EBSD microfabric study of pre-Cambrian deformations recorded in quartz pebbles from the Sierra de la Demanda (N Spain)

We describe a new method for the reorientation of lattice preferred orientation data in the absence of a pre-constrained kinematic reference frame. The method enables us to present conventional quartz fabric diagrams after measurements taken from rock sections with a general orientation with respect to foliation and lineation. A microstructural and Electron Back-Scattered Diffraction (EBSD) study of quartz pebbles in early Cambrian conglomerates following this method permit us to recognize a variety of fabrics that resulted from syn-metamorphic ductile deformation under variable temperatures up to 650 °C. The likely source area of the conglomerates was a Proterozoic basement. Candidates for source rock correlations include Neoproterozoic units similar to those outcropping in the northern Iberian Massif, Neoproterozoic medium- to high-grade metamorphic rocks as those outcropping in SW Iberia, or a Neoarchean to Mesoproterozoic concealed basement.

► Quartz LPO data were measured in pebble sections with a general orientation. ► A reorientation method permits presentation of conventional quartz fabric diagrams. ► Fabrics resulted from deformation under temperatures up to 650 °C. ► The source area of the pebbles was a metamorphosed Proterozoic basement.