Yukon-Tanana Terrane (YTT) in Frances Lake area consists of three domains: the Money/Jules Creek thrust sheet, the foot wall of the Jules Creek thrust, and a northeastern domain defined primarily by Permian (?) conglomerate. The Money/Jules Creek thrust sheet comprises chert, dark argillite and limestone, Mississippian meta-volcanic and meta-plutonic rocks, and Pennsylvanian carbonate. A dark argillite, chert, and coarse clastic unit of probable Pennsylvanian age unconformably overlies both the hanging wall and foot wall of the Money Creek thrust. The foot wall of the Jules Creek thrust comprises a lower unit of dark argillite, chert, chert-pebble conglomerate, and rare sandstone, limestone and variegated chert, and unconformably overlying conglomerate and basalt. The Pennsylvanian-Permian Campbell Range basalt overlies, probably unconformably, rock units of both domains. The northeastern domain comprises mainly Permian (?) polymictic conglomerate and sandstone. Conglomerate clasts come from YTT, implying an unconformable relationship. The back-arc rocks of YTT that host the Finlayson Lake volcanogenic massive sulphide (VMS) deposits are truncated by the Money Creek thrust; however, VMS-style prospects occur in coeval volcanic arc rocks in the Money Creek thrust sheet, attesting to the potential for new deposits in these rocks.
