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Katherine Groundwater Investigations, Cretaceous Sediments near the King River,1985.



Katherine Groundwater Investigations, Cretaceous Sediments near the King River,1985.


Yin Foo, Des


E-Publications; E-Books; PublicationNT; Report ; 3/1985




Made available via the Publications (Legal Deposit) Act 2004 (NT).





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Dept. of Mines and Energy

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Report ; 3/1985

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Technical Report WRD85003 Viewed at 14:07:03 on 29/07/2010 Page 11 of 45. 2. HYDROGEOLOGY This section is a surmnary of the interpretation of results obtained by drilling, geophysical downhole logging, test pumping and field observations during the investigation between October and November 1984. Results from the groundwater investigations in the Venn area the preceding year and at Bamyili in mid 1984 were also used in correlating the data. Bores are The bores to 23429 these and Table AI. referred to by their registered numbers. drilled during this investigation were 23424 inclusive and 23540. Lithological logs of other relevant bores have been included in Their locations are shown on Figure 2.l(a). 2.1 Geology The study area (shown on Figure 2.1 (a) ) is predominantly masked by the Mullaman Beds (KIm) which are of Lower Cretaceous age. These sediments include in sequence, a basal, medium to coarse sandstone; siltstone and sandy siltstone; and claystone and silty claystone at the top. A significant thickness of sandy Cainozoic deposit overlies some of the study area, and a laterised surface exists throughout. Exposures of the basement Tollis Formation (Pbt) have resulted from incisions by creek and valley systems in the region of higher elevation to the north of the study area. This Formation consists mainly of greywacke and siltstone. The Formation deepens in a south westerly direction and has been capped in the lower parts by basalt flows of the Antrim Plateau Volcanics. (CIa) Table 2.1 contains a summary of the lithologies of the geological sequence in the area. The deepening basement east of the King River has favoured up-slope deposition during the Cretaceous transgression of seas. This has resulted in thicker sequences of sand and clay in bores 23425 and 20509 which were drilled in the south of the study area, and indicated the base of the Cretaceous strata to be at depths of about 70m. A further deepening of the strata tmvards the south is suggested by the cross-section on Figure 2.1 (b). Bores drilled through the Cretaceous sequence in the project area have usually intersected a dark red to chocolate brown mudstone ,vi th cherts. These may be identified as remnants from the DYF:TJ:79 04:REP4