AR-40 AR-39 DATING OF METAMORPHIC SOLES FROM THE ALBANIAN OPHIOLITES - IMPLICATIONS FOR THEIR EMPLACEMENT MODELS/

The metamorphic soles of the Albanian ophiolites, 0.5 km thick: highly deformed, show an inverted metamorphic gradient, formed during the ea rly stages of intra-oceanic thrusting. Twenty-Sour Ar-40/Ar-39 radiome tric ages were obtained on amphiboles and micas from the different sol es and ophiolitic igneous genesis rocks. The main results are the Midd le Jurassic age (160-174 Ma) of the the metamorphic soles, an importan t north-south diachronism (up to 14 Ma) over 150 km, and a synchronism between the metamorphism and the late magmatic events. The closure of the triangular oceanic basin, cut by ENE-WSW transform faults, can ex plain these results. (C) Academie des sciences / Elsevier; Paris.