Interference directions in the Cretaceous-Tertiary folds between Coello and Gualanday.

Abstract

The present study describes a section of the Upper Magdalena Valley between Gualanday, Coello and Doima in the department of Tolima. Guaduas and Gualanday formations cover the Western part, while the Cretaceous, represented from Maestrichtian to Coniacian, outcrop towards the East. Interesting to note is the difference between the folding of the Cretaceous and Lower Tertiary, and the folds of the Upper Gualanday. While the fírst strike NNE-SSW, the latter have a N-S orientation. Direct consequence of this difference are local angular and progressive unconformities, and the opposition of some Cretaceous anticlinals with Tertiary synclinal structures, besides the lack of continuity in others. Although the N-S strike dominates in some cases, the older direction still is maintained in the folds of some younger strata, so there is a real interference between these two directions.