Comment on ‘Evidence for an Early-Middle Miocene age of the Navidad Formation (central Chile): Paleontological, paleoclimatic and tectonic implications’ of Gutiérrez et al. (2013, Andean Geology 40: 66-78)

Abstract

The Navidad Formation has been the reference unit for the marine Neogene of Chile and the debate about its age and depositional paleoenvironment has a long history. In their recent contribution, Gutiérrez et al. present an interpretation of the Navidad Formation that contrasts with that our research group concluded and incorporated in several publications (Encinas, 2006; Encinas et al., 2006; Finger et al., 2007; Encinas et al., 2008; Nielsen and Glodny, 2009). Gutiérrez et al. base their conclusions mostly on our and others’ data, adding eight new 87Sr/86Sr and two new 40Ar/39Ar age determinations. Most of the arguments presented in their work have been debated by our group for more than a decade, and Finger et al. (2007) expounded upon them. Despite our previous attempt to make sense of the contradictory data, we expected the issues were likely to remain controversial. We therefore welcome further discussion on these subjects.