Geological Fieldwork a summary of field activities of the geological division, mineral resources branch 1974 Britch Columbia Department of Mines and Petroleum Rerource~ FOREWORD GeologicalFieldwork, 1974 is a new publication designed to acquaintthe interested public with the preliminary results of the Geological Division as soon as possible after the field season. Fieldwork describedincludes reportsof Project and District Geologists as well as those of graduate students whose work represents an integral part of tlle Division's projects. The reports are written mainly without the benefit of laboratory or extensive office studies. To speed publication,editing hasbeen minimal and figures havebeen draughted by the authors. Geological Fieldwork, 1974 is not designed to replace Geology, Exploration, and Mining in British Columbia which will continue as the colnprehensive volume on the work of the Industry and of the Department. A. Sutherland Brown, Deputy Chief Geologist. Mineral Resources Branch 3 TABLE OF CONTENTS Page REPORTS OF PROJECT GEOLOGISTS nay. Trygve: Zinc Deposits. Southeastern British Columbia ...... 7 Preto. V . A. Geology of the Nicola Group between Missezula Lake and Allison Lake ............................ 9 Lefebure. David V .. Stratigraphy and Copper Mineralization of the hlicola Group. Fairweather Hills ...................... 14 Christopher. P. A. Giant Mascot Mine .......................... 17 Northcote . K . E. Geology of the Northwest Halfof Iron Mask Batholith .................................. 22 McMillan. W . J .. StratigraphicSection from the Jurassic Ahcroft Formation and Triassic Nicola Group contiguous to the Guichon Creek Batholith ................... 27 Peanon. David E. Bridge River Map-Area ....................... 35 Garnett. J . A. Current Activity - Hogem Batholith ............. 40 Meade. H . D .. Geology of Germansen Lake Area ............... 43 Carter. N . C .. Property Examinations. West CentralBritish Columbia .................................. 47 Church. B . N. Geology of the Sustut Area ................... 51 Church. B. N. and Winsby. J .. Dentonia Mine. Jewel Lake Area ................ 56 Panteleyev. A. Galore Creek Map-Area ....................... 59 McMillan. W. J., Panteleyev. A.. and Preto. V . A. Geochemical Sampling. Geology.and Magnetics of the Kaketsa Stock ........................... 63 REPORTS OF DISTRICTGEOLOGISTS White. Gordon P. E .. SouthCentral British Columbia ................. 69 5 Page REPORTS OF DISTRICTGEOLOGISTS (Continued) Easiwood. G.E.P.: VancouverIsland ............................ 73 Schroeter . T . G. NorthwesternBritish Columbia ................. 78 REPORTS ONINDUSTRIAL MINERALS AND STRUCTURALMATERIALS McCammon. J. W .. Barite. Niobium. Sandand Gravel. Talc ........... 85 6 REPORTS OF PROJECTGEOLOGISTS ZINC DEPOSITS SOUTHEASTERNBRITISH COLUMBIA By Twgve Hoy A study of lead-zinc deposits in southeastern British Columbia was initiated ill the latter partof the1974 field season. The following deposits were visited andsampled: the Kootenay King and Sullivan mines, stratabound zinc-lead deposits in Aldridge Formation (Lower Purcell) argillites and quartzites; the St. Eugene mine, a transgressive vein deposit in argillaceous quartzites of the Aldridge Formation; the Mineral King mine, sphalerite. galena. pyrite - barite replacement deposits inMount Nelson Formation dolomites. 'Shuswap-type' deposits visitedinclude the CK property,40 kilometresnortheast of Clearwater. and Colby Mines Ltd.'s property, 30 kilometres east-northeast of Enderby. These two occurrences are described in more detail as both are being actively explored. CK - RIO TINTO (82M113E) TheCK property. owned byRio Tinto Canadian ExplorationLimited, includes 270 claims located just north of the Raft River-Ritchie Creek junction. The area i'iaccessible by a logging road branching north from Highway 5, 12 kilometres east of Clearwater and continuing north approximately 65 kilometres along the west side of the Raft River. The area is underlain by metasedimentary rocks of the Shuswap Metamorphic Complex (Campbell, 1963). These include biotite. quartz - muscovite - feldspar * garnet gneisses with minor amphibolite, quartzite, calc-silicate gneiss,and marble units. In the western part, a light-coloured, fine to medium.grained 'granitic'intrusive rock is present. Quartz-feldsparpegmatite sills and dykes. up to 80 metres thick,intrude the metasedimentary rocks. Sulphide mineralization occurs as massive sphalerite, pyrrhotite, and minor galena within an original quartz-plagioclase-rich metasedimentary rock I?),and as disseminated sphal- erite and minor galena within biotite-diopside quartziteand tremolite-calcite marble. The observed mineralization is confined to patches within a 20-metre stratigraphic thickness of metasedimentary rocks andover a strikelength of 120 metres. Solne of the mineralized patches are marked bypronounced gossan breccias consisting of rotated blocks of massive sulphide cemented by limonitic material. FX, FC - COLBY 182L/10E) Colby Mines Ltd.'s property is located 48 kilometresby road east of Enderby, 15 kilometres north of the Shuswap River, and just east of Kingfisher Creek. 7 The area is underlain by garnet . biotite .quartz -feldspar gneiss, tremolitecalcite marble, calcareous quartzite, and Occasional amphiboliteunits. Quartz - feldspar f garnet pegmatite dykes are common throughout the area, and 'quartz-eye' porphyry dykes are less common. Sulphide mineralization consists of sphalerite and pyrrhotite with minorgalena and pyrite inquartz-rich biotite gneiss, biotite quartzite, and calc-silicate gneiss. Sphalerite, pyrrhotite, and galena are also concentrated in quartzite breccia zones and sphalerite and pyrrhotite are disseminated in a tremolite-calcite marble. Themarble is at least 300 metres thick and appears continuous over a strike length of at least 6 kilometres. Sulphide mineralization within the marble unit is restricted to distinct zones near the centre of the claim group, and at both the northern and southern extensions of the marbleunit. REFERENCE Campbell, R. 8. (1963): Adams Lake, British Columbia, Geol. Surv., Canada, Map 48-1963.82MlW. 8 GEOLOGY OF THENICOLA GROUP BETWEEN MISSEZULALAKE AND ALLISON LAKE (92H/15E. 10E1 By V. A. Preto INTRODUCTION Mapping was continued southward from the area covered in 1973 and an additional 55 square miles was completed (Fig. 1). Of the three belts that had previously been described as comprisingthe Nicola assemblage in the AspenGrove area (Preto. 197'11, onlythe Central andEastern Belts are recognized in the presentmaparea, and these differ appreciably from their northern counterparts in the composition andlor types of rocks involved. The boundary between the Eastern and Central Belts in the map-area is marked by a major fault system, locally known as the Summers Creek fault, which is the southern extension of the Alleyne.Kentucky fault system. CENTRAL BELT As in the Aspen Grove area, the Central Belt is composed of a thick sequence of massive and fragmental volcanic rocks but the individual rock units differconsiderably from their northerncounterparts. Pyroxene-rich flow units,probably of basaltic to andesitic composition, are still common but no longer predominate. A common type of flow rock is a massive, greenish grey andesite or dacitic andesite with abundant plagioclase and a lesser amount of pyroxene crystals. Fine-grained variations of these rocks are very light green to green-grey in colour and are commonly interlayered with thinly latninated tuffs of similar composition. The fragmental units also differ from their counterparts to the north. The red and green breccias which are SO common in theAspen Grove area, where theyar? thought to represent high.density mudflow or landslidedeposits. are found only in theextreme north-centralpart of thepresent map-area and are rapidly replaced to .the south by comparably thick accumulations of flow breccia and rubble breccia derived from nearby flow units. Typical of these breccia units are reaction rims around many of the clasts, and close similarity in compmition between clasts and matrix. Theeastern part of theCentral Belt consists of dacitic andesite flows andwidespread lithic tuff withabundant fragments of grey and light grey fine-grained rhyolitic rocks. Sedimentaryrocks in theCentral Belt are limited to small, widely scattered lenses of impurereefoid limestoneand to a few layers of generallygraded bedded volcanic siltstone, sandstone, and conglomerate. With the exception of the southern part of a smallstock of syenite-monzonite that is found in the extreme northwestern corner of the belt, intrusive rocks in th?Central Belt 9 10 Figure 1. Generalized geology, Mmerula-Allison Lake area. LEGEND JURASSIC ALLISONLAKE INTRUSIVE BODY xxx REDGRANITE AND QUARTZ MONZONITE, GREY GRANO- rlxxx DIORITE,DIORITE, AND QUARTZ DIORITE UPPER TRIASSIC NICOLA GROUP EASTERN BELT MEDIUM-GRAINEDPORPHYRITIC SYENITE AND MONZONITE; LAHAR DEPOSITS, VOLCANICCONGLOMERATE, AND SAND- STONE;MINOR FLOWS ANDTUFF CENTRALBELT MEDIUM-GRAINEDGREY MONZONITE AND DIORITE ANDESITICAND DAClTlC FLOWS, FLOWBRECCIA. RUBBLE BRECCIA.AND TUFF; MINOR VOLCANIC SEDIME!NTS AND IMPURELIMESTONE SYMBOLS MINERAL SHOWINGS FAULT POWER TRANSMISSIONLINE 11 are a rather uniform, grey, medium-grained pyroxene monzonite and diorite that form five distinct plutons. Most of the mineral occurrences in the belt are associated with these plutons. Areas of pink K-feldspar flooding and associated brecciation are common in the largest of these intrusive