Comment on “Tethyan calpionellids in the Neuquen Basin (Argentine Andes), their significance in defining the Jurassic/Cretaceous boundary and pathways for Tethyan-Eastern Pacific connections” by R. Lopez-Martínez, et al

Diego A. Kietzmann, María Paula Iglesia Llanos
Año de la publicación: 
2 017
Journal of South American Earth Sciences xxx (2017) 1-4
Introduction In this contribution, Lopez-Martínez et al. (2017) state that they achieved to define the position of the Jurassic- Cretaceous (J-K) boundary from the finding of Tethyan calpionellids in the Vaca Muerta Formation at Las Loicas section, Neuquen Basin. The authors analyzed ten samples in a reduced interval of the Vaca Muerta Formation where the boundary would lie. Las Loicas section represents a basinal section of c. 270 m with large covered intervals (c. 90 m) bearing ammonites of the Lower Tithonian Virgatosphinctes mendozanus Zone to at least the Upper Berriasian Spiticeras damesi Zone (Aguirre-Urreta et al., 2014). The upper part is covered. We do consider that the data presented by Lopez-Martínez et al. are important for the discussion on the J-K boundary in Argentina, provided that the knowledge of calpionellids in the Neuquen basin is very poor. The aim of this Comment is to better explain some data derived from previous biostratigraphic and magnetostratigraphic studies (i.e. Fernandez Carmona and Riccardi, 1999, Kietzmann et al., 2011a; Kietzmann, 2017; Iglesia Llanos et al., 2017) that Lopez-Martínez et al. (2017) failed to interpret correctly.