Rob
Speak to Ian Parsons at Edinburgh.
Clive
On Tue, 15 Feb 2000 14:31:38 +0000 Robert Willan
<[log in to unmask]> wrote:
> Best wishes for 2000 everyone!
>
> Has anyone come across sanidine in plutonic rocks, and if so what is its significance?
>
> It looks like orthoclase (brownish colour, dusty appearance), is anhedral and interstitial, replacing plag and forming graphic intergrowths with quartz.
>
> But it has a small 2V (10-30°) is almost uniaxial (characteristic of sanidine) and is optically negative .
>
> The intrusion is a small (1-2 km) med grained granodiorite stock with marginal propylitic alteration. It contains granophyric intergrowths, miarolitic cavities and mm-scale veinlets of quartz, pyrite, pyrrhotite, magnetite, chalcopyrite and bornite. There is an extensive propylitised aureole and about 1 km away, areas of argillic, sericitic and advanced argillic alteration.
>
> Any examples of sanidine in plutons?
>
> Thanks - Rob
>
> ----------------------------------------------
> Dr Robert CR Willan,
> Magmatic-Hydrothermal Processes
> Geological Sciences Division,
> British Antarctic Survey,
> Cambridge CB3 0ET, UK
> Tel: 01223 221420
> FAX: 01223 362616
> Email: [log in to unmask]
> -----------------------------------------
>
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clive rice
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