“…Tripaldi et al, 2001;Limarino et al, 2001;Ciccioli, 2008;Ciccioli and Marenssi, 2012;Ciccioli et al, 2011Ciccioli et al, , 2013bCiccioli et al, , 2014aMarenssi et al, 2015).In particular, the modal composition of sandstones and conglomerates has proven an effective means to establish source areas and to explorethe relation between shifts in compositional framework and changes in watershed configuration (Ciccioli, 2008;Ciccioli et al, 2014a). Sandstone composition does not, however, depend exclusively on the source rocks: it may be affected by the physiography and chemical weathering in the source area, by reworking and abrasion of the sediments during transportation and sedimentation, by recycling of older sediments, and by diagenetic effects (Amorosi and Zuffa, 2011;Dickinson and Suczek, 1979;Espejo and Lopez-Gamundi, 1994). Additionally, uncertainty regarding the age of the Toro Negro Formation has prevented sedimentological observations from being interpreted in a well-dated regional framework.…”