COMINCO LTD. EXPLORATION WESTERN DISTRICT NTS: 921 13E/14W ASSESSMENT REPORT 1980 GEOLOGICAL AND GEOCHEMICAL REPORT ON THE ASH 1. 2 and 3 MINERAL CLAIMS IN THE HAT--- CREEK AREA KAMLOOPS MINING DIVISION, BRITISH COLUMBIA MINERAL RESOURCES BRANCH ASSESSMENT REPORT 22 MAY 19.81 R.J. SHARP TABLE . OF. CONTENTS Page SUMMARY.' ..................... 1 INTRODUCTION .................. 1 PROPERTY AND OWNERSHIP ............. 2 LOCATION AND ACCESS ............... 2 SUMMARY OF WORK ................. 2 DETAILED TECHNICAL DATA AND INTERPRETAION .... 2 Regional Geology .............. 2 Detailed Geology .............. 3 Unitl. ................. 3 Uni t-2 : ..................3 Unit3. ................. 3 Structural Geology ...............4 MINERALIZATION ................. 4 GEOCHEMICAL SURVEY ............... 4 Field and Analytical Techniques ....... 4 RESULTS ..................... 5 DISCUSSION OF RESULTS .............. 6 CONCLUSIONS AND RECOMMENDATIONS ......... 7 REFERENCES ...................7 ATTACHMENTS Appendix A: Exhibit "A" . Itemized Cost Statement Appendix B: Author's Qualifi cati ons Figure 1: General Location Map Figure 2: Location Map 1.250. 000 Scale Figure 3: Claim Outline Map Figure 4: Geology and Geochemistry Figure 5: Geochemistry .Au Figure 6: Geochemistry . Ag Figure 7: Geochemistry . As Figure 8: Geochemistry . Cu Figure 9: Geochemistry . Pb Figure 10: Geochemistry . Zn Figure 11: Regional Geochemistry .......... _...-. .....- COMINCO LTD. EXP LO RAT I ON WESTERN DISTRICT NTS: 921 13E/14W 22 May 1981 ASSESSMENT REPORT 1980 GEOLOGICAL AND GEOCHEMICAL REPORT ON THE ASH 1, 2 and 3 MINERAL CLAIMS IN THE HAT CREEK AREA KAMLOOPS MINING DIVISION, BRITISH COLUMBIA SUMMARY The Ash claims are located 12 km west of Cache Creek British Columbia and cover gold-silver-arsenic-mercury anomalies in soil, silt and rock sampl es. Work in 1980 consisted of silt, soil and rock geochemistry and geological mappi ng. This work confirms the presence of anomalous gold values in soils and rocks of Tertiary Co ldwater Beds (sandstone and conglomerate ) intruded by a rhyolite dome. INTRODUCTION This report describes the geology, rock, soil and silt geochemistry on Cominco's ASH claims, 12 krn west of Cache Creek, Br- tish Columbia, (see figures 1 and 2 for location). The report is based upon field investi- gations by R.J. Sharp and assistant A.D. Croft during the period May 16 to May 20, 1980 and by R.J. Sharp and M.L. Serack during the period Octo- ber 8 to October 15, 1980. The work was supervised by R.Y. Watanabe. The program this year consisted of geological mapping, silt, soil and rock geochemistry. Soil samples were collected along grid lines, silt samples were collected on all major drainage channels crossing the property and rock samples were collected from rock outcrops on the claims. Data are presented on a scale of 1:10,000. Assessment ReportjAsh Mineral C1 aims/ 22 May 1981lPage 21 The Ash claim group is made up of three claims comprising 55 units, all owned 100% by Cominco Limited (see Figure 3). This report files credit for all three Ash claims which are listed below: Claim Name Record Number Due Date Ash 1 2570 May 2, 1981 Ash 2 2571 May 2, 1981 Ash 3 2572 May 2, 1981 Legal corner posts, identification posts, and claim boundaries were lo- cated by chain and compass surveying and are plotted on a 1:10,000 scale topographic map. LOCATION AND ACCESS . The property is situated in the Kamloops Mining Division at 50’48’N and 12l03O’W, NTS 921 13, approximately 12 km west of the town of Cache Creek, British Columbia. Access is by road from Cache Creek. The claims are situated in low mountainous terrain (900 to 1500 m above sea level) in the Trachyte Hills. .Open forests of pine cover most of a the claims; in creek valleys,willow and spruce thickets are common. SUMMARY OF WORK A geological map of the Ash Claims was prepared using an enlarged 1:50,000 scale topographic map to provide a base map of 1:10,000 scale. A total of 216 samples weye collected on a grid tied irlto the claim grid, of these samples 11 were analyzed 3 times for gold and 14 were analyzed twice. The repeat analyses were made to test the reproducability of the gold analyses obtained from the claim group. In addition, 27 silt samples and 43 rock samples were analyzed. All samples were assayed for gold, silver and arsenic, selected samples were run for copper, lead, z inc , f 1 uori ne , mercury, molybdenum and tungsten. DETAILED TECHNICAL DATA AND INTERPRETATION Regional Geology: The regional geology of the area surrounding the Ash Claims has been described by Duffel1 and McTaggart (1952) and by Church (1977). The oldest rocks on the claim group are Permian and belong to the Cache Creek Group; they are composed of metamorphosed cherty silt- stone, basaltic tuff and serpentine. Early Tertiary sandstone and con- glomerate belonging to the Coldwater Beds overlie the Cache Creek Group. A mass of fine-grained rhyolite, ‘2 km in diameter, cuts the Coldwater Beds in the southern portion of the claim group. ~ .- ....... .-. Assessment Report/Ash Mineral Claims/ 22 May 1981/Page 31 Detailed Geology: A map of the detailed geology of the claim group is 0 shown in Figure 4. The rock types are simple and distinct; the basement rocks are the Cache Creek Group which are overlain by sandstone and con- glomerate of the Coldwater Beds into which a rhyolite body has been emplaced. These three rock types are described in the following section. Unit 1: Cache Creek Group The Cache Creek Group is exposed in several outcrops in the northeast portion of the claims. Metabasaltic tuff, siliceous metasediments and chert plus serpentine comprise the exposures of Cache Creek Group on the Ash claims. An altered serpentine mass, outcropping 500 m west of Gallagher Lake, contains dolomite veinlets (5 mm wide) and chalcedony veins (2 mm to 2 cm wide). Black chert pebbles are very abundant in the overlying Coldwater Beds and were most likely derived from the Cache Creek Group. 'No geologic contacts were observed on the property but the great difference in ages between the Cache Creek Group (Permian) and Tertiary sedimentary and volcanic rocks suggests either structural or unconformable contacts ex- ist. Unit 2: Coldwater Beds The unit described here as "Coldwater Beds" is identical to that of Church's (1977) and does not include any of the "Hat Creek Coal Formation" or the "Medi ci ne Creek Formati on". The Col dwater Beds exposed on the cl aims a are lithologically similar to those underlying the Hat Creek area to the west and are described by Church (1977) as being "firmly indurated brown sandstones and conglomerates". Layers, up to 1 m thick, composed domi- nantly of pebbles are interbedded with medium to coarse-grained sandstone. The pebbles are rounded to subrounded, up to 5 cm in diameter but aver- aging 2 cm in diameter. The most common pebble lithology is black chert (65%; with 10% white quartz and 5% felsitf: or rhyolite pebbles composing 80% of the layer with the remaining 20% made up by sandstone matrix. The black chert pebbles are derived from the Cache Creek Group, the rhyolite or felsite pebbles are probably derived from the Spences Bridge Group of Cretaceous rhyolites exposed to the south of the Hat Creek area. Unit 3: Rhyolite The rhyolite unit on the claim group is composed of'a fine-grained rhyo- litic rock mass about 2 km in diameter, and forms the highest point on .the claim group. Typically the rhyolite is a homogenous, fine grained rock occasionally with a bimodal character containing small phenocrysts of quartz, sanidine, biotite or plagioclase. The phenocrysts are rarely over 1 m in diameter and seldom compose more than 5% of the rock. Quartz, sanidine, and biotite are most easily seen in fresh specimens whilst plagioclase is more visible in glacially polished outcrops. Rhyolite is usually massive and featureless, except for sections of highly jointed lava. The highly jointed rhyolite is believed to be a cooling phenomena because fractures cross-cut phenocrysts which indicates fract- 0 uring occurred after crystallization. I'n the southeastern part of the _...__.......... -.--_.r..._...._..._. - - .. .. .. .. .. .. .. .. .... .. .. .... ... .. .. ... .. .. .. .. __ ... .. .. .. .. .- .. .. .. .. .. .. ___ ._..... ,_. .. __ .. .. - .__ .. _. Assessment Report/Ash Mineral Claims/ 22 May 1981/Page 41 claim group a small area about 1.5 m thick and 5 m long shows vesicu- lation and a crude layering that may be fl%w banding. No other textures were observed to indicate that the rhyolite was extruded hence it is concluded that the rhyolite represents an intrusive dome. Structural Geology: The predominant structural trend on the Ash claims is NW-SE. Topographic linears and traces of faults run in the NW-SE direction as do the strike of most bedded rocks. Structural measurements made on the Coldwater beds show the strata to strike SSE to S (135' to 174O) and dip from 2Oo-5O0 westerly. Radial drainage patterns surround the rhyolite dome and indicate normal faulting assoicated with emplacement of the intrusive body. North-south trending faults cross-cut the rhyolite and suggest that some movement occurred along the major normal faults in the area after intrusion of the dome. The structural geology of the rock units on the Ash claims supports Church's (1977) contention that the Hat Creek area is a fault-bounded graben. The Ash claims lie on the upper eastern portion of the graben and most deformation has been tensional whereby blocks have downdropped along N-S trending normal faults. MI NE RAL I Z AT I ON No mineralization was observed in outcrop or. float. The only evidence of gold mineralization is found in the results of the geochemical sampling work. There are no pyritic or silicified zones evident in either the rhyolite dome or the Coldwater Beds,however,the contact zone between these two units is obscured by overburden.