Quantitative Textural Insights into the Formation of Gabbro in Mafic Intrusions

Rock textures provide a key to deciphering the physical processes by which gabbro forms in mafic intrusions. Developments in both direct optical and crystallographic methods, as well as indirect magnetic fabric measurements, promise significant advances in understanding gabbroic textures. Here, we illustrate how bulk magnetic fabric data, particularly from intrusions with sparse silicate-hosted magnetite, may be used to extend direct crystallographic observations from thin sections. We also present a scheme for characterizing crystallographic foliation and lineation and use this to suggest that the strength of gabbro plagioclase foliations and lineations varies significantly with geodynamic environment.