Clay mineral evolution in diagenetic and very low-grade metamorphic sedimentary rocks from the Maláguide Complex was studied using the following parameters: illite and chlorite crystallinity, b cell dimension of illite, chemistry of chlorite, and the occurrence and distribution of the following phyllosilicates: I-S mixed-layer minerals, kaolin polytypes, chlorite-bearing mixed-layer minerals (tosudite and mica-chlorite interstratifications), vermiculite-like minerals, paragonite and biotite. The distribution of IC values permits the subdivision of the study area into three zones: diagenetic, anchizone and epizone. On the contrary, the distribution of CC values cannot be used in the study of the metamorphic zonation. The mineralogy and b dimension of illite indicate that the Maláguide samples display a low to low-medium pressure metamorphism, also characterized by steep temperature gradients.

The correlation between IC data and distribution of other significant minerals has permitted the establishment of a zonation within the chlorite zone, which is confirmed by the appearance of some index minerals, such as paragonite, biotite, chloritoid and andalusite.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.