Uranium ore-forming systems of the - Geoscience Australia

Uranium ore-forming systems of the Lake Frome regionUnion Corporation geologists in the 1970s recognised paleochannel stratigraphy in the drill holesof ELs 5-6 but the four-mile grid spacing of drilling prevented mapping of the possible channels(Randell, 1973). Their preferred model invoked a deltaic environment with westward paleo-flowtowards a larger ancestral Lake Frome (in which the Namba carbonates and dolomitic ooze in thesouth-western corner of the tenements were deposited).It is notable that the possible eastern paleochannel in the upper parts of the Namba Formationcorrelates well with the position and orientation of the Yarramba Paleochannel in the underlyingEyre Formation to the south. One interpretation is that a general northwards direction of sedimenttransport was via paleochannels was extant during both the deposition of the Eyre Formation andNamba Formation. Similar northerly transport of sediment in the Beverley paleochannel seemsprobable, based on branching geometry of the channel (see Chapter 5). However, it cannot beassumed that groundwater flow during uranium mineralising events followed the same directionsas the channels because of possible neotectonic modifications to paleodips in the region.Page 56 of 151