cretaceous Slollicum Schist on the east side.

The Doctors Point area is underlain by a northwest-striking, gently (30 degrees) east-dipping sequence of interbedded sediments, volcanics and volcaniclastics assigned to the Early Cretaceous Brokenback Hill Formation, which has been correlated as part of the Fire Lake Group (Journeay and Csontos, 1989; Lynch, 1990). Here, the formation consists of volcanic flows and tuff with minor argillite, volcanic sandstone, siltstone and polymictic conglomerate.

These rocks are intruded by the Tertiary Doctors Point pluton and four smaller (25 to 2000-metre-diameter) diorite to quartz diorite plutons (Nagy, Island, Peninsula and Doctors Bay plutons). Potassium-argon age dates for the Doctors Point pluton are 22 to 24 Ma (Geological Survey of Canada Paper 89-1E, page 186) and 20.4 ± 0.8 Ma (Economic Geology, Volume 86, Table 2, 1991).

The diorite plutons are surrounded by a 100 to 300-metre-wide hornfels aureole characterized by silicification, pyrrhotite (up to 15 per cent), pyrite, magnetite and red biotite flake. Cordierite, andalusite, garnet and coarse, poikiloblastic biotite have also developed in the rocks adjacent to the intrusions. Major faults trend 330 and 360 degrees across the property, with numerous conjugate and en echelon fractures.

Gold-silver mineralization at Doctors Point is hosted in narrow, gently dipping, vuggy quartz-sulphide veins that show an overall spatial association to the pluton margins in that they appear to have followed pre-existing low-angle cone sheet–type fractures resulting from the emplacement of the diorite intrusions. Veins are found in 12 localities, are hosted by either diorite or hornfelsic rocks and contain variable amounts of potassium feldspar, sericite and carbonate. On surface, they vary from 1 centimetre to more than 1 metre in width. Pyrite and arsenopyrite are the most abundant sulphides, with traces of galena and sphalerite and minor chalcopyrite. Locally, the veins comprise coarse, massive sulphide material in which quartz is subordinate. Surface leaching has resulted in abundant boxwork structures in the quartz veins, and many mineralized outcrops are coated with green scorodite. Petrographic work done in 1983 suggests the native gold occurs along the grain boundaries of pyrite crystals as well as to a lesser extent with arsenopyrite. Microfracturing of these sulphides are infilled with calcite, pyrite, clay, native bismuth, argentite and lead bismuth sulphosalts. The veins have experienced at least two episodes of precious metal mineralization—one with the introduction of gold and the second with the introduction of silver-bismuth minerals.

The southernmost mineralized fracture lies outside the hornfelsic aureole that surrounds the plutons. It is not associated with quartz veining and contains little gold but is enriched in silver, lead, zinc and arsenic. The zone contains pyrite, arsenopyrite, tetrahedrite and galena, together with alteration minerals that include scorodite, anglesite, schultenite, jarosite and malachite. This would suggest that a temperature-related mineral and element zoning probably exists in the area, with gold being found closer to the pluton margins and base metals predominating outside the hornfelsic envelope (Fieldwork 1984).

Drill-indicated reserves based on closely spaced grid drilling are 113 600 tonnes grading 2.16 grams per tonne gold and 6.2 grams per tonne silver, and occur near surface in a triangular mass at the Main zone (Assessment Report 18365). The interbedded volcanics and sediments underlying this zone appear to be intruded by at least two phases of diorite, including dikes and sills. The zone is controlled in the northeast and southwest by faults trending 330 degrees, which appear to serve as a locus for veining. The majority of the veins at the Main zone strike between 300 and 330 degrees. A later fault system, striking between 360 and 020 degrees, has produced a small offset in the veins.

The North zone, 1400 metres north-northwest of the Main zone, is situated on and near the boundary of adjoining NTS map sheet 92G/9E, just east of Doctors Creek. Underlying the North zone is a portion of the Doctors Point pluton, which is cut by a major fault trending 330 degrees. This fault is traceable to the southeast, back to the Main zone. A series of 30-degree, east-dipping, gold-bearing quartz-sulphide veins occur in close proximity to this fault. A drillhole intersection near the centre of the zone assayed 1.5 grams per tonne over 1.22 metres (Assessment Report 18365).

The South Swamp–Pylon zone is situated 850 metres north-northwest of the Main zone, between the Main and North zones. It is underlain by volcanic and volcaniclastic rocks. The southern half of the zone is intruded by the Doctors Point pluton and the major fault trending south from the North zone truncates its eastern boundary. Stockwork-style, less than 1-centimetre-wide quartz-sulphide veins assaying up to 100.09 grams per tonne gold are hosted by the diorite (Assessment Report 18365).

Mineralization in the Doctors Point area is believed to be genetically and temporally related to the diorite plutons and probably represents a late hydrothermal phase of this magmatic event. The Nagy and Doctors Bay plutons, and the siliceous hornfels immediately adjacent to their margins, locally contain abundant pyrite and pyrrhotite, although these sulphide-rich pockets are not enriched in gold or silver. The gold-silver mineralization postdates both the intrusion of the plutons and a late suite of mafic dikes. The postulated sequence is (1) emplacement of the diorite plutons with some barren sulphide mineralization, accompanied by low-angle cone sheet fracturing in the hornfels aureole, (2) intrusion of the mafic dikes, (3) minor thrust faulting along the fractures, (4) gold-silver-arsenic mineralization along some of the cone sheet fractures and (5) late subvertical faulting. Veins generally dip toward the pluton cores and are predominantly associated with the Doctors Bay pluton, although a few veins lie within or adjacent to the Doctors Point and Nagy plutons. This suggests that the five diorite bodies in the area are related and probably represent apophyses of a single major body (Fieldwork, 1984).

The occurrence was discovered by George Nagy in 1975 and later purchased by Rhyolite Resources Ltd. Over the next seven years, 12 vein structures were isolated and at least three of these were drilled.

In 1981, Rhyolite Resources Inc. completed 13 diamond drill holes totalling 889.9 metres, resulting in a noncompliant possible reserve estimate of 31 510 tonnes grading 4.25 grams per tonne gold (Assessment Report 10491).

In 1983, Rhyolite Resources Inc. collected soil samples, drilled one hole on Doctors Point totalling 61 metres, and conducted airborne magnetometer and very low-frequency electromagnetic surveys. Drilling did not encounter significant intercepts (Assessment Report 12709).

Between October and December 1983, Rhyolite Resources Inc. completed 23 diamond drill holes totalling 981.4 metres as well as a multiple induced polarization and magnetometer survey, identifying new exploration targets (Assessment Report 13029).

In 1988, Universal Trident Industries carried out soil and rock sampling, trenching and geological mapping (Assessment Report 18365).

In 1994, the property lapsed and was subsequently restaked as the Crystal claim by J. Cuttle. Several undeveloped targets were prospected (23907).

In 1995, Cuttle continued mapping the Crystal claim (Assessment Report 24488).

In 2006, Academy Ventures Inc. conducted geological mapping and soil and rock-chip sampling, with chip samples reporting elevated gold and silver values up to 68.7 grams per tonne gold and 188 grams per tonne silver (Assessment Report 28666).

In 2008, Urastar Energy Inc. conducted diamond drilling and an induced polarization survey, largely confirming the results of previous drilling (Academy Ventures Inc., Technical Report, March 13, 2009).

From 2009 to 2010, Johan Shearer collected soil samples reporting up to 994 parts per billion gold (Assessment Report 31667).

From 2011 to 2012, Johan Shearer conducted mapping and soil sampling and identified sporadic gold and arsenic anomalies west of the occurrence (Assessment Report 33502).

Bibliography
EMPR ASS RPT *10491, 12709, 13029, 14625, 18248, 18365, 18412, 23907, *31667, *33502
EMPR EXPL 1983-263; 1986-C221-C222
EMPR FIELDWORK 1982, pp. 55-61; 1983, pp. 42-49; *1984, pp.121-123; 1985, pp. 95-97; 1990, pp. 41-46
EMPR MAP 65 (1989)
EMPR OF 1992-1
EMPR PF (K.L.S. Investments Ltd., Various maps, 1997; Regional Geologist's notes, 1983; Photos, undated)
EMR MIN BULL MR 223 B.C. 122
EMR MP CORPFILE (Rhyolite Resources Inc.)
GSC EC GEOL #86, pp. 833-891; Vol. 68, 1991
GSC MAP 737A; 12-1969; 1386A; 41-1989
GSC MEM 335
GSC P 69-47; 89-1E, pp. 177-187; 90-1E, pp. 183-195, 197-204; 90-1F, pp. 95-107
GAC Guidebook, Precious Metal Mineralization, Section 9, 1985
GCNL #193,#169,#36,#32,#30,#71, 1983; #219,#16, 1984; #197, #229,#230, 1985; #197(Oct.9), #204(Oct.24), #237(Dec.9), 1988; #6(Jan.10), #16(Jan.24), 1989
MIN REV July/August 1983
N MINER May 19, July 7, Sept.8, 1983
N MINER MAG March 1986
V STOCKWATCH Nov.25, 1987
Arthur, A. (1987): Mesozoic Stratigraphy and Paleontology of the West Side of Harrison Lake, Southwestern British Columbia, Unpub. M.Sc. Thesis, University of British Columbia
Ditson, G.M. (1978): Metallogeny of the Vancouver-Hope Area, British Columbia, M.Sc. Thesis, University of British Columbia

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