ETUDE DE LA MICROTEXTURE ORGANO-MINERALE DES ROCHES MERES EN MICROSCOPIE ELECTRONIQUE A BALAYAGE (ELECTRONS RETRODIFFUSES); RELATIONS AVEC L'ENVIRONNEMENT DE DEPOT ;ORGANO-MINERAL MICROTEXTURE OF SOURCE ROCKS IN SCANNING ELECTRON MICROSCOPY (BACKSCATTERED ELECTRON); RELATIONSHIPS WITH THE DEPOSITIONAL ENVIRONMENT
