Lithostratigraphy and sedimentology of the lower Cambrian carbonate Gonnesa Group of Iglesiente (SW Sardinia, Italy): data from the Oridda area

In the Iglesiente (SW Sardinia, Italy) the lower Cambrian carbonate Gonnesa Group succession of the Oridda area was investigated. A reconnaissance survey was developed to find well-preserved outcrops and lithostratigraphic sections worth to be described, sampled and compared with the Gonnesa Group successions exposed in other areas of SW Sardinia. Sedimentological data suggest during the deposition of the Lower Cambrian Gonnesa Group the Oridda was an inner area of the carbonate platform featured by supra-intertidal conditions that passed to inter-subtidal lagoonal conditions with supratidal episodes. In the topmost part of the succession possible peritidal cycles have been evidenced. Lately the platform drowned during the uppermost early Cambrian, as marked by the covering Campo Pisano Fm. A comparison of the Gonnesa Group Oridda lithostratigraphic succession was attempted with close areas. The results delineate the evolution of the carbonate sedimentation in this extreme NE area of the early Cambrian platform.