Eileen J. Farley

The Turner tin prospect and the Walker molybdenite deposit are situated in the New Ross - Vaughan complex, a large 2-mica adamellite body which diapirically intruded the biotite granodiorite of the South Mountain batholith.

The Turner tin prospect lies in a host of 2-mica adamellite and consists of three quartz greisen zones and a quartz porphyry. The Walker deposit lies in a host of leucoadamellite and greisenised aplite and pegmatite are the main mineralised rocks.

Ten samples were analysed for major elements, sixteen for trace elements Rb, Sr, Ba, Zr, Nb, La and Ce. Eight samples were analysed for rare earth elements and other trace elements.

Opaque minerals are disseminated in the greisens of both deposits and the Walker pegmatite carries molybdenite. Silicates and opaque minerals were analysed by microprobe.

In the Turner prospect the following minerals were identified. Arsenopyrite, pyrite, sphalerite, chalcopyrite, stannite, wittichenite, bornite, cassiterite, covellite and chalcocite.

The Walker deposit contains molybdenite, wolframite, gahnite, cassiterite, uraninite, bornite, mawsonite, tennantite, wittichenite, chalcopyrite, digenite, covellite and bismuth metal.

Fluid inclusion studies revealed a range of temperatures from 170^oC-410^oC. Age relations indicate a close temporal relationship between the greisen and host rocks.

The evidence suggests that the greisenising fluid is the end product of differentiation of the granitic melt. It was rich in volatiles, incompatible elements and rare metals. The Walker pegmatite and greisen were apparently derived from the same fluid.

The quartz porphyry in the Turner tin prospect intruded greisen and was apparently derived from a deep still molten magma source.

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Pages: 268
Supervisor:  D. B. Clarke