THE BUBBLE HOTSPRING DEPOSIT BLACK DOME AREA (920/8W) By B. N. Church INTRODUCTION DISCUSSION The Bubble Hotspring deposit cccurs onthe Bubble claimgroup Although the general geologlcal setting of the Bubble Hotspring owned by Malabbar Mines Ltd. Tht deposit is readily accessibleon deposit is similar to the Blackdome mine a few kilometres to the the old Porcupine Creek road 2.5 kilometres east of Black Dome west (that is, Eocenehornblende andesite and rhyolite coun:ry Mountain and 25 kilometres soutt west of the Fraser River suspen- rocks), the obsidian immediately underlying the Bubble deposll is sion bridge near the Gang Ranch (Figure 2-5-1). The airstrip half a probably Miocene age and contemporaneous with the Black Dame kilometre southeast of the deposil is mostly overgrown by young basalt and the Porcupine Creek obsidian. Thermal and aquews spruce and jackpine trees. discharge from the cooling obsidian is the suspected origin of :his yellowstone siliceous sinter deposit. GEOLOGICAL SETTING REFERENCES The property is extensively covcred by glacial till and alluvium. KC. Ministry aJ'Energy, Mines and Petroleum Resources, Assms- Bedrock exposuresare mostly along themain road near thecentre of men1 Reports 10486 to 11261 the properly and on the hillside lo the southwest. Church, B.N. (1980): Exploration for Gold in the Black Dome The hotspring deposit is brighta yellow siliceous encrustation, IO Mountain Area, B.C. Minisrry ofEnerg): MinesandPerrole~m Resources, Geological Fieldwork, 1979, Paper 1980-1, paEes to 30 metres thick, formmga terraced structure immediatelyoverly- 52-54. ing rhyolite obsidian (Plates 2-5-1 and 2-5-2). It covers an area measuring at least 150 metres acro!is. as viewed on a switchback on ~ (1982): The Black Dome Mountain Gold-Silver Pms- the Porcupine Creek road. The dislinctly layered aspect and bossed pect, B.C. Minisrry of Energy, Mines and Petroleurn Re- sources. GeologicalFieldwork, 1981, &per 1982-1, pa;:es surface of the deposit suggest a thermal spring origin. Opalescent 106-108. quartz, including a small amounl of fire opal. fills crosscutting fissures and interstices between th: yellowstone layers. Faulkner, E.L. (1986): Blackdame Deposit (920/7E, SW), B I:. Ministry uf Energy, Mines and Petroleum Resources, GK- Similar deposits occur near the AuNn Mines Ltd. perlite oper- logical Fieldwork, 1985, Paper 1986-1, pages 107-109. ation in the Empire Valley, 6 kilometres lo the east (Z.D. Hora, Mathews, W.H. and Rouse, G.E. (1984): TheGangRanch-Big Bar personal communication, 1986). They are correlated with obsidian Area,South-central British Columbia: Stratigraphy, Go,- on Porcupine Creek dated 26. I 2 0.9 million years, which is similar chronology, and Palynology of the Tertiary Beds and their to the age of the Black Dome basalt dated 24.0 z0.8 million years Relationship to the Fraser Fault, Canadian Journal of Eavth (Faulkner, 1986; Mathews, et al., 1984). Sciences, Volume 21, pages 1132.1 144. ~ British Culumbia Ministry of Energy, Miner and Petroleum Resources, Geological Fieldwork, 1986, &per 1987-1. 39 LEGEND SYMBOLS MIOCENE @ Basaltlava and agglomerate Geologicalcontact ....... Yellowstone siliceous sinter and obsidian Fault "- EOCENE Road ====== a Daciticandesite domes Stream w" Andesite lava and breccia groupClaim boundary "" Rhvolite lava and tuffs Portal Lwl + Aphyric dacite, andesite and basalt Figure 2-5-1. Geology in vicinity of the Bubble Hotspring deposit. Black Dome area 40 Platc 2-51, Bossed surfacc of yellowstone silica sinter. Plate 2-5-2. Ycllowstonc silica sinter, Bubble Hotspring dcposit 41 .