Grantham, GHThomas, RJEglington, BMDebruin, DAtanasov, AEvans, MJ2007-03-282007-06-072007-03-282007-06-071993Grantham, GH, et al. 1993. Corona textures in Proterozoic olivine melanorites of the equeefa suite, Natal metamorphic province, South-Africa. Mineralogy and Petrology, vol. 49, 02 January, pp 91-1020930-0708http://hdl.handle.net/10204/2162http://hdl.handle.net/10204/2162Olivine-plagioclase and phlogopite-plagioclase coronas have been identified from olivine melanorites of the mid- to late Proterozoic Equeefa Suite in southern Natal, South Africa. Olivine, in contact with plagioclase, is mantled by a shell of clear orthopyroxene, in turn rimmed by pale green (pargasitic) clinoamphibole. Locally a third rim, composed of a fine pargasite-spinel symplectite is developed adjacent to the plagioclase. The second corona reaction has produced greenish-brown pargasite at phlogopite-plagioclase interfaces. A third, less obvious reaction, between olivine and phlogopite is also noted. Analytical data of all the mineral phases present, along with the coronas, are given. Two-pyroxene thermometry yields magmatic core temperatures (approximately 1120-degrees-C), with rim compositions indicating equilibration at approximately 850-degrees-C. Consistent with this, the modelled olivine-plagioclase reaction occurs between 830-1050-degrees-C with a(water) between 0.1 and 1.0 at 7 kbar. The three reactions took place during a prolonged history of cooling and partial hydration of the magmatic olivine melanorites from over 1000-degrees-C down to approximately 600-degrees-C. The P-T conditions indicated by the reactions suggest this cooling process was essentially isobaric, indicating that the area was not subjected to rapid uplift or burial throughout this entire period.1326904 bytesapplication/pdfenCopyright: 1993 Springer-Verlag WienOlivine-PlagioclasePhlogopite plagioclaseOlivine melaronoritesProterozoic equeefa suiteNatalSouth AfricaMineralogyArticleGrantham, G., Thomas, R., Eglington, B., Debruin, D., Atanasov, A., & Evans, M. (1993). Corona textures in Proterozoic olivine melanorites of the equeefa suite, Natal metamorphic province, South-Africa. http://hdl.handle.net/10204/2162Grantham, GH, RJ Thomas, BM Eglington, D Debruin, A Atanasov, and MJ Evans "Corona textures in Proterozoic olivine melanorites of the equeefa suite, Natal metamorphic province, South-Africa." (1993) http://hdl.handle.net/10204/2162Grantham G, Thomas R, Eglington B, Debruin D, Atanasov A, Evans M. Corona textures in Proterozoic olivine melanorites of the equeefa suite, Natal metamorphic province, South-Africa. 1993; http://hdl.handle.net/10204/2162.TY - Article AU - Grantham, GH AU - Thomas, RJ AU - Eglington, BM AU - Debruin, D AU - Atanasov, A AU - Evans, MJ AB - Olivine-plagioclase and phlogopite-plagioclase coronas have been identified from olivine melanorites of the mid- to late Proterozoic Equeefa Suite in southern Natal, South Africa. Olivine, in contact with plagioclase, is mantled by a shell of clear orthopyroxene, in turn rimmed by pale green (pargasitic) clinoamphibole. Locally a third rim, composed of a fine pargasite-spinel symplectite is developed adjacent to the plagioclase. The second corona reaction has produced greenish-brown pargasite at phlogopite-plagioclase interfaces. A third, less obvious reaction, between olivine and phlogopite is also noted. Analytical data of all the mineral phases present, along with the coronas, are given. Two-pyroxene thermometry yields magmatic core temperatures (approximately 1120-degrees-C), with rim compositions indicating equilibration at approximately 850-degrees-C. Consistent with this, the modelled olivine-plagioclase reaction occurs between 830-1050-degrees-C with a(water) between 0.1 and 1.0 at 7 kbar. The three reactions took place during a prolonged history of cooling and partial hydration of the magmatic olivine melanorites from over 1000-degrees-C down to approximately 600-degrees-C. The P-T conditions indicated by the reactions suggest this cooling process was essentially isobaric, indicating that the area was not subjected to rapid uplift or burial throughout this entire period. DA - 1993 DB - ResearchSpace DP - CSIR KW - Olivine-Plagioclase KW - Phlogopite plagioclase KW - Olivine melaronorites KW - Proterozoic equeefa suite KW - Natal KW - South Africa KW - Mineralogy LK - https://researchspace.csir.co.za PY - 1993 SM - 0930-0708 T1 - Corona textures in Proterozoic olivine melanorites of the equeefa suite, Natal metamorphic province, South-Africa TI - Corona textures in Proterozoic olivine melanorites of the equeefa suite, Natal metamorphic province, South-Africa UR - http://hdl.handle.net/10204/2162 ER -