Abstract

The area discussed is a 30 km transect along the Mendoza City to Santiago de Chile road in western Mendoza Province, Argentina (32O25'-33"10', 69"- 69'20). The most southerly point on the map (Fig. I) is situated 30 km west of Mendoza City. Previous work by Caminos (1965) showed that two stocks of granitic rocks, Guido and Cacheuta, lie in a NNE/SSW trending basin of mainly acidic volcanic rocks of the Choi Yoi Lower Triassic, and syn and post rift sedimentary rocks of Upper Triassic age. Although both stocks intrude the Choi Yoi, they remain to be dated isotopically. Sedimentary rocks of Carboniferous and Devonian age crop out in the area, as well as a faulted basement slice. To the south of Cacheuta Stock is an contact between granitic and older dioritic rocks. Dykes of basalt and basaltic andesite intrude both stocks. All older lithologies have been affected subsequently by extensive brittle deformation.