L019 Seismic reflection and refraction survey on the Fenton Fault at Barnes Flow, WA, 1955.

Brief description

The Fenton Fault, one of the major tectonic lines in the Canning and Fitzroy Basins, has always presented a major problem to geologists seeking to determine its true nature and significance. The investigation described in this report was intended to contribute towards a solution of the problem. This investigation included a seismic reflection traverse across the Fault in the area of Barnes Flow, near where previous gravity and airborne magnetic traverses had crossed it, together with refraction traverses on each side of and across the fault. The results of previous surveys are discussed, and show that the gravity meter is a most useful tool for the further investigation of the Fenton Fault. However, unless new and effective treatment of results can be devised, it is of doubtful value in investigating folding within the Fitzroy Basin, though this does not necessarily detract from its value for regional surveys. The airborne magnetometer on the other hand, is not a reasonable tool for investigating the Fault. It is concluded that the Fenton Fault at Barnes Flow is a normal fault, downthrown to the north-east, with a throw probably exceeding 10,000 feet. The thickness of the sedimentary section on the north side of the Fault near Barnes Flow probably exceeds 16,000 feet. On the south side a velocity of over 20,000 ft/sec. was recorded from a depth of 5,500 feet. This probably indicates the depth to basement at this point. On the south side of the Fault at Jurgurra Creek the sedimentary section appears to be about 7,000 feet thick. The conclusion that baaement is relatively shallow to the south of the fault could be tested by drilling. The rig used should be capable of drilling to at least 6,000 feet to ensure that the 20,000 ft/sec. refractor may be penetrated and identified.

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Maintenance and Update Frequency: asNeeded

Statement: The first extensive mapping of the Fenton Fault was carried out by Wade in 1934. Later investigators, including Dr. F. Reeves (1951) have given it a lot of attention during their investigations in the Fitzroy and/or southern Canning Basins. During the past few years, it has been mapped in comparative detail from surface geology and crossed by geophysical traverses (airborne magnetometer, gravity and seismic), by geological and geophysical parties of the Bureau of Mineral Resources and of the West Australian Petroleum Pty.Ltd. The investigations have not, in general, been carried more than a few miles to the south-west of the known part of the Fenton Fault, because of masking of the geology and difficulty of access caused by the sand dunes of the north-west desert.