On the kinetics of textural equilibration in forsterite marbles; reply

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Authors:Holness, M. B.; Bickle, M. J.; Graham, C. M.
Author Affiliations:Primary:
Univ. Edinburgh, Dep. Geol. Geophys., Edinburgh, United Kingdom
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 111(3), p.421-422. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1992
Note:In English. 5 refs.
Summary:The present authors defend their use of a thermal model of the aureole of the Beinn an Dubhaich granite which was necessary in order to compare the textural changes observed in the forsterite marbles of the aureole with those seen in laboratory experiments. The only constraints on the thermal development of the aureole were the observed spacing of the isograds and an estimate of the crystallization T of the granite. The assumptions made in order to construct the model were: 1) that the narrowest observed isograd spacing represented the true spacing of the isograds; 2) that the spacing of the isograds had not been altered after their development by stretching of the rocks of the aureole; 3) that the P of metamorphism was in the region of 0.5-1 kbar (based on a published estimate [A.M. 66-491] of overburden at the time of intrusion). This assumption permitted the calculation of reaction T's which lead in turn to an estimate of the maximum T in the aureole as a function of distance from the granite. The T of the country rock prior to intrusion of the granite and the time during which the contact was held at the intrusion T of the granite were estimated by comparison with the loci of maximum T's obtained using the model with those given by spacing of the isograds. It was found that the best fit was given if the country-rock T did not exceed 150 degrees C and the contact did not remain at the intrusion T for > 1000 yr. The estimate for country-rock T obtained in this way is similar to that expected for an active volcanic field. [P.Br.]
Subjects:Aureoles; Calcite; Carbonates; Deformation; Equilibrium; Forsterite; Granites; Host rocks; Igneous rocks; Ion exchange; Kinetics; Marbles; Metamorphic rocks; Models; Nesosilicates; Olivine group; Ordovician; Orthosilicates; Paleozoic; Plutonic rocks; Silicates; Temperature; Textures; Europe; Great Britain; Hebrides; Highland region Scotland; Inner Hebrides; Inverness-shire Scotland; Isle of Skye; Scotland; United Kingdom; Western Europe
Abstract Numbers:93M/569
Record ID:1993028796
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe
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