The North West

Tasmanian North West and West Coast Range regional Geology

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The North West

Postby admin » Thu Sep 27, 2012 10:06 pm

The North West and West Coast of Tasmania is breathtaking geologically. The earth history is staggering. Glaciation, Volcanics, Major Tectonic events and upheavals. It floats my boat.

i havent been to all areas so can only write what i have seen. If anyone can elaborate on other areas please do.

The West coast is the oldest place in Tassie, the east coast didnt exist until we hit the spreading Pacific / NZ plate that hit around Hobart imo, driving the East coast of Tasmania up and over. This is gondwanaland breaking up. and is the same event that runs from below Hobart in the south to cape York in Qld. Everything east of the Range is sea floor and volcanics. The central highlands of Tassie was pushed up and over creating the West coast range. The second orogeny created the belt from Zeehan through Tullah and up to Que River. The Aurthur Lineament is a 110km long dolerite running at right angles to Hobart and the West coast range. The area NW of their i dont know at all.
Corrina - Savage River. The Oldest known rocks on mainland Tasmania are in the Tarkine and correspond to those on King Island. 720 million years old. the rest of Tasmania is only 530mil +/- It is also unique in that you get all 4 types of ultrabasic acid rock in one area. Granite Dolerite Basalt and,,, i cant remember. im not a geo :lol: .. The nw is Divided by the Aurthur Lineament running from Trial harbour up to Doctors rocks in a NE / direction. Mount Meridith to the south is the main Granite Pluton and in my opinion set, off the gold horizon to the North.

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Melba Flats

Postby Philski » Wed Nov 21, 2012 6:21 pm

Melba Flats is an interesting mineral field in quite a remote part of Tasmania The area has Osmiridium, Gold, Silver, Lead, Zinc, Copper, Nickel, Crocoite, Serpentine with Stitchtite (Atlantasite) are East. And is surrounded on all sides by active and historical mines and looks to be tectonic driven as apposed to volcanic. One quartz vein i encountered was a good 30 feet wide at its widest and highest point. The strike Length (N/S) was 50 meters+ at surface. But contained no economic mineralization or evidence of ever worked. The north west Contains a mountain of Serpentine with visible Asbestos. This extends south to the rail shed and isnt encountered in the S/W. There is some evidence of cross faulting. The area contains some nice specimens of Serpentine.

We examined the area with two gpx 5000, hand sampling creeks etc. so had a fair crack at it. Mineralization in the forestry area South west of the Train shed, Saw no Gold or anything really. However its a good chance to know there is none there. The chance to see the Earth after they have ripped it to grow trees is amazing. Im not sure what the Gorse in the area will do however, if they get into the open area of forestry? It stopped us prospecting in one creek at Melba Flats. The first time in my life a plant has stopped me prospecting i think.

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