 Most of the sediments was deposited in the near-coastal semiarid setting with shallow, wide, muddy, prograding shore, affected by tides, frequent storms and fluctuating sea level of tectonic or, possibly, eustatic origin (Andean-Saharan glaciation).Prior to lithification, the mud deposits had been frequently exposed subaerially and desiccated, as evidenced by the numerous mudcracks, while evaporites (mostly, gypsum) were deposited in isolated pools.The formation is composed of 14 facies, grouped into 4 facies associations, named A through D, corresponding to the specific depositional environments.