Significance of 40Ar-39Ar encapsulation ages of metapelites from late Palaeozoic metamorphic complexes of Aysén, Chile

摘要: The ages obtained by the 40 Ar– 39 Ar encapsulation technique (retention and total gas ages) on 2 μm fractions of five metapelites from Eastern Andean Metamorphic Complex two Chonos allow discussion latest recorded metamorphic event in each zone. Kubler Index (KI) illite/muscovite (principal component metapelites) varies between 0.15° 0.45° Δ° 𝛉 , indicating regional variation diagenetic to epizonal grade. analyses reveal loss varying 21 25 %, which shows a limited positive correlation with KI values. retention metapelite reflect distinct conditions. Retention most probably indicate burial or events without plutonic influence southern Complex. Total contact for close intrusions northern thermal overprinting occurred Early Cretaceous times at 130 Ma 145 is related metamorphism an emplacement pulse North Patagonian Batholith. western belt suggest