%0 Journal Article
%A Romeo Briones, Ignacio
%A Capote Del Villar, Ramón
%A Lunar Hernández, María Del Rosario
%A Cayzer, N.
%T Polymineralic orientation analysis of magmatic rocks using ElectronBack-Scatter Diffraction: Implications for igneousfabric origin and evolution
%D 2007
%@ 0040-1951
%U https://hdl.handle.net/20.500.14352/49727
%X Electron Back-Scatter Diffraction (EBSD), which provides an easy way of acquiring large numbers of individual crystallographicorientation data from different phases, has been applied to the study of magmatic fabrics. Using this technique, the crystallographicpreferred orientation (CPO) of plagioclase, biotite, orthopyroxene, hornblende and quartz in natural tonalites and quartzdiorites (fromthe Santa Olalla Igneous Complex, SW Iberia) deformed during the magmatic stage have been determined. Plagioclase is the coarserphase defining the main fabric in each sample, whereas biotite can display either the same fabric as plagioclase or a completelydifferent one. The differences between these two phases occur because: (1) smaller phases interact with the larger ones to producemore random orientations, (2) under simple shear, finer phases can completely rotate giving a girdle included in the XZ plane, (3) finerphases can more easily preserve relict fabrics, while the coarser phases are completely reoriented by the last stress tensor. The lastphases to crystallize show weak to completely random CPOs (hornblende) or completely random distributions (quartz). The study wascompleted with a shape preferred orientation analysis using the Intercept Method in order to detect weak magmatic lineations, andnumerical modelling simulations of theoretically equivalent simple shear situations for each sample.
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