Incised Valleys and Channel Fills in the Puerto Madryn Formation (Miocene) of Península Valdés, Patagonia, Argentina

SCASSO, ROBERTO; CUITIÑO, JOSÉ; DOZO, MARÍA TERESA

Puerto Madryn

Conferencia; Tidalites 2015. 9th International Conference on Tidal Sedimentology; 2015

Asociación Argentina de Sedimentología; CENPAT-CONICET

Incised valleys form in response to a relative fall of the sea level and, unlike distributary channels, they are not in facies relationship with the surrounding sediments into which they are incised (Van Wagoner et al., 1990; Maynard et al., 2010). However, it is not an easy task to distinguish one from the other. Diagnostic criteria mostly rely on the shape, scale (depth of scour and area) and correlation of the erosion surface to a sequence boundary (Van Wagoner, 1990; 1995; Zaitlin et al., 1994; Posamentier, 2001; Gibling, 2006) although some criteria are still under revision (Maynard et al., 2010).Superb exposures on coastal cliffs and gullies along the coast of Golfo Nuevo and Golfo San José in Peninsula Valdés (Chubut - Figure 1) allow reconstructing 3-D geometry of channel fills and tracing erosion surfaces along tens of kilometers. We analyze here two stratigraphic intervals of the Miocene Puerto Madryn Formation with prominent erosion surfaces and channel deposits which are thought to fill two incised valleys, namely the Co. Olazábal-Punta Alt and the La Pastosa-Punta Fósil incised valleys.