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File Created: 08-Mar-1988 by Larry Jones (LDJ)
Last Edit:  10-Jan-2022 by Del Ferguson (DF)

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Name JUNCTION, MYLONITE, EAST, URSUS Mining Division Alberni
BCGS Map 092F033
Status Prospect NTS Map 092F05E
Latitude 049º 22' 16'' UTM 10 (NAD 83)
Longitude 125º 35' 15'' Northing 5471932
Easting 312163
Commodities Gold Deposit Types I02 : Intrusion-related Au pyrrhotite veins
Tectonic Belt Insular Terrane Wrangell
Capsule Geology

The Junction zone, also known as the East or Mylonite zone, is exposed in cliffs along the south side of Ursus Creek, about 50 metres upstream from Junction Creek, approximately 34 kilometres northeast of Tofino, B.C.

A major fault cuts volcanic rocks of the Upper Triassic Karmutsen Formation (Vancouver Group) and granodiorite to quartz diorite of the Early to Middle Jurassic Island Plutonic Suite. The volcanics are fine-grained to aphanitic, dark green andesite. The intrusive contact is marked by a medium to fine-grained dark, mafic-rich diorite, which is cut by many dykes of leucocratic granodiorite.

The main direction of shearing is about 112 degrees. Shear features such as gouge-filled fractures, rehealed brecciation and zones of shattered rock are abundant throughout the area.

Pyrite, with associated gold, is disseminated in tectonically crushed granodiorite. The hard greenish cataclastic rock (mylonite) contains numerous subangular, elongate fragments of quartz up to 5 centimetres. The matrix is composed of quartz, sericite and calcite. The pyrite is locally oxidized to limonite.

The Ursus Creek cataclasis zone is interpreted as gold-bearing quartz-carbonate-minor pyrite vein-stockwork related to narrower, but laterally extensive cataclastic deformation zones. Chlorite zones are developed in Triassic Karmutsen andesite-basalt that is characterized by finely disseminated pyrite and carbonate blebs, streaks and late-stage fracture fillings. Gold values are related to late-phase albite enriched end phases of mid-Jurassic intrusive activity, and mineralization is considered to be of intrusion-related vein-stockwork-breccia type.

Grab samples assayed up to 24.9 grams per tonne gold and a 0.5 metre chip sample assayed 3.94 grams per tonne gold (Assessement Report 16450). From one of five holes drilled in 1988 a 1.8 metre interval assayed 9.19 grams per tonne gold (George Cross News Letter #31, 1989).

Fieldwork performed in 2017 by Oakley Ventures Inc includes geochemical analysis of 8 rock chip and 20 soil samples that cover a 225 by 550 metre area immediately south of Ursus Creek, and east of Junction Creek. The eight rock chip samples returned low Au values from geochemical analysis. One of the rock chip samples (17Thun-3) that had a high content of pyrite and weak quartz stockwork texture developed, returned a value of 0.014 grams per tonne Au. Soil samples taken over a 125 metre interval immediately south of Ursus Creek and 200 metres east of the confluence of Junction and Ursus Creek returned geochemical analysis results ranging from 0.041 to 0.178 grams per tonne Au (Assessment Report 37525).

Refer to THUNDERBIRD (092F 067) and MID PAD (092F 449) for more information on the Ursus Creek mineral showings.

EMPR ASS RPT 9378, 12623, *16450, 19374, 20474, 24426, 26412, *37525
EMPR EXPL 1980-171; 1984-162,163; 1987-C145
EMPR PF (Prospectus, Pacific Sentinel Gold Corp., August 31, 1987; Filing Statement, Pacific Sentinel Gold Corp., May 9, 1988; Prospectors Report 1995-24 by Simon Salmon)
GSC MAP 17-1968; 1386A
GSC OF 463
GSC P 68-50; 72-44; 79-30; 80-16
GCNL #67, 1984; #11,#13,#104,#227, 1988; *#4,*#31, 1989, #32, 1990
N MINER June 12, 1995
V STOCKWATCH Jan.18, 1988
Carson, D.J.T. (1968): Metallogenic Study of Vancouver Island with Emphasis on the Relationships of Mineral Deposits to Plutonic Rocks, Unpublished Ph.D. Thesis, Carleton University