PHASE-TRANSFORMATION DURING THE GLAUCONITIZATION PROCESS AS REVEALED BY HRTEM AND MICROCHEMICAL STUDY

New insight about the structure, chemistry and genesis of glauconite minerals was possible thanks to simulaneous use of HRTEM and EDX microanalysis. This study reveals that glauconitization constitutes an evolutionary process including the successive formation of different layered phase, all finely characterized, and their subsequent destabilization. Particularly, the intimate organization of the glauconite pellets, the curious polytypic behaviour of the glauconite sensu stricto and the detailed transformation mechanism from one layer phase to another are evidenced and discussed. EDX analyses reveal also the complexity of the geochemical ways permiting these transformations.