Characterisation of grain-size, shape and orientation of plagioclase in the Rooi Rand dyke swarm, South Africa

W.W. Hastie (1) , M.K. Watkeys (1) , Charles Aubourg (2)

1 School of Geological and Computer sciences
2 LFCR - Laboratoire des Fluides Complexes et leurs Réservoirs

Magmatic (type-A) fabric co-exists with dyke-orthogonal (type-B) fabric in both the plagioclase and opaque grain fractions in dykes of the Rooi Rand dyke swarm (RRDS). We present new data from the RRDS pertaining to the size, shape, texture and orientation of plagioclase. Texturally, the samples range from intersertal to sub-ophitic and phenocrystic (plagioclase-phyric). More than 90% of plagioclase grains are <33μm in size and the modal size is 12.3μm. The smallest, most abundant grains have modest shape ratios (1.40

Keywords: Grain-size; Magmatic fabric; Plagioclase; Shape preferred orientation

Domains: Earth Sciences

W.W. Hastie, M.K. Watkeys, Charles Aubourg. Characterisation of grain-size, shape and orientation of plagioclase in the Rooi Rand dyke swarm, South Africa. Tectonophysics, 2013, 583, pp.145-157. ⟨10.1016/j.tecto.2012.10.035⟩. ⟨hal-00832711⟩