K/Ar dating of clays associated with mineralizations, and diagenetic processes, in relation with the South Atlantic Ocean breakup history

K/Ar dating of clays associated with some vein ore-deposits and with diagenetic alterations were performed on samples collected from various locations along the Atlantic coast of South America and in the Parana Basin. After mineralogical and geochemical control, especially concerning the Ti O2 content, the calculated ages show the following results: the ages of clays associated with fluorite mineralizations of the Santa Catarina Mine (SC) and uranium deposits at Pocos de Caldas (MG) are 87 and 67,5 Ma, respectively; the ages of clays from the 2TB 1SP hole in the Parana Basin define an older high temperature diagenetic episode dated between 140 and 130 Ma and a subsequent lower temperature event dated between 120 and 100 Ma; K/Ar determinations of celadonites and apophylites of diagenetic alterations of the Serra Geral flood basalts put this event between 120 and 100 Ma; all these results can be correlated with the geodynamic and magmatic evolution of South America during the breakup of the South Atlantic Ocean; the relationship in space and time between diagenesis and vein-type mineralizations on one hand and tensional tectonics on the other hand was already defined and accepted by various authors along the North Atlantic. Comparison between the new data of the present work with those used to define the model for North Atlantic lead to the conclusion that the same mechanisms have been operating during South Atlantic breakup. (author). 1 fig,. 3 tabs