contact aureole

contact aureole

[′kän‚takt ′ȯr·ē‚ōl]
(geology)
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Structures associated with folding and cleavage development are overprinted by the contact aureole of the Halifax Pluton, one of the constituent intrusions of the South Mountain Batholith.
A high-temperature origin for deformation structures can be excluded, even in the case of thermally metamorphosed rocks in the contact aureole of the Halifax Pluton, because thermal metamorphism in the aureole overprints cleavage, and therefore post-dates the regional deformation event; in contrast the deformation features characteristic of the Chain Rock member clearly pre-date this cleavage.
The contact aureole of the South Mountain Batholith in Halifax, Nova Scotia: geology, mineral assemblages, and isograds.
Although it is possible to observe local silicification in the outcrops near the contact, the regional metamorphic foliation is still present in rocks from the contact aureole and the overprinting contact metamorphism is mainly evident in thin section.
The thermal behavior in the contact aureole shows that the thermal peak is not reached at the same time in all areas around the pluton, while rocks in the inner aureole start cooling after its thermal peak those further out of the contact are still below their thermal peak.
Model predicts that, at a depth of 11 km, temperatures above 400 [degrees]C that could produce a metamorphic contact aureole in the country rock are only reached in a narrow zone of less than 200 m around the contact and that the peak temperature is reached soon after the intrusion (ca.
The Ubehebe Peak contact aureole, in California, USA (Fig.
In normal contact aureoles, exploration geologists should expect the following (or similar sequence): unaffected carbonate rock, first appearance of talc followed by first appearances of tremolite, forsterite with periclase and/or brucite directly in contact with the intrusive rock (Fig.
and Rumble, D., 1997, Formation and destruction of periclase by fluid flow in two contact aureoles: Contributions to Mineralogy and Petrology, v.
The fluids conveyed heat, silica, alumina and water to the marble and removed C[O.sub.2] from carbonates, producing the contact aureole. Temperatures during these reactions exceeded 700[degrees]C, and pressures reached 2000 bars.