[Aqualist] Lacustrine sediments far west NSW

[Jeanette Hope]

Last Sunday, while I was helping to pull sheep out of ground tanks on Pimpara Lake Station northwest of Broken Hill, I saw an unusual sedimentary sequence in a ground tank currently being excavated:

Ca 1-2    Red aeolian sand
Ca 2m    White fine grained clay with some small gypsum crystals
Ca 3+m  Black fine-grained clay with a couple of red layers
Ca 2+m   White fine grained clay.

The contrast between the black and white layers was dramatic. Both black and white layers are very hard.   I've never seen anything like this sequence in western NSW and I've looked at a lot of ground tanks and other exposures.  

The station is west of Lake Bancannia/Lake Cobham, and the tank was being excavated in the general floodplain of Packsaddle Creek (but not near Lake Pimpara - a salt lake further west) which flows west towards Lake Frome.    I am told that the similar sediments have been exposed in other ground tanks along the creek.

I'd be interested to hear of any palaeo / geomorph studies on lake sediments in this area (I'm aware of the archaeological work at Fowlers Gap, to the south).  And I can provide some samples, if anyone's interested in seeing what might be in the sediments.      

Regards

Jeannette Hope 
River Junction Research
PO Box 144
Wentworth NSW 2648
03 5027 3049