metamorphic aureole

metamorphic aureole

[¦med·ə¦mȯr·fik ′ȯr·ē‚ōl]
(geology)
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The sharp offset in the andalusite-in isograd assists mapping the stratigraphic contact within the metamorphic aureole.
All these units and structures are overprinted by regional Neoacadian folds and cleavage, and by the metamorphic aureole of the Halifax Pluton.
Especially, our research addresses the emplacement conditions of the pluton in the low--medium grade metamorphic country rock that produced a contact metamorphic aureole around the pluton.
The name Parashi Pluton was proposed by Renz (1959) and redefined by Lookwood (1965) as Parashi Quartzdiorite, who characterized the body as a mesozonal intrusion with a narrow contact metamorphic aureole in the country rock and reported a hornblende K/Ar age of 48 [+ or -] 4 Ma in a quartzdiorite sample from the pluton.
A contact metamorphic aureole is observed around the pluton, in the west margin, the width of the aureole is about 50 m.
It is estimated that a pluton at depth could have a diameter of roughly 1,000 m, based on the width of the contact metamorphic aureole on surface, whereas the intrusion at the centre of the deposit is roughly 200 m in diameter.
Contact metamorphic aureoles that overprint siliceous dolomite-bearing carbonates are divided into two categories: those aureoles that, at the peak of high-grade metamorphism, contained periclase-forsterite-calcite and those that contained dolomite-forsterite-calcite (no periclase) assemblages.
Such settings coincide with the highest metamorphic grade of metamorphic aureoles (near intrusive-carbonate contacts and along nearby fault and fracture zones), where the hydrothermal fluid travels quickly without cooling down because of its reactions with the host rock.
Although brucite is relatively widespread as an accessory mineral in a variety of rock types, Mg-rich carbonate horizons within contact metamorphic aureoles have the best exploration potential.