Geology 1977 in British Columbia 1981 Province of British Columbia Ministry of Energy, Mines and Petroleum Resources I! ,? :j, ., ': British Columbia Cataloguing in Publication Data Main entry under title: Geology in British Columbia.-- 1975-1977/81. Irregular. With: Exploration in British Columbia; and, Mining in British Columbia, ISSN 0823-1265, continues: Geology, exploration and miningin British Columbia, ISSN 0085-1027. 1976 published in 1983. 1977/81 published as a1 volume cummulation. Issuing body varies:1975, Ministry of Mines and Petroleum Resources;1976-1977/81, Ministry of Energy, Mines and Petroleum Resources. ISSN 0823-1257 = Geology in British Columbia 1. Geology - British Columbia - Periodicals. 2. Geology, Economic - British Columbia - Periodicals. 3. Mines and mineral resources- British Columbia- Per- iodicals. I. British Columbia. Ministry of Mines and Petroleum Resources. 11. British Columbia. Ministry of Energy, Mines and Petroleum Resources. ~~187.G46 557.1105 TABLE OF CONTENTS Page Preface ............................................................................................................................................................................................... vii Southeast British Columbia: Geology.. of the Skomac Mine and Boundary Falls Area (82E12) ........................ 1 Fuki, Donen, PB, Kettle, Venus (82E17) ....................................................................................... 12 Geology and Rank Distribution of the Elk Valley Coalfield (82G115; 82J12, 17 24 34 41 44 57 67 69 76 88 91 98 101 103 108 108 110 113 115 120 121 122 123 125 127 129 129 130 132 134 134 139 142 145 148 iii Shas (94Ei2W.3E) ............................................................................................................................................ 156 ToodoggoneRiver (94E).............................................................................................................................. 156 Driftpile Creek(94W4W) ............................................................................................................................. 163 Northwest British Columbia: Star Copper Prospect (104J/4, 5) ....................................................................................................... 175 Moly-Taku (1 04Ki6W) ..................................................................................................................................... 180 CYENG (104NilOW) ..................................................................................................................................... 182 MIR (104NilOW) ................................................................................................................................................. 183 Atlin Silver (Ruffner) Mine (104NillW) ........................................................................................ 184 Cinbar(104N/1 1W)........................................................................................................................................... 185 iv 181 186 188 62 Geology of the Hum Bird area ............................................................................................................. 192 PHOTOGRAPHS PLATES I Panorama of the Skomac minesite, looking northerly at the main portals 2 IIA Chevron folds in Skomac metasedimentary rocks.......................................................... 9 iIB Polished section of sample of Skomac quartz vein showing pyrite, galena, tetrahedrite, and sphalerite................................................................................................ 9 111 View of the study area fromthe south, note anticline-syncline pair on east limb of Alexander Creek syncline, Cadomin Formation con- glomerate exposed in the core of the syncline; Mount Banner Peak in the distance at the left of the photograph ........................................ 27 IV Northwest-plunging dragfold in the hangingwall ofasplay ofthe Ewin Pass thrust ................................................................................................................................................... 27 V View from the north into the Ewin Pass property, approximate Mist Moun- tain-Elk Formation contact marked with arrow, strata dip to the west or right-hand side of the photograph...................................................... 33 V VIView of western crosscutting contact of Cross Kimberlite (K) and the Pennsylvanian country rock................................................................................................ 35 VI1 Viewof easternshear-zone contact of Cross Kimberlite; hard dense intrusive material (lithologies 2 and 3) comprise the outcrops in foreground ............................................................................................................................................ 35 Vlli Boulder of Cross Kimberlite showing texture of lithology 2 ....................................... 36 IX Rounded ultrabasic inclusion of 0.75-metrediameter in crumblyhighly weathered material (lithology1) near the western contactof Cross Kimberlite exposure.................................................................................................................... 36 XA Metavolcanic breccia, map-unit 2, Red Ridge........................................................................ 46 XB Polished hand specimen from exposure in plate................................................................. 46 XIA Massive trachtye porphyry breccia, Rexspar A zone...................................................... 47 XIB Strongly foliated trachyte porphyry breccia, Rexspar A zone................................. 47 XI1 Rootless phase 1 folds outlined by quartzite layers in quartz mica schist, north face of Mount McClennan, looking east.................................................. 48 XlllA Backscattered electron photographof Rexspar ore from A zone........................ 49 XlllB Thorian uraninite grain (light grey)and monzonite [medium grey)in pyrite 49 XlllC Uranium thorium electron scan area in Plate XlllB ........................................................... 50 XlllD Cerium-lanthanum scan of area in Plate XlllB ...................................................................... 50 XlVA Pleochronic rings in fluorphlogopite, Rexspar A zone ................................................... 52 XlVB Strain slip cleavage in fluorphlogopite with fluorite-filled tension gashes, Rexspar Azone .............................................................................................................................. 52 XVA Sheared pyrite and fluorite (dark grey) in ore from Rexspar A zone ................ 53 XVB Sheared pyrite and fluorite (dark grey) in ore from Rexspar A zone ................ 53 XVI Massive banded pyrite with dark grey carbonate nodules ......................................... 170 XVll Sample of dark grey barite with diffuse bands of galena (white) collected from trenches near diamond drillhole 7 ................................................................. 170 XVlll Drill core showing deformed partly recrystallized laminae of white barite . 170 XIX Drill core of finely laminated pyrite showing graded bedding and slump structures ............................................................................................................................................... 170 XX Drillcore of very fine-grained pyrite and argillitelaminae disrupted by secondary dark grey carbonate nodules............................................................... 172 XXI Drill core showing chaotic mixing and slumping of pyrite laminae about secondary carbonate nodules.......................................................................................... 172 XXll Bulldozer trenches at the Star prospect ........................................................ 175 vi In 1969, the Annual Report of the Ministry grew to such a size that it was decided to divide it and initiate anew publication entitled Geologl: Exploration and Mining in British Columbia. The new volume was concerned with publishing geological and technical reports and recording exploration activity in the Province. The first edition, Geology, Exploration and Mining in British Columbia, 1969, was 466 pages, by 1970 it was 561 pages. Exploration activity continued to bloom but our staff did not expand. Inthe mid-1970's re- organizations within the Ministry shifted priorities and put severe pressureon publications production section. Staff turnover was rapid, the section did not grow to match new workload, backlogs began and built rapidly. Weare making a concentrated effort to attempt to eliminate the backlogs and get back on schedule. This volume represents such an attempt. It contains contributions that span four years. The publication, Geology in British Columbia, is supposed to be released annually; we apologize thatproduction difficulties have forcedus to combine several issues in order to catch up. Also because of production difficulties, the volume is small, since little material was submitted after 1977. Ministry geologists switched their efforts and published more preliminary maps, reports in Geological Fieldwork and the Paper series,and in external publications. vii SOUTHEAST BRITISH COLUMBIA (NTS DIVISION 82) 1977"GEOLOGY OF THE SKOMAC MINE AND BOUNDARY FALLS AREA (82El2) By B. N. Church INTRODUCTION: The Skomac mine is a recently revived small gold and silveropera- tion in the Boundary Falls area located 5.5 kilometres