PAULINGITE FROM JUNIN DE LOS ANDES, PATAGONIA, ARGENTINA

MARIA ELENA VATTUONE; SABRINA CROSTA; LATORRE, CARLOS OSCAR; LEAL, PABLO; BERBEGLIA, YANINA

Santa Fe, EEUU

Congreso; 44° Annual Meeting of the Clay Mineral Society; 2007

Paulingite in assemblage with Ca-K-Na phillipsite and chabazite was found on the border of amygdales of Tertiary amygdaloid alkaline basalts located near Junin de los Andes, Patagonia. The outcrop is located at 39°54'57" south and 71°03'10" west. The zeolites were studied by SEM, EDS and XRD.  Analcime, natrolite, thomsonite, mesolite and scolecite also occurs filing different amygdales. In the matrix of these rocks, there are albite, interestratified chlorite/smectite, pumpellyite, and very scarce yugawaralite. Altered olivine and fresh pyroxene are the primary minerals that remain in few samples of these rocks (Vattuone et al., 2006).  Paulingite is isotropic with dodecahedral, trapezohedral and cubic forms (Fig. 1). The XRD spacings are coincident with 39-1378 JCPDS-ICDD (1994). The parameters of the unit cell are: a0 = 35.10 Å, according to Armbruster and Gunter (2001). Table 1 shows a chemical composition that evidences a low Tsi= 0.71/0.72. The amount of Ca and K indicate that this paulingite is in the range proposed by Passaglia and Sheppard (2001) for this species. The paulingite-phillipsite assemblage indicates that temperature of formation occurs in 60°C/80°C range (Deer et al., 2004). On the other hand their crystallization in basalt amygdales suggests deuteric processes.