Surficial Geology in the Chilanko Forks and Chezacut Areas

This report describes the preliminary re.wlts of surficial geological mapping during the 1992 field season in the Chilanko Forks (93Cil) and Chezacut 193CiX) map areas (Figure 4. IO-1 ). As part of the Canad;~ f3ritish Cofumhia Mineral Developme~~t Agreement, the British Columbia Geological Survey Rranch proposed to map the surlicial geology of these weiis to deriw drift exploration potential maps. The two map sheets to the tnorth, Clusko River (93(-/Y) and Toil MoLmtain (93C/l6) wcrc also mapped as part of this program (Proudfoot. 1993, this volume). The pmject’s main goals .rrc: . To produce I:%1 000 surficial geology map\ of NTS sheets YIC/I and Y3UX. . To define the regional Quaternary stratigraphy and glacial history. . To derive surficial drift exploration potential maps. This project illustr.rtcs the use of baseline surficial geology data, combined with a drift sampling program, for mineral exploration on a lowrelicf plateau with thick till cover. The Chilnnko Forks and Chelacut map xeu were selected hecausc mineral exploration in the region is hnmpered hy the thick and variable cover of swficial sediment, which masks the gx~logical. geochemic;d and <eophysial signatures 01’ mineral occurrencs:s, Furthermor :, the sttri’icial geology has not yet heen meppe~j and little is knowrl :f the Quatcrnary geological history. Derivative d-ill explor:itim potential maps. which will aid in detailed planning ,:f re@onal gcochemical and drili exploration sur\ eys, will he one of the products resulting Srom this invest& tion. A I;x:k of mineral exploration has led to a low demand for geolagical data in the reeion and few mapping projccl~ have hecn completed. Now, with increasing pressure on the mining and exploration industry in British Columbia a ( the invertory of caily explorahle lands decreases. new nethods WC being tested in areas previously avoided. The study region lies within the Fraser Pkteau, in t’le west-central part of the fnterior PI:ateau ifiollzu d, 1976). In the study area, the plateau is appl-onimately I 00 to I400 mares ahove sea level and is deeply dissected by the Talla Lake. Chilanko River and Chilcotin River ‘alleys. Tic plateau has llat to gently rolling topqraph) hrokcn Ihy occasional mountains or ridges (Pl;~te 4~~ IO11, Elevations range from a high of 1615 mettr:; on Arc Mountain in tie Inorthwest oC the Chuacut t,Up shcet~ t” a low o ~YOO met,es in the Chilanko River valley in the southeast of he Chilan co Forks sheet. The topography bsccomes gen :ratly mct’e diverse towards the north of tht study area.