Anorthite megacrysts from island arc basalts

DOI Web Site 9 Citations

Bibliographic Information

Published
1995-03
Rights Information
  • https://www.cambridge.org/core/terms
DOI
  • 10.1180/minmag.1995.59.394.01
Publisher
Mineralogical Society

Search this article

Description

<jats:title>Abstract</jats:title><jats:p>Anorthite megacrysts are common in basalts from the Japanese Island Arc, and signally rare in other global fields. These anorthites are 1 to 3 cm in size and often contain several corroded Mg-olivine inclusions. The megacrysts generally range from An<jats:sub>94</jats:sub>Ab<jats:sub>4</jats:sub>Ot<jats:sub>2</jats:sub> to An<jats:sub>89</jats:sub>Ab<jats:sub>6</jats:sub>Ot<jats:sub>5</jats:sub> (Ot: other minor end-members, including CaFeSi<jats:sub>3</jats:sub>O<jats:sub>8</jats:sub>, CaMgSi<jats:sub>3</jats:sub>O<jats:sub>8</jats:sub>, AlAl<jats:sub>3</jats:sub>SiO<jats:sub>8</jats:sub>, □Si<jats:sub>4</jats:sub>O<jats:sub>8</jats:sub>) and show no chemical zoning. They often show parting. Redclouded megacrysts contain microcrystals of native copper with a distribution reminiscent of the shape of a planetary nebula. Hydrocarbons are also present, both in the anorthite megacrysts and in the olivines included within them. Implications of lateral variations in the Fe/Mg ratio of the included olivines, in Sr-content and in Sr-isotope ratio of the anorthite megacrysts with respect to the Japanese island arc, relate to mixing of crustal components and subducted slab-sediments into the basaltic magmas.</jats:p>

Journal

Citations (9)*help

See more

Details 詳細情報について

Report a problem

Back to top